1 //===- AddressSanitizer.cpp - memory error detector -----------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file is a part of AddressSanitizer, an address sanity checker.
10 // Details of the algorithm:
11 // https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/DepthFirstIterator.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/Statistic.h"
22 #include "llvm/ADT/StringExtras.h"
23 #include "llvm/ADT/StringRef.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/ADT/Twine.h"
26 #include "llvm/Analysis/MemoryBuiltins.h"
27 #include "llvm/Analysis/TargetLibraryInfo.h"
28 #include "llvm/Analysis/ValueTracking.h"
29 #include "llvm/BinaryFormat/MachO.h"
30 #include "llvm/IR/Argument.h"
31 #include "llvm/IR/Attributes.h"
32 #include "llvm/IR/BasicBlock.h"
33 #include "llvm/IR/CallSite.h"
34 #include "llvm/IR/Comdat.h"
35 #include "llvm/IR/Constant.h"
36 #include "llvm/IR/Constants.h"
37 #include "llvm/IR/DIBuilder.h"
38 #include "llvm/IR/DataLayout.h"
39 #include "llvm/IR/DebugInfoMetadata.h"
40 #include "llvm/IR/DebugLoc.h"
41 #include "llvm/IR/DerivedTypes.h"
42 #include "llvm/IR/Dominators.h"
43 #include "llvm/IR/Function.h"
44 #include "llvm/IR/GlobalAlias.h"
45 #include "llvm/IR/GlobalValue.h"
46 #include "llvm/IR/GlobalVariable.h"
47 #include "llvm/IR/IRBuilder.h"
48 #include "llvm/IR/InlineAsm.h"
49 #include "llvm/IR/InstVisitor.h"
50 #include "llvm/IR/InstrTypes.h"
51 #include "llvm/IR/Instruction.h"
52 #include "llvm/IR/Instructions.h"
53 #include "llvm/IR/IntrinsicInst.h"
54 #include "llvm/IR/Intrinsics.h"
55 #include "llvm/IR/LLVMContext.h"
56 #include "llvm/IR/MDBuilder.h"
57 #include "llvm/IR/Metadata.h"
58 #include "llvm/IR/Module.h"
59 #include "llvm/IR/Type.h"
60 #include "llvm/IR/Use.h"
61 #include "llvm/IR/Value.h"
62 #include "llvm/MC/MCSectionMachO.h"
63 #include "llvm/Pass.h"
64 #include "llvm/Support/Casting.h"
65 #include "llvm/Support/CommandLine.h"
66 #include "llvm/Support/Debug.h"
67 #include "llvm/Support/ErrorHandling.h"
68 #include "llvm/Support/MathExtras.h"
69 #include "llvm/Support/ScopedPrinter.h"
70 #include "llvm/Support/raw_ostream.h"
71 #include "llvm/Transforms/Instrumentation.h"
72 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
73 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
74 #include "llvm/Transforms/Utils/Local.h"
75 #include "llvm/Transforms/Utils/ModuleUtils.h"
76 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
90 #define DEBUG_TYPE "asan"
92 static const uint64_t kDefaultShadowScale = 3;
93 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
94 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
95 static const uint64_t kDynamicShadowSentinel =
96 std::numeric_limits<uint64_t>::max();
97 static const uint64_t kSmallX86_64ShadowOffsetBase = 0x7FFFFFFF; // < 2G.
98 static const uint64_t kSmallX86_64ShadowOffsetAlignMask = ~0xFFFULL;
99 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
100 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 44;
101 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
102 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
103 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
104 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
105 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
106 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
107 static const uint64_t kNetBSD_ShadowOffset32 = 1ULL << 30;
108 static const uint64_t kNetBSD_ShadowOffset64 = 1ULL << 46;
109 static const uint64_t kNetBSDKasan_ShadowOffset64 = 0xdfff900000000000;
110 static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;
111 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
112 static const uint64_t kEmscriptenShadowOffset = 0;
114 static const uint64_t kMyriadShadowScale = 5;
115 static const uint64_t kMyriadMemoryOffset32 = 0x80000000ULL;
116 static const uint64_t kMyriadMemorySize32 = 0x20000000ULL;
117 static const uint64_t kMyriadTagShift = 29;
118 static const uint64_t kMyriadDDRTag = 4;
119 static const uint64_t kMyriadCacheBitMask32 = 0x40000000ULL;
121 // The shadow memory space is dynamically allocated.
122 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
124 static const size_t kMinStackMallocSize = 1 << 6; // 64B
125 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
126 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
127 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
129 static const char *const kAsanModuleCtorName = "asan.module_ctor";
130 static const char *const kAsanModuleDtorName = "asan.module_dtor";
131 static const uint64_t kAsanCtorAndDtorPriority = 1;
132 static const char *const kAsanReportErrorTemplate = "__asan_report_";
133 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
134 static const char *const kAsanUnregisterGlobalsName =
135 "__asan_unregister_globals";
136 static const char *const kAsanRegisterImageGlobalsName =
137 "__asan_register_image_globals";
138 static const char *const kAsanUnregisterImageGlobalsName =
139 "__asan_unregister_image_globals";
140 static const char *const kAsanRegisterElfGlobalsName =
141 "__asan_register_elf_globals";
142 static const char *const kAsanUnregisterElfGlobalsName =
143 "__asan_unregister_elf_globals";
144 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
145 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
146 static const char *const kAsanInitName = "__asan_init";
147 static const char *const kAsanVersionCheckNamePrefix =
148 "__asan_version_mismatch_check_v";
149 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
150 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
151 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
152 static const int kMaxAsanStackMallocSizeClass = 10;
153 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
154 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
155 static const char *const kAsanGenPrefix = "___asan_gen_";
156 static const char *const kODRGenPrefix = "__odr_asan_gen_";
157 static const char *const kSanCovGenPrefix = "__sancov_gen_";
158 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
159 static const char *const kAsanPoisonStackMemoryName =
160 "__asan_poison_stack_memory";
161 static const char *const kAsanUnpoisonStackMemoryName =
162 "__asan_unpoison_stack_memory";
164 // ASan version script has __asan_* wildcard. Triple underscore prevents a
165 // linker (gold) warning about attempting to export a local symbol.
166 static const char *const kAsanGlobalsRegisteredFlagName =
167 "___asan_globals_registered";
169 static const char *const kAsanOptionDetectUseAfterReturn =
170 "__asan_option_detect_stack_use_after_return";
172 static const char *const kAsanShadowMemoryDynamicAddress =
173 "__asan_shadow_memory_dynamic_address";
175 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
176 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
178 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
179 static const size_t kNumberOfAccessSizes = 5;
181 static const unsigned kAllocaRzSize = 32;
183 // Command-line flags.
185 static cl::opt<bool> ClEnableKasan(
186 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
187 cl::Hidden, cl::init(false));
189 static cl::opt<bool> ClRecover(
191 cl::desc("Enable recovery mode (continue-after-error)."),
192 cl::Hidden, cl::init(false));
194 // This flag may need to be replaced with -f[no-]asan-reads.
195 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
196 cl::desc("instrument read instructions"),
197 cl::Hidden, cl::init(true));
199 static cl::opt<bool> ClInstrumentWrites(
200 "asan-instrument-writes", cl::desc("instrument write instructions"),
201 cl::Hidden, cl::init(true));
203 static cl::opt<bool> ClInstrumentAtomics(
204 "asan-instrument-atomics",
205 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
208 static cl::opt<bool> ClAlwaysSlowPath(
209 "asan-always-slow-path",
210 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
213 static cl::opt<bool> ClForceDynamicShadow(
214 "asan-force-dynamic-shadow",
215 cl::desc("Load shadow address into a local variable for each function"),
216 cl::Hidden, cl::init(false));
219 ClWithIfunc("asan-with-ifunc",
220 cl::desc("Access dynamic shadow through an ifunc global on "
221 "platforms that support this"),
222 cl::Hidden, cl::init(true));
224 static cl::opt<bool> ClWithIfuncSuppressRemat(
225 "asan-with-ifunc-suppress-remat",
226 cl::desc("Suppress rematerialization of dynamic shadow address by passing "
227 "it through inline asm in prologue."),
228 cl::Hidden, cl::init(true));
230 // This flag limits the number of instructions to be instrumented
231 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
232 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
234 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
235 "asan-max-ins-per-bb", cl::init(10000),
236 cl::desc("maximal number of instructions to instrument in any given BB"),
239 // This flag may need to be replaced with -f[no]asan-stack.
240 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
241 cl::Hidden, cl::init(true));
242 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
243 "asan-max-inline-poisoning-size",
245 "Inline shadow poisoning for blocks up to the given size in bytes."),
246 cl::Hidden, cl::init(64));
248 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
249 cl::desc("Check stack-use-after-return"),
250 cl::Hidden, cl::init(true));
252 static cl::opt<bool> ClRedzoneByvalArgs("asan-redzone-byval-args",
253 cl::desc("Create redzones for byval "
254 "arguments (extra copy "
255 "required)"), cl::Hidden,
258 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
259 cl::desc("Check stack-use-after-scope"),
260 cl::Hidden, cl::init(false));
262 // This flag may need to be replaced with -f[no]asan-globals.
263 static cl::opt<bool> ClGlobals("asan-globals",
264 cl::desc("Handle global objects"), cl::Hidden,
267 static cl::opt<bool> ClInitializers("asan-initialization-order",
268 cl::desc("Handle C++ initializer order"),
269 cl::Hidden, cl::init(true));
271 static cl::opt<bool> ClInvalidPointerPairs(
272 "asan-detect-invalid-pointer-pair",
273 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
276 static cl::opt<bool> ClInvalidPointerCmp(
277 "asan-detect-invalid-pointer-cmp",
278 cl::desc("Instrument <, <=, >, >= with pointer operands"), cl::Hidden,
281 static cl::opt<bool> ClInvalidPointerSub(
282 "asan-detect-invalid-pointer-sub",
283 cl::desc("Instrument - operations with pointer operands"), cl::Hidden,
286 static cl::opt<unsigned> ClRealignStack(
287 "asan-realign-stack",
288 cl::desc("Realign stack to the value of this flag (power of two)"),
289 cl::Hidden, cl::init(32));
291 static cl::opt<int> ClInstrumentationWithCallsThreshold(
292 "asan-instrumentation-with-call-threshold",
294 "If the function being instrumented contains more than "
295 "this number of memory accesses, use callbacks instead of "
296 "inline checks (-1 means never use callbacks)."),
297 cl::Hidden, cl::init(7000));
299 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
300 "asan-memory-access-callback-prefix",
301 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
302 cl::init("__asan_"));
305 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
306 cl::desc("instrument dynamic allocas"),
307 cl::Hidden, cl::init(true));
309 static cl::opt<bool> ClSkipPromotableAllocas(
310 "asan-skip-promotable-allocas",
311 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
314 // These flags allow to change the shadow mapping.
315 // The shadow mapping looks like
316 // Shadow = (Mem >> scale) + offset
318 static cl::opt<int> ClMappingScale("asan-mapping-scale",
319 cl::desc("scale of asan shadow mapping"),
320 cl::Hidden, cl::init(0));
322 static cl::opt<uint64_t>
323 ClMappingOffset("asan-mapping-offset",
324 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"),
325 cl::Hidden, cl::init(0));
327 // Optimization flags. Not user visible, used mostly for testing
328 // and benchmarking the tool.
330 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
331 cl::Hidden, cl::init(true));
333 static cl::opt<bool> ClOptSameTemp(
334 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
335 cl::Hidden, cl::init(true));
337 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
338 cl::desc("Don't instrument scalar globals"),
339 cl::Hidden, cl::init(true));
341 static cl::opt<bool> ClOptStack(
342 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
343 cl::Hidden, cl::init(false));
345 static cl::opt<bool> ClDynamicAllocaStack(
346 "asan-stack-dynamic-alloca",
347 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
350 static cl::opt<uint32_t> ClForceExperiment(
351 "asan-force-experiment",
352 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
356 ClUsePrivateAlias("asan-use-private-alias",
357 cl::desc("Use private aliases for global variables"),
358 cl::Hidden, cl::init(false));
361 ClUseOdrIndicator("asan-use-odr-indicator",
362 cl::desc("Use odr indicators to improve ODR reporting"),
363 cl::Hidden, cl::init(false));
366 ClUseGlobalsGC("asan-globals-live-support",
367 cl::desc("Use linker features to support dead "
368 "code stripping of globals"),
369 cl::Hidden, cl::init(true));
371 // This is on by default even though there is a bug in gold:
372 // https://sourceware.org/bugzilla/show_bug.cgi?id=19002
374 ClWithComdat("asan-with-comdat",
375 cl::desc("Place ASan constructors in comdat sections"),
376 cl::Hidden, cl::init(true));
380 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
383 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
384 cl::Hidden, cl::init(0));
386 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
387 cl::desc("Debug func"));
389 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
390 cl::Hidden, cl::init(-1));
392 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
393 cl::Hidden, cl::init(-1));
395 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
396 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
397 STATISTIC(NumOptimizedAccessesToGlobalVar,
398 "Number of optimized accesses to global vars");
399 STATISTIC(NumOptimizedAccessesToStackVar,
400 "Number of optimized accesses to stack vars");
404 /// This struct defines the shadow mapping using the rule:
405 /// shadow = (mem >> Scale) ADD-or-OR Offset.
406 /// If InGlobal is true, then
407 /// extern char __asan_shadow[];
408 /// shadow = (mem >> Scale) + &__asan_shadow
409 struct ShadowMapping {
416 } // end anonymous namespace
418 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
420 bool IsAndroid = TargetTriple.isAndroid();
421 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
422 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
423 bool IsNetBSD = TargetTriple.isOSNetBSD();
424 bool IsPS4CPU = TargetTriple.isPS4CPU();
425 bool IsLinux = TargetTriple.isOSLinux();
426 bool IsPPC64 = TargetTriple.getArch() == Triple::ppc64 ||
427 TargetTriple.getArch() == Triple::ppc64le;
428 bool IsSystemZ = TargetTriple.getArch() == Triple::systemz;
429 bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
430 bool IsMIPS32 = TargetTriple.isMIPS32();
431 bool IsMIPS64 = TargetTriple.isMIPS64();
432 bool IsArmOrThumb = TargetTriple.isARM() || TargetTriple.isThumb();
433 bool IsAArch64 = TargetTriple.getArch() == Triple::aarch64;
434 bool IsWindows = TargetTriple.isOSWindows();
435 bool IsFuchsia = TargetTriple.isOSFuchsia();
436 bool IsMyriad = TargetTriple.getVendor() == llvm::Triple::Myriad;
437 bool IsEmscripten = TargetTriple.isOSEmscripten();
439 ShadowMapping Mapping;
441 Mapping.Scale = IsMyriad ? kMyriadShadowScale : kDefaultShadowScale;
442 if (ClMappingScale.getNumOccurrences() > 0) {
443 Mapping.Scale = ClMappingScale;
446 if (LongSize == 32) {
448 Mapping.Offset = kDynamicShadowSentinel;
450 Mapping.Offset = kMIPS32_ShadowOffset32;
452 Mapping.Offset = kFreeBSD_ShadowOffset32;
454 Mapping.Offset = kNetBSD_ShadowOffset32;
456 Mapping.Offset = kDynamicShadowSentinel;
458 Mapping.Offset = kWindowsShadowOffset32;
459 else if (IsEmscripten)
460 Mapping.Offset = kEmscriptenShadowOffset;
462 uint64_t ShadowOffset = (kMyriadMemoryOffset32 + kMyriadMemorySize32 -
463 (kMyriadMemorySize32 >> Mapping.Scale));
464 Mapping.Offset = ShadowOffset - (kMyriadMemoryOffset32 >> Mapping.Scale);
467 Mapping.Offset = kDefaultShadowOffset32;
468 } else { // LongSize == 64
469 // Fuchsia is always PIE, which means that the beginning of the address
470 // space is always available.
474 Mapping.Offset = kPPC64_ShadowOffset64;
476 Mapping.Offset = kSystemZ_ShadowOffset64;
477 else if (IsFreeBSD && !IsMIPS64)
478 Mapping.Offset = kFreeBSD_ShadowOffset64;
481 Mapping.Offset = kNetBSDKasan_ShadowOffset64;
483 Mapping.Offset = kNetBSD_ShadowOffset64;
485 Mapping.Offset = kPS4CPU_ShadowOffset64;
486 else if (IsLinux && IsX86_64) {
488 Mapping.Offset = kLinuxKasan_ShadowOffset64;
490 Mapping.Offset = (kSmallX86_64ShadowOffsetBase &
491 (kSmallX86_64ShadowOffsetAlignMask << Mapping.Scale));
492 } else if (IsWindows && IsX86_64) {
493 Mapping.Offset = kWindowsShadowOffset64;
495 Mapping.Offset = kMIPS64_ShadowOffset64;
497 Mapping.Offset = kDynamicShadowSentinel;
499 Mapping.Offset = kAArch64_ShadowOffset64;
501 Mapping.Offset = kDefaultShadowOffset64;
504 if (ClForceDynamicShadow) {
505 Mapping.Offset = kDynamicShadowSentinel;
508 if (ClMappingOffset.getNumOccurrences() > 0) {
509 Mapping.Offset = ClMappingOffset;
512 // OR-ing shadow offset if more efficient (at least on x86) if the offset
513 // is a power of two, but on ppc64 we have to use add since the shadow
514 // offset is not necessary 1/8-th of the address space. On SystemZ,
515 // we could OR the constant in a single instruction, but it's more
516 // efficient to load it once and use indexed addressing.
517 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
518 !(Mapping.Offset & (Mapping.Offset - 1)) &&
519 Mapping.Offset != kDynamicShadowSentinel;
520 bool IsAndroidWithIfuncSupport =
521 IsAndroid && !TargetTriple.isAndroidVersionLT(21);
522 Mapping.InGlobal = ClWithIfunc && IsAndroidWithIfuncSupport && IsArmOrThumb;
527 static size_t RedzoneSizeForScale(int MappingScale) {
528 // Redzone used for stack and globals is at least 32 bytes.
529 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
530 return std::max(32U, 1U << MappingScale);
535 /// Module analysis for getting various metadata about the module.
536 class ASanGlobalsMetadataWrapperPass : public ModulePass {
540 ASanGlobalsMetadataWrapperPass() : ModulePass(ID) {
541 initializeASanGlobalsMetadataWrapperPassPass(
542 *PassRegistry::getPassRegistry());
545 bool runOnModule(Module &M) override {
546 GlobalsMD = GlobalsMetadata(M);
550 StringRef getPassName() const override {
551 return "ASanGlobalsMetadataWrapperPass";
554 void getAnalysisUsage(AnalysisUsage &AU) const override {
555 AU.setPreservesAll();
558 GlobalsMetadata &getGlobalsMD() { return GlobalsMD; }
561 GlobalsMetadata GlobalsMD;
564 char ASanGlobalsMetadataWrapperPass::ID = 0;
566 /// AddressSanitizer: instrument the code in module to find memory bugs.
567 struct AddressSanitizer {
568 AddressSanitizer(Module &M, GlobalsMetadata &GlobalsMD,
569 bool CompileKernel = false, bool Recover = false,
570 bool UseAfterScope = false)
571 : UseAfterScope(UseAfterScope || ClUseAfterScope), GlobalsMD(GlobalsMD) {
572 this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;
573 this->CompileKernel =
574 ClEnableKasan.getNumOccurrences() > 0 ? ClEnableKasan : CompileKernel;
576 C = &(M.getContext());
577 LongSize = M.getDataLayout().getPointerSizeInBits();
578 IntptrTy = Type::getIntNTy(*C, LongSize);
579 TargetTriple = Triple(M.getTargetTriple());
581 Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
584 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
585 uint64_t ArraySize = 1;
586 if (AI.isArrayAllocation()) {
587 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
588 assert(CI && "non-constant array size");
589 ArraySize = CI->getZExtValue();
591 Type *Ty = AI.getAllocatedType();
592 uint64_t SizeInBytes =
593 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
594 return SizeInBytes * ArraySize;
597 /// Check if we want (and can) handle this alloca.
598 bool isInterestingAlloca(const AllocaInst &AI);
600 /// If it is an interesting memory access, return the PointerOperand
601 /// and set IsWrite/Alignment. Otherwise return nullptr.
602 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
603 /// masked load/store.
604 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
605 uint64_t *TypeSize, unsigned *Alignment,
606 Value **MaybeMask = nullptr);
608 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
609 bool UseCalls, const DataLayout &DL);
610 void instrumentPointerComparisonOrSubtraction(Instruction *I);
611 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
612 Value *Addr, uint32_t TypeSize, bool IsWrite,
613 Value *SizeArgument, bool UseCalls, uint32_t Exp);
614 void instrumentUnusualSizeOrAlignment(Instruction *I,
615 Instruction *InsertBefore, Value *Addr,
616 uint32_t TypeSize, bool IsWrite,
617 Value *SizeArgument, bool UseCalls,
619 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
620 Value *ShadowValue, uint32_t TypeSize);
621 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
622 bool IsWrite, size_t AccessSizeIndex,
623 Value *SizeArgument, uint32_t Exp);
624 void instrumentMemIntrinsic(MemIntrinsic *MI);
625 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
626 bool instrumentFunction(Function &F, const TargetLibraryInfo *TLI);
627 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
628 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
629 void markEscapedLocalAllocas(Function &F);
632 friend struct FunctionStackPoisoner;
634 void initializeCallbacks(Module &M);
636 bool LooksLikeCodeInBug11395(Instruction *I);
637 bool GlobalIsLinkerInitialized(GlobalVariable *G);
638 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
639 uint64_t TypeSize) const;
641 /// Helper to cleanup per-function state.
642 struct FunctionStateRAII {
643 AddressSanitizer *Pass;
645 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
646 assert(Pass->ProcessedAllocas.empty() &&
647 "last pass forgot to clear cache");
648 assert(!Pass->LocalDynamicShadow);
651 ~FunctionStateRAII() {
652 Pass->LocalDynamicShadow = nullptr;
653 Pass->ProcessedAllocas.clear();
664 ShadowMapping Mapping;
665 FunctionCallee AsanHandleNoReturnFunc;
666 FunctionCallee AsanPtrCmpFunction, AsanPtrSubFunction;
667 Constant *AsanShadowGlobal;
669 // These arrays is indexed by AccessIsWrite, Experiment and log2(AccessSize).
670 FunctionCallee AsanErrorCallback[2][2][kNumberOfAccessSizes];
671 FunctionCallee AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
673 // These arrays is indexed by AccessIsWrite and Experiment.
674 FunctionCallee AsanErrorCallbackSized[2][2];
675 FunctionCallee AsanMemoryAccessCallbackSized[2][2];
677 FunctionCallee AsanMemmove, AsanMemcpy, AsanMemset;
679 Value *LocalDynamicShadow = nullptr;
680 GlobalsMetadata GlobalsMD;
681 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
684 class AddressSanitizerLegacyPass : public FunctionPass {
688 explicit AddressSanitizerLegacyPass(bool CompileKernel = false,
689 bool Recover = false,
690 bool UseAfterScope = false)
691 : FunctionPass(ID), CompileKernel(CompileKernel), Recover(Recover),
692 UseAfterScope(UseAfterScope) {
693 initializeAddressSanitizerLegacyPassPass(*PassRegistry::getPassRegistry());
696 StringRef getPassName() const override {
697 return "AddressSanitizerFunctionPass";
700 void getAnalysisUsage(AnalysisUsage &AU) const override {
701 AU.addRequired<ASanGlobalsMetadataWrapperPass>();
702 AU.addRequired<TargetLibraryInfoWrapperPass>();
705 bool runOnFunction(Function &F) override {
706 GlobalsMetadata &GlobalsMD =
707 getAnalysis<ASanGlobalsMetadataWrapperPass>().getGlobalsMD();
708 const TargetLibraryInfo *TLI =
709 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
710 AddressSanitizer ASan(*F.getParent(), GlobalsMD, CompileKernel, Recover,
712 return ASan.instrumentFunction(F, TLI);
721 class ModuleAddressSanitizer {
723 ModuleAddressSanitizer(Module &M, GlobalsMetadata &GlobalsMD,
724 bool CompileKernel = false, bool Recover = false,
725 bool UseGlobalsGC = true, bool UseOdrIndicator = false)
726 : GlobalsMD(GlobalsMD), UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC),
727 // Enable aliases as they should have no downside with ODR indicators.
728 UsePrivateAlias(UseOdrIndicator || ClUsePrivateAlias),
729 UseOdrIndicator(UseOdrIndicator || ClUseOdrIndicator),
730 // Not a typo: ClWithComdat is almost completely pointless without
731 // ClUseGlobalsGC (because then it only works on modules without
732 // globals, which are rare); it is a prerequisite for ClUseGlobalsGC;
733 // and both suffer from gold PR19002 for which UseGlobalsGC constructor
734 // argument is designed as workaround. Therefore, disable both
735 // ClWithComdat and ClUseGlobalsGC unless the frontend says it's ok to
737 UseCtorComdat(UseGlobalsGC && ClWithComdat) {
738 this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;
739 this->CompileKernel =
740 ClEnableKasan.getNumOccurrences() > 0 ? ClEnableKasan : CompileKernel;
742 C = &(M.getContext());
743 int LongSize = M.getDataLayout().getPointerSizeInBits();
744 IntptrTy = Type::getIntNTy(*C, LongSize);
745 TargetTriple = Triple(M.getTargetTriple());
746 Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
749 bool instrumentModule(Module &);
752 void initializeCallbacks(Module &M);
754 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat);
755 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
756 ArrayRef<GlobalVariable *> ExtendedGlobals,
757 ArrayRef<Constant *> MetadataInitializers);
758 void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
759 ArrayRef<GlobalVariable *> ExtendedGlobals,
760 ArrayRef<Constant *> MetadataInitializers,
761 const std::string &UniqueModuleId);
762 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
763 ArrayRef<GlobalVariable *> ExtendedGlobals,
764 ArrayRef<Constant *> MetadataInitializers);
766 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
767 ArrayRef<GlobalVariable *> ExtendedGlobals,
768 ArrayRef<Constant *> MetadataInitializers);
770 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
771 StringRef OriginalName);
772 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
773 StringRef InternalSuffix);
774 IRBuilder<> CreateAsanModuleDtor(Module &M);
776 bool ShouldInstrumentGlobal(GlobalVariable *G);
777 bool ShouldUseMachOGlobalsSection() const;
778 StringRef getGlobalMetadataSection() const;
779 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
780 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
781 size_t MinRedzoneSizeForGlobal() const {
782 return RedzoneSizeForScale(Mapping.Scale);
784 int GetAsanVersion(const Module &M) const;
786 GlobalsMetadata GlobalsMD;
790 bool UsePrivateAlias;
791 bool UseOdrIndicator;
796 ShadowMapping Mapping;
797 FunctionCallee AsanPoisonGlobals;
798 FunctionCallee AsanUnpoisonGlobals;
799 FunctionCallee AsanRegisterGlobals;
800 FunctionCallee AsanUnregisterGlobals;
801 FunctionCallee AsanRegisterImageGlobals;
802 FunctionCallee AsanUnregisterImageGlobals;
803 FunctionCallee AsanRegisterElfGlobals;
804 FunctionCallee AsanUnregisterElfGlobals;
806 Function *AsanCtorFunction = nullptr;
807 Function *AsanDtorFunction = nullptr;
810 class ModuleAddressSanitizerLegacyPass : public ModulePass {
814 explicit ModuleAddressSanitizerLegacyPass(bool CompileKernel = false,
815 bool Recover = false,
816 bool UseGlobalGC = true,
817 bool UseOdrIndicator = false)
818 : ModulePass(ID), CompileKernel(CompileKernel), Recover(Recover),
819 UseGlobalGC(UseGlobalGC), UseOdrIndicator(UseOdrIndicator) {
820 initializeModuleAddressSanitizerLegacyPassPass(
821 *PassRegistry::getPassRegistry());
824 StringRef getPassName() const override { return "ModuleAddressSanitizer"; }
826 void getAnalysisUsage(AnalysisUsage &AU) const override {
827 AU.addRequired<ASanGlobalsMetadataWrapperPass>();
830 bool runOnModule(Module &M) override {
831 GlobalsMetadata &GlobalsMD =
832 getAnalysis<ASanGlobalsMetadataWrapperPass>().getGlobalsMD();
833 ModuleAddressSanitizer ASanModule(M, GlobalsMD, CompileKernel, Recover,
834 UseGlobalGC, UseOdrIndicator);
835 return ASanModule.instrumentModule(M);
842 bool UseOdrIndicator;
845 // Stack poisoning does not play well with exception handling.
846 // When an exception is thrown, we essentially bypass the code
847 // that unpoisones the stack. This is why the run-time library has
848 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
849 // stack in the interceptor. This however does not work inside the
850 // actual function which catches the exception. Most likely because the
851 // compiler hoists the load of the shadow value somewhere too high.
852 // This causes asan to report a non-existing bug on 453.povray.
853 // It sounds like an LLVM bug.
854 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
856 AddressSanitizer &ASan;
861 ShadowMapping Mapping;
863 SmallVector<AllocaInst *, 16> AllocaVec;
864 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
865 SmallVector<Instruction *, 8> RetVec;
866 unsigned StackAlignment;
868 FunctionCallee AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
869 AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
870 FunctionCallee AsanSetShadowFunc[0x100] = {};
871 FunctionCallee AsanPoisonStackMemoryFunc, AsanUnpoisonStackMemoryFunc;
872 FunctionCallee AsanAllocaPoisonFunc, AsanAllocasUnpoisonFunc;
874 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
875 struct AllocaPoisonCall {
876 IntrinsicInst *InsBefore;
881 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
882 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
883 bool HasUntracedLifetimeIntrinsic = false;
885 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
886 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
887 AllocaInst *DynamicAllocaLayout = nullptr;
888 IntrinsicInst *LocalEscapeCall = nullptr;
890 // Maps Value to an AllocaInst from which the Value is originated.
891 using AllocaForValueMapTy = DenseMap<Value *, AllocaInst *>;
892 AllocaForValueMapTy AllocaForValue;
894 bool HasNonEmptyInlineAsm = false;
895 bool HasReturnsTwiceCall = false;
896 std::unique_ptr<CallInst> EmptyInlineAsm;
898 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
899 : F(F), ASan(ASan), DIB(*F.getParent(), /*AllowUnresolved*/ false),
900 C(ASan.C), IntptrTy(ASan.IntptrTy),
901 IntptrPtrTy(PointerType::get(IntptrTy, 0)), Mapping(ASan.Mapping),
902 StackAlignment(1 << Mapping.Scale),
903 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
905 bool runOnFunction() {
906 if (!ClStack) return false;
908 if (ClRedzoneByvalArgs)
909 copyArgsPassedByValToAllocas();
911 // Collect alloca, ret, lifetime instructions etc.
912 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
914 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
916 initializeCallbacks(*F.getParent());
918 if (HasUntracedLifetimeIntrinsic) {
919 // If there are lifetime intrinsics which couldn't be traced back to an
920 // alloca, we may not know exactly when a variable enters scope, and
921 // therefore should "fail safe" by not poisoning them.
922 StaticAllocaPoisonCallVec.clear();
923 DynamicAllocaPoisonCallVec.clear();
926 processDynamicAllocas();
927 processStaticAllocas();
930 LLVM_DEBUG(dbgs() << F);
935 // Arguments marked with the "byval" attribute are implicitly copied without
936 // using an alloca instruction. To produce redzones for those arguments, we
937 // copy them a second time into memory allocated with an alloca instruction.
938 void copyArgsPassedByValToAllocas();
940 // Finds all Alloca instructions and puts
941 // poisoned red zones around all of them.
942 // Then unpoison everything back before the function returns.
943 void processStaticAllocas();
944 void processDynamicAllocas();
946 void createDynamicAllocasInitStorage();
948 // ----------------------- Visitors.
949 /// Collect all Ret instructions.
950 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
952 /// Collect all Resume instructions.
953 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
955 /// Collect all CatchReturnInst instructions.
956 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
958 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
960 IRBuilder<> IRB(InstBefore);
961 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
962 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
963 // need to adjust extracted SP to compute the address of the most recent
964 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
966 if (!isa<ReturnInst>(InstBefore)) {
967 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
968 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
971 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
973 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
978 AsanAllocasUnpoisonFunc,
979 {IRB.CreateLoad(IntptrTy, DynamicAllocaLayout), DynamicAreaPtr});
982 // Unpoison dynamic allocas redzones.
983 void unpoisonDynamicAllocas() {
984 for (auto &Ret : RetVec)
985 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
987 for (auto &StackRestoreInst : StackRestoreVec)
988 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
989 StackRestoreInst->getOperand(0));
992 // Deploy and poison redzones around dynamic alloca call. To do this, we
993 // should replace this call with another one with changed parameters and
994 // replace all its uses with new address, so
995 // addr = alloca type, old_size, align
997 // new_size = (old_size + additional_size) * sizeof(type)
998 // tmp = alloca i8, new_size, max(align, 32)
999 // addr = tmp + 32 (first 32 bytes are for the left redzone).
1000 // Additional_size is added to make new memory allocation contain not only
1001 // requested memory, but also left, partial and right redzones.
1002 void handleDynamicAllocaCall(AllocaInst *AI);
1004 /// Collect Alloca instructions we want (and can) handle.
1005 void visitAllocaInst(AllocaInst &AI) {
1006 if (!ASan.isInterestingAlloca(AI)) {
1007 if (AI.isStaticAlloca()) {
1008 // Skip over allocas that are present *before* the first instrumented
1009 // alloca, we don't want to move those around.
1010 if (AllocaVec.empty())
1013 StaticAllocasToMoveUp.push_back(&AI);
1018 StackAlignment = std::max(StackAlignment, AI.getAlignment());
1019 if (!AI.isStaticAlloca())
1020 DynamicAllocaVec.push_back(&AI);
1022 AllocaVec.push_back(&AI);
1025 /// Collect lifetime intrinsic calls to check for use-after-scope
1027 void visitIntrinsicInst(IntrinsicInst &II) {
1028 Intrinsic::ID ID = II.getIntrinsicID();
1029 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
1030 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
1031 if (!ASan.UseAfterScope)
1033 if (!II.isLifetimeStartOrEnd())
1035 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1036 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
1037 // If size argument is undefined, don't do anything.
1038 if (Size->isMinusOne()) return;
1039 // Check that size doesn't saturate uint64_t and can
1040 // be stored in IntptrTy.
1041 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1042 if (SizeValue == ~0ULL ||
1043 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
1045 // Find alloca instruction that corresponds to llvm.lifetime argument.
1047 llvm::findAllocaForValue(II.getArgOperand(1), AllocaForValue);
1049 HasUntracedLifetimeIntrinsic = true;
1052 // We're interested only in allocas we can handle.
1053 if (!ASan.isInterestingAlloca(*AI))
1055 bool DoPoison = (ID == Intrinsic::lifetime_end);
1056 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
1057 if (AI->isStaticAlloca())
1058 StaticAllocaPoisonCallVec.push_back(APC);
1059 else if (ClInstrumentDynamicAllocas)
1060 DynamicAllocaPoisonCallVec.push_back(APC);
1063 void visitCallSite(CallSite CS) {
1064 Instruction *I = CS.getInstruction();
1065 if (CallInst *CI = dyn_cast<CallInst>(I)) {
1066 HasNonEmptyInlineAsm |= CI->isInlineAsm() &&
1067 !CI->isIdenticalTo(EmptyInlineAsm.get()) &&
1068 I != ASan.LocalDynamicShadow;
1069 HasReturnsTwiceCall |= CI->canReturnTwice();
1073 // ---------------------- Helpers.
1074 void initializeCallbacks(Module &M);
1076 // Copies bytes from ShadowBytes into shadow memory for indexes where
1077 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
1078 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
1079 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
1080 IRBuilder<> &IRB, Value *ShadowBase);
1081 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
1082 size_t Begin, size_t End, IRBuilder<> &IRB,
1084 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
1085 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
1086 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
1088 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
1090 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
1092 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
1093 Instruction *ThenTerm, Value *ValueIfFalse);
1096 } // end anonymous namespace
1098 void LocationMetadata::parse(MDNode *MDN) {
1099 assert(MDN->getNumOperands() == 3);
1100 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
1101 Filename = DIFilename->getString();
1102 LineNo = mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
1104 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
1107 // FIXME: It would be cleaner to instead attach relevant metadata to the globals
1108 // we want to sanitize instead and reading this metadata on each pass over a
1109 // function instead of reading module level metadata at first.
1110 GlobalsMetadata::GlobalsMetadata(Module &M) {
1111 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
1114 for (auto MDN : Globals->operands()) {
1115 // Metadata node contains the global and the fields of "Entry".
1116 assert(MDN->getNumOperands() == 5);
1117 auto *V = mdconst::extract_or_null<Constant>(MDN->getOperand(0));
1118 // The optimizer may optimize away a global entirely.
1121 auto *StrippedV = V->stripPointerCasts();
1122 auto *GV = dyn_cast<GlobalVariable>(StrippedV);
1125 // We can already have an entry for GV if it was merged with another
1127 Entry &E = Entries[GV];
1128 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
1129 E.SourceLoc.parse(Loc);
1130 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
1131 E.Name = Name->getString();
1132 ConstantInt *IsDynInit = mdconst::extract<ConstantInt>(MDN->getOperand(3));
1133 E.IsDynInit |= IsDynInit->isOne();
1134 ConstantInt *IsBlacklisted =
1135 mdconst::extract<ConstantInt>(MDN->getOperand(4));
1136 E.IsBlacklisted |= IsBlacklisted->isOne();
1140 AnalysisKey ASanGlobalsMetadataAnalysis::Key;
1142 GlobalsMetadata ASanGlobalsMetadataAnalysis::run(Module &M,
1143 ModuleAnalysisManager &AM) {
1144 return GlobalsMetadata(M);
1147 AddressSanitizerPass::AddressSanitizerPass(bool CompileKernel, bool Recover,
1149 : CompileKernel(CompileKernel), Recover(Recover),
1150 UseAfterScope(UseAfterScope) {}
1152 PreservedAnalyses AddressSanitizerPass::run(Function &F,
1153 AnalysisManager<Function> &AM) {
1154 auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
1155 auto &MAM = MAMProxy.getManager();
1156 Module &M = *F.getParent();
1157 if (auto *R = MAM.getCachedResult<ASanGlobalsMetadataAnalysis>(M)) {
1158 const TargetLibraryInfo *TLI = &AM.getResult<TargetLibraryAnalysis>(F);
1159 AddressSanitizer Sanitizer(M, *R, CompileKernel, Recover, UseAfterScope);
1160 if (Sanitizer.instrumentFunction(F, TLI))
1161 return PreservedAnalyses::none();
1162 return PreservedAnalyses::all();
1166 "The ASanGlobalsMetadataAnalysis is required to run before "
1167 "AddressSanitizer can run");
1168 return PreservedAnalyses::all();
1171 ModuleAddressSanitizerPass::ModuleAddressSanitizerPass(bool CompileKernel,
1174 bool UseOdrIndicator)
1175 : CompileKernel(CompileKernel), Recover(Recover), UseGlobalGC(UseGlobalGC),
1176 UseOdrIndicator(UseOdrIndicator) {}
1178 PreservedAnalyses ModuleAddressSanitizerPass::run(Module &M,
1179 AnalysisManager<Module> &AM) {
1180 GlobalsMetadata &GlobalsMD = AM.getResult<ASanGlobalsMetadataAnalysis>(M);
1181 ModuleAddressSanitizer Sanitizer(M, GlobalsMD, CompileKernel, Recover,
1182 UseGlobalGC, UseOdrIndicator);
1183 if (Sanitizer.instrumentModule(M))
1184 return PreservedAnalyses::none();
1185 return PreservedAnalyses::all();
1188 INITIALIZE_PASS(ASanGlobalsMetadataWrapperPass, "asan-globals-md",
1189 "Read metadata to mark which globals should be instrumented "
1190 "when running ASan.",
1193 char AddressSanitizerLegacyPass::ID = 0;
1195 INITIALIZE_PASS_BEGIN(
1196 AddressSanitizerLegacyPass, "asan",
1197 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
1199 INITIALIZE_PASS_DEPENDENCY(ASanGlobalsMetadataWrapperPass)
1200 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
1201 INITIALIZE_PASS_END(
1202 AddressSanitizerLegacyPass, "asan",
1203 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
1206 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
1208 bool UseAfterScope) {
1209 assert(!CompileKernel || Recover);
1210 return new AddressSanitizerLegacyPass(CompileKernel, Recover, UseAfterScope);
1213 char ModuleAddressSanitizerLegacyPass::ID = 0;
1216 ModuleAddressSanitizerLegacyPass, "asan-module",
1217 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
1221 ModulePass *llvm::createModuleAddressSanitizerLegacyPassPass(
1222 bool CompileKernel, bool Recover, bool UseGlobalsGC, bool UseOdrIndicator) {
1223 assert(!CompileKernel || Recover);
1224 return new ModuleAddressSanitizerLegacyPass(CompileKernel, Recover,
1225 UseGlobalsGC, UseOdrIndicator);
1228 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
1229 size_t Res = countTrailingZeros(TypeSize / 8);
1230 assert(Res < kNumberOfAccessSizes);
1234 /// Create a global describing a source location.
1235 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
1236 LocationMetadata MD) {
1237 Constant *LocData[] = {
1238 createPrivateGlobalForString(M, MD.Filename, true, kAsanGenPrefix),
1239 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
1240 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
1242 auto LocStruct = ConstantStruct::getAnon(LocData);
1243 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
1244 GlobalValue::PrivateLinkage, LocStruct,
1246 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
1250 /// Check if \p G has been created by a trusted compiler pass.
1251 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
1252 // Do not instrument @llvm.global_ctors, @llvm.used, etc.
1253 if (G->getName().startswith("llvm."))
1256 // Do not instrument asan globals.
1257 if (G->getName().startswith(kAsanGenPrefix) ||
1258 G->getName().startswith(kSanCovGenPrefix) ||
1259 G->getName().startswith(kODRGenPrefix))
1262 // Do not instrument gcov counter arrays.
1263 if (G->getName() == "__llvm_gcov_ctr")
1269 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
1271 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
1272 if (Mapping.Offset == 0) return Shadow;
1273 // (Shadow >> scale) | offset
1275 if (LocalDynamicShadow)
1276 ShadowBase = LocalDynamicShadow;
1278 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
1279 if (Mapping.OrShadowOffset)
1280 return IRB.CreateOr(Shadow, ShadowBase);
1282 return IRB.CreateAdd(Shadow, ShadowBase);
1285 // Instrument memset/memmove/memcpy
1286 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
1287 IRBuilder<> IRB(MI);
1288 if (isa<MemTransferInst>(MI)) {
1290 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
1291 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1292 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
1293 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1294 } else if (isa<MemSetInst>(MI)) {
1297 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1298 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
1299 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1301 MI->eraseFromParent();
1304 /// Check if we want (and can) handle this alloca.
1305 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1306 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1308 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1309 return PreviouslySeenAllocaInfo->getSecond();
1311 bool IsInteresting =
1312 (AI.getAllocatedType()->isSized() &&
1313 // alloca() may be called with 0 size, ignore it.
1314 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1315 // We are only interested in allocas not promotable to registers.
1316 // Promotable allocas are common under -O0.
1317 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1318 // inalloca allocas are not treated as static, and we don't want
1319 // dynamic alloca instrumentation for them as well.
1320 !AI.isUsedWithInAlloca() &&
1321 // swifterror allocas are register promoted by ISel
1322 !AI.isSwiftError());
1324 ProcessedAllocas[&AI] = IsInteresting;
1325 return IsInteresting;
1328 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1331 unsigned *Alignment,
1332 Value **MaybeMask) {
1333 // Skip memory accesses inserted by another instrumentation.
1334 if (I->getMetadata("nosanitize")) return nullptr;
1336 // Do not instrument the load fetching the dynamic shadow address.
1337 if (LocalDynamicShadow == I)
1340 Value *PtrOperand = nullptr;
1341 const DataLayout &DL = I->getModule()->getDataLayout();
1342 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1343 if (!ClInstrumentReads) return nullptr;
1345 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1346 *Alignment = LI->getAlignment();
1347 PtrOperand = LI->getPointerOperand();
1348 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1349 if (!ClInstrumentWrites) return nullptr;
1351 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1352 *Alignment = SI->getAlignment();
1353 PtrOperand = SI->getPointerOperand();
1354 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1355 if (!ClInstrumentAtomics) return nullptr;
1357 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1359 PtrOperand = RMW->getPointerOperand();
1360 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1361 if (!ClInstrumentAtomics) return nullptr;
1363 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1365 PtrOperand = XCHG->getPointerOperand();
1366 } else if (auto CI = dyn_cast<CallInst>(I)) {
1367 auto *F = dyn_cast<Function>(CI->getCalledValue());
1368 if (F && (F->getName().startswith("llvm.masked.load.") ||
1369 F->getName().startswith("llvm.masked.store."))) {
1370 unsigned OpOffset = 0;
1371 if (F->getName().startswith("llvm.masked.store.")) {
1372 if (!ClInstrumentWrites)
1374 // Masked store has an initial operand for the value.
1378 if (!ClInstrumentReads)
1383 auto BasePtr = CI->getOperand(0 + OpOffset);
1384 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1385 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1386 if (auto AlignmentConstant =
1387 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1388 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1390 *Alignment = 1; // No alignment guarantees. We probably got Undef
1392 *MaybeMask = CI->getOperand(2 + OpOffset);
1393 PtrOperand = BasePtr;
1398 // Do not instrument acesses from different address spaces; we cannot deal
1400 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1401 if (PtrTy->getPointerAddressSpace() != 0)
1404 // Ignore swifterror addresses.
1405 // swifterror memory addresses are mem2reg promoted by instruction
1406 // selection. As such they cannot have regular uses like an instrumentation
1407 // function and it makes no sense to track them as memory.
1408 if (PtrOperand->isSwiftError())
1412 // Treat memory accesses to promotable allocas as non-interesting since they
1413 // will not cause memory violations. This greatly speeds up the instrumented
1414 // executable at -O0.
1415 if (ClSkipPromotableAllocas)
1416 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1417 return isInterestingAlloca(*AI) ? AI : nullptr;
1422 static bool isPointerOperand(Value *V) {
1423 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1426 // This is a rough heuristic; it may cause both false positives and
1427 // false negatives. The proper implementation requires cooperation with
1429 static bool isInterestingPointerComparison(Instruction *I) {
1430 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1431 if (!Cmp->isRelational())
1436 return isPointerOperand(I->getOperand(0)) &&
1437 isPointerOperand(I->getOperand(1));
1440 // This is a rough heuristic; it may cause both false positives and
1441 // false negatives. The proper implementation requires cooperation with
1443 static bool isInterestingPointerSubtraction(Instruction *I) {
1444 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1445 if (BO->getOpcode() != Instruction::Sub)
1450 return isPointerOperand(I->getOperand(0)) &&
1451 isPointerOperand(I->getOperand(1));
1454 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1455 // If a global variable does not have dynamic initialization we don't
1456 // have to instrument it. However, if a global does not have initializer
1457 // at all, we assume it has dynamic initializer (in other TU).
1459 // FIXME: Metadata should be attched directly to the global directly instead
1460 // of being added to llvm.asan.globals.
1461 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1464 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1467 FunctionCallee F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1468 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1469 for (Value *&i : Param) {
1470 if (i->getType()->isPointerTy())
1471 i = IRB.CreatePointerCast(i, IntptrTy);
1473 IRB.CreateCall(F, Param);
1476 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1477 Instruction *InsertBefore, Value *Addr,
1478 unsigned Alignment, unsigned Granularity,
1479 uint32_t TypeSize, bool IsWrite,
1480 Value *SizeArgument, bool UseCalls,
1482 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1483 // if the data is properly aligned.
1484 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1486 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1487 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1488 nullptr, UseCalls, Exp);
1489 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1490 IsWrite, nullptr, UseCalls, Exp);
1493 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1494 const DataLayout &DL, Type *IntptrTy,
1495 Value *Mask, Instruction *I,
1496 Value *Addr, unsigned Alignment,
1497 unsigned Granularity, uint32_t TypeSize,
1498 bool IsWrite, Value *SizeArgument,
1499 bool UseCalls, uint32_t Exp) {
1500 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1501 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1502 unsigned Num = VTy->getVectorNumElements();
1503 auto Zero = ConstantInt::get(IntptrTy, 0);
1504 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1505 Value *InstrumentedAddress = nullptr;
1506 Instruction *InsertBefore = I;
1507 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1508 // dyn_cast as we might get UndefValue
1509 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1510 if (Masked->isZero())
1511 // Mask is constant false, so no instrumentation needed.
1513 // If we have a true or undef value, fall through to doInstrumentAddress
1514 // with InsertBefore == I
1518 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1519 Instruction *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1520 InsertBefore = ThenTerm;
1523 IRBuilder<> IRB(InsertBefore);
1524 InstrumentedAddress =
1525 IRB.CreateGEP(VTy, Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1526 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1527 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1532 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1533 Instruction *I, bool UseCalls,
1534 const DataLayout &DL) {
1535 bool IsWrite = false;
1536 unsigned Alignment = 0;
1537 uint64_t TypeSize = 0;
1538 Value *MaybeMask = nullptr;
1540 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1543 // Optimization experiments.
1544 // The experiments can be used to evaluate potential optimizations that remove
1545 // instrumentation (assess false negatives). Instead of completely removing
1546 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1547 // experiments that want to remove instrumentation of this instruction).
1548 // If Exp is non-zero, this pass will emit special calls into runtime
1549 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1550 // make runtime terminate the program in a special way (with a different
1551 // exit status). Then you run the new compiler on a buggy corpus, collect
1552 // the special terminations (ideally, you don't see them at all -- no false
1553 // negatives) and make the decision on the optimization.
1554 uint32_t Exp = ClForceExperiment;
1556 if (ClOpt && ClOptGlobals) {
1557 // If initialization order checking is disabled, a simple access to a
1558 // dynamically initialized global is always valid.
1559 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1560 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1561 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1562 NumOptimizedAccessesToGlobalVar++;
1567 if (ClOpt && ClOptStack) {
1568 // A direct inbounds access to a stack variable is always valid.
1569 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1570 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1571 NumOptimizedAccessesToStackVar++;
1577 NumInstrumentedWrites++;
1579 NumInstrumentedReads++;
1581 unsigned Granularity = 1 << Mapping.Scale;
1583 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1584 Alignment, Granularity, TypeSize, IsWrite,
1585 nullptr, UseCalls, Exp);
1587 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1588 IsWrite, nullptr, UseCalls, Exp);
1592 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1593 Value *Addr, bool IsWrite,
1594 size_t AccessSizeIndex,
1595 Value *SizeArgument,
1597 IRBuilder<> IRB(InsertBefore);
1598 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1599 CallInst *Call = nullptr;
1602 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1603 {Addr, SizeArgument});
1605 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1606 {Addr, SizeArgument, ExpVal});
1610 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1612 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1616 // We don't do Call->setDoesNotReturn() because the BB already has
1617 // UnreachableInst at the end.
1618 // This EmptyAsm is required to avoid callback merge.
1619 IRB.CreateCall(EmptyAsm, {});
1623 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1625 uint32_t TypeSize) {
1626 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1627 // Addr & (Granularity - 1)
1628 Value *LastAccessedByte =
1629 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1630 // (Addr & (Granularity - 1)) + size - 1
1631 if (TypeSize / 8 > 1)
1632 LastAccessedByte = IRB.CreateAdd(
1633 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1634 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1636 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1637 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1638 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1641 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1642 Instruction *InsertBefore, Value *Addr,
1643 uint32_t TypeSize, bool IsWrite,
1644 Value *SizeArgument, bool UseCalls,
1646 bool IsMyriad = TargetTriple.getVendor() == llvm::Triple::Myriad;
1648 IRBuilder<> IRB(InsertBefore);
1649 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1650 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1654 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1657 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1658 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1663 // Strip the cache bit and do range check.
1664 // AddrLong &= ~kMyriadCacheBitMask32
1665 AddrLong = IRB.CreateAnd(AddrLong, ~kMyriadCacheBitMask32);
1666 // Tag = AddrLong >> kMyriadTagShift
1667 Value *Tag = IRB.CreateLShr(AddrLong, kMyriadTagShift);
1668 // Tag == kMyriadDDRTag
1670 IRB.CreateICmpEQ(Tag, ConstantInt::get(IntptrTy, kMyriadDDRTag));
1672 Instruction *TagCheckTerm =
1673 SplitBlockAndInsertIfThen(TagCheck, InsertBefore, false,
1674 MDBuilder(*C).createBranchWeights(1, 100000));
1675 assert(cast<BranchInst>(TagCheckTerm)->isUnconditional());
1676 IRB.SetInsertPoint(TagCheckTerm);
1677 InsertBefore = TagCheckTerm;
1681 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1682 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1683 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1684 Value *CmpVal = Constant::getNullValue(ShadowTy);
1685 Value *ShadowValue =
1686 IRB.CreateLoad(ShadowTy, IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1688 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1689 size_t Granularity = 1ULL << Mapping.Scale;
1690 Instruction *CrashTerm = nullptr;
1692 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1693 // We use branch weights for the slow path check, to indicate that the slow
1694 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1695 Instruction *CheckTerm = SplitBlockAndInsertIfThen(
1696 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1697 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1698 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1699 IRB.SetInsertPoint(CheckTerm);
1700 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1702 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1704 BasicBlock *CrashBlock =
1705 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1706 CrashTerm = new UnreachableInst(*C, CrashBlock);
1707 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1708 ReplaceInstWithInst(CheckTerm, NewTerm);
1711 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1714 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1715 AccessSizeIndex, SizeArgument, Exp);
1716 Crash->setDebugLoc(OrigIns->getDebugLoc());
1719 // Instrument unusual size or unusual alignment.
1720 // We can not do it with a single check, so we do 1-byte check for the first
1721 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1722 // to report the actual access size.
1723 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1724 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1725 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1726 IRBuilder<> IRB(InsertBefore);
1727 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1728 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1731 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1734 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1735 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1737 Value *LastByte = IRB.CreateIntToPtr(
1738 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1740 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1741 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1745 void ModuleAddressSanitizer::poisonOneInitializer(Function &GlobalInit,
1746 GlobalValue *ModuleName) {
1747 // Set up the arguments to our poison/unpoison functions.
1748 IRBuilder<> IRB(&GlobalInit.front(),
1749 GlobalInit.front().getFirstInsertionPt());
1751 // Add a call to poison all external globals before the given function starts.
1752 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1753 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1755 // Add calls to unpoison all globals before each return instruction.
1756 for (auto &BB : GlobalInit.getBasicBlockList())
1757 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1758 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1761 void ModuleAddressSanitizer::createInitializerPoisonCalls(
1762 Module &M, GlobalValue *ModuleName) {
1763 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1767 ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
1771 for (Use &OP : CA->operands()) {
1772 if (isa<ConstantAggregateZero>(OP)) continue;
1773 ConstantStruct *CS = cast<ConstantStruct>(OP);
1775 // Must have a function or null ptr.
1776 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1777 if (F->getName() == kAsanModuleCtorName) continue;
1778 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1779 // Don't instrument CTORs that will run before asan.module_ctor.
1780 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1781 poisonOneInitializer(*F, ModuleName);
1786 bool ModuleAddressSanitizer::ShouldInstrumentGlobal(GlobalVariable *G) {
1787 Type *Ty = G->getValueType();
1788 LLVM_DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1790 // FIXME: Metadata should be attched directly to the global directly instead
1791 // of being added to llvm.asan.globals.
1792 if (GlobalsMD.get(G).IsBlacklisted) return false;
1793 if (!Ty->isSized()) return false;
1794 if (!G->hasInitializer()) return false;
1795 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1796 // Two problems with thread-locals:
1797 // - The address of the main thread's copy can't be computed at link-time.
1798 // - Need to poison all copies, not just the main thread's one.
1799 if (G->isThreadLocal()) return false;
1800 // For now, just ignore this Global if the alignment is large.
1801 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1803 // For non-COFF targets, only instrument globals known to be defined by this
1805 // FIXME: We can instrument comdat globals on ELF if we are using the
1806 // GC-friendly metadata scheme.
1807 if (!TargetTriple.isOSBinFormatCOFF()) {
1808 if (!G->hasExactDefinition() || G->hasComdat())
1811 // On COFF, don't instrument non-ODR linkages.
1812 if (G->isInterposable())
1816 // If a comdat is present, it must have a selection kind that implies ODR
1817 // semantics: no duplicates, any, or exact match.
1818 if (Comdat *C = G->getComdat()) {
1819 switch (C->getSelectionKind()) {
1821 case Comdat::ExactMatch:
1822 case Comdat::NoDuplicates:
1824 case Comdat::Largest:
1825 case Comdat::SameSize:
1830 if (G->hasSection()) {
1831 StringRef Section = G->getSection();
1833 // Globals from llvm.metadata aren't emitted, do not instrument them.
1834 if (Section == "llvm.metadata") return false;
1835 // Do not instrument globals from special LLVM sections.
1836 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1838 // Do not instrument function pointers to initialization and termination
1839 // routines: dynamic linker will not properly handle redzones.
1840 if (Section.startswith(".preinit_array") ||
1841 Section.startswith(".init_array") ||
1842 Section.startswith(".fini_array")) {
1846 // On COFF, if the section name contains '$', it is highly likely that the
1847 // user is using section sorting to create an array of globals similar to
1848 // the way initialization callbacks are registered in .init_array and
1849 // .CRT$XCU. The ATL also registers things in .ATL$__[azm]. Adding redzones
1850 // to such globals is counterproductive, because the intent is that they
1851 // will form an array, and out-of-bounds accesses are expected.
1852 // See https://github.com/google/sanitizers/issues/305
1853 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1854 if (TargetTriple.isOSBinFormatCOFF() && Section.contains('$')) {
1855 LLVM_DEBUG(dbgs() << "Ignoring global in sorted section (contains '$'): "
1860 if (TargetTriple.isOSBinFormatMachO()) {
1861 StringRef ParsedSegment, ParsedSection;
1862 unsigned TAA = 0, StubSize = 0;
1864 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1865 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1866 assert(ErrorCode.empty() && "Invalid section specifier.");
1868 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1869 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1871 if (ParsedSegment == "__OBJC" ||
1872 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1873 LLVM_DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1876 // See https://github.com/google/sanitizers/issues/32
1877 // Constant CFString instances are compiled in the following way:
1878 // -- the string buffer is emitted into
1879 // __TEXT,__cstring,cstring_literals
1880 // -- the constant NSConstantString structure referencing that buffer
1881 // is placed into __DATA,__cfstring
1882 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1883 // Moreover, it causes the linker to crash on OS X 10.7
1884 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1885 LLVM_DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1888 // The linker merges the contents of cstring_literals and removes the
1890 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1891 LLVM_DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1900 // On Mach-O platforms, we emit global metadata in a separate section of the
1901 // binary in order to allow the linker to properly dead strip. This is only
1902 // supported on recent versions of ld64.
1903 bool ModuleAddressSanitizer::ShouldUseMachOGlobalsSection() const {
1904 if (!TargetTriple.isOSBinFormatMachO())
1907 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1909 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1911 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1917 StringRef ModuleAddressSanitizer::getGlobalMetadataSection() const {
1918 switch (TargetTriple.getObjectFormat()) {
1919 case Triple::COFF: return ".ASAN$GL";
1920 case Triple::ELF: return "asan_globals";
1921 case Triple::MachO: return "__DATA,__asan_globals,regular";
1924 llvm_unreachable("unsupported object format");
1927 void ModuleAddressSanitizer::initializeCallbacks(Module &M) {
1928 IRBuilder<> IRB(*C);
1930 // Declare our poisoning and unpoisoning functions.
1932 M.getOrInsertFunction(kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy);
1933 AsanUnpoisonGlobals =
1934 M.getOrInsertFunction(kAsanUnpoisonGlobalsName, IRB.getVoidTy());
1936 // Declare functions that register/unregister globals.
1937 AsanRegisterGlobals = M.getOrInsertFunction(
1938 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy);
1939 AsanUnregisterGlobals = M.getOrInsertFunction(
1940 kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy);
1942 // Declare the functions that find globals in a shared object and then invoke
1943 // the (un)register function on them.
1944 AsanRegisterImageGlobals = M.getOrInsertFunction(
1945 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy);
1946 AsanUnregisterImageGlobals = M.getOrInsertFunction(
1947 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy);
1949 AsanRegisterElfGlobals =
1950 M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
1951 IntptrTy, IntptrTy, IntptrTy);
1952 AsanUnregisterElfGlobals =
1953 M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
1954 IntptrTy, IntptrTy, IntptrTy);
1957 // Put the metadata and the instrumented global in the same group. This ensures
1958 // that the metadata is discarded if the instrumented global is discarded.
1959 void ModuleAddressSanitizer::SetComdatForGlobalMetadata(
1960 GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
1961 Module &M = *G->getParent();
1962 Comdat *C = G->getComdat();
1964 if (!G->hasName()) {
1965 // If G is unnamed, it must be internal. Give it an artificial name
1966 // so we can put it in a comdat.
1967 assert(G->hasLocalLinkage());
1968 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1971 if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
1972 std::string Name = G->getName();
1973 Name += InternalSuffix;
1974 C = M.getOrInsertComdat(Name);
1976 C = M.getOrInsertComdat(G->getName());
1979 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF. Also upgrade private
1980 // linkage to internal linkage so that a symbol table entry is emitted. This
1981 // is necessary in order to create the comdat group.
1982 if (TargetTriple.isOSBinFormatCOFF()) {
1983 C->setSelectionKind(Comdat::NoDuplicates);
1984 if (G->hasPrivateLinkage())
1985 G->setLinkage(GlobalValue::InternalLinkage);
1990 assert(G->hasComdat());
1991 Metadata->setComdat(G->getComdat());
1994 // Create a separate metadata global and put it in the appropriate ASan
1995 // global registration section.
1997 ModuleAddressSanitizer::CreateMetadataGlobal(Module &M, Constant *Initializer,
1998 StringRef OriginalName) {
1999 auto Linkage = TargetTriple.isOSBinFormatMachO()
2000 ? GlobalVariable::InternalLinkage
2001 : GlobalVariable::PrivateLinkage;
2002 GlobalVariable *Metadata = new GlobalVariable(
2003 M, Initializer->getType(), false, Linkage, Initializer,
2004 Twine("__asan_global_") + GlobalValue::dropLLVMManglingEscape(OriginalName));
2005 Metadata->setSection(getGlobalMetadataSection());
2009 IRBuilder<> ModuleAddressSanitizer::CreateAsanModuleDtor(Module &M) {
2011 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
2012 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
2013 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
2015 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
2018 void ModuleAddressSanitizer::InstrumentGlobalsCOFF(
2019 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2020 ArrayRef<Constant *> MetadataInitializers) {
2021 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2022 auto &DL = M.getDataLayout();
2024 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2025 Constant *Initializer = MetadataInitializers[i];
2026 GlobalVariable *G = ExtendedGlobals[i];
2027 GlobalVariable *Metadata =
2028 CreateMetadataGlobal(M, Initializer, G->getName());
2030 // The MSVC linker always inserts padding when linking incrementally. We
2031 // cope with that by aligning each struct to its size, which must be a power
2033 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
2034 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
2035 "global metadata will not be padded appropriately");
2036 Metadata->setAlignment(SizeOfGlobalStruct);
2038 SetComdatForGlobalMetadata(G, Metadata, "");
2042 void ModuleAddressSanitizer::InstrumentGlobalsELF(
2043 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2044 ArrayRef<Constant *> MetadataInitializers,
2045 const std::string &UniqueModuleId) {
2046 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2048 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
2049 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2050 GlobalVariable *G = ExtendedGlobals[i];
2051 GlobalVariable *Metadata =
2052 CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
2053 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
2054 Metadata->setMetadata(LLVMContext::MD_associated, MD);
2055 MetadataGlobals[i] = Metadata;
2057 SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
2060 // Update llvm.compiler.used, adding the new metadata globals. This is
2061 // needed so that during LTO these variables stay alive.
2062 if (!MetadataGlobals.empty())
2063 appendToCompilerUsed(M, MetadataGlobals);
2065 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
2066 // to look up the loaded image that contains it. Second, we can store in it
2067 // whether registration has already occurred, to prevent duplicate
2070 // Common linkage ensures that there is only one global per shared library.
2071 GlobalVariable *RegisteredFlag = new GlobalVariable(
2072 M, IntptrTy, false, GlobalVariable::CommonLinkage,
2073 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
2074 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
2076 // Create start and stop symbols.
2077 GlobalVariable *StartELFMetadata = new GlobalVariable(
2078 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
2079 "__start_" + getGlobalMetadataSection());
2080 StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
2081 GlobalVariable *StopELFMetadata = new GlobalVariable(
2082 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
2083 "__stop_" + getGlobalMetadataSection());
2084 StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
2086 // Create a call to register the globals with the runtime.
2087 IRB.CreateCall(AsanRegisterElfGlobals,
2088 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
2089 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
2090 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
2092 // We also need to unregister globals at the end, e.g., when a shared library
2094 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
2095 IRB_Dtor.CreateCall(AsanUnregisterElfGlobals,
2096 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
2097 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
2098 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
2101 void ModuleAddressSanitizer::InstrumentGlobalsMachO(
2102 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2103 ArrayRef<Constant *> MetadataInitializers) {
2104 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2106 // On recent Mach-O platforms, use a structure which binds the liveness of
2107 // the global variable to the metadata struct. Keep the list of "Liveness" GV
2108 // created to be added to llvm.compiler.used
2109 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy);
2110 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
2112 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2113 Constant *Initializer = MetadataInitializers[i];
2114 GlobalVariable *G = ExtendedGlobals[i];
2115 GlobalVariable *Metadata =
2116 CreateMetadataGlobal(M, Initializer, G->getName());
2118 // On recent Mach-O platforms, we emit the global metadata in a way that
2119 // allows the linker to properly strip dead globals.
2120 auto LivenessBinder =
2121 ConstantStruct::get(LivenessTy, Initializer->getAggregateElement(0u),
2122 ConstantExpr::getPointerCast(Metadata, IntptrTy));
2123 GlobalVariable *Liveness = new GlobalVariable(
2124 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
2125 Twine("__asan_binder_") + G->getName());
2126 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
2127 LivenessGlobals[i] = Liveness;
2130 // Update llvm.compiler.used, adding the new liveness globals. This is
2131 // needed so that during LTO these variables stay alive. The alternative
2132 // would be to have the linker handling the LTO symbols, but libLTO
2133 // current API does not expose access to the section for each symbol.
2134 if (!LivenessGlobals.empty())
2135 appendToCompilerUsed(M, LivenessGlobals);
2137 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
2138 // to look up the loaded image that contains it. Second, we can store in it
2139 // whether registration has already occurred, to prevent duplicate
2142 // common linkage ensures that there is only one global per shared library.
2143 GlobalVariable *RegisteredFlag = new GlobalVariable(
2144 M, IntptrTy, false, GlobalVariable::CommonLinkage,
2145 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
2146 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
2148 IRB.CreateCall(AsanRegisterImageGlobals,
2149 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
2151 // We also need to unregister globals at the end, e.g., when a shared library
2153 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
2154 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
2155 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
2158 void ModuleAddressSanitizer::InstrumentGlobalsWithMetadataArray(
2159 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2160 ArrayRef<Constant *> MetadataInitializers) {
2161 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2162 unsigned N = ExtendedGlobals.size();
2165 // On platforms that don't have a custom metadata section, we emit an array
2166 // of global metadata structures.
2167 ArrayType *ArrayOfGlobalStructTy =
2168 ArrayType::get(MetadataInitializers[0]->getType(), N);
2169 auto AllGlobals = new GlobalVariable(
2170 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
2171 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
2172 if (Mapping.Scale > 3)
2173 AllGlobals->setAlignment(1ULL << Mapping.Scale);
2175 IRB.CreateCall(AsanRegisterGlobals,
2176 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
2177 ConstantInt::get(IntptrTy, N)});
2179 // We also need to unregister globals at the end, e.g., when a shared library
2181 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
2182 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
2183 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
2184 ConstantInt::get(IntptrTy, N)});
2187 // This function replaces all global variables with new variables that have
2188 // trailing redzones. It also creates a function that poisons
2189 // redzones and inserts this function into llvm.global_ctors.
2190 // Sets *CtorComdat to true if the global registration code emitted into the
2191 // asan constructor is comdat-compatible.
2192 bool ModuleAddressSanitizer::InstrumentGlobals(IRBuilder<> &IRB, Module &M,
2194 *CtorComdat = false;
2196 SmallVector<GlobalVariable *, 16> GlobalsToChange;
2198 for (auto &G : M.globals()) {
2199 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
2202 size_t n = GlobalsToChange.size();
2208 auto &DL = M.getDataLayout();
2210 // A global is described by a structure
2213 // size_t size_with_redzone;
2214 // const char *name;
2215 // const char *module_name;
2216 // size_t has_dynamic_init;
2217 // void *source_location;
2218 // size_t odr_indicator;
2219 // We initialize an array of such structures and pass it to a run-time call.
2220 StructType *GlobalStructTy =
2221 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
2222 IntptrTy, IntptrTy, IntptrTy);
2223 SmallVector<GlobalVariable *, 16> NewGlobals(n);
2224 SmallVector<Constant *, 16> Initializers(n);
2226 bool HasDynamicallyInitializedGlobals = false;
2228 // We shouldn't merge same module names, as this string serves as unique
2229 // module ID in runtime.
2230 GlobalVariable *ModuleName = createPrivateGlobalForString(
2231 M, M.getModuleIdentifier(), /*AllowMerging*/ false, kAsanGenPrefix);
2233 for (size_t i = 0; i < n; i++) {
2234 static const uint64_t kMaxGlobalRedzone = 1 << 18;
2235 GlobalVariable *G = GlobalsToChange[i];
2237 // FIXME: Metadata should be attched directly to the global directly instead
2238 // of being added to llvm.asan.globals.
2239 auto MD = GlobalsMD.get(G);
2240 StringRef NameForGlobal = G->getName();
2241 // Create string holding the global name (use global name from metadata
2242 // if it's available, otherwise just write the name of global variable).
2243 GlobalVariable *Name = createPrivateGlobalForString(
2244 M, MD.Name.empty() ? NameForGlobal : MD.Name,
2245 /*AllowMerging*/ true, kAsanGenPrefix);
2247 Type *Ty = G->getValueType();
2248 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
2249 uint64_t MinRZ = MinRedzoneSizeForGlobal();
2250 // MinRZ <= RZ <= kMaxGlobalRedzone
2251 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
2252 uint64_t RZ = std::max(
2253 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
2254 uint64_t RightRedzoneSize = RZ;
2255 // Round up to MinRZ
2256 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
2257 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
2258 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
2260 StructType *NewTy = StructType::get(Ty, RightRedZoneTy);
2261 Constant *NewInitializer = ConstantStruct::get(
2262 NewTy, G->getInitializer(), Constant::getNullValue(RightRedZoneTy));
2264 // Create a new global variable with enough space for a redzone.
2265 GlobalValue::LinkageTypes Linkage = G->getLinkage();
2266 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
2267 Linkage = GlobalValue::InternalLinkage;
2268 GlobalVariable *NewGlobal =
2269 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
2270 "", G, G->getThreadLocalMode());
2271 NewGlobal->copyAttributesFrom(G);
2272 NewGlobal->setComdat(G->getComdat());
2273 NewGlobal->setAlignment(MinRZ);
2274 // Don't fold globals with redzones. ODR violation detector and redzone
2275 // poisoning implicitly creates a dependence on the global's address, so it
2276 // is no longer valid for it to be marked unnamed_addr.
2277 NewGlobal->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
2279 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
2280 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
2282 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
2283 if (Seq && Seq->isCString())
2284 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
2287 // Transfer the debug info. The payload starts at offset zero so we can
2288 // copy the debug info over as is.
2289 SmallVector<DIGlobalVariableExpression *, 1> GVs;
2290 G->getDebugInfo(GVs);
2291 for (auto *GV : GVs)
2292 NewGlobal->addDebugInfo(GV);
2295 Indices2[0] = IRB.getInt32(0);
2296 Indices2[1] = IRB.getInt32(0);
2298 G->replaceAllUsesWith(
2299 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
2300 NewGlobal->takeName(G);
2301 G->eraseFromParent();
2302 NewGlobals[i] = NewGlobal;
2304 Constant *SourceLoc;
2305 if (!MD.SourceLoc.empty()) {
2306 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
2307 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
2309 SourceLoc = ConstantInt::get(IntptrTy, 0);
2312 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
2313 GlobalValue *InstrumentedGlobal = NewGlobal;
2315 bool CanUsePrivateAliases =
2316 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
2317 TargetTriple.isOSBinFormatWasm();
2318 if (CanUsePrivateAliases && UsePrivateAlias) {
2319 // Create local alias for NewGlobal to avoid crash on ODR between
2320 // instrumented and non-instrumented libraries.
2321 InstrumentedGlobal =
2322 GlobalAlias::create(GlobalValue::PrivateLinkage, "", NewGlobal);
2325 // ODR should not happen for local linkage.
2326 if (NewGlobal->hasLocalLinkage()) {
2327 ODRIndicator = ConstantExpr::getIntToPtr(ConstantInt::get(IntptrTy, -1),
2328 IRB.getInt8PtrTy());
2329 } else if (UseOdrIndicator) {
2330 // With local aliases, we need to provide another externally visible
2331 // symbol __odr_asan_XXX to detect ODR violation.
2332 auto *ODRIndicatorSym =
2333 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
2334 Constant::getNullValue(IRB.getInt8Ty()),
2335 kODRGenPrefix + NameForGlobal, nullptr,
2336 NewGlobal->getThreadLocalMode());
2338 // Set meaningful attributes for indicator symbol.
2339 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
2340 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
2341 ODRIndicatorSym->setAlignment(1);
2342 ODRIndicator = ODRIndicatorSym;
2345 Constant *Initializer = ConstantStruct::get(
2347 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
2348 ConstantInt::get(IntptrTy, SizeInBytes),
2349 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
2350 ConstantExpr::getPointerCast(Name, IntptrTy),
2351 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
2352 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
2353 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy));
2355 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
2357 LLVM_DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
2359 Initializers[i] = Initializer;
2362 // Add instrumented globals to llvm.compiler.used list to avoid LTO from
2363 // ConstantMerge'ing them.
2364 SmallVector<GlobalValue *, 16> GlobalsToAddToUsedList;
2365 for (size_t i = 0; i < n; i++) {
2366 GlobalVariable *G = NewGlobals[i];
2367 if (G->getName().empty()) continue;
2368 GlobalsToAddToUsedList.push_back(G);
2370 appendToCompilerUsed(M, ArrayRef<GlobalValue *>(GlobalsToAddToUsedList));
2372 std::string ELFUniqueModuleId =
2373 (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
2376 if (!ELFUniqueModuleId.empty()) {
2377 InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
2379 } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
2380 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
2381 } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
2382 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
2384 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
2387 // Create calls for poisoning before initializers run and unpoisoning after.
2388 if (HasDynamicallyInitializedGlobals)
2389 createInitializerPoisonCalls(M, ModuleName);
2391 LLVM_DEBUG(dbgs() << M);
2395 int ModuleAddressSanitizer::GetAsanVersion(const Module &M) const {
2396 int LongSize = M.getDataLayout().getPointerSizeInBits();
2397 bool isAndroid = Triple(M.getTargetTriple()).isAndroid();
2399 // 32-bit Android is one version ahead because of the switch to dynamic
2401 Version += (LongSize == 32 && isAndroid);
2405 bool ModuleAddressSanitizer::instrumentModule(Module &M) {
2406 initializeCallbacks(M);
2411 // Create a module constructor. A destructor is created lazily because not all
2412 // platforms, and not all modules need it.
2413 std::string VersionCheckName =
2414 kAsanVersionCheckNamePrefix + std::to_string(GetAsanVersion(M));
2415 std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
2416 M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
2417 /*InitArgs=*/{}, VersionCheckName);
2419 bool CtorComdat = true;
2420 bool Changed = false;
2421 // TODO(glider): temporarily disabled globals instrumentation for KASan.
2423 IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
2424 Changed |= InstrumentGlobals(IRB, M, &CtorComdat);
2427 // Put the constructor and destructor in comdat if both
2428 // (1) global instrumentation is not TU-specific
2429 // (2) target is ELF.
2430 if (UseCtorComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
2431 AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
2432 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority,
2434 if (AsanDtorFunction) {
2435 AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
2436 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority,
2440 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
2441 if (AsanDtorFunction)
2442 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
2448 void AddressSanitizer::initializeCallbacks(Module &M) {
2449 IRBuilder<> IRB(*C);
2450 // Create __asan_report* callbacks.
2451 // IsWrite, TypeSize and Exp are encoded in the function name.
2452 for (int Exp = 0; Exp < 2; Exp++) {
2453 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
2454 const std::string TypeStr = AccessIsWrite ? "store" : "load";
2455 const std::string ExpStr = Exp ? "exp_" : "";
2456 const std::string EndingStr = Recover ? "_noabort" : "";
2458 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
2459 SmallVector<Type *, 2> Args1{1, IntptrTy};
2461 Type *ExpType = Type::getInt32Ty(*C);
2462 Args2.push_back(ExpType);
2463 Args1.push_back(ExpType);
2465 AsanErrorCallbackSized[AccessIsWrite][Exp] = M.getOrInsertFunction(
2466 kAsanReportErrorTemplate + ExpStr + TypeStr + "_n" + EndingStr,
2467 FunctionType::get(IRB.getVoidTy(), Args2, false));
2469 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] = M.getOrInsertFunction(
2470 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
2471 FunctionType::get(IRB.getVoidTy(), Args2, false));
2473 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
2474 AccessSizeIndex++) {
2475 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
2476 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2477 M.getOrInsertFunction(
2478 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
2479 FunctionType::get(IRB.getVoidTy(), Args1, false));
2481 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2482 M.getOrInsertFunction(
2483 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
2484 FunctionType::get(IRB.getVoidTy(), Args1, false));
2489 const std::string MemIntrinCallbackPrefix =
2490 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
2491 AsanMemmove = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memmove",
2492 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2493 IRB.getInt8PtrTy(), IntptrTy);
2494 AsanMemcpy = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memcpy",
2495 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2496 IRB.getInt8PtrTy(), IntptrTy);
2497 AsanMemset = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memset",
2498 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2499 IRB.getInt32Ty(), IntptrTy);
2501 AsanHandleNoReturnFunc =
2502 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy());
2504 AsanPtrCmpFunction =
2505 M.getOrInsertFunction(kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy);
2506 AsanPtrSubFunction =
2507 M.getOrInsertFunction(kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy);
2508 // We insert an empty inline asm after __asan_report* to avoid callback merge.
2509 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
2510 StringRef(""), StringRef(""),
2511 /*hasSideEffects=*/true);
2512 if (Mapping.InGlobal)
2513 AsanShadowGlobal = M.getOrInsertGlobal("__asan_shadow",
2514 ArrayType::get(IRB.getInt8Ty(), 0));
2517 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2518 // For each NSObject descendant having a +load method, this method is invoked
2519 // by the ObjC runtime before any of the static constructors is called.
2520 // Therefore we need to instrument such methods with a call to __asan_init
2521 // at the beginning in order to initialize our runtime before any access to
2522 // the shadow memory.
2523 // We cannot just ignore these methods, because they may call other
2524 // instrumented functions.
2525 if (F.getName().find(" load]") != std::string::npos) {
2526 FunctionCallee AsanInitFunction =
2527 declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
2528 IRBuilder<> IRB(&F.front(), F.front().begin());
2529 IRB.CreateCall(AsanInitFunction, {});
2535 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2536 // Generate code only when dynamic addressing is needed.
2537 if (Mapping.Offset != kDynamicShadowSentinel)
2540 IRBuilder<> IRB(&F.front().front());
2541 if (Mapping.InGlobal) {
2542 if (ClWithIfuncSuppressRemat) {
2543 // An empty inline asm with input reg == output reg.
2544 // An opaque pointer-to-int cast, basically.
2545 InlineAsm *Asm = InlineAsm::get(
2546 FunctionType::get(IntptrTy, {AsanShadowGlobal->getType()}, false),
2547 StringRef(""), StringRef("=r,0"),
2548 /*hasSideEffects=*/false);
2549 LocalDynamicShadow =
2550 IRB.CreateCall(Asm, {AsanShadowGlobal}, ".asan.shadow");
2552 LocalDynamicShadow =
2553 IRB.CreatePointerCast(AsanShadowGlobal, IntptrTy, ".asan.shadow");
2556 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2557 kAsanShadowMemoryDynamicAddress, IntptrTy);
2558 LocalDynamicShadow = IRB.CreateLoad(IntptrTy, GlobalDynamicAddress);
2562 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2563 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2564 // to it as uninteresting. This assumes we haven't started processing allocas
2565 // yet. This check is done up front because iterating the use list in
2566 // isInterestingAlloca would be algorithmically slower.
2567 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2569 // Try to get the declaration of llvm.localescape. If it's not in the module,
2570 // we can exit early.
2571 if (!F.getParent()->getFunction("llvm.localescape")) return;
2573 // Look for a call to llvm.localescape call in the entry block. It can't be in
2575 for (Instruction &I : F.getEntryBlock()) {
2576 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2577 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2578 // We found a call. Mark all the allocas passed in as uninteresting.
2579 for (Value *Arg : II->arg_operands()) {
2580 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2581 assert(AI && AI->isStaticAlloca() &&
2582 "non-static alloca arg to localescape");
2583 ProcessedAllocas[AI] = false;
2590 bool AddressSanitizer::instrumentFunction(Function &F,
2591 const TargetLibraryInfo *TLI) {
2592 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2593 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2594 if (F.getName().startswith("__asan_")) return false;
2596 bool FunctionModified = false;
2598 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2599 // This function needs to be called even if the function body is not
2601 if (maybeInsertAsanInitAtFunctionEntry(F))
2602 FunctionModified = true;
2604 // Leave if the function doesn't need instrumentation.
2605 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2607 LLVM_DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2609 initializeCallbacks(*F.getParent());
2611 FunctionStateRAII CleanupObj(this);
2613 maybeInsertDynamicShadowAtFunctionEntry(F);
2615 // We can't instrument allocas used with llvm.localescape. Only static allocas
2616 // can be passed to that intrinsic.
2617 markEscapedLocalAllocas(F);
2619 // We want to instrument every address only once per basic block (unless there
2620 // are calls between uses).
2621 SmallPtrSet<Value *, 16> TempsToInstrument;
2622 SmallVector<Instruction *, 16> ToInstrument;
2623 SmallVector<Instruction *, 8> NoReturnCalls;
2624 SmallVector<BasicBlock *, 16> AllBlocks;
2625 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2631 // Fill the set of memory operations to instrument.
2632 for (auto &BB : F) {
2633 AllBlocks.push_back(&BB);
2634 TempsToInstrument.clear();
2635 int NumInsnsPerBB = 0;
2636 for (auto &Inst : BB) {
2637 if (LooksLikeCodeInBug11395(&Inst)) return false;
2638 Value *MaybeMask = nullptr;
2639 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2640 &Alignment, &MaybeMask)) {
2641 if (ClOpt && ClOptSameTemp) {
2642 // If we have a mask, skip instrumentation if we've already
2643 // instrumented the full object. But don't add to TempsToInstrument
2644 // because we might get another load/store with a different mask.
2646 if (TempsToInstrument.count(Addr))
2647 continue; // We've seen this (whole) temp in the current BB.
2649 if (!TempsToInstrument.insert(Addr).second)
2650 continue; // We've seen this temp in the current BB.
2653 } else if (((ClInvalidPointerPairs || ClInvalidPointerCmp) &&
2654 isInterestingPointerComparison(&Inst)) ||
2655 ((ClInvalidPointerPairs || ClInvalidPointerSub) &&
2656 isInterestingPointerSubtraction(&Inst))) {
2657 PointerComparisonsOrSubtracts.push_back(&Inst);
2659 } else if (isa<MemIntrinsic>(Inst)) {
2662 if (isa<AllocaInst>(Inst)) NumAllocas++;
2665 // A call inside BB.
2666 TempsToInstrument.clear();
2667 if (CS.doesNotReturn() && !CS->getMetadata("nosanitize"))
2668 NoReturnCalls.push_back(CS.getInstruction());
2670 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2671 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2674 ToInstrument.push_back(&Inst);
2676 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2681 (ClInstrumentationWithCallsThreshold >= 0 &&
2682 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2683 const DataLayout &DL = F.getParent()->getDataLayout();
2684 ObjectSizeOpts ObjSizeOpts;
2685 ObjSizeOpts.RoundToAlign = true;
2686 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
2689 int NumInstrumented = 0;
2690 for (auto Inst : ToInstrument) {
2691 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2692 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2693 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2694 instrumentMop(ObjSizeVis, Inst, UseCalls,
2695 F.getParent()->getDataLayout());
2697 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2702 FunctionStackPoisoner FSP(F, *this);
2703 bool ChangedStack = FSP.runOnFunction();
2705 // We must unpoison the stack before NoReturn calls (throw, _exit, etc).
2706 // See e.g. https://github.com/google/sanitizers/issues/37
2707 for (auto CI : NoReturnCalls) {
2708 IRBuilder<> IRB(CI);
2709 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2712 for (auto Inst : PointerComparisonsOrSubtracts) {
2713 instrumentPointerComparisonOrSubtraction(Inst);
2717 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2718 FunctionModified = true;
2720 LLVM_DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2723 return FunctionModified;
2726 // Workaround for bug 11395: we don't want to instrument stack in functions
2727 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2728 // FIXME: remove once the bug 11395 is fixed.
2729 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2730 if (LongSize != 32) return false;
2731 CallInst *CI = dyn_cast<CallInst>(I);
2732 if (!CI || !CI->isInlineAsm()) return false;
2733 if (CI->getNumArgOperands() <= 5) return false;
2734 // We have inline assembly with quite a few arguments.
2738 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2739 IRBuilder<> IRB(*C);
2740 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2741 std::string Suffix = itostr(i);
2742 AsanStackMallocFunc[i] = M.getOrInsertFunction(
2743 kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy);
2744 AsanStackFreeFunc[i] =
2745 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2746 IRB.getVoidTy(), IntptrTy, IntptrTy);
2748 if (ASan.UseAfterScope) {
2749 AsanPoisonStackMemoryFunc = M.getOrInsertFunction(
2750 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2751 AsanUnpoisonStackMemoryFunc = M.getOrInsertFunction(
2752 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2755 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2756 std::ostringstream Name;
2757 Name << kAsanSetShadowPrefix;
2758 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2759 AsanSetShadowFunc[Val] =
2760 M.getOrInsertFunction(Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy);
2763 AsanAllocaPoisonFunc = M.getOrInsertFunction(
2764 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy);
2765 AsanAllocasUnpoisonFunc = M.getOrInsertFunction(
2766 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy);
2769 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2770 ArrayRef<uint8_t> ShadowBytes,
2771 size_t Begin, size_t End,
2773 Value *ShadowBase) {
2777 const size_t LargestStoreSizeInBytes =
2778 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2780 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2782 // Poison given range in shadow using larges store size with out leading and
2783 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2784 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2785 // middle of a store.
2786 for (size_t i = Begin; i < End;) {
2787 if (!ShadowMask[i]) {
2788 assert(!ShadowBytes[i]);
2793 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2794 // Fit store size into the range.
2795 while (StoreSizeInBytes > End - i)
2796 StoreSizeInBytes /= 2;
2798 // Minimize store size by trimming trailing zeros.
2799 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2800 while (j <= StoreSizeInBytes / 2)
2801 StoreSizeInBytes /= 2;
2805 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2807 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2809 Val = (Val << 8) | ShadowBytes[i + j];
2812 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2813 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2814 IRB.CreateAlignedStore(
2815 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2817 i += StoreSizeInBytes;
2821 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2822 ArrayRef<uint8_t> ShadowBytes,
2823 IRBuilder<> &IRB, Value *ShadowBase) {
2824 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2827 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2828 ArrayRef<uint8_t> ShadowBytes,
2829 size_t Begin, size_t End,
2830 IRBuilder<> &IRB, Value *ShadowBase) {
2831 assert(ShadowMask.size() == ShadowBytes.size());
2832 size_t Done = Begin;
2833 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2834 if (!ShadowMask[i]) {
2835 assert(!ShadowBytes[i]);
2838 uint8_t Val = ShadowBytes[i];
2839 if (!AsanSetShadowFunc[Val])
2842 // Skip same values.
2843 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2846 if (j - i >= ClMaxInlinePoisoningSize) {
2847 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2848 IRB.CreateCall(AsanSetShadowFunc[Val],
2849 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2850 ConstantInt::get(IntptrTy, j - i)});
2855 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2858 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2859 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2860 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2861 assert(LocalStackSize <= kMaxStackMallocSize);
2862 uint64_t MaxSize = kMinStackMallocSize;
2863 for (int i = 0;; i++, MaxSize *= 2)
2864 if (LocalStackSize <= MaxSize) return i;
2865 llvm_unreachable("impossible LocalStackSize");
2868 void FunctionStackPoisoner::copyArgsPassedByValToAllocas() {
2869 Instruction *CopyInsertPoint = &F.front().front();
2870 if (CopyInsertPoint == ASan.LocalDynamicShadow) {
2871 // Insert after the dynamic shadow location is determined
2872 CopyInsertPoint = CopyInsertPoint->getNextNode();
2873 assert(CopyInsertPoint);
2875 IRBuilder<> IRB(CopyInsertPoint);
2876 const DataLayout &DL = F.getParent()->getDataLayout();
2877 for (Argument &Arg : F.args()) {
2878 if (Arg.hasByValAttr()) {
2879 Type *Ty = Arg.getType()->getPointerElementType();
2880 unsigned Align = Arg.getParamAlignment();
2881 if (Align == 0) Align = DL.getABITypeAlignment(Ty);
2883 AllocaInst *AI = IRB.CreateAlloca(
2885 (Arg.hasName() ? Arg.getName() : "Arg" + Twine(Arg.getArgNo())) +
2887 AI->setAlignment(Align);
2888 Arg.replaceAllUsesWith(AI);
2890 uint64_t AllocSize = DL.getTypeAllocSize(Ty);
2891 IRB.CreateMemCpy(AI, Align, &Arg, Align, AllocSize);
2896 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2898 Instruction *ThenTerm,
2899 Value *ValueIfFalse) {
2900 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2901 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2902 PHI->addIncoming(ValueIfFalse, CondBlock);
2903 BasicBlock *ThenBlock = ThenTerm->getParent();
2904 PHI->addIncoming(ValueIfTrue, ThenBlock);
2908 Value *FunctionStackPoisoner::createAllocaForLayout(
2909 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2912 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2913 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2916 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2917 nullptr, "MyAlloca");
2918 assert(Alloca->isStaticAlloca());
2920 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2921 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2922 Alloca->setAlignment(FrameAlignment);
2923 return IRB.CreatePointerCast(Alloca, IntptrTy);
2926 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2927 BasicBlock &FirstBB = *F.begin();
2928 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2929 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2930 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2931 DynamicAllocaLayout->setAlignment(32);
2934 void FunctionStackPoisoner::processDynamicAllocas() {
2935 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2936 assert(DynamicAllocaPoisonCallVec.empty());
2940 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2941 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2942 assert(APC.InsBefore);
2944 assert(ASan.isInterestingAlloca(*APC.AI));
2945 assert(!APC.AI->isStaticAlloca());
2947 IRBuilder<> IRB(APC.InsBefore);
2948 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2949 // Dynamic allocas will be unpoisoned unconditionally below in
2950 // unpoisonDynamicAllocas.
2951 // Flag that we need unpoison static allocas.
2954 // Handle dynamic allocas.
2955 createDynamicAllocasInitStorage();
2956 for (auto &AI : DynamicAllocaVec)
2957 handleDynamicAllocaCall(AI);
2958 unpoisonDynamicAllocas();
2961 void FunctionStackPoisoner::processStaticAllocas() {
2962 if (AllocaVec.empty()) {
2963 assert(StaticAllocaPoisonCallVec.empty());
2967 int StackMallocIdx = -1;
2968 DebugLoc EntryDebugLocation;
2969 if (auto SP = F.getSubprogram())
2970 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2972 Instruction *InsBefore = AllocaVec[0];
2973 IRBuilder<> IRB(InsBefore);
2974 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2976 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2977 // debug info is broken, because only entry-block allocas are treated as
2978 // regular stack slots.
2979 auto InsBeforeB = InsBefore->getParent();
2980 assert(InsBeforeB == &F.getEntryBlock());
2981 for (auto *AI : StaticAllocasToMoveUp)
2982 if (AI->getParent() == InsBeforeB)
2983 AI->moveBefore(InsBefore);
2985 // If we have a call to llvm.localescape, keep it in the entry block.
2986 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2988 SmallVector<ASanStackVariableDescription, 16> SVD;
2989 SVD.reserve(AllocaVec.size());
2990 for (AllocaInst *AI : AllocaVec) {
2991 ASanStackVariableDescription D = {AI->getName().data(),
2992 ASan.getAllocaSizeInBytes(*AI),
3001 // Minimal header size (left redzone) is 4 pointers,
3002 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
3003 size_t Granularity = 1ULL << Mapping.Scale;
3004 size_t MinHeaderSize = std::max((size_t)ASan.LongSize / 2, Granularity);
3005 const ASanStackFrameLayout &L =
3006 ComputeASanStackFrameLayout(SVD, Granularity, MinHeaderSize);
3008 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
3009 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
3010 for (auto &Desc : SVD)
3011 AllocaToSVDMap[Desc.AI] = &Desc;
3013 // Update SVD with information from lifetime intrinsics.
3014 for (const auto &APC : StaticAllocaPoisonCallVec) {
3015 assert(APC.InsBefore);
3017 assert(ASan.isInterestingAlloca(*APC.AI));
3018 assert(APC.AI->isStaticAlloca());
3020 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
3021 Desc.LifetimeSize = Desc.Size;
3022 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
3023 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
3024 if (LifetimeLoc->getFile() == FnLoc->getFile())
3025 if (unsigned Line = LifetimeLoc->getLine())
3026 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
3031 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
3032 LLVM_DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
3033 uint64_t LocalStackSize = L.FrameSize;
3034 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
3035 LocalStackSize <= kMaxStackMallocSize;
3036 bool DoDynamicAlloca = ClDynamicAllocaStack;
3037 // Don't do dynamic alloca or stack malloc if:
3038 // 1) There is inline asm: too often it makes assumptions on which registers
3040 // 2) There is a returns_twice call (typically setjmp), which is
3041 // optimization-hostile, and doesn't play well with introduced indirect
3042 // register-relative calculation of local variable addresses.
3043 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
3044 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
3046 Value *StaticAlloca =
3047 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
3050 Value *LocalStackBase;
3051 Value *LocalStackBaseAlloca;
3052 uint8_t DIExprFlags = DIExpression::ApplyOffset;
3054 if (DoStackMalloc) {
3055 LocalStackBaseAlloca =
3056 IRB.CreateAlloca(IntptrTy, nullptr, "asan_local_stack_base");
3057 // void *FakeStack = __asan_option_detect_stack_use_after_return
3058 // ? __asan_stack_malloc_N(LocalStackSize)
3060 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
3061 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
3062 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
3063 Value *UseAfterReturnIsEnabled = IRB.CreateICmpNE(
3064 IRB.CreateLoad(IRB.getInt32Ty(), OptionDetectUseAfterReturn),
3065 Constant::getNullValue(IRB.getInt32Ty()));
3067 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
3068 IRBuilder<> IRBIf(Term);
3069 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
3070 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
3071 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
3072 Value *FakeStackValue =
3073 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
3074 ConstantInt::get(IntptrTy, LocalStackSize));
3075 IRB.SetInsertPoint(InsBefore);
3076 IRB.SetCurrentDebugLocation(EntryDebugLocation);
3077 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
3078 ConstantInt::get(IntptrTy, 0));
3080 Value *NoFakeStack =
3081 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
3082 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
3083 IRBIf.SetInsertPoint(Term);
3084 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
3085 Value *AllocaValue =
3086 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
3088 IRB.SetInsertPoint(InsBefore);
3089 IRB.SetCurrentDebugLocation(EntryDebugLocation);
3090 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
3091 IRB.SetCurrentDebugLocation(EntryDebugLocation);
3092 IRB.CreateStore(LocalStackBase, LocalStackBaseAlloca);
3093 DIExprFlags |= DIExpression::DerefBefore;
3095 // void *FakeStack = nullptr;
3096 // void *LocalStackBase = alloca(LocalStackSize);
3097 FakeStack = ConstantInt::get(IntptrTy, 0);
3099 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
3100 LocalStackBaseAlloca = LocalStackBase;
3103 // Replace Alloca instructions with base+offset.
3104 for (const auto &Desc : SVD) {
3105 AllocaInst *AI = Desc.AI;
3106 replaceDbgDeclareForAlloca(AI, LocalStackBaseAlloca, DIB, DIExprFlags,
3108 Value *NewAllocaPtr = IRB.CreateIntToPtr(
3109 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
3111 AI->replaceAllUsesWith(NewAllocaPtr);
3114 // The left-most redzone has enough space for at least 4 pointers.
3115 // Write the Magic value to redzone[0].
3116 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
3117 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
3119 // Write the frame description constant to redzone[1].
3120 Value *BasePlus1 = IRB.CreateIntToPtr(
3121 IRB.CreateAdd(LocalStackBase,
3122 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
3124 GlobalVariable *StackDescriptionGlobal =
3125 createPrivateGlobalForString(*F.getParent(), DescriptionString,
3126 /*AllowMerging*/ true, kAsanGenPrefix);
3127 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
3128 IRB.CreateStore(Description, BasePlus1);
3129 // Write the PC to redzone[2].
3130 Value *BasePlus2 = IRB.CreateIntToPtr(
3131 IRB.CreateAdd(LocalStackBase,
3132 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
3134 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
3136 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
3138 // Poison the stack red zones at the entry.
3139 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
3140 // As mask we must use most poisoned case: red zones and after scope.
3141 // As bytes we can use either the same or just red zones only.
3142 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
3144 if (!StaticAllocaPoisonCallVec.empty()) {
3145 const auto &ShadowInScope = GetShadowBytes(SVD, L);
3147 // Poison static allocas near lifetime intrinsics.
3148 for (const auto &APC : StaticAllocaPoisonCallVec) {
3149 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
3150 assert(Desc.Offset % L.Granularity == 0);
3151 size_t Begin = Desc.Offset / L.Granularity;
3152 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
3154 IRBuilder<> IRB(APC.InsBefore);
3155 copyToShadow(ShadowAfterScope,
3156 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
3161 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
3162 SmallVector<uint8_t, 64> ShadowAfterReturn;
3164 // (Un)poison the stack before all ret instructions.
3165 for (auto Ret : RetVec) {
3166 IRBuilder<> IRBRet(Ret);
3167 // Mark the current frame as retired.
3168 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
3170 if (DoStackMalloc) {
3171 assert(StackMallocIdx >= 0);
3172 // if FakeStack != 0 // LocalStackBase == FakeStack
3173 // // In use-after-return mode, poison the whole stack frame.
3174 // if StackMallocIdx <= 4
3175 // // For small sizes inline the whole thing:
3176 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
3177 // **SavedFlagPtr(FakeStack) = 0
3179 // __asan_stack_free_N(FakeStack, LocalStackSize)
3181 // <This is not a fake stack; unpoison the redzones>
3183 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
3184 Instruction *ThenTerm, *ElseTerm;
3185 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
3187 IRBuilder<> IRBPoison(ThenTerm);
3188 if (StackMallocIdx <= 4) {
3189 int ClassSize = kMinStackMallocSize << StackMallocIdx;
3190 ShadowAfterReturn.resize(ClassSize / L.Granularity,
3191 kAsanStackUseAfterReturnMagic);
3192 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
3194 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
3196 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
3197 Value *SavedFlagPtr = IRBPoison.CreateLoad(
3198 IntptrTy, IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
3199 IRBPoison.CreateStore(
3200 Constant::getNullValue(IRBPoison.getInt8Ty()),
3201 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
3203 // For larger frames call __asan_stack_free_*.
3204 IRBPoison.CreateCall(
3205 AsanStackFreeFunc[StackMallocIdx],
3206 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
3209 IRBuilder<> IRBElse(ElseTerm);
3210 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
3212 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
3216 // We are done. Remove the old unused alloca instructions.
3217 for (auto AI : AllocaVec) AI->eraseFromParent();
3220 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
3221 IRBuilder<> &IRB, bool DoPoison) {
3222 // For now just insert the call to ASan runtime.
3223 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
3224 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
3226 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
3227 {AddrArg, SizeArg});
3230 // Handling llvm.lifetime intrinsics for a given %alloca:
3231 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
3232 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
3233 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
3234 // could be poisoned by previous llvm.lifetime.end instruction, as the
3235 // variable may go in and out of scope several times, e.g. in loops).
3236 // (3) if we poisoned at least one %alloca in a function,
3237 // unpoison the whole stack frame at function exit.
3238 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
3239 IRBuilder<> IRB(AI);
3241 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
3242 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
3244 Value *Zero = Constant::getNullValue(IntptrTy);
3245 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
3246 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
3248 // Since we need to extend alloca with additional memory to locate
3249 // redzones, and OldSize is number of allocated blocks with
3250 // ElementSize size, get allocated memory size in bytes by
3251 // OldSize * ElementSize.
3252 const unsigned ElementSize =
3253 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
3255 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
3256 ConstantInt::get(IntptrTy, ElementSize));
3258 // PartialSize = OldSize % 32
3259 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
3261 // Misalign = kAllocaRzSize - PartialSize;
3262 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
3264 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
3265 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
3266 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
3268 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
3269 // Align is added to locate left redzone, PartialPadding for possible
3270 // partial redzone and kAllocaRzSize for right redzone respectively.
3271 Value *AdditionalChunkSize = IRB.CreateAdd(
3272 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
3274 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
3276 // Insert new alloca with new NewSize and Align params.
3277 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
3278 NewAlloca->setAlignment(Align);
3280 // NewAddress = Address + Align
3281 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
3282 ConstantInt::get(IntptrTy, Align));
3284 // Insert __asan_alloca_poison call for new created alloca.
3285 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
3287 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
3288 // for unpoisoning stuff.
3289 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
3291 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
3293 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
3294 AI->replaceAllUsesWith(NewAddressPtr);
3296 // We are done. Erase old alloca from parent.
3297 AI->eraseFromParent();
3300 // isSafeAccess returns true if Addr is always inbounds with respect to its
3301 // base object. For example, it is a field access or an array access with
3302 // constant inbounds index.
3303 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
3304 Value *Addr, uint64_t TypeSize) const {
3305 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
3306 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
3307 uint64_t Size = SizeOffset.first.getZExtValue();
3308 int64_t Offset = SizeOffset.second.getSExtValue();
3309 // Three checks are required to ensure safety:
3310 // . Offset >= 0 (since the offset is given from the base ptr)
3311 // . Size >= Offset (unsigned)
3312 // . Size - Offset >= NeededSize (unsigned)
3313 return Offset >= 0 && Size >= uint64_t(Offset) &&
3314 Size - uint64_t(Offset) >= TypeSize / 8;