1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/DepthFirstIterator.h"
19 #include "llvm/ADT/SetVector.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/ADT/StringExtras.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/IR/Argument.h"
30 #include "llvm/IR/CallSite.h"
31 #include "llvm/IR/DIBuilder.h"
32 #include "llvm/IR/DataLayout.h"
33 #include "llvm/IR/Dominators.h"
34 #include "llvm/IR/Function.h"
35 #include "llvm/IR/IRBuilder.h"
36 #include "llvm/IR/InlineAsm.h"
37 #include "llvm/IR/InstVisitor.h"
38 #include "llvm/IR/IntrinsicInst.h"
39 #include "llvm/IR/LLVMContext.h"
40 #include "llvm/IR/MDBuilder.h"
41 #include "llvm/IR/Module.h"
42 #include "llvm/IR/Type.h"
43 #include "llvm/MC/MCSectionMachO.h"
44 #include "llvm/Support/CommandLine.h"
45 #include "llvm/Support/DataTypes.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/Endian.h"
48 #include "llvm/Support/ScopedPrinter.h"
49 #include "llvm/Support/SwapByteOrder.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include "llvm/Transforms/Instrumentation.h"
52 #include "llvm/Transforms/Scalar.h"
53 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
54 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
55 #include "llvm/Transforms/Utils/Cloning.h"
56 #include "llvm/Transforms/Utils/Local.h"
57 #include "llvm/Transforms/Utils/ModuleUtils.h"
58 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
64 #include <system_error>
68 #define DEBUG_TYPE "asan"
70 static const uint64_t kDefaultShadowScale = 3;
71 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
72 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
73 static const uint64_t kDynamicShadowSentinel = ~(uint64_t)0;
74 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
75 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
76 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
77 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
78 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
79 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
80 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
81 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
82 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
83 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
84 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
85 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
86 static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;
87 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
88 // The shadow memory space is dynamically allocated.
89 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
91 static const size_t kMinStackMallocSize = 1 << 6; // 64B
92 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
93 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
94 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
96 static const char *const kAsanModuleCtorName = "asan.module_ctor";
97 static const char *const kAsanModuleDtorName = "asan.module_dtor";
98 static const uint64_t kAsanCtorAndDtorPriority = 1;
99 static const char *const kAsanReportErrorTemplate = "__asan_report_";
100 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
101 static const char *const kAsanUnregisterGlobalsName =
102 "__asan_unregister_globals";
103 static const char *const kAsanRegisterImageGlobalsName =
104 "__asan_register_image_globals";
105 static const char *const kAsanUnregisterImageGlobalsName =
106 "__asan_unregister_image_globals";
107 static const char *const kAsanRegisterElfGlobalsName =
108 "__asan_register_elf_globals";
109 static const char *const kAsanUnregisterElfGlobalsName =
110 "__asan_unregister_elf_globals";
111 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
112 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
113 static const char *const kAsanInitName = "__asan_init";
114 static const char *const kAsanVersionCheckName =
115 "__asan_version_mismatch_check_v8";
116 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
117 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
118 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
119 static const int kMaxAsanStackMallocSizeClass = 10;
120 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
121 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
122 static const char *const kAsanGenPrefix = "__asan_gen_";
123 static const char *const kODRGenPrefix = "__odr_asan_gen_";
124 static const char *const kSanCovGenPrefix = "__sancov_gen_";
125 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
126 static const char *const kAsanPoisonStackMemoryName =
127 "__asan_poison_stack_memory";
128 static const char *const kAsanUnpoisonStackMemoryName =
129 "__asan_unpoison_stack_memory";
131 // ASan version script has __asan_* wildcard. Triple underscore prevents a
132 // linker (gold) warning about attempting to export a local symbol.
133 static const char *const kAsanGlobalsRegisteredFlagName =
134 "___asan_globals_registered";
136 static const char *const kAsanOptionDetectUseAfterReturn =
137 "__asan_option_detect_stack_use_after_return";
139 static const char *const kAsanShadowMemoryDynamicAddress =
140 "__asan_shadow_memory_dynamic_address";
142 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
143 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
145 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
146 static const size_t kNumberOfAccessSizes = 5;
148 static const unsigned kAllocaRzSize = 32;
150 // Command-line flags.
151 static cl::opt<bool> ClEnableKasan(
152 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
153 cl::Hidden, cl::init(false));
154 static cl::opt<bool> ClRecover(
156 cl::desc("Enable recovery mode (continue-after-error)."),
157 cl::Hidden, cl::init(false));
159 // This flag may need to be replaced with -f[no-]asan-reads.
160 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
161 cl::desc("instrument read instructions"),
162 cl::Hidden, cl::init(true));
163 static cl::opt<bool> ClInstrumentWrites(
164 "asan-instrument-writes", cl::desc("instrument write instructions"),
165 cl::Hidden, cl::init(true));
166 static cl::opt<bool> ClInstrumentAtomics(
167 "asan-instrument-atomics",
168 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
170 static cl::opt<bool> ClAlwaysSlowPath(
171 "asan-always-slow-path",
172 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
174 static cl::opt<bool> ClForceDynamicShadow(
175 "asan-force-dynamic-shadow",
176 cl::desc("Load shadow address into a local variable for each function"),
177 cl::Hidden, cl::init(false));
179 // This flag limits the number of instructions to be instrumented
180 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
181 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
183 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
184 "asan-max-ins-per-bb", cl::init(10000),
185 cl::desc("maximal number of instructions to instrument in any given BB"),
187 // This flag may need to be replaced with -f[no]asan-stack.
188 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
189 cl::Hidden, cl::init(true));
190 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
191 "asan-max-inline-poisoning-size",
193 "Inline shadow poisoning for blocks up to the given size in bytes."),
194 cl::Hidden, cl::init(64));
195 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
196 cl::desc("Check stack-use-after-return"),
197 cl::Hidden, cl::init(true));
198 static cl::opt<bool> ClRedzoneByvalArgs("asan-redzone-byval-args",
199 cl::desc("Create redzones for byval "
200 "arguments (extra copy "
201 "required)"), cl::Hidden,
203 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
204 cl::desc("Check stack-use-after-scope"),
205 cl::Hidden, cl::init(false));
206 // This flag may need to be replaced with -f[no]asan-globals.
207 static cl::opt<bool> ClGlobals("asan-globals",
208 cl::desc("Handle global objects"), cl::Hidden,
210 static cl::opt<bool> ClInitializers("asan-initialization-order",
211 cl::desc("Handle C++ initializer order"),
212 cl::Hidden, cl::init(true));
213 static cl::opt<bool> ClInvalidPointerPairs(
214 "asan-detect-invalid-pointer-pair",
215 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
217 static cl::opt<unsigned> ClRealignStack(
218 "asan-realign-stack",
219 cl::desc("Realign stack to the value of this flag (power of two)"),
220 cl::Hidden, cl::init(32));
221 static cl::opt<int> ClInstrumentationWithCallsThreshold(
222 "asan-instrumentation-with-call-threshold",
224 "If the function being instrumented contains more than "
225 "this number of memory accesses, use callbacks instead of "
226 "inline checks (-1 means never use callbacks)."),
227 cl::Hidden, cl::init(7000));
228 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
229 "asan-memory-access-callback-prefix",
230 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
231 cl::init("__asan_"));
233 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
234 cl::desc("instrument dynamic allocas"),
235 cl::Hidden, cl::init(true));
236 static cl::opt<bool> ClSkipPromotableAllocas(
237 "asan-skip-promotable-allocas",
238 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
241 // These flags allow to change the shadow mapping.
242 // The shadow mapping looks like
243 // Shadow = (Mem >> scale) + offset
244 static cl::opt<int> ClMappingScale("asan-mapping-scale",
245 cl::desc("scale of asan shadow mapping"),
246 cl::Hidden, cl::init(0));
247 static cl::opt<unsigned long long> ClMappingOffset(
248 "asan-mapping-offset",
249 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
252 // Optimization flags. Not user visible, used mostly for testing
253 // and benchmarking the tool.
254 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
255 cl::Hidden, cl::init(true));
256 static cl::opt<bool> ClOptSameTemp(
257 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
258 cl::Hidden, cl::init(true));
259 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
260 cl::desc("Don't instrument scalar globals"),
261 cl::Hidden, cl::init(true));
262 static cl::opt<bool> ClOptStack(
263 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
264 cl::Hidden, cl::init(false));
266 static cl::opt<bool> ClDynamicAllocaStack(
267 "asan-stack-dynamic-alloca",
268 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
271 static cl::opt<uint32_t> ClForceExperiment(
272 "asan-force-experiment",
273 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
277 ClUsePrivateAliasForGlobals("asan-use-private-alias",
278 cl::desc("Use private aliases for global"
280 cl::Hidden, cl::init(false));
283 ClUseGlobalsGC("asan-globals-live-support",
284 cl::desc("Use linker features to support dead "
285 "code stripping of globals"),
286 cl::Hidden, cl::init(true));
288 // This is on by default even though there is a bug in gold:
289 // https://sourceware.org/bugzilla/show_bug.cgi?id=19002
291 ClWithComdat("asan-with-comdat",
292 cl::desc("Place ASan constructors in comdat sections"),
293 cl::Hidden, cl::init(true));
296 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
298 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
299 cl::Hidden, cl::init(0));
300 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
301 cl::desc("Debug func"));
302 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
303 cl::Hidden, cl::init(-1));
304 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
305 cl::Hidden, cl::init(-1));
307 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
308 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
309 STATISTIC(NumOptimizedAccessesToGlobalVar,
310 "Number of optimized accesses to global vars");
311 STATISTIC(NumOptimizedAccessesToStackVar,
312 "Number of optimized accesses to stack vars");
315 /// Frontend-provided metadata for source location.
316 struct LocationMetadata {
321 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
323 bool empty() const { return Filename.empty(); }
325 void parse(MDNode *MDN) {
326 assert(MDN->getNumOperands() == 3);
327 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
328 Filename = DIFilename->getString();
330 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
332 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
336 /// Frontend-provided metadata for global variables.
337 class GlobalsMetadata {
340 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
341 LocationMetadata SourceLoc;
347 GlobalsMetadata() : inited_(false) {}
354 void init(Module &M) {
357 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
358 if (!Globals) return;
359 for (auto MDN : Globals->operands()) {
360 // Metadata node contains the global and the fields of "Entry".
361 assert(MDN->getNumOperands() == 5);
362 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
363 // The optimizer may optimize away a global entirely.
365 // We can already have an entry for GV if it was merged with another
367 Entry &E = Entries[GV];
368 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
369 E.SourceLoc.parse(Loc);
370 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
371 E.Name = Name->getString();
372 ConstantInt *IsDynInit =
373 mdconst::extract<ConstantInt>(MDN->getOperand(3));
374 E.IsDynInit |= IsDynInit->isOne();
375 ConstantInt *IsBlacklisted =
376 mdconst::extract<ConstantInt>(MDN->getOperand(4));
377 E.IsBlacklisted |= IsBlacklisted->isOne();
381 /// Returns metadata entry for a given global.
382 Entry get(GlobalVariable *G) const {
383 auto Pos = Entries.find(G);
384 return (Pos != Entries.end()) ? Pos->second : Entry();
389 DenseMap<GlobalVariable *, Entry> Entries;
392 /// This struct defines the shadow mapping using the rule:
393 /// shadow = (mem >> Scale) ADD-or-OR Offset.
394 struct ShadowMapping {
400 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
402 bool IsAndroid = TargetTriple.isAndroid();
403 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
404 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
405 bool IsPS4CPU = TargetTriple.isPS4CPU();
406 bool IsLinux = TargetTriple.isOSLinux();
407 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
408 TargetTriple.getArch() == llvm::Triple::ppc64le;
409 bool IsSystemZ = TargetTriple.getArch() == llvm::Triple::systemz;
410 bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86;
411 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
412 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
413 TargetTriple.getArch() == llvm::Triple::mipsel;
414 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
415 TargetTriple.getArch() == llvm::Triple::mips64el;
416 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
417 bool IsWindows = TargetTriple.isOSWindows();
418 bool IsFuchsia = TargetTriple.isOSFuchsia();
420 ShadowMapping Mapping;
422 if (LongSize == 32) {
423 // Android is always PIE, which means that the beginning of the address
424 // space is always available.
428 Mapping.Offset = kMIPS32_ShadowOffset32;
430 Mapping.Offset = kFreeBSD_ShadowOffset32;
432 // If we're targeting iOS and x86, the binary is built for iOS simulator.
433 Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
435 Mapping.Offset = kWindowsShadowOffset32;
437 Mapping.Offset = kDefaultShadowOffset32;
438 } else { // LongSize == 64
439 // Fuchsia is always PIE, which means that the beginning of the address
440 // space is always available.
444 Mapping.Offset = kPPC64_ShadowOffset64;
446 Mapping.Offset = kSystemZ_ShadowOffset64;
448 Mapping.Offset = kFreeBSD_ShadowOffset64;
450 Mapping.Offset = kPS4CPU_ShadowOffset64;
451 else if (IsLinux && IsX86_64) {
453 Mapping.Offset = kLinuxKasan_ShadowOffset64;
455 Mapping.Offset = kSmallX86_64ShadowOffset;
456 } else if (IsWindows && IsX86_64) {
457 Mapping.Offset = kWindowsShadowOffset64;
459 Mapping.Offset = kMIPS64_ShadowOffset64;
461 // If we're targeting iOS and x86, the binary is built for iOS simulator.
462 // We are using dynamic shadow offset on the 64-bit devices.
464 IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
466 Mapping.Offset = kAArch64_ShadowOffset64;
468 Mapping.Offset = kDefaultShadowOffset64;
471 if (ClForceDynamicShadow) {
472 Mapping.Offset = kDynamicShadowSentinel;
475 Mapping.Scale = kDefaultShadowScale;
476 if (ClMappingScale.getNumOccurrences() > 0) {
477 Mapping.Scale = ClMappingScale;
480 if (ClMappingOffset.getNumOccurrences() > 0) {
481 Mapping.Offset = ClMappingOffset;
484 // OR-ing shadow offset if more efficient (at least on x86) if the offset
485 // is a power of two, but on ppc64 we have to use add since the shadow
486 // offset is not necessary 1/8-th of the address space. On SystemZ,
487 // we could OR the constant in a single instruction, but it's more
488 // efficient to load it once and use indexed addressing.
489 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
490 !(Mapping.Offset & (Mapping.Offset - 1)) &&
491 Mapping.Offset != kDynamicShadowSentinel;
496 static size_t RedzoneSizeForScale(int MappingScale) {
497 // Redzone used for stack and globals is at least 32 bytes.
498 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
499 return std::max(32U, 1U << MappingScale);
502 /// AddressSanitizer: instrument the code in module to find memory bugs.
503 struct AddressSanitizer : public FunctionPass {
504 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false,
505 bool UseAfterScope = false)
506 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
507 Recover(Recover || ClRecover),
508 UseAfterScope(UseAfterScope || ClUseAfterScope),
509 LocalDynamicShadow(nullptr) {
510 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
512 StringRef getPassName() const override {
513 return "AddressSanitizerFunctionPass";
515 void getAnalysisUsage(AnalysisUsage &AU) const override {
516 AU.addRequired<DominatorTreeWrapperPass>();
517 AU.addRequired<TargetLibraryInfoWrapperPass>();
519 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
520 uint64_t ArraySize = 1;
521 if (AI.isArrayAllocation()) {
522 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
523 assert(CI && "non-constant array size");
524 ArraySize = CI->getZExtValue();
526 Type *Ty = AI.getAllocatedType();
527 uint64_t SizeInBytes =
528 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
529 return SizeInBytes * ArraySize;
531 /// Check if we want (and can) handle this alloca.
532 bool isInterestingAlloca(const AllocaInst &AI);
534 /// If it is an interesting memory access, return the PointerOperand
535 /// and set IsWrite/Alignment. Otherwise return nullptr.
536 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
537 /// masked load/store.
538 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
539 uint64_t *TypeSize, unsigned *Alignment,
540 Value **MaybeMask = nullptr);
541 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
542 bool UseCalls, const DataLayout &DL);
543 void instrumentPointerComparisonOrSubtraction(Instruction *I);
544 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
545 Value *Addr, uint32_t TypeSize, bool IsWrite,
546 Value *SizeArgument, bool UseCalls, uint32_t Exp);
547 void instrumentUnusualSizeOrAlignment(Instruction *I,
548 Instruction *InsertBefore, Value *Addr,
549 uint32_t TypeSize, bool IsWrite,
550 Value *SizeArgument, bool UseCalls,
552 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
553 Value *ShadowValue, uint32_t TypeSize);
554 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
555 bool IsWrite, size_t AccessSizeIndex,
556 Value *SizeArgument, uint32_t Exp);
557 void instrumentMemIntrinsic(MemIntrinsic *MI);
558 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
559 bool runOnFunction(Function &F) override;
560 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
561 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
562 void markEscapedLocalAllocas(Function &F);
563 bool doInitialization(Module &M) override;
564 bool doFinalization(Module &M) override;
565 static char ID; // Pass identification, replacement for typeid
567 DominatorTree &getDominatorTree() const { return *DT; }
570 void initializeCallbacks(Module &M);
572 bool LooksLikeCodeInBug11395(Instruction *I);
573 bool GlobalIsLinkerInitialized(GlobalVariable *G);
574 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
575 uint64_t TypeSize) const;
577 /// Helper to cleanup per-function state.
578 struct FunctionStateRAII {
579 AddressSanitizer *Pass;
580 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
581 assert(Pass->ProcessedAllocas.empty() &&
582 "last pass forgot to clear cache");
583 assert(!Pass->LocalDynamicShadow);
585 ~FunctionStateRAII() {
586 Pass->LocalDynamicShadow = nullptr;
587 Pass->ProcessedAllocas.clear();
598 ShadowMapping Mapping;
600 Function *AsanHandleNoReturnFunc;
601 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
602 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
603 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
604 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
605 // This array is indexed by AccessIsWrite and Experiment.
606 Function *AsanErrorCallbackSized[2][2];
607 Function *AsanMemoryAccessCallbackSized[2][2];
608 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
610 Value *LocalDynamicShadow;
611 GlobalsMetadata GlobalsMD;
612 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
614 friend struct FunctionStackPoisoner;
617 class AddressSanitizerModule : public ModulePass {
619 explicit AddressSanitizerModule(bool CompileKernel = false,
620 bool Recover = false,
621 bool UseGlobalsGC = true)
622 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
623 Recover(Recover || ClRecover),
624 UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC),
625 // Not a typo: ClWithComdat is almost completely pointless without
626 // ClUseGlobalsGC (because then it only works on modules without
627 // globals, which are rare); it is a prerequisite for ClUseGlobalsGC;
628 // and both suffer from gold PR19002 for which UseGlobalsGC constructor
629 // argument is designed as workaround. Therefore, disable both
630 // ClWithComdat and ClUseGlobalsGC unless the frontend says it's ok to
632 UseCtorComdat(UseGlobalsGC && ClWithComdat) {}
633 bool runOnModule(Module &M) override;
634 static char ID; // Pass identification, replacement for typeid
635 StringRef getPassName() const override { return "AddressSanitizerModule"; }
638 void initializeCallbacks(Module &M);
640 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat);
641 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
642 ArrayRef<GlobalVariable *> ExtendedGlobals,
643 ArrayRef<Constant *> MetadataInitializers);
644 void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
645 ArrayRef<GlobalVariable *> ExtendedGlobals,
646 ArrayRef<Constant *> MetadataInitializers,
647 const std::string &UniqueModuleId);
648 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
649 ArrayRef<GlobalVariable *> ExtendedGlobals,
650 ArrayRef<Constant *> MetadataInitializers);
652 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
653 ArrayRef<GlobalVariable *> ExtendedGlobals,
654 ArrayRef<Constant *> MetadataInitializers);
656 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
657 StringRef OriginalName);
658 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
659 StringRef InternalSuffix);
660 IRBuilder<> CreateAsanModuleDtor(Module &M);
662 bool ShouldInstrumentGlobal(GlobalVariable *G);
663 bool ShouldUseMachOGlobalsSection() const;
664 StringRef getGlobalMetadataSection() const;
665 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
666 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
667 size_t MinRedzoneSizeForGlobal() const {
668 return RedzoneSizeForScale(Mapping.Scale);
671 GlobalsMetadata GlobalsMD;
679 ShadowMapping Mapping;
680 Function *AsanPoisonGlobals;
681 Function *AsanUnpoisonGlobals;
682 Function *AsanRegisterGlobals;
683 Function *AsanUnregisterGlobals;
684 Function *AsanRegisterImageGlobals;
685 Function *AsanUnregisterImageGlobals;
686 Function *AsanRegisterElfGlobals;
687 Function *AsanUnregisterElfGlobals;
689 Function *AsanCtorFunction = nullptr;
690 Function *AsanDtorFunction = nullptr;
693 // Stack poisoning does not play well with exception handling.
694 // When an exception is thrown, we essentially bypass the code
695 // that unpoisones the stack. This is why the run-time library has
696 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
697 // stack in the interceptor. This however does not work inside the
698 // actual function which catches the exception. Most likely because the
699 // compiler hoists the load of the shadow value somewhere too high.
700 // This causes asan to report a non-existing bug on 453.povray.
701 // It sounds like an LLVM bug.
702 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
704 AddressSanitizer &ASan;
709 ShadowMapping Mapping;
711 SmallVector<AllocaInst *, 16> AllocaVec;
712 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
713 SmallVector<Instruction *, 8> RetVec;
714 unsigned StackAlignment;
716 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
717 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
718 Function *AsanSetShadowFunc[0x100] = {};
719 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
720 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
722 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
723 struct AllocaPoisonCall {
724 IntrinsicInst *InsBefore;
729 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
730 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
732 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
733 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
734 AllocaInst *DynamicAllocaLayout = nullptr;
735 IntrinsicInst *LocalEscapeCall = nullptr;
737 // Maps Value to an AllocaInst from which the Value is originated.
738 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
739 AllocaForValueMapTy AllocaForValue;
741 bool HasNonEmptyInlineAsm = false;
742 bool HasReturnsTwiceCall = false;
743 std::unique_ptr<CallInst> EmptyInlineAsm;
745 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
748 DIB(*F.getParent(), /*AllowUnresolved*/ false),
750 IntptrTy(ASan.IntptrTy),
751 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
752 Mapping(ASan.Mapping),
753 StackAlignment(1 << Mapping.Scale),
754 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
756 bool runOnFunction() {
757 if (!ClStack) return false;
759 if (ClRedzoneByvalArgs) copyArgsPassedByValToAllocas();
761 // Collect alloca, ret, lifetime instructions etc.
762 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
764 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
766 initializeCallbacks(*F.getParent());
768 processDynamicAllocas();
769 processStaticAllocas();
777 // Arguments marked with the "byval" attribute are implicitly copied without
778 // using an alloca instruction. To produce redzones for those arguments, we
779 // copy them a second time into memory allocated with an alloca instruction.
780 void copyArgsPassedByValToAllocas();
782 // Finds all Alloca instructions and puts
783 // poisoned red zones around all of them.
784 // Then unpoison everything back before the function returns.
785 void processStaticAllocas();
786 void processDynamicAllocas();
788 void createDynamicAllocasInitStorage();
790 // ----------------------- Visitors.
791 /// \brief Collect all Ret instructions.
792 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
794 /// \brief Collect all Resume instructions.
795 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
797 /// \brief Collect all CatchReturnInst instructions.
798 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
800 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
802 IRBuilder<> IRB(InstBefore);
803 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
804 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
805 // need to adjust extracted SP to compute the address of the most recent
806 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
808 if (!isa<ReturnInst>(InstBefore)) {
809 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
810 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
813 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
815 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
819 IRB.CreateCall(AsanAllocasUnpoisonFunc,
820 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
823 // Unpoison dynamic allocas redzones.
824 void unpoisonDynamicAllocas() {
825 for (auto &Ret : RetVec)
826 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
828 for (auto &StackRestoreInst : StackRestoreVec)
829 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
830 StackRestoreInst->getOperand(0));
833 // Deploy and poison redzones around dynamic alloca call. To do this, we
834 // should replace this call with another one with changed parameters and
835 // replace all its uses with new address, so
836 // addr = alloca type, old_size, align
838 // new_size = (old_size + additional_size) * sizeof(type)
839 // tmp = alloca i8, new_size, max(align, 32)
840 // addr = tmp + 32 (first 32 bytes are for the left redzone).
841 // Additional_size is added to make new memory allocation contain not only
842 // requested memory, but also left, partial and right redzones.
843 void handleDynamicAllocaCall(AllocaInst *AI);
845 /// \brief Collect Alloca instructions we want (and can) handle.
846 void visitAllocaInst(AllocaInst &AI) {
847 if (!ASan.isInterestingAlloca(AI)) {
848 if (AI.isStaticAlloca()) {
849 // Skip over allocas that are present *before* the first instrumented
850 // alloca, we don't want to move those around.
851 if (AllocaVec.empty())
854 StaticAllocasToMoveUp.push_back(&AI);
859 StackAlignment = std::max(StackAlignment, AI.getAlignment());
860 if (!AI.isStaticAlloca())
861 DynamicAllocaVec.push_back(&AI);
863 AllocaVec.push_back(&AI);
866 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
868 void visitIntrinsicInst(IntrinsicInst &II) {
869 Intrinsic::ID ID = II.getIntrinsicID();
870 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
871 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
872 if (!ASan.UseAfterScope)
874 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
876 // Found lifetime intrinsic, add ASan instrumentation if necessary.
877 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
878 // If size argument is undefined, don't do anything.
879 if (Size->isMinusOne()) return;
880 // Check that size doesn't saturate uint64_t and can
881 // be stored in IntptrTy.
882 const uint64_t SizeValue = Size->getValue().getLimitedValue();
883 if (SizeValue == ~0ULL ||
884 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
886 // Find alloca instruction that corresponds to llvm.lifetime argument.
887 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
888 if (!AI || !ASan.isInterestingAlloca(*AI))
890 bool DoPoison = (ID == Intrinsic::lifetime_end);
891 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
892 if (AI->isStaticAlloca())
893 StaticAllocaPoisonCallVec.push_back(APC);
894 else if (ClInstrumentDynamicAllocas)
895 DynamicAllocaPoisonCallVec.push_back(APC);
898 void visitCallSite(CallSite CS) {
899 Instruction *I = CS.getInstruction();
900 if (CallInst *CI = dyn_cast<CallInst>(I)) {
901 HasNonEmptyInlineAsm |=
902 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
903 HasReturnsTwiceCall |= CI->canReturnTwice();
907 // ---------------------- Helpers.
908 void initializeCallbacks(Module &M);
910 bool doesDominateAllExits(const Instruction *I) const {
911 for (auto Ret : RetVec) {
912 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
917 /// Finds alloca where the value comes from.
918 AllocaInst *findAllocaForValue(Value *V);
920 // Copies bytes from ShadowBytes into shadow memory for indexes where
921 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
922 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
923 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
924 IRBuilder<> &IRB, Value *ShadowBase);
925 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
926 size_t Begin, size_t End, IRBuilder<> &IRB,
928 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
929 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
930 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
932 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
934 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
936 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
937 Instruction *ThenTerm, Value *ValueIfFalse);
940 } // anonymous namespace
942 char AddressSanitizer::ID = 0;
943 INITIALIZE_PASS_BEGIN(
944 AddressSanitizer, "asan",
945 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
947 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
948 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
950 AddressSanitizer, "asan",
951 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
953 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
955 bool UseAfterScope) {
956 assert(!CompileKernel || Recover);
957 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
960 char AddressSanitizerModule::ID = 0;
962 AddressSanitizerModule, "asan-module",
963 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
966 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
969 assert(!CompileKernel || Recover);
970 return new AddressSanitizerModule(CompileKernel, Recover, UseGlobalsGC);
973 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
974 size_t Res = countTrailingZeros(TypeSize / 8);
975 assert(Res < kNumberOfAccessSizes);
979 // \brief Create a constant for Str so that we can pass it to the run-time lib.
980 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
982 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
983 // We use private linkage for module-local strings. If they can be merged
984 // with another one, we set the unnamed_addr attribute.
986 new GlobalVariable(M, StrConst->getType(), true,
987 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
988 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
989 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
993 /// \brief Create a global describing a source location.
994 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
995 LocationMetadata MD) {
996 Constant *LocData[] = {
997 createPrivateGlobalForString(M, MD.Filename, true),
998 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
999 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
1001 auto LocStruct = ConstantStruct::getAnon(LocData);
1002 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
1003 GlobalValue::PrivateLinkage, LocStruct,
1005 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
1009 /// \brief Check if \p G has been created by a trusted compiler pass.
1010 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
1011 // Do not instrument asan globals.
1012 if (G->getName().startswith(kAsanGenPrefix) ||
1013 G->getName().startswith(kSanCovGenPrefix) ||
1014 G->getName().startswith(kODRGenPrefix))
1017 // Do not instrument gcov counter arrays.
1018 if (G->getName() == "__llvm_gcov_ctr")
1024 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
1026 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
1027 if (Mapping.Offset == 0) return Shadow;
1028 // (Shadow >> scale) | offset
1030 if (LocalDynamicShadow)
1031 ShadowBase = LocalDynamicShadow;
1033 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
1034 if (Mapping.OrShadowOffset)
1035 return IRB.CreateOr(Shadow, ShadowBase);
1037 return IRB.CreateAdd(Shadow, ShadowBase);
1040 // Instrument memset/memmove/memcpy
1041 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
1042 IRBuilder<> IRB(MI);
1043 if (isa<MemTransferInst>(MI)) {
1045 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
1046 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1047 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
1048 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1049 } else if (isa<MemSetInst>(MI)) {
1052 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1053 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
1054 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1056 MI->eraseFromParent();
1059 /// Check if we want (and can) handle this alloca.
1060 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1061 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1063 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1064 return PreviouslySeenAllocaInfo->getSecond();
1066 bool IsInteresting =
1067 (AI.getAllocatedType()->isSized() &&
1068 // alloca() may be called with 0 size, ignore it.
1069 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1070 // We are only interested in allocas not promotable to registers.
1071 // Promotable allocas are common under -O0.
1072 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1073 // inalloca allocas are not treated as static, and we don't want
1074 // dynamic alloca instrumentation for them as well.
1075 !AI.isUsedWithInAlloca() &&
1076 // swifterror allocas are register promoted by ISel
1077 !AI.isSwiftError());
1079 ProcessedAllocas[&AI] = IsInteresting;
1080 return IsInteresting;
1083 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1086 unsigned *Alignment,
1087 Value **MaybeMask) {
1088 // Skip memory accesses inserted by another instrumentation.
1089 if (I->getMetadata("nosanitize")) return nullptr;
1091 // Do not instrument the load fetching the dynamic shadow address.
1092 if (LocalDynamicShadow == I)
1095 Value *PtrOperand = nullptr;
1096 const DataLayout &DL = I->getModule()->getDataLayout();
1097 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1098 if (!ClInstrumentReads) return nullptr;
1100 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1101 *Alignment = LI->getAlignment();
1102 PtrOperand = LI->getPointerOperand();
1103 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1104 if (!ClInstrumentWrites) return nullptr;
1106 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1107 *Alignment = SI->getAlignment();
1108 PtrOperand = SI->getPointerOperand();
1109 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1110 if (!ClInstrumentAtomics) return nullptr;
1112 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1114 PtrOperand = RMW->getPointerOperand();
1115 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1116 if (!ClInstrumentAtomics) return nullptr;
1118 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1120 PtrOperand = XCHG->getPointerOperand();
1121 } else if (auto CI = dyn_cast<CallInst>(I)) {
1122 auto *F = dyn_cast<Function>(CI->getCalledValue());
1123 if (F && (F->getName().startswith("llvm.masked.load.") ||
1124 F->getName().startswith("llvm.masked.store."))) {
1125 unsigned OpOffset = 0;
1126 if (F->getName().startswith("llvm.masked.store.")) {
1127 if (!ClInstrumentWrites)
1129 // Masked store has an initial operand for the value.
1133 if (!ClInstrumentReads)
1138 auto BasePtr = CI->getOperand(0 + OpOffset);
1139 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1140 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1141 if (auto AlignmentConstant =
1142 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1143 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1145 *Alignment = 1; // No alignment guarantees. We probably got Undef
1147 *MaybeMask = CI->getOperand(2 + OpOffset);
1148 PtrOperand = BasePtr;
1153 // Do not instrument acesses from different address spaces; we cannot deal
1155 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1156 if (PtrTy->getPointerAddressSpace() != 0)
1159 // Ignore swifterror addresses.
1160 // swifterror memory addresses are mem2reg promoted by instruction
1161 // selection. As such they cannot have regular uses like an instrumentation
1162 // function and it makes no sense to track them as memory.
1163 if (PtrOperand->isSwiftError())
1167 // Treat memory accesses to promotable allocas as non-interesting since they
1168 // will not cause memory violations. This greatly speeds up the instrumented
1169 // executable at -O0.
1170 if (ClSkipPromotableAllocas)
1171 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1172 return isInterestingAlloca(*AI) ? AI : nullptr;
1177 static bool isPointerOperand(Value *V) {
1178 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1181 // This is a rough heuristic; it may cause both false positives and
1182 // false negatives. The proper implementation requires cooperation with
1184 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1185 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1186 if (!Cmp->isRelational()) return false;
1187 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1188 if (BO->getOpcode() != Instruction::Sub) return false;
1192 return isPointerOperand(I->getOperand(0)) &&
1193 isPointerOperand(I->getOperand(1));
1196 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1197 // If a global variable does not have dynamic initialization we don't
1198 // have to instrument it. However, if a global does not have initializer
1199 // at all, we assume it has dynamic initializer (in other TU).
1200 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1203 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1206 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1207 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1208 for (Value *&i : Param) {
1209 if (i->getType()->isPointerTy())
1210 i = IRB.CreatePointerCast(i, IntptrTy);
1212 IRB.CreateCall(F, Param);
1215 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1216 Instruction *InsertBefore, Value *Addr,
1217 unsigned Alignment, unsigned Granularity,
1218 uint32_t TypeSize, bool IsWrite,
1219 Value *SizeArgument, bool UseCalls,
1221 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1222 // if the data is properly aligned.
1223 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1225 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1226 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1227 nullptr, UseCalls, Exp);
1228 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1229 IsWrite, nullptr, UseCalls, Exp);
1232 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1233 const DataLayout &DL, Type *IntptrTy,
1234 Value *Mask, Instruction *I,
1235 Value *Addr, unsigned Alignment,
1236 unsigned Granularity, uint32_t TypeSize,
1237 bool IsWrite, Value *SizeArgument,
1238 bool UseCalls, uint32_t Exp) {
1239 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1240 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1241 unsigned Num = VTy->getVectorNumElements();
1242 auto Zero = ConstantInt::get(IntptrTy, 0);
1243 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1244 Value *InstrumentedAddress = nullptr;
1245 Instruction *InsertBefore = I;
1246 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1247 // dyn_cast as we might get UndefValue
1248 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1249 if (Masked->isZero())
1250 // Mask is constant false, so no instrumentation needed.
1252 // If we have a true or undef value, fall through to doInstrumentAddress
1253 // with InsertBefore == I
1257 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1258 TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1259 InsertBefore = ThenTerm;
1262 IRBuilder<> IRB(InsertBefore);
1263 InstrumentedAddress =
1264 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1265 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1266 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1271 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1272 Instruction *I, bool UseCalls,
1273 const DataLayout &DL) {
1274 bool IsWrite = false;
1275 unsigned Alignment = 0;
1276 uint64_t TypeSize = 0;
1277 Value *MaybeMask = nullptr;
1279 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1282 // Optimization experiments.
1283 // The experiments can be used to evaluate potential optimizations that remove
1284 // instrumentation (assess false negatives). Instead of completely removing
1285 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1286 // experiments that want to remove instrumentation of this instruction).
1287 // If Exp is non-zero, this pass will emit special calls into runtime
1288 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1289 // make runtime terminate the program in a special way (with a different
1290 // exit status). Then you run the new compiler on a buggy corpus, collect
1291 // the special terminations (ideally, you don't see them at all -- no false
1292 // negatives) and make the decision on the optimization.
1293 uint32_t Exp = ClForceExperiment;
1295 if (ClOpt && ClOptGlobals) {
1296 // If initialization order checking is disabled, a simple access to a
1297 // dynamically initialized global is always valid.
1298 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1299 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1300 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1301 NumOptimizedAccessesToGlobalVar++;
1306 if (ClOpt && ClOptStack) {
1307 // A direct inbounds access to a stack variable is always valid.
1308 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1309 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1310 NumOptimizedAccessesToStackVar++;
1316 NumInstrumentedWrites++;
1318 NumInstrumentedReads++;
1320 unsigned Granularity = 1 << Mapping.Scale;
1322 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1323 Alignment, Granularity, TypeSize, IsWrite,
1324 nullptr, UseCalls, Exp);
1326 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1327 IsWrite, nullptr, UseCalls, Exp);
1331 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1332 Value *Addr, bool IsWrite,
1333 size_t AccessSizeIndex,
1334 Value *SizeArgument,
1336 IRBuilder<> IRB(InsertBefore);
1337 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1338 CallInst *Call = nullptr;
1341 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1342 {Addr, SizeArgument});
1344 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1345 {Addr, SizeArgument, ExpVal});
1349 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1351 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1355 // We don't do Call->setDoesNotReturn() because the BB already has
1356 // UnreachableInst at the end.
1357 // This EmptyAsm is required to avoid callback merge.
1358 IRB.CreateCall(EmptyAsm, {});
1362 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1364 uint32_t TypeSize) {
1365 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1366 // Addr & (Granularity - 1)
1367 Value *LastAccessedByte =
1368 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1369 // (Addr & (Granularity - 1)) + size - 1
1370 if (TypeSize / 8 > 1)
1371 LastAccessedByte = IRB.CreateAdd(
1372 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1373 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1375 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1376 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1377 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1380 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1381 Instruction *InsertBefore, Value *Addr,
1382 uint32_t TypeSize, bool IsWrite,
1383 Value *SizeArgument, bool UseCalls,
1385 IRBuilder<> IRB(InsertBefore);
1386 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1387 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1391 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1394 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1395 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1400 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1401 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1402 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1403 Value *CmpVal = Constant::getNullValue(ShadowTy);
1404 Value *ShadowValue =
1405 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1407 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1408 size_t Granularity = 1ULL << Mapping.Scale;
1409 TerminatorInst *CrashTerm = nullptr;
1411 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1412 // We use branch weights for the slow path check, to indicate that the slow
1413 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1414 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1415 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1416 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1417 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1418 IRB.SetInsertPoint(CheckTerm);
1419 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1421 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1423 BasicBlock *CrashBlock =
1424 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1425 CrashTerm = new UnreachableInst(*C, CrashBlock);
1426 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1427 ReplaceInstWithInst(CheckTerm, NewTerm);
1430 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1433 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1434 AccessSizeIndex, SizeArgument, Exp);
1435 Crash->setDebugLoc(OrigIns->getDebugLoc());
1438 // Instrument unusual size or unusual alignment.
1439 // We can not do it with a single check, so we do 1-byte check for the first
1440 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1441 // to report the actual access size.
1442 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1443 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1444 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1445 IRBuilder<> IRB(InsertBefore);
1446 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1447 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1450 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1453 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1454 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1456 Value *LastByte = IRB.CreateIntToPtr(
1457 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1459 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1460 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1464 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1465 GlobalValue *ModuleName) {
1466 // Set up the arguments to our poison/unpoison functions.
1467 IRBuilder<> IRB(&GlobalInit.front(),
1468 GlobalInit.front().getFirstInsertionPt());
1470 // Add a call to poison all external globals before the given function starts.
1471 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1472 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1474 // Add calls to unpoison all globals before each return instruction.
1475 for (auto &BB : GlobalInit.getBasicBlockList())
1476 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1477 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1480 void AddressSanitizerModule::createInitializerPoisonCalls(
1481 Module &M, GlobalValue *ModuleName) {
1482 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1486 ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
1490 for (Use &OP : CA->operands()) {
1491 if (isa<ConstantAggregateZero>(OP)) continue;
1492 ConstantStruct *CS = cast<ConstantStruct>(OP);
1494 // Must have a function or null ptr.
1495 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1496 if (F->getName() == kAsanModuleCtorName) continue;
1497 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1498 // Don't instrument CTORs that will run before asan.module_ctor.
1499 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1500 poisonOneInitializer(*F, ModuleName);
1505 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1506 Type *Ty = G->getValueType();
1507 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1509 if (GlobalsMD.get(G).IsBlacklisted) return false;
1510 if (!Ty->isSized()) return false;
1511 if (!G->hasInitializer()) return false;
1512 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1513 // Touch only those globals that will not be defined in other modules.
1514 // Don't handle ODR linkage types and COMDATs since other modules may be built
1516 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1517 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1518 G->getLinkage() != GlobalVariable::InternalLinkage)
1520 if (G->hasComdat()) return false;
1521 // Two problems with thread-locals:
1522 // - The address of the main thread's copy can't be computed at link-time.
1523 // - Need to poison all copies, not just the main thread's one.
1524 if (G->isThreadLocal()) return false;
1525 // For now, just ignore this Global if the alignment is large.
1526 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1528 if (G->hasSection()) {
1529 StringRef Section = G->getSection();
1531 // Globals from llvm.metadata aren't emitted, do not instrument them.
1532 if (Section == "llvm.metadata") return false;
1533 // Do not instrument globals from special LLVM sections.
1534 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1536 // Do not instrument function pointers to initialization and termination
1537 // routines: dynamic linker will not properly handle redzones.
1538 if (Section.startswith(".preinit_array") ||
1539 Section.startswith(".init_array") ||
1540 Section.startswith(".fini_array")) {
1544 // Callbacks put into the CRT initializer/terminator sections
1545 // should not be instrumented.
1546 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1547 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1548 if (Section.startswith(".CRT")) {
1549 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1553 if (TargetTriple.isOSBinFormatMachO()) {
1554 StringRef ParsedSegment, ParsedSection;
1555 unsigned TAA = 0, StubSize = 0;
1557 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1558 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1559 assert(ErrorCode.empty() && "Invalid section specifier.");
1561 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1562 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1564 if (ParsedSegment == "__OBJC" ||
1565 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1566 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1569 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1570 // Constant CFString instances are compiled in the following way:
1571 // -- the string buffer is emitted into
1572 // __TEXT,__cstring,cstring_literals
1573 // -- the constant NSConstantString structure referencing that buffer
1574 // is placed into __DATA,__cfstring
1575 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1576 // Moreover, it causes the linker to crash on OS X 10.7
1577 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1578 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1581 // The linker merges the contents of cstring_literals and removes the
1583 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1584 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1593 // On Mach-O platforms, we emit global metadata in a separate section of the
1594 // binary in order to allow the linker to properly dead strip. This is only
1595 // supported on recent versions of ld64.
1596 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1597 if (!TargetTriple.isOSBinFormatMachO())
1600 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1602 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1604 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1610 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1611 switch (TargetTriple.getObjectFormat()) {
1612 case Triple::COFF: return ".ASAN$GL";
1613 case Triple::ELF: return "asan_globals";
1614 case Triple::MachO: return "__DATA,__asan_globals,regular";
1617 llvm_unreachable("unsupported object format");
1620 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1621 IRBuilder<> IRB(*C);
1623 // Declare our poisoning and unpoisoning functions.
1624 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1625 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy));
1626 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1627 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1628 kAsanUnpoisonGlobalsName, IRB.getVoidTy()));
1629 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1631 // Declare functions that register/unregister globals.
1632 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1633 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy));
1634 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1635 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1636 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1637 IntptrTy, IntptrTy));
1638 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1640 // Declare the functions that find globals in a shared object and then invoke
1641 // the (un)register function on them.
1642 AsanRegisterImageGlobals =
1643 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1644 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
1645 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1647 AsanUnregisterImageGlobals =
1648 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1649 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
1650 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1652 AsanRegisterElfGlobals = checkSanitizerInterfaceFunction(
1653 M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
1654 IntptrTy, IntptrTy, IntptrTy));
1655 AsanRegisterElfGlobals->setLinkage(Function::ExternalLinkage);
1657 AsanUnregisterElfGlobals = checkSanitizerInterfaceFunction(
1658 M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
1659 IntptrTy, IntptrTy, IntptrTy));
1660 AsanUnregisterElfGlobals->setLinkage(Function::ExternalLinkage);
1663 // Put the metadata and the instrumented global in the same group. This ensures
1664 // that the metadata is discarded if the instrumented global is discarded.
1665 void AddressSanitizerModule::SetComdatForGlobalMetadata(
1666 GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
1667 Module &M = *G->getParent();
1668 Comdat *C = G->getComdat();
1670 if (!G->hasName()) {
1671 // If G is unnamed, it must be internal. Give it an artificial name
1672 // so we can put it in a comdat.
1673 assert(G->hasLocalLinkage());
1674 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1677 if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
1678 std::string Name = G->getName();
1679 Name += InternalSuffix;
1680 C = M.getOrInsertComdat(Name);
1682 C = M.getOrInsertComdat(G->getName());
1685 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1686 if (TargetTriple.isOSBinFormatCOFF())
1687 C->setSelectionKind(Comdat::NoDuplicates);
1691 assert(G->hasComdat());
1692 Metadata->setComdat(G->getComdat());
1695 // Create a separate metadata global and put it in the appropriate ASan
1696 // global registration section.
1698 AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
1699 StringRef OriginalName) {
1700 auto Linkage = TargetTriple.isOSBinFormatMachO()
1701 ? GlobalVariable::InternalLinkage
1702 : GlobalVariable::PrivateLinkage;
1703 GlobalVariable *Metadata = new GlobalVariable(
1704 M, Initializer->getType(), false, Linkage, Initializer,
1705 Twine("__asan_global_") + GlobalValue::dropLLVMManglingEscape(OriginalName));
1706 Metadata->setSection(getGlobalMetadataSection());
1710 IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) {
1712 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1713 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1714 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1716 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
1719 void AddressSanitizerModule::InstrumentGlobalsCOFF(
1720 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1721 ArrayRef<Constant *> MetadataInitializers) {
1722 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1723 auto &DL = M.getDataLayout();
1725 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1726 Constant *Initializer = MetadataInitializers[i];
1727 GlobalVariable *G = ExtendedGlobals[i];
1728 GlobalVariable *Metadata =
1729 CreateMetadataGlobal(M, Initializer, G->getName());
1731 // The MSVC linker always inserts padding when linking incrementally. We
1732 // cope with that by aligning each struct to its size, which must be a power
1734 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
1735 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
1736 "global metadata will not be padded appropriately");
1737 Metadata->setAlignment(SizeOfGlobalStruct);
1739 SetComdatForGlobalMetadata(G, Metadata, "");
1743 void AddressSanitizerModule::InstrumentGlobalsELF(
1744 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1745 ArrayRef<Constant *> MetadataInitializers,
1746 const std::string &UniqueModuleId) {
1747 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1749 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
1750 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1751 GlobalVariable *G = ExtendedGlobals[i];
1752 GlobalVariable *Metadata =
1753 CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
1754 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
1755 Metadata->setMetadata(LLVMContext::MD_associated, MD);
1756 MetadataGlobals[i] = Metadata;
1758 SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
1761 // Update llvm.compiler.used, adding the new metadata globals. This is
1762 // needed so that during LTO these variables stay alive.
1763 if (!MetadataGlobals.empty())
1764 appendToCompilerUsed(M, MetadataGlobals);
1766 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1767 // to look up the loaded image that contains it. Second, we can store in it
1768 // whether registration has already occurred, to prevent duplicate
1771 // Common linkage ensures that there is only one global per shared library.
1772 GlobalVariable *RegisteredFlag = new GlobalVariable(
1773 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1774 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1775 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1777 // Create start and stop symbols.
1778 GlobalVariable *StartELFMetadata = new GlobalVariable(
1779 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
1780 "__start_" + getGlobalMetadataSection());
1781 StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
1782 GlobalVariable *StopELFMetadata = new GlobalVariable(
1783 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
1784 "__stop_" + getGlobalMetadataSection());
1785 StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
1787 // Create a call to register the globals with the runtime.
1788 IRB.CreateCall(AsanRegisterElfGlobals,
1789 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
1790 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
1791 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
1793 // We also need to unregister globals at the end, e.g., when a shared library
1795 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1796 IRB_Dtor.CreateCall(AsanUnregisterElfGlobals,
1797 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
1798 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
1799 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
1802 void AddressSanitizerModule::InstrumentGlobalsMachO(
1803 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1804 ArrayRef<Constant *> MetadataInitializers) {
1805 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1807 // On recent Mach-O platforms, use a structure which binds the liveness of
1808 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1809 // created to be added to llvm.compiler.used
1810 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy);
1811 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
1813 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1814 Constant *Initializer = MetadataInitializers[i];
1815 GlobalVariable *G = ExtendedGlobals[i];
1816 GlobalVariable *Metadata =
1817 CreateMetadataGlobal(M, Initializer, G->getName());
1819 // On recent Mach-O platforms, we emit the global metadata in a way that
1820 // allows the linker to properly strip dead globals.
1821 auto LivenessBinder =
1822 ConstantStruct::get(LivenessTy, Initializer->getAggregateElement(0u),
1823 ConstantExpr::getPointerCast(Metadata, IntptrTy));
1824 GlobalVariable *Liveness = new GlobalVariable(
1825 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1826 Twine("__asan_binder_") + G->getName());
1827 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1828 LivenessGlobals[i] = Liveness;
1831 // Update llvm.compiler.used, adding the new liveness globals. This is
1832 // needed so that during LTO these variables stay alive. The alternative
1833 // would be to have the linker handling the LTO symbols, but libLTO
1834 // current API does not expose access to the section for each symbol.
1835 if (!LivenessGlobals.empty())
1836 appendToCompilerUsed(M, LivenessGlobals);
1838 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1839 // to look up the loaded image that contains it. Second, we can store in it
1840 // whether registration has already occurred, to prevent duplicate
1843 // common linkage ensures that there is only one global per shared library.
1844 GlobalVariable *RegisteredFlag = new GlobalVariable(
1845 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1846 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1847 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1849 IRB.CreateCall(AsanRegisterImageGlobals,
1850 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1852 // We also need to unregister globals at the end, e.g., when a shared library
1854 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1855 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1856 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1859 void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
1860 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1861 ArrayRef<Constant *> MetadataInitializers) {
1862 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1863 unsigned N = ExtendedGlobals.size();
1866 // On platforms that don't have a custom metadata section, we emit an array
1867 // of global metadata structures.
1868 ArrayType *ArrayOfGlobalStructTy =
1869 ArrayType::get(MetadataInitializers[0]->getType(), N);
1870 auto AllGlobals = new GlobalVariable(
1871 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1872 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
1874 IRB.CreateCall(AsanRegisterGlobals,
1875 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1876 ConstantInt::get(IntptrTy, N)});
1878 // We also need to unregister globals at the end, e.g., when a shared library
1880 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1881 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1882 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1883 ConstantInt::get(IntptrTy, N)});
1886 // This function replaces all global variables with new variables that have
1887 // trailing redzones. It also creates a function that poisons
1888 // redzones and inserts this function into llvm.global_ctors.
1889 // Sets *CtorComdat to true if the global registration code emitted into the
1890 // asan constructor is comdat-compatible.
1891 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat) {
1892 *CtorComdat = false;
1895 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1897 for (auto &G : M.globals()) {
1898 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1901 size_t n = GlobalsToChange.size();
1907 auto &DL = M.getDataLayout();
1909 // A global is described by a structure
1912 // size_t size_with_redzone;
1913 // const char *name;
1914 // const char *module_name;
1915 // size_t has_dynamic_init;
1916 // void *source_location;
1917 // size_t odr_indicator;
1918 // We initialize an array of such structures and pass it to a run-time call.
1919 StructType *GlobalStructTy =
1920 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1921 IntptrTy, IntptrTy, IntptrTy);
1922 SmallVector<GlobalVariable *, 16> NewGlobals(n);
1923 SmallVector<Constant *, 16> Initializers(n);
1925 bool HasDynamicallyInitializedGlobals = false;
1927 // We shouldn't merge same module names, as this string serves as unique
1928 // module ID in runtime.
1929 GlobalVariable *ModuleName = createPrivateGlobalForString(
1930 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1932 for (size_t i = 0; i < n; i++) {
1933 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1934 GlobalVariable *G = GlobalsToChange[i];
1936 auto MD = GlobalsMD.get(G);
1937 StringRef NameForGlobal = G->getName();
1938 // Create string holding the global name (use global name from metadata
1939 // if it's available, otherwise just write the name of global variable).
1940 GlobalVariable *Name = createPrivateGlobalForString(
1941 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1942 /*AllowMerging*/ true);
1944 Type *Ty = G->getValueType();
1945 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1946 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1947 // MinRZ <= RZ <= kMaxGlobalRedzone
1948 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1949 uint64_t RZ = std::max(
1950 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1951 uint64_t RightRedzoneSize = RZ;
1952 // Round up to MinRZ
1953 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1954 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1955 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1957 StructType *NewTy = StructType::get(Ty, RightRedZoneTy);
1958 Constant *NewInitializer = ConstantStruct::get(
1959 NewTy, G->getInitializer(), Constant::getNullValue(RightRedZoneTy));
1961 // Create a new global variable with enough space for a redzone.
1962 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1963 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1964 Linkage = GlobalValue::InternalLinkage;
1965 GlobalVariable *NewGlobal =
1966 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1967 "", G, G->getThreadLocalMode());
1968 NewGlobal->copyAttributesFrom(G);
1969 NewGlobal->setAlignment(MinRZ);
1971 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1972 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1974 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1975 if (Seq && Seq->isCString())
1976 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1979 // Transfer the debug info. The payload starts at offset zero so we can
1980 // copy the debug info over as is.
1981 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1982 G->getDebugInfo(GVs);
1983 for (auto *GV : GVs)
1984 NewGlobal->addDebugInfo(GV);
1987 Indices2[0] = IRB.getInt32(0);
1988 Indices2[1] = IRB.getInt32(0);
1990 G->replaceAllUsesWith(
1991 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1992 NewGlobal->takeName(G);
1993 G->eraseFromParent();
1994 NewGlobals[i] = NewGlobal;
1996 Constant *SourceLoc;
1997 if (!MD.SourceLoc.empty()) {
1998 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1999 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
2001 SourceLoc = ConstantInt::get(IntptrTy, 0);
2004 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
2005 GlobalValue *InstrumentedGlobal = NewGlobal;
2007 bool CanUsePrivateAliases =
2008 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
2009 TargetTriple.isOSBinFormatWasm();
2010 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
2011 // Create local alias for NewGlobal to avoid crash on ODR between
2012 // instrumented and non-instrumented libraries.
2013 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
2014 NameForGlobal + M.getName(), NewGlobal);
2016 // With local aliases, we need to provide another externally visible
2017 // symbol __odr_asan_XXX to detect ODR violation.
2018 auto *ODRIndicatorSym =
2019 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
2020 Constant::getNullValue(IRB.getInt8Ty()),
2021 kODRGenPrefix + NameForGlobal, nullptr,
2022 NewGlobal->getThreadLocalMode());
2024 // Set meaningful attributes for indicator symbol.
2025 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
2026 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
2027 ODRIndicatorSym->setAlignment(1);
2028 ODRIndicator = ODRIndicatorSym;
2029 InstrumentedGlobal = GA;
2032 Constant *Initializer = ConstantStruct::get(
2034 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
2035 ConstantInt::get(IntptrTy, SizeInBytes),
2036 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
2037 ConstantExpr::getPointerCast(Name, IntptrTy),
2038 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
2039 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
2040 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy));
2042 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
2044 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
2046 Initializers[i] = Initializer;
2049 std::string ELFUniqueModuleId =
2050 (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
2053 if (!ELFUniqueModuleId.empty()) {
2054 InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
2056 } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
2057 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
2058 } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
2059 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
2061 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
2064 // Create calls for poisoning before initializers run and unpoisoning after.
2065 if (HasDynamicallyInitializedGlobals)
2066 createInitializerPoisonCalls(M, ModuleName);
2072 bool AddressSanitizerModule::runOnModule(Module &M) {
2073 C = &(M.getContext());
2074 int LongSize = M.getDataLayout().getPointerSizeInBits();
2075 IntptrTy = Type::getIntNTy(*C, LongSize);
2076 TargetTriple = Triple(M.getTargetTriple());
2077 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2078 initializeCallbacks(M);
2083 // Create a module constructor. A destructor is created lazily because not all
2084 // platforms, and not all modules need it.
2085 std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
2086 M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
2087 /*InitArgs=*/{}, kAsanVersionCheckName);
2089 bool CtorComdat = true;
2090 bool Changed = false;
2091 // TODO(glider): temporarily disabled globals instrumentation for KASan.
2093 IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
2094 Changed |= InstrumentGlobals(IRB, M, &CtorComdat);
2097 // Put the constructor and destructor in comdat if both
2098 // (1) global instrumentation is not TU-specific
2099 // (2) target is ELF.
2100 if (UseCtorComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
2101 AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
2102 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority,
2104 if (AsanDtorFunction) {
2105 AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
2106 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority,
2110 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
2111 if (AsanDtorFunction)
2112 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
2118 void AddressSanitizer::initializeCallbacks(Module &M) {
2119 IRBuilder<> IRB(*C);
2120 // Create __asan_report* callbacks.
2121 // IsWrite, TypeSize and Exp are encoded in the function name.
2122 for (int Exp = 0; Exp < 2; Exp++) {
2123 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
2124 const std::string TypeStr = AccessIsWrite ? "store" : "load";
2125 const std::string ExpStr = Exp ? "exp_" : "";
2126 const std::string SuffixStr = CompileKernel ? "N" : "_n";
2127 const std::string EndingStr = Recover ? "_noabort" : "";
2129 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
2130 SmallVector<Type *, 2> Args1{1, IntptrTy};
2132 Type *ExpType = Type::getInt32Ty(*C);
2133 Args2.push_back(ExpType);
2134 Args1.push_back(ExpType);
2136 AsanErrorCallbackSized[AccessIsWrite][Exp] =
2137 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2138 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr +
2140 FunctionType::get(IRB.getVoidTy(), Args2, false)));
2142 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
2143 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2144 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
2145 FunctionType::get(IRB.getVoidTy(), Args2, false)));
2147 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
2148 AccessSizeIndex++) {
2149 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
2150 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2151 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2152 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
2153 FunctionType::get(IRB.getVoidTy(), Args1, false)));
2155 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2156 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2157 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
2158 FunctionType::get(IRB.getVoidTy(), Args1, false)));
2163 const std::string MemIntrinCallbackPrefix =
2164 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
2165 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2166 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
2167 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy));
2168 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2169 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
2170 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy));
2171 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2172 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
2173 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy));
2175 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
2176 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy()));
2178 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2179 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy));
2180 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2181 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy));
2182 // We insert an empty inline asm after __asan_report* to avoid callback merge.
2183 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
2184 StringRef(""), StringRef(""),
2185 /*hasSideEffects=*/true);
2189 bool AddressSanitizer::doInitialization(Module &M) {
2190 // Initialize the private fields. No one has accessed them before.
2193 C = &(M.getContext());
2194 LongSize = M.getDataLayout().getPointerSizeInBits();
2195 IntptrTy = Type::getIntNTy(*C, LongSize);
2196 TargetTriple = Triple(M.getTargetTriple());
2198 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2202 bool AddressSanitizer::doFinalization(Module &M) {
2207 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2208 // For each NSObject descendant having a +load method, this method is invoked
2209 // by the ObjC runtime before any of the static constructors is called.
2210 // Therefore we need to instrument such methods with a call to __asan_init
2211 // at the beginning in order to initialize our runtime before any access to
2212 // the shadow memory.
2213 // We cannot just ignore these methods, because they may call other
2214 // instrumented functions.
2215 if (F.getName().find(" load]") != std::string::npos) {
2216 Function *AsanInitFunction =
2217 declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
2218 IRBuilder<> IRB(&F.front(), F.front().begin());
2219 IRB.CreateCall(AsanInitFunction, {});
2225 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2226 // Generate code only when dynamic addressing is needed.
2227 if (Mapping.Offset != kDynamicShadowSentinel)
2230 IRBuilder<> IRB(&F.front().front());
2231 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2232 kAsanShadowMemoryDynamicAddress, IntptrTy);
2233 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
2236 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2237 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2238 // to it as uninteresting. This assumes we haven't started processing allocas
2239 // yet. This check is done up front because iterating the use list in
2240 // isInterestingAlloca would be algorithmically slower.
2241 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2243 // Try to get the declaration of llvm.localescape. If it's not in the module,
2244 // we can exit early.
2245 if (!F.getParent()->getFunction("llvm.localescape")) return;
2247 // Look for a call to llvm.localescape call in the entry block. It can't be in
2249 for (Instruction &I : F.getEntryBlock()) {
2250 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2251 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2252 // We found a call. Mark all the allocas passed in as uninteresting.
2253 for (Value *Arg : II->arg_operands()) {
2254 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2255 assert(AI && AI->isStaticAlloca() &&
2256 "non-static alloca arg to localescape");
2257 ProcessedAllocas[AI] = false;
2264 bool AddressSanitizer::runOnFunction(Function &F) {
2265 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2266 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2267 if (F.getName().startswith("__asan_")) return false;
2269 bool FunctionModified = false;
2271 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2272 // This function needs to be called even if the function body is not
2274 if (maybeInsertAsanInitAtFunctionEntry(F))
2275 FunctionModified = true;
2277 // Leave if the function doesn't need instrumentation.
2278 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2280 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2282 initializeCallbacks(*F.getParent());
2283 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2285 FunctionStateRAII CleanupObj(this);
2287 maybeInsertDynamicShadowAtFunctionEntry(F);
2289 // We can't instrument allocas used with llvm.localescape. Only static allocas
2290 // can be passed to that intrinsic.
2291 markEscapedLocalAllocas(F);
2293 // We want to instrument every address only once per basic block (unless there
2294 // are calls between uses).
2295 SmallSet<Value *, 16> TempsToInstrument;
2296 SmallVector<Instruction *, 16> ToInstrument;
2297 SmallVector<Instruction *, 8> NoReturnCalls;
2298 SmallVector<BasicBlock *, 16> AllBlocks;
2299 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2304 const TargetLibraryInfo *TLI =
2305 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2307 // Fill the set of memory operations to instrument.
2308 for (auto &BB : F) {
2309 AllBlocks.push_back(&BB);
2310 TempsToInstrument.clear();
2311 int NumInsnsPerBB = 0;
2312 for (auto &Inst : BB) {
2313 if (LooksLikeCodeInBug11395(&Inst)) return false;
2314 Value *MaybeMask = nullptr;
2315 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2316 &Alignment, &MaybeMask)) {
2317 if (ClOpt && ClOptSameTemp) {
2318 // If we have a mask, skip instrumentation if we've already
2319 // instrumented the full object. But don't add to TempsToInstrument
2320 // because we might get another load/store with a different mask.
2322 if (TempsToInstrument.count(Addr))
2323 continue; // We've seen this (whole) temp in the current BB.
2325 if (!TempsToInstrument.insert(Addr).second)
2326 continue; // We've seen this temp in the current BB.
2329 } else if (ClInvalidPointerPairs &&
2330 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2331 PointerComparisonsOrSubtracts.push_back(&Inst);
2333 } else if (isa<MemIntrinsic>(Inst)) {
2336 if (isa<AllocaInst>(Inst)) NumAllocas++;
2339 // A call inside BB.
2340 TempsToInstrument.clear();
2341 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2343 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2344 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2347 ToInstrument.push_back(&Inst);
2349 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2355 (ClInstrumentationWithCallsThreshold >= 0 &&
2356 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2357 const DataLayout &DL = F.getParent()->getDataLayout();
2358 ObjectSizeOpts ObjSizeOpts;
2359 ObjSizeOpts.RoundToAlign = true;
2360 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
2363 int NumInstrumented = 0;
2364 for (auto Inst : ToInstrument) {
2365 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2366 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2367 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2368 instrumentMop(ObjSizeVis, Inst, UseCalls,
2369 F.getParent()->getDataLayout());
2371 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2376 FunctionStackPoisoner FSP(F, *this);
2377 bool ChangedStack = FSP.runOnFunction();
2379 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2380 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2381 for (auto CI : NoReturnCalls) {
2382 IRBuilder<> IRB(CI);
2383 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2386 for (auto Inst : PointerComparisonsOrSubtracts) {
2387 instrumentPointerComparisonOrSubtraction(Inst);
2391 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2392 FunctionModified = true;
2394 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2397 return FunctionModified;
2400 // Workaround for bug 11395: we don't want to instrument stack in functions
2401 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2402 // FIXME: remove once the bug 11395 is fixed.
2403 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2404 if (LongSize != 32) return false;
2405 CallInst *CI = dyn_cast<CallInst>(I);
2406 if (!CI || !CI->isInlineAsm()) return false;
2407 if (CI->getNumArgOperands() <= 5) return false;
2408 // We have inline assembly with quite a few arguments.
2412 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2413 IRBuilder<> IRB(*C);
2414 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2415 std::string Suffix = itostr(i);
2416 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2417 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2419 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2420 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2421 IRB.getVoidTy(), IntptrTy, IntptrTy));
2423 if (ASan.UseAfterScope) {
2424 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2425 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2426 IntptrTy, IntptrTy));
2427 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2428 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2429 IntptrTy, IntptrTy));
2432 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2433 std::ostringstream Name;
2434 Name << kAsanSetShadowPrefix;
2435 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2436 AsanSetShadowFunc[Val] =
2437 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2438 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy));
2441 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2442 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy));
2443 AsanAllocasUnpoisonFunc =
2444 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2445 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy));
2448 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2449 ArrayRef<uint8_t> ShadowBytes,
2450 size_t Begin, size_t End,
2452 Value *ShadowBase) {
2456 const size_t LargestStoreSizeInBytes =
2457 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2459 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2461 // Poison given range in shadow using larges store size with out leading and
2462 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2463 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2464 // middle of a store.
2465 for (size_t i = Begin; i < End;) {
2466 if (!ShadowMask[i]) {
2467 assert(!ShadowBytes[i]);
2472 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2473 // Fit store size into the range.
2474 while (StoreSizeInBytes > End - i)
2475 StoreSizeInBytes /= 2;
2477 // Minimize store size by trimming trailing zeros.
2478 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2479 while (j <= StoreSizeInBytes / 2)
2480 StoreSizeInBytes /= 2;
2484 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2486 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2488 Val = (Val << 8) | ShadowBytes[i + j];
2491 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2492 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2493 IRB.CreateAlignedStore(
2494 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2496 i += StoreSizeInBytes;
2500 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2501 ArrayRef<uint8_t> ShadowBytes,
2502 IRBuilder<> &IRB, Value *ShadowBase) {
2503 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2506 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2507 ArrayRef<uint8_t> ShadowBytes,
2508 size_t Begin, size_t End,
2509 IRBuilder<> &IRB, Value *ShadowBase) {
2510 assert(ShadowMask.size() == ShadowBytes.size());
2511 size_t Done = Begin;
2512 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2513 if (!ShadowMask[i]) {
2514 assert(!ShadowBytes[i]);
2517 uint8_t Val = ShadowBytes[i];
2518 if (!AsanSetShadowFunc[Val])
2521 // Skip same values.
2522 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2525 if (j - i >= ClMaxInlinePoisoningSize) {
2526 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2527 IRB.CreateCall(AsanSetShadowFunc[Val],
2528 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2529 ConstantInt::get(IntptrTy, j - i)});
2534 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2537 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2538 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2539 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2540 assert(LocalStackSize <= kMaxStackMallocSize);
2541 uint64_t MaxSize = kMinStackMallocSize;
2542 for (int i = 0;; i++, MaxSize *= 2)
2543 if (LocalStackSize <= MaxSize) return i;
2544 llvm_unreachable("impossible LocalStackSize");
2547 void FunctionStackPoisoner::copyArgsPassedByValToAllocas() {
2548 BasicBlock &FirstBB = *F.begin();
2549 IRBuilder<> IRB(&FirstBB, FirstBB.getFirstInsertionPt());
2550 const DataLayout &DL = F.getParent()->getDataLayout();
2551 for (Argument &Arg : F.args()) {
2552 if (Arg.hasByValAttr()) {
2553 Type *Ty = Arg.getType()->getPointerElementType();
2554 unsigned Align = Arg.getParamAlignment();
2555 if (Align == 0) Align = DL.getABITypeAlignment(Ty);
2557 const std::string &Name = Arg.hasName() ? Arg.getName().str() :
2558 "Arg" + llvm::to_string(Arg.getArgNo());
2559 AllocaInst *AI = IRB.CreateAlloca(Ty, nullptr, Twine(Name) + ".byval");
2560 AI->setAlignment(Align);
2561 Arg.replaceAllUsesWith(AI);
2563 uint64_t AllocSize = DL.getTypeAllocSize(Ty);
2564 IRB.CreateMemCpy(AI, &Arg, AllocSize, Align);
2569 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2571 Instruction *ThenTerm,
2572 Value *ValueIfFalse) {
2573 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2574 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2575 PHI->addIncoming(ValueIfFalse, CondBlock);
2576 BasicBlock *ThenBlock = ThenTerm->getParent();
2577 PHI->addIncoming(ValueIfTrue, ThenBlock);
2581 Value *FunctionStackPoisoner::createAllocaForLayout(
2582 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2585 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2586 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2589 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2590 nullptr, "MyAlloca");
2591 assert(Alloca->isStaticAlloca());
2593 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2594 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2595 Alloca->setAlignment(FrameAlignment);
2596 return IRB.CreatePointerCast(Alloca, IntptrTy);
2599 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2600 BasicBlock &FirstBB = *F.begin();
2601 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2602 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2603 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2604 DynamicAllocaLayout->setAlignment(32);
2607 void FunctionStackPoisoner::processDynamicAllocas() {
2608 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2609 assert(DynamicAllocaPoisonCallVec.empty());
2613 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2614 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2615 assert(APC.InsBefore);
2617 assert(ASan.isInterestingAlloca(*APC.AI));
2618 assert(!APC.AI->isStaticAlloca());
2620 IRBuilder<> IRB(APC.InsBefore);
2621 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2622 // Dynamic allocas will be unpoisoned unconditionally below in
2623 // unpoisonDynamicAllocas.
2624 // Flag that we need unpoison static allocas.
2627 // Handle dynamic allocas.
2628 createDynamicAllocasInitStorage();
2629 for (auto &AI : DynamicAllocaVec)
2630 handleDynamicAllocaCall(AI);
2631 unpoisonDynamicAllocas();
2634 void FunctionStackPoisoner::processStaticAllocas() {
2635 if (AllocaVec.empty()) {
2636 assert(StaticAllocaPoisonCallVec.empty());
2640 int StackMallocIdx = -1;
2641 DebugLoc EntryDebugLocation;
2642 if (auto SP = F.getSubprogram())
2643 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2645 Instruction *InsBefore = AllocaVec[0];
2646 IRBuilder<> IRB(InsBefore);
2647 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2649 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2650 // debug info is broken, because only entry-block allocas are treated as
2651 // regular stack slots.
2652 auto InsBeforeB = InsBefore->getParent();
2653 assert(InsBeforeB == &F.getEntryBlock());
2654 for (auto *AI : StaticAllocasToMoveUp)
2655 if (AI->getParent() == InsBeforeB)
2656 AI->moveBefore(InsBefore);
2658 // If we have a call to llvm.localescape, keep it in the entry block.
2659 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2661 SmallVector<ASanStackVariableDescription, 16> SVD;
2662 SVD.reserve(AllocaVec.size());
2663 for (AllocaInst *AI : AllocaVec) {
2664 ASanStackVariableDescription D = {AI->getName().data(),
2665 ASan.getAllocaSizeInBytes(*AI),
2674 // Minimal header size (left redzone) is 4 pointers,
2675 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2676 size_t MinHeaderSize = ASan.LongSize / 2;
2677 const ASanStackFrameLayout &L =
2678 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2680 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2681 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2682 for (auto &Desc : SVD)
2683 AllocaToSVDMap[Desc.AI] = &Desc;
2685 // Update SVD with information from lifetime intrinsics.
2686 for (const auto &APC : StaticAllocaPoisonCallVec) {
2687 assert(APC.InsBefore);
2689 assert(ASan.isInterestingAlloca(*APC.AI));
2690 assert(APC.AI->isStaticAlloca());
2692 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2693 Desc.LifetimeSize = Desc.Size;
2694 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2695 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2696 if (LifetimeLoc->getFile() == FnLoc->getFile())
2697 if (unsigned Line = LifetimeLoc->getLine())
2698 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2703 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2704 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2705 uint64_t LocalStackSize = L.FrameSize;
2706 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2707 LocalStackSize <= kMaxStackMallocSize;
2708 bool DoDynamicAlloca = ClDynamicAllocaStack;
2709 // Don't do dynamic alloca or stack malloc if:
2710 // 1) There is inline asm: too often it makes assumptions on which registers
2712 // 2) There is a returns_twice call (typically setjmp), which is
2713 // optimization-hostile, and doesn't play well with introduced indirect
2714 // register-relative calculation of local variable addresses.
2715 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2716 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2718 Value *StaticAlloca =
2719 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2722 Value *LocalStackBase;
2724 if (DoStackMalloc) {
2725 // void *FakeStack = __asan_option_detect_stack_use_after_return
2726 // ? __asan_stack_malloc_N(LocalStackSize)
2728 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2729 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2730 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2731 Value *UseAfterReturnIsEnabled =
2732 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2733 Constant::getNullValue(IRB.getInt32Ty()));
2735 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2736 IRBuilder<> IRBIf(Term);
2737 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2738 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2739 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2740 Value *FakeStackValue =
2741 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2742 ConstantInt::get(IntptrTy, LocalStackSize));
2743 IRB.SetInsertPoint(InsBefore);
2744 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2745 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2746 ConstantInt::get(IntptrTy, 0));
2748 Value *NoFakeStack =
2749 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2750 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2751 IRBIf.SetInsertPoint(Term);
2752 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2753 Value *AllocaValue =
2754 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2755 IRB.SetInsertPoint(InsBefore);
2756 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2757 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2759 // void *FakeStack = nullptr;
2760 // void *LocalStackBase = alloca(LocalStackSize);
2761 FakeStack = ConstantInt::get(IntptrTy, 0);
2763 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2766 // Replace Alloca instructions with base+offset.
2767 for (const auto &Desc : SVD) {
2768 AllocaInst *AI = Desc.AI;
2769 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2770 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2772 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, DIExpression::NoDeref);
2773 AI->replaceAllUsesWith(NewAllocaPtr);
2776 // The left-most redzone has enough space for at least 4 pointers.
2777 // Write the Magic value to redzone[0].
2778 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2779 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2781 // Write the frame description constant to redzone[1].
2782 Value *BasePlus1 = IRB.CreateIntToPtr(
2783 IRB.CreateAdd(LocalStackBase,
2784 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2786 GlobalVariable *StackDescriptionGlobal =
2787 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2788 /*AllowMerging*/ true);
2789 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2790 IRB.CreateStore(Description, BasePlus1);
2791 // Write the PC to redzone[2].
2792 Value *BasePlus2 = IRB.CreateIntToPtr(
2793 IRB.CreateAdd(LocalStackBase,
2794 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2796 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2798 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2800 // Poison the stack red zones at the entry.
2801 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2802 // As mask we must use most poisoned case: red zones and after scope.
2803 // As bytes we can use either the same or just red zones only.
2804 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2806 if (!StaticAllocaPoisonCallVec.empty()) {
2807 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2809 // Poison static allocas near lifetime intrinsics.
2810 for (const auto &APC : StaticAllocaPoisonCallVec) {
2811 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2812 assert(Desc.Offset % L.Granularity == 0);
2813 size_t Begin = Desc.Offset / L.Granularity;
2814 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2816 IRBuilder<> IRB(APC.InsBefore);
2817 copyToShadow(ShadowAfterScope,
2818 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2823 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2824 SmallVector<uint8_t, 64> ShadowAfterReturn;
2826 // (Un)poison the stack before all ret instructions.
2827 for (auto Ret : RetVec) {
2828 IRBuilder<> IRBRet(Ret);
2829 // Mark the current frame as retired.
2830 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2832 if (DoStackMalloc) {
2833 assert(StackMallocIdx >= 0);
2834 // if FakeStack != 0 // LocalStackBase == FakeStack
2835 // // In use-after-return mode, poison the whole stack frame.
2836 // if StackMallocIdx <= 4
2837 // // For small sizes inline the whole thing:
2838 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2839 // **SavedFlagPtr(FakeStack) = 0
2841 // __asan_stack_free_N(FakeStack, LocalStackSize)
2843 // <This is not a fake stack; unpoison the redzones>
2845 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2846 TerminatorInst *ThenTerm, *ElseTerm;
2847 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2849 IRBuilder<> IRBPoison(ThenTerm);
2850 if (StackMallocIdx <= 4) {
2851 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2852 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2853 kAsanStackUseAfterReturnMagic);
2854 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2856 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2858 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2859 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2860 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2861 IRBPoison.CreateStore(
2862 Constant::getNullValue(IRBPoison.getInt8Ty()),
2863 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2865 // For larger frames call __asan_stack_free_*.
2866 IRBPoison.CreateCall(
2867 AsanStackFreeFunc[StackMallocIdx],
2868 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2871 IRBuilder<> IRBElse(ElseTerm);
2872 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2874 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2878 // We are done. Remove the old unused alloca instructions.
2879 for (auto AI : AllocaVec) AI->eraseFromParent();
2882 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2883 IRBuilder<> &IRB, bool DoPoison) {
2884 // For now just insert the call to ASan runtime.
2885 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2886 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2888 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2889 {AddrArg, SizeArg});
2892 // Handling llvm.lifetime intrinsics for a given %alloca:
2893 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2894 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2895 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2896 // could be poisoned by previous llvm.lifetime.end instruction, as the
2897 // variable may go in and out of scope several times, e.g. in loops).
2898 // (3) if we poisoned at least one %alloca in a function,
2899 // unpoison the whole stack frame at function exit.
2901 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2902 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2903 // We're interested only in allocas we can handle.
2904 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2905 // See if we've already calculated (or started to calculate) alloca for a
2907 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2908 if (I != AllocaForValue.end()) return I->second;
2909 // Store 0 while we're calculating alloca for value V to avoid
2910 // infinite recursion if the value references itself.
2911 AllocaForValue[V] = nullptr;
2912 AllocaInst *Res = nullptr;
2913 if (CastInst *CI = dyn_cast<CastInst>(V))
2914 Res = findAllocaForValue(CI->getOperand(0));
2915 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2916 for (Value *IncValue : PN->incoming_values()) {
2917 // Allow self-referencing phi-nodes.
2918 if (IncValue == PN) continue;
2919 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2920 // AI for incoming values should exist and should all be equal.
2921 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2925 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2926 Res = findAllocaForValue(EP->getPointerOperand());
2928 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2930 if (Res) AllocaForValue[V] = Res;
2934 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2935 IRBuilder<> IRB(AI);
2937 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2938 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2940 Value *Zero = Constant::getNullValue(IntptrTy);
2941 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2942 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2944 // Since we need to extend alloca with additional memory to locate
2945 // redzones, and OldSize is number of allocated blocks with
2946 // ElementSize size, get allocated memory size in bytes by
2947 // OldSize * ElementSize.
2948 const unsigned ElementSize =
2949 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2951 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2952 ConstantInt::get(IntptrTy, ElementSize));
2954 // PartialSize = OldSize % 32
2955 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2957 // Misalign = kAllocaRzSize - PartialSize;
2958 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2960 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2961 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2962 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2964 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2965 // Align is added to locate left redzone, PartialPadding for possible
2966 // partial redzone and kAllocaRzSize for right redzone respectively.
2967 Value *AdditionalChunkSize = IRB.CreateAdd(
2968 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2970 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2972 // Insert new alloca with new NewSize and Align params.
2973 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2974 NewAlloca->setAlignment(Align);
2976 // NewAddress = Address + Align
2977 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2978 ConstantInt::get(IntptrTy, Align));
2980 // Insert __asan_alloca_poison call for new created alloca.
2981 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2983 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2984 // for unpoisoning stuff.
2985 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2987 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2989 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2990 AI->replaceAllUsesWith(NewAddressPtr);
2992 // We are done. Erase old alloca from parent.
2993 AI->eraseFromParent();
2996 // isSafeAccess returns true if Addr is always inbounds with respect to its
2997 // base object. For example, it is a field access or an array access with
2998 // constant inbounds index.
2999 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
3000 Value *Addr, uint64_t TypeSize) const {
3001 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
3002 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
3003 uint64_t Size = SizeOffset.first.getZExtValue();
3004 int64_t Offset = SizeOffset.second.getSExtValue();
3005 // Three checks are required to ensure safety:
3006 // . Offset >= 0 (since the offset is given from the base ptr)
3007 // . Size >= Offset (unsigned)
3008 // . Size - Offset >= NeededSize (unsigned)
3009 return Offset >= 0 && Size >= uint64_t(Offset) &&
3010 Size - uint64_t(Offset) >= TypeSize / 8;