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/Analysis/MemoryBuiltins.h"
26 #include "llvm/Analysis/TargetLibraryInfo.h"
27 #include "llvm/Analysis/ValueTracking.h"
28 #include "llvm/IR/CallSite.h"
29 #include "llvm/IR/DIBuilder.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/Dominators.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/IRBuilder.h"
34 #include "llvm/IR/InlineAsm.h"
35 #include "llvm/IR/InstVisitor.h"
36 #include "llvm/IR/IntrinsicInst.h"
37 #include "llvm/IR/LLVMContext.h"
38 #include "llvm/IR/MDBuilder.h"
39 #include "llvm/IR/Module.h"
40 #include "llvm/IR/Type.h"
41 #include "llvm/MC/MCSectionMachO.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/DataTypes.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/Support/Endian.h"
46 #include "llvm/Support/SwapByteOrder.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include "llvm/Transforms/Instrumentation.h"
49 #include "llvm/Transforms/Scalar.h"
50 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
51 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
52 #include "llvm/Transforms/Utils/Cloning.h"
53 #include "llvm/Transforms/Utils/Local.h"
54 #include "llvm/Transforms/Utils/ModuleUtils.h"
55 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
61 #include <system_error>
65 #define DEBUG_TYPE "asan"
67 static const uint64_t kDefaultShadowScale = 3;
68 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
69 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
70 static const uint64_t kDynamicShadowSentinel = ~(uint64_t)0;
71 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
72 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
73 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
74 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
75 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
76 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
77 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
78 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
79 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
80 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
81 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
82 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
83 static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;
84 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
85 // The shadow memory space is dynamically allocated.
86 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
88 static const size_t kMinStackMallocSize = 1 << 6; // 64B
89 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
90 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
91 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
93 static const char *const kAsanModuleCtorName = "asan.module_ctor";
94 static const char *const kAsanModuleDtorName = "asan.module_dtor";
95 static const uint64_t kAsanCtorAndDtorPriority = 1;
96 static const char *const kAsanReportErrorTemplate = "__asan_report_";
97 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
98 static const char *const kAsanUnregisterGlobalsName =
99 "__asan_unregister_globals";
100 static const char *const kAsanRegisterImageGlobalsName =
101 "__asan_register_image_globals";
102 static const char *const kAsanUnregisterImageGlobalsName =
103 "__asan_unregister_image_globals";
104 static const char *const kAsanRegisterElfGlobalsName =
105 "__asan_register_elf_globals";
106 static const char *const kAsanUnregisterElfGlobalsName =
107 "__asan_unregister_elf_globals";
108 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
109 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
110 static const char *const kAsanInitName = "__asan_init";
111 static const char *const kAsanVersionCheckName =
112 "__asan_version_mismatch_check_v8";
113 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
114 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
115 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
116 static const int kMaxAsanStackMallocSizeClass = 10;
117 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
118 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
119 static const char *const kAsanGenPrefix = "__asan_gen_";
120 static const char *const kODRGenPrefix = "__odr_asan_gen_";
121 static const char *const kSanCovGenPrefix = "__sancov_gen_";
122 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
123 static const char *const kAsanPoisonStackMemoryName =
124 "__asan_poison_stack_memory";
125 static const char *const kAsanUnpoisonStackMemoryName =
126 "__asan_unpoison_stack_memory";
128 // ASan version script has __asan_* wildcard. Triple underscore prevents a
129 // linker (gold) warning about attempting to export a local symbol.
130 static const char *const kAsanGlobalsRegisteredFlagName =
131 "___asan_globals_registered";
133 static const char *const kAsanOptionDetectUseAfterReturn =
134 "__asan_option_detect_stack_use_after_return";
136 static const char *const kAsanShadowMemoryDynamicAddress =
137 "__asan_shadow_memory_dynamic_address";
139 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
140 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
142 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
143 static const size_t kNumberOfAccessSizes = 5;
145 static const unsigned kAllocaRzSize = 32;
147 // Command-line flags.
148 static cl::opt<bool> ClEnableKasan(
149 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
150 cl::Hidden, cl::init(false));
151 static cl::opt<bool> ClRecover(
153 cl::desc("Enable recovery mode (continue-after-error)."),
154 cl::Hidden, cl::init(false));
156 // This flag may need to be replaced with -f[no-]asan-reads.
157 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
158 cl::desc("instrument read instructions"),
159 cl::Hidden, cl::init(true));
160 static cl::opt<bool> ClInstrumentWrites(
161 "asan-instrument-writes", cl::desc("instrument write instructions"),
162 cl::Hidden, cl::init(true));
163 static cl::opt<bool> ClInstrumentAtomics(
164 "asan-instrument-atomics",
165 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
167 static cl::opt<bool> ClAlwaysSlowPath(
168 "asan-always-slow-path",
169 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
171 static cl::opt<bool> ClForceDynamicShadow(
172 "asan-force-dynamic-shadow",
173 cl::desc("Load shadow address into a local variable for each function"),
174 cl::Hidden, cl::init(false));
176 // This flag limits the number of instructions to be instrumented
177 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
178 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
180 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
181 "asan-max-ins-per-bb", cl::init(10000),
182 cl::desc("maximal number of instructions to instrument in any given BB"),
184 // This flag may need to be replaced with -f[no]asan-stack.
185 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
186 cl::Hidden, cl::init(true));
187 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
188 "asan-max-inline-poisoning-size",
190 "Inline shadow poisoning for blocks up to the given size in bytes."),
191 cl::Hidden, cl::init(64));
192 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
193 cl::desc("Check stack-use-after-return"),
194 cl::Hidden, cl::init(true));
195 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
196 cl::desc("Check stack-use-after-scope"),
197 cl::Hidden, cl::init(false));
198 // This flag may need to be replaced with -f[no]asan-globals.
199 static cl::opt<bool> ClGlobals("asan-globals",
200 cl::desc("Handle global objects"), cl::Hidden,
202 static cl::opt<bool> ClInitializers("asan-initialization-order",
203 cl::desc("Handle C++ initializer order"),
204 cl::Hidden, cl::init(true));
205 static cl::opt<bool> ClInvalidPointerPairs(
206 "asan-detect-invalid-pointer-pair",
207 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
209 static cl::opt<unsigned> ClRealignStack(
210 "asan-realign-stack",
211 cl::desc("Realign stack to the value of this flag (power of two)"),
212 cl::Hidden, cl::init(32));
213 static cl::opt<int> ClInstrumentationWithCallsThreshold(
214 "asan-instrumentation-with-call-threshold",
216 "If the function being instrumented contains more than "
217 "this number of memory accesses, use callbacks instead of "
218 "inline checks (-1 means never use callbacks)."),
219 cl::Hidden, cl::init(7000));
220 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
221 "asan-memory-access-callback-prefix",
222 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
223 cl::init("__asan_"));
225 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
226 cl::desc("instrument dynamic allocas"),
227 cl::Hidden, cl::init(true));
228 static cl::opt<bool> ClSkipPromotableAllocas(
229 "asan-skip-promotable-allocas",
230 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
233 // These flags allow to change the shadow mapping.
234 // The shadow mapping looks like
235 // Shadow = (Mem >> scale) + offset
236 static cl::opt<int> ClMappingScale("asan-mapping-scale",
237 cl::desc("scale of asan shadow mapping"),
238 cl::Hidden, cl::init(0));
239 static cl::opt<unsigned long long> ClMappingOffset(
240 "asan-mapping-offset",
241 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
244 // Optimization flags. Not user visible, used mostly for testing
245 // and benchmarking the tool.
246 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
247 cl::Hidden, cl::init(true));
248 static cl::opt<bool> ClOptSameTemp(
249 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
250 cl::Hidden, cl::init(true));
251 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
252 cl::desc("Don't instrument scalar globals"),
253 cl::Hidden, cl::init(true));
254 static cl::opt<bool> ClOptStack(
255 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
256 cl::Hidden, cl::init(false));
258 static cl::opt<bool> ClDynamicAllocaStack(
259 "asan-stack-dynamic-alloca",
260 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
263 static cl::opt<uint32_t> ClForceExperiment(
264 "asan-force-experiment",
265 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
269 ClUsePrivateAliasForGlobals("asan-use-private-alias",
270 cl::desc("Use private aliases for global"
272 cl::Hidden, cl::init(false));
275 ClUseGlobalsGC("asan-globals-live-support",
276 cl::desc("Use linker features to support dead "
277 "code stripping of globals"),
278 cl::Hidden, cl::init(true));
280 // This is on by default even though there is a bug in gold:
281 // https://sourceware.org/bugzilla/show_bug.cgi?id=19002
283 ClWithComdat("asan-with-comdat",
284 cl::desc("Place ASan constructors in comdat sections"),
285 cl::Hidden, cl::init(true));
288 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
290 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
291 cl::Hidden, cl::init(0));
292 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
293 cl::desc("Debug func"));
294 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
295 cl::Hidden, cl::init(-1));
296 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
297 cl::Hidden, cl::init(-1));
299 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
300 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
301 STATISTIC(NumOptimizedAccessesToGlobalVar,
302 "Number of optimized accesses to global vars");
303 STATISTIC(NumOptimizedAccessesToStackVar,
304 "Number of optimized accesses to stack vars");
307 /// Frontend-provided metadata for source location.
308 struct LocationMetadata {
313 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
315 bool empty() const { return Filename.empty(); }
317 void parse(MDNode *MDN) {
318 assert(MDN->getNumOperands() == 3);
319 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
320 Filename = DIFilename->getString();
322 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
324 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
328 /// Frontend-provided metadata for global variables.
329 class GlobalsMetadata {
332 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
333 LocationMetadata SourceLoc;
339 GlobalsMetadata() : inited_(false) {}
346 void init(Module &M) {
349 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
350 if (!Globals) return;
351 for (auto MDN : Globals->operands()) {
352 // Metadata node contains the global and the fields of "Entry".
353 assert(MDN->getNumOperands() == 5);
354 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
355 // The optimizer may optimize away a global entirely.
357 // We can already have an entry for GV if it was merged with another
359 Entry &E = Entries[GV];
360 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
361 E.SourceLoc.parse(Loc);
362 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
363 E.Name = Name->getString();
364 ConstantInt *IsDynInit =
365 mdconst::extract<ConstantInt>(MDN->getOperand(3));
366 E.IsDynInit |= IsDynInit->isOne();
367 ConstantInt *IsBlacklisted =
368 mdconst::extract<ConstantInt>(MDN->getOperand(4));
369 E.IsBlacklisted |= IsBlacklisted->isOne();
373 /// Returns metadata entry for a given global.
374 Entry get(GlobalVariable *G) const {
375 auto Pos = Entries.find(G);
376 return (Pos != Entries.end()) ? Pos->second : Entry();
381 DenseMap<GlobalVariable *, Entry> Entries;
384 /// This struct defines the shadow mapping using the rule:
385 /// shadow = (mem >> Scale) ADD-or-OR Offset.
386 struct ShadowMapping {
392 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
394 bool IsAndroid = TargetTriple.isAndroid();
395 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
396 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
397 bool IsPS4CPU = TargetTriple.isPS4CPU();
398 bool IsLinux = TargetTriple.isOSLinux();
399 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
400 TargetTriple.getArch() == llvm::Triple::ppc64le;
401 bool IsSystemZ = TargetTriple.getArch() == llvm::Triple::systemz;
402 bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86;
403 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
404 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
405 TargetTriple.getArch() == llvm::Triple::mipsel;
406 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
407 TargetTriple.getArch() == llvm::Triple::mips64el;
408 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
409 bool IsWindows = TargetTriple.isOSWindows();
410 bool IsFuchsia = TargetTriple.isOSFuchsia();
412 ShadowMapping Mapping;
414 if (LongSize == 32) {
415 // Android is always PIE, which means that the beginning of the address
416 // space is always available.
420 Mapping.Offset = kMIPS32_ShadowOffset32;
422 Mapping.Offset = kFreeBSD_ShadowOffset32;
424 // If we're targeting iOS and x86, the binary is built for iOS simulator.
425 Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
427 Mapping.Offset = kWindowsShadowOffset32;
429 Mapping.Offset = kDefaultShadowOffset32;
430 } else { // LongSize == 64
431 // Fuchsia is always PIE, which means that the beginning of the address
432 // space is always available.
436 Mapping.Offset = kPPC64_ShadowOffset64;
438 Mapping.Offset = kSystemZ_ShadowOffset64;
440 Mapping.Offset = kFreeBSD_ShadowOffset64;
442 Mapping.Offset = kPS4CPU_ShadowOffset64;
443 else if (IsLinux && IsX86_64) {
445 Mapping.Offset = kLinuxKasan_ShadowOffset64;
447 Mapping.Offset = kSmallX86_64ShadowOffset;
448 } else if (IsWindows && IsX86_64) {
449 Mapping.Offset = kWindowsShadowOffset64;
451 Mapping.Offset = kMIPS64_ShadowOffset64;
453 // If we're targeting iOS and x86, the binary is built for iOS simulator.
454 // We are using dynamic shadow offset on the 64-bit devices.
456 IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
458 Mapping.Offset = kAArch64_ShadowOffset64;
460 Mapping.Offset = kDefaultShadowOffset64;
463 if (ClForceDynamicShadow) {
464 Mapping.Offset = kDynamicShadowSentinel;
467 Mapping.Scale = kDefaultShadowScale;
468 if (ClMappingScale.getNumOccurrences() > 0) {
469 Mapping.Scale = ClMappingScale;
472 if (ClMappingOffset.getNumOccurrences() > 0) {
473 Mapping.Offset = ClMappingOffset;
476 // OR-ing shadow offset if more efficient (at least on x86) if the offset
477 // is a power of two, but on ppc64 we have to use add since the shadow
478 // offset is not necessary 1/8-th of the address space. On SystemZ,
479 // we could OR the constant in a single instruction, but it's more
480 // efficient to load it once and use indexed addressing.
481 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
482 !(Mapping.Offset & (Mapping.Offset - 1)) &&
483 Mapping.Offset != kDynamicShadowSentinel;
488 static size_t RedzoneSizeForScale(int MappingScale) {
489 // Redzone used for stack and globals is at least 32 bytes.
490 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
491 return std::max(32U, 1U << MappingScale);
494 /// AddressSanitizer: instrument the code in module to find memory bugs.
495 struct AddressSanitizer : public FunctionPass {
496 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false,
497 bool UseAfterScope = false)
498 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
499 Recover(Recover || ClRecover),
500 UseAfterScope(UseAfterScope || ClUseAfterScope),
501 LocalDynamicShadow(nullptr) {
502 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
504 StringRef getPassName() const override {
505 return "AddressSanitizerFunctionPass";
507 void getAnalysisUsage(AnalysisUsage &AU) const override {
508 AU.addRequired<DominatorTreeWrapperPass>();
509 AU.addRequired<TargetLibraryInfoWrapperPass>();
511 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
512 uint64_t ArraySize = 1;
513 if (AI.isArrayAllocation()) {
514 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
515 assert(CI && "non-constant array size");
516 ArraySize = CI->getZExtValue();
518 Type *Ty = AI.getAllocatedType();
519 uint64_t SizeInBytes =
520 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
521 return SizeInBytes * ArraySize;
523 /// Check if we want (and can) handle this alloca.
524 bool isInterestingAlloca(const AllocaInst &AI);
526 /// If it is an interesting memory access, return the PointerOperand
527 /// and set IsWrite/Alignment. Otherwise return nullptr.
528 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
529 /// masked load/store.
530 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
531 uint64_t *TypeSize, unsigned *Alignment,
532 Value **MaybeMask = nullptr);
533 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
534 bool UseCalls, const DataLayout &DL);
535 void instrumentPointerComparisonOrSubtraction(Instruction *I);
536 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
537 Value *Addr, uint32_t TypeSize, bool IsWrite,
538 Value *SizeArgument, bool UseCalls, uint32_t Exp);
539 void instrumentUnusualSizeOrAlignment(Instruction *I,
540 Instruction *InsertBefore, Value *Addr,
541 uint32_t TypeSize, bool IsWrite,
542 Value *SizeArgument, bool UseCalls,
544 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
545 Value *ShadowValue, uint32_t TypeSize);
546 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
547 bool IsWrite, size_t AccessSizeIndex,
548 Value *SizeArgument, uint32_t Exp);
549 void instrumentMemIntrinsic(MemIntrinsic *MI);
550 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
551 bool runOnFunction(Function &F) override;
552 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
553 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
554 void markEscapedLocalAllocas(Function &F);
555 bool doInitialization(Module &M) override;
556 bool doFinalization(Module &M) override;
557 static char ID; // Pass identification, replacement for typeid
559 DominatorTree &getDominatorTree() const { return *DT; }
562 void initializeCallbacks(Module &M);
564 bool LooksLikeCodeInBug11395(Instruction *I);
565 bool GlobalIsLinkerInitialized(GlobalVariable *G);
566 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
567 uint64_t TypeSize) const;
569 /// Helper to cleanup per-function state.
570 struct FunctionStateRAII {
571 AddressSanitizer *Pass;
572 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
573 assert(Pass->ProcessedAllocas.empty() &&
574 "last pass forgot to clear cache");
575 assert(!Pass->LocalDynamicShadow);
577 ~FunctionStateRAII() {
578 Pass->LocalDynamicShadow = nullptr;
579 Pass->ProcessedAllocas.clear();
590 ShadowMapping Mapping;
592 Function *AsanHandleNoReturnFunc;
593 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
594 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
595 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
596 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
597 // This array is indexed by AccessIsWrite and Experiment.
598 Function *AsanErrorCallbackSized[2][2];
599 Function *AsanMemoryAccessCallbackSized[2][2];
600 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
602 Value *LocalDynamicShadow;
603 GlobalsMetadata GlobalsMD;
604 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
606 friend struct FunctionStackPoisoner;
609 class AddressSanitizerModule : public ModulePass {
611 explicit AddressSanitizerModule(bool CompileKernel = false,
612 bool Recover = false,
613 bool UseGlobalsGC = true)
614 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
615 Recover(Recover || ClRecover),
616 UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC),
617 // Not a typo: ClWithComdat is almost completely pointless without
618 // ClUseGlobalsGC (because then it only works on modules without
619 // globals, which are rare); it is a prerequisite for ClUseGlobalsGC;
620 // and both suffer from gold PR19002 for which UseGlobalsGC constructor
621 // argument is designed as workaround. Therefore, disable both
622 // ClWithComdat and ClUseGlobalsGC unless the frontend says it's ok to
624 UseCtorComdat(UseGlobalsGC && ClWithComdat) {}
625 bool runOnModule(Module &M) override;
626 static char ID; // Pass identification, replacement for typeid
627 StringRef getPassName() const override { return "AddressSanitizerModule"; }
630 void initializeCallbacks(Module &M);
632 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat);
633 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
634 ArrayRef<GlobalVariable *> ExtendedGlobals,
635 ArrayRef<Constant *> MetadataInitializers);
636 void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
637 ArrayRef<GlobalVariable *> ExtendedGlobals,
638 ArrayRef<Constant *> MetadataInitializers,
639 const std::string &UniqueModuleId);
640 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
641 ArrayRef<GlobalVariable *> ExtendedGlobals,
642 ArrayRef<Constant *> MetadataInitializers);
644 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
645 ArrayRef<GlobalVariable *> ExtendedGlobals,
646 ArrayRef<Constant *> MetadataInitializers);
648 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
649 StringRef OriginalName);
650 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
651 StringRef InternalSuffix);
652 IRBuilder<> CreateAsanModuleDtor(Module &M);
654 bool ShouldInstrumentGlobal(GlobalVariable *G);
655 bool ShouldUseMachOGlobalsSection() const;
656 StringRef getGlobalMetadataSection() const;
657 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
658 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
659 size_t MinRedzoneSizeForGlobal() const {
660 return RedzoneSizeForScale(Mapping.Scale);
663 GlobalsMetadata GlobalsMD;
671 ShadowMapping Mapping;
672 Function *AsanPoisonGlobals;
673 Function *AsanUnpoisonGlobals;
674 Function *AsanRegisterGlobals;
675 Function *AsanUnregisterGlobals;
676 Function *AsanRegisterImageGlobals;
677 Function *AsanUnregisterImageGlobals;
678 Function *AsanRegisterElfGlobals;
679 Function *AsanUnregisterElfGlobals;
681 Function *AsanCtorFunction = nullptr;
682 Function *AsanDtorFunction = nullptr;
685 // Stack poisoning does not play well with exception handling.
686 // When an exception is thrown, we essentially bypass the code
687 // that unpoisones the stack. This is why the run-time library has
688 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
689 // stack in the interceptor. This however does not work inside the
690 // actual function which catches the exception. Most likely because the
691 // compiler hoists the load of the shadow value somewhere too high.
692 // This causes asan to report a non-existing bug on 453.povray.
693 // It sounds like an LLVM bug.
694 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
696 AddressSanitizer &ASan;
701 ShadowMapping Mapping;
703 SmallVector<AllocaInst *, 16> AllocaVec;
704 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
705 SmallVector<Instruction *, 8> RetVec;
706 unsigned StackAlignment;
708 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
709 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
710 Function *AsanSetShadowFunc[0x100] = {};
711 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
712 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
714 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
715 struct AllocaPoisonCall {
716 IntrinsicInst *InsBefore;
721 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
722 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
724 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
725 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
726 AllocaInst *DynamicAllocaLayout = nullptr;
727 IntrinsicInst *LocalEscapeCall = nullptr;
729 // Maps Value to an AllocaInst from which the Value is originated.
730 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
731 AllocaForValueMapTy AllocaForValue;
733 bool HasNonEmptyInlineAsm = false;
734 bool HasReturnsTwiceCall = false;
735 std::unique_ptr<CallInst> EmptyInlineAsm;
737 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
740 DIB(*F.getParent(), /*AllowUnresolved*/ false),
742 IntptrTy(ASan.IntptrTy),
743 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
744 Mapping(ASan.Mapping),
745 StackAlignment(1 << Mapping.Scale),
746 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
748 bool runOnFunction() {
749 if (!ClStack) return false;
750 // Collect alloca, ret, lifetime instructions etc.
751 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
753 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
755 initializeCallbacks(*F.getParent());
757 processDynamicAllocas();
758 processStaticAllocas();
766 // Finds all Alloca instructions and puts
767 // poisoned red zones around all of them.
768 // Then unpoison everything back before the function returns.
769 void processStaticAllocas();
770 void processDynamicAllocas();
772 void createDynamicAllocasInitStorage();
774 // ----------------------- Visitors.
775 /// \brief Collect all Ret instructions.
776 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
778 /// \brief Collect all Resume instructions.
779 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
781 /// \brief Collect all CatchReturnInst instructions.
782 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
784 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
786 IRBuilder<> IRB(InstBefore);
787 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
788 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
789 // need to adjust extracted SP to compute the address of the most recent
790 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
792 if (!isa<ReturnInst>(InstBefore)) {
793 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
794 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
797 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
799 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
803 IRB.CreateCall(AsanAllocasUnpoisonFunc,
804 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
807 // Unpoison dynamic allocas redzones.
808 void unpoisonDynamicAllocas() {
809 for (auto &Ret : RetVec)
810 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
812 for (auto &StackRestoreInst : StackRestoreVec)
813 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
814 StackRestoreInst->getOperand(0));
817 // Deploy and poison redzones around dynamic alloca call. To do this, we
818 // should replace this call with another one with changed parameters and
819 // replace all its uses with new address, so
820 // addr = alloca type, old_size, align
822 // new_size = (old_size + additional_size) * sizeof(type)
823 // tmp = alloca i8, new_size, max(align, 32)
824 // addr = tmp + 32 (first 32 bytes are for the left redzone).
825 // Additional_size is added to make new memory allocation contain not only
826 // requested memory, but also left, partial and right redzones.
827 void handleDynamicAllocaCall(AllocaInst *AI);
829 /// \brief Collect Alloca instructions we want (and can) handle.
830 void visitAllocaInst(AllocaInst &AI) {
831 if (!ASan.isInterestingAlloca(AI)) {
832 if (AI.isStaticAlloca()) {
833 // Skip over allocas that are present *before* the first instrumented
834 // alloca, we don't want to move those around.
835 if (AllocaVec.empty())
838 StaticAllocasToMoveUp.push_back(&AI);
843 StackAlignment = std::max(StackAlignment, AI.getAlignment());
844 if (!AI.isStaticAlloca())
845 DynamicAllocaVec.push_back(&AI);
847 AllocaVec.push_back(&AI);
850 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
852 void visitIntrinsicInst(IntrinsicInst &II) {
853 Intrinsic::ID ID = II.getIntrinsicID();
854 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
855 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
856 if (!ASan.UseAfterScope)
858 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
860 // Found lifetime intrinsic, add ASan instrumentation if necessary.
861 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
862 // If size argument is undefined, don't do anything.
863 if (Size->isMinusOne()) return;
864 // Check that size doesn't saturate uint64_t and can
865 // be stored in IntptrTy.
866 const uint64_t SizeValue = Size->getValue().getLimitedValue();
867 if (SizeValue == ~0ULL ||
868 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
870 // Find alloca instruction that corresponds to llvm.lifetime argument.
871 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
872 if (!AI || !ASan.isInterestingAlloca(*AI))
874 bool DoPoison = (ID == Intrinsic::lifetime_end);
875 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
876 if (AI->isStaticAlloca())
877 StaticAllocaPoisonCallVec.push_back(APC);
878 else if (ClInstrumentDynamicAllocas)
879 DynamicAllocaPoisonCallVec.push_back(APC);
882 void visitCallSite(CallSite CS) {
883 Instruction *I = CS.getInstruction();
884 if (CallInst *CI = dyn_cast<CallInst>(I)) {
885 HasNonEmptyInlineAsm |=
886 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
887 HasReturnsTwiceCall |= CI->canReturnTwice();
891 // ---------------------- Helpers.
892 void initializeCallbacks(Module &M);
894 bool doesDominateAllExits(const Instruction *I) const {
895 for (auto Ret : RetVec) {
896 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
901 /// Finds alloca where the value comes from.
902 AllocaInst *findAllocaForValue(Value *V);
904 // Copies bytes from ShadowBytes into shadow memory for indexes where
905 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
906 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
907 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
908 IRBuilder<> &IRB, Value *ShadowBase);
909 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
910 size_t Begin, size_t End, IRBuilder<> &IRB,
912 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
913 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
914 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
916 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
918 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
920 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
921 Instruction *ThenTerm, Value *ValueIfFalse);
924 } // anonymous namespace
926 char AddressSanitizer::ID = 0;
927 INITIALIZE_PASS_BEGIN(
928 AddressSanitizer, "asan",
929 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
931 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
932 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
934 AddressSanitizer, "asan",
935 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
937 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
939 bool UseAfterScope) {
940 assert(!CompileKernel || Recover);
941 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
944 char AddressSanitizerModule::ID = 0;
946 AddressSanitizerModule, "asan-module",
947 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
950 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
953 assert(!CompileKernel || Recover);
954 return new AddressSanitizerModule(CompileKernel, Recover, UseGlobalsGC);
957 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
958 size_t Res = countTrailingZeros(TypeSize / 8);
959 assert(Res < kNumberOfAccessSizes);
963 // \brief Create a constant for Str so that we can pass it to the run-time lib.
964 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
966 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
967 // We use private linkage for module-local strings. If they can be merged
968 // with another one, we set the unnamed_addr attribute.
970 new GlobalVariable(M, StrConst->getType(), true,
971 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
972 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
973 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
977 /// \brief Create a global describing a source location.
978 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
979 LocationMetadata MD) {
980 Constant *LocData[] = {
981 createPrivateGlobalForString(M, MD.Filename, true),
982 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
983 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
985 auto LocStruct = ConstantStruct::getAnon(LocData);
986 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
987 GlobalValue::PrivateLinkage, LocStruct,
989 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
993 /// \brief Check if \p G has been created by a trusted compiler pass.
994 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
995 // Do not instrument asan globals.
996 if (G->getName().startswith(kAsanGenPrefix) ||
997 G->getName().startswith(kSanCovGenPrefix) ||
998 G->getName().startswith(kODRGenPrefix))
1001 // Do not instrument gcov counter arrays.
1002 if (G->getName() == "__llvm_gcov_ctr")
1008 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
1010 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
1011 if (Mapping.Offset == 0) return Shadow;
1012 // (Shadow >> scale) | offset
1014 if (LocalDynamicShadow)
1015 ShadowBase = LocalDynamicShadow;
1017 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
1018 if (Mapping.OrShadowOffset)
1019 return IRB.CreateOr(Shadow, ShadowBase);
1021 return IRB.CreateAdd(Shadow, ShadowBase);
1024 // Instrument memset/memmove/memcpy
1025 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
1026 IRBuilder<> IRB(MI);
1027 if (isa<MemTransferInst>(MI)) {
1029 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
1030 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1031 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
1032 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1033 } else if (isa<MemSetInst>(MI)) {
1036 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1037 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
1038 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1040 MI->eraseFromParent();
1043 /// Check if we want (and can) handle this alloca.
1044 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1045 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1047 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1048 return PreviouslySeenAllocaInfo->getSecond();
1050 bool IsInteresting =
1051 (AI.getAllocatedType()->isSized() &&
1052 // alloca() may be called with 0 size, ignore it.
1053 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1054 // We are only interested in allocas not promotable to registers.
1055 // Promotable allocas are common under -O0.
1056 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1057 // inalloca allocas are not treated as static, and we don't want
1058 // dynamic alloca instrumentation for them as well.
1059 !AI.isUsedWithInAlloca() &&
1060 // swifterror allocas are register promoted by ISel
1061 !AI.isSwiftError());
1063 ProcessedAllocas[&AI] = IsInteresting;
1064 return IsInteresting;
1067 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1070 unsigned *Alignment,
1071 Value **MaybeMask) {
1072 // Skip memory accesses inserted by another instrumentation.
1073 if (I->getMetadata("nosanitize")) return nullptr;
1075 // Do not instrument the load fetching the dynamic shadow address.
1076 if (LocalDynamicShadow == I)
1079 Value *PtrOperand = nullptr;
1080 const DataLayout &DL = I->getModule()->getDataLayout();
1081 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1082 if (!ClInstrumentReads) return nullptr;
1084 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1085 *Alignment = LI->getAlignment();
1086 PtrOperand = LI->getPointerOperand();
1087 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1088 if (!ClInstrumentWrites) return nullptr;
1090 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1091 *Alignment = SI->getAlignment();
1092 PtrOperand = SI->getPointerOperand();
1093 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1094 if (!ClInstrumentAtomics) return nullptr;
1096 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1098 PtrOperand = RMW->getPointerOperand();
1099 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1100 if (!ClInstrumentAtomics) return nullptr;
1102 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1104 PtrOperand = XCHG->getPointerOperand();
1105 } else if (auto CI = dyn_cast<CallInst>(I)) {
1106 auto *F = dyn_cast<Function>(CI->getCalledValue());
1107 if (F && (F->getName().startswith("llvm.masked.load.") ||
1108 F->getName().startswith("llvm.masked.store."))) {
1109 unsigned OpOffset = 0;
1110 if (F->getName().startswith("llvm.masked.store.")) {
1111 if (!ClInstrumentWrites)
1113 // Masked store has an initial operand for the value.
1117 if (!ClInstrumentReads)
1122 auto BasePtr = CI->getOperand(0 + OpOffset);
1123 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1124 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1125 if (auto AlignmentConstant =
1126 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1127 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1129 *Alignment = 1; // No alignment guarantees. We probably got Undef
1131 *MaybeMask = CI->getOperand(2 + OpOffset);
1132 PtrOperand = BasePtr;
1137 // Do not instrument acesses from different address spaces; we cannot deal
1139 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1140 if (PtrTy->getPointerAddressSpace() != 0)
1143 // Ignore swifterror addresses.
1144 // swifterror memory addresses are mem2reg promoted by instruction
1145 // selection. As such they cannot have regular uses like an instrumentation
1146 // function and it makes no sense to track them as memory.
1147 if (PtrOperand->isSwiftError())
1151 // Treat memory accesses to promotable allocas as non-interesting since they
1152 // will not cause memory violations. This greatly speeds up the instrumented
1153 // executable at -O0.
1154 if (ClSkipPromotableAllocas)
1155 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1156 return isInterestingAlloca(*AI) ? AI : nullptr;
1161 static bool isPointerOperand(Value *V) {
1162 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1165 // This is a rough heuristic; it may cause both false positives and
1166 // false negatives. The proper implementation requires cooperation with
1168 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1169 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1170 if (!Cmp->isRelational()) return false;
1171 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1172 if (BO->getOpcode() != Instruction::Sub) return false;
1176 return isPointerOperand(I->getOperand(0)) &&
1177 isPointerOperand(I->getOperand(1));
1180 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1181 // If a global variable does not have dynamic initialization we don't
1182 // have to instrument it. However, if a global does not have initializer
1183 // at all, we assume it has dynamic initializer (in other TU).
1184 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1187 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1190 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1191 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1192 for (Value *&i : Param) {
1193 if (i->getType()->isPointerTy())
1194 i = IRB.CreatePointerCast(i, IntptrTy);
1196 IRB.CreateCall(F, Param);
1199 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1200 Instruction *InsertBefore, Value *Addr,
1201 unsigned Alignment, unsigned Granularity,
1202 uint32_t TypeSize, bool IsWrite,
1203 Value *SizeArgument, bool UseCalls,
1205 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1206 // if the data is properly aligned.
1207 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1209 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1210 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1211 nullptr, UseCalls, Exp);
1212 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1213 IsWrite, nullptr, UseCalls, Exp);
1216 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1217 const DataLayout &DL, Type *IntptrTy,
1218 Value *Mask, Instruction *I,
1219 Value *Addr, unsigned Alignment,
1220 unsigned Granularity, uint32_t TypeSize,
1221 bool IsWrite, Value *SizeArgument,
1222 bool UseCalls, uint32_t Exp) {
1223 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1224 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1225 unsigned Num = VTy->getVectorNumElements();
1226 auto Zero = ConstantInt::get(IntptrTy, 0);
1227 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1228 Value *InstrumentedAddress = nullptr;
1229 Instruction *InsertBefore = I;
1230 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1231 // dyn_cast as we might get UndefValue
1232 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1233 if (Masked->isNullValue())
1234 // Mask is constant false, so no instrumentation needed.
1236 // If we have a true or undef value, fall through to doInstrumentAddress
1237 // with InsertBefore == I
1241 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1242 TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1243 InsertBefore = ThenTerm;
1246 IRBuilder<> IRB(InsertBefore);
1247 InstrumentedAddress =
1248 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1249 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1250 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1255 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1256 Instruction *I, bool UseCalls,
1257 const DataLayout &DL) {
1258 bool IsWrite = false;
1259 unsigned Alignment = 0;
1260 uint64_t TypeSize = 0;
1261 Value *MaybeMask = nullptr;
1263 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1266 // Optimization experiments.
1267 // The experiments can be used to evaluate potential optimizations that remove
1268 // instrumentation (assess false negatives). Instead of completely removing
1269 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1270 // experiments that want to remove instrumentation of this instruction).
1271 // If Exp is non-zero, this pass will emit special calls into runtime
1272 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1273 // make runtime terminate the program in a special way (with a different
1274 // exit status). Then you run the new compiler on a buggy corpus, collect
1275 // the special terminations (ideally, you don't see them at all -- no false
1276 // negatives) and make the decision on the optimization.
1277 uint32_t Exp = ClForceExperiment;
1279 if (ClOpt && ClOptGlobals) {
1280 // If initialization order checking is disabled, a simple access to a
1281 // dynamically initialized global is always valid.
1282 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1283 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1284 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1285 NumOptimizedAccessesToGlobalVar++;
1290 if (ClOpt && ClOptStack) {
1291 // A direct inbounds access to a stack variable is always valid.
1292 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1293 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1294 NumOptimizedAccessesToStackVar++;
1300 NumInstrumentedWrites++;
1302 NumInstrumentedReads++;
1304 unsigned Granularity = 1 << Mapping.Scale;
1306 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1307 Alignment, Granularity, TypeSize, IsWrite,
1308 nullptr, UseCalls, Exp);
1310 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1311 IsWrite, nullptr, UseCalls, Exp);
1315 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1316 Value *Addr, bool IsWrite,
1317 size_t AccessSizeIndex,
1318 Value *SizeArgument,
1320 IRBuilder<> IRB(InsertBefore);
1321 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1322 CallInst *Call = nullptr;
1325 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1326 {Addr, SizeArgument});
1328 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1329 {Addr, SizeArgument, ExpVal});
1333 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1335 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1339 // We don't do Call->setDoesNotReturn() because the BB already has
1340 // UnreachableInst at the end.
1341 // This EmptyAsm is required to avoid callback merge.
1342 IRB.CreateCall(EmptyAsm, {});
1346 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1348 uint32_t TypeSize) {
1349 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1350 // Addr & (Granularity - 1)
1351 Value *LastAccessedByte =
1352 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1353 // (Addr & (Granularity - 1)) + size - 1
1354 if (TypeSize / 8 > 1)
1355 LastAccessedByte = IRB.CreateAdd(
1356 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1357 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1359 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1360 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1361 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1364 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1365 Instruction *InsertBefore, Value *Addr,
1366 uint32_t TypeSize, bool IsWrite,
1367 Value *SizeArgument, bool UseCalls,
1369 IRBuilder<> IRB(InsertBefore);
1370 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1371 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1375 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1378 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1379 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1384 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1385 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1386 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1387 Value *CmpVal = Constant::getNullValue(ShadowTy);
1388 Value *ShadowValue =
1389 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1391 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1392 size_t Granularity = 1ULL << Mapping.Scale;
1393 TerminatorInst *CrashTerm = nullptr;
1395 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1396 // We use branch weights for the slow path check, to indicate that the slow
1397 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1398 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1399 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1400 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1401 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1402 IRB.SetInsertPoint(CheckTerm);
1403 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1405 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1407 BasicBlock *CrashBlock =
1408 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1409 CrashTerm = new UnreachableInst(*C, CrashBlock);
1410 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1411 ReplaceInstWithInst(CheckTerm, NewTerm);
1414 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1417 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1418 AccessSizeIndex, SizeArgument, Exp);
1419 Crash->setDebugLoc(OrigIns->getDebugLoc());
1422 // Instrument unusual size or unusual alignment.
1423 // We can not do it with a single check, so we do 1-byte check for the first
1424 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1425 // to report the actual access size.
1426 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1427 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1428 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1429 IRBuilder<> IRB(InsertBefore);
1430 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1431 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1434 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1437 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1438 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1440 Value *LastByte = IRB.CreateIntToPtr(
1441 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1443 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1444 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1448 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1449 GlobalValue *ModuleName) {
1450 // Set up the arguments to our poison/unpoison functions.
1451 IRBuilder<> IRB(&GlobalInit.front(),
1452 GlobalInit.front().getFirstInsertionPt());
1454 // Add a call to poison all external globals before the given function starts.
1455 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1456 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1458 // Add calls to unpoison all globals before each return instruction.
1459 for (auto &BB : GlobalInit.getBasicBlockList())
1460 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1461 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1464 void AddressSanitizerModule::createInitializerPoisonCalls(
1465 Module &M, GlobalValue *ModuleName) {
1466 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1470 ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
1474 for (Use &OP : CA->operands()) {
1475 if (isa<ConstantAggregateZero>(OP)) continue;
1476 ConstantStruct *CS = cast<ConstantStruct>(OP);
1478 // Must have a function or null ptr.
1479 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1480 if (F->getName() == kAsanModuleCtorName) continue;
1481 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1482 // Don't instrument CTORs that will run before asan.module_ctor.
1483 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1484 poisonOneInitializer(*F, ModuleName);
1489 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1490 Type *Ty = G->getValueType();
1491 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1493 if (GlobalsMD.get(G).IsBlacklisted) return false;
1494 if (!Ty->isSized()) return false;
1495 if (!G->hasInitializer()) return false;
1496 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1497 // Touch only those globals that will not be defined in other modules.
1498 // Don't handle ODR linkage types and COMDATs since other modules may be built
1500 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1501 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1502 G->getLinkage() != GlobalVariable::InternalLinkage)
1504 if (G->hasComdat()) return false;
1505 // Two problems with thread-locals:
1506 // - The address of the main thread's copy can't be computed at link-time.
1507 // - Need to poison all copies, not just the main thread's one.
1508 if (G->isThreadLocal()) return false;
1509 // For now, just ignore this Global if the alignment is large.
1510 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1512 if (G->hasSection()) {
1513 StringRef Section = G->getSection();
1515 // Globals from llvm.metadata aren't emitted, do not instrument them.
1516 if (Section == "llvm.metadata") return false;
1517 // Do not instrument globals from special LLVM sections.
1518 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1520 // Do not instrument function pointers to initialization and termination
1521 // routines: dynamic linker will not properly handle redzones.
1522 if (Section.startswith(".preinit_array") ||
1523 Section.startswith(".init_array") ||
1524 Section.startswith(".fini_array")) {
1528 // Callbacks put into the CRT initializer/terminator sections
1529 // should not be instrumented.
1530 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1531 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1532 if (Section.startswith(".CRT")) {
1533 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1537 if (TargetTriple.isOSBinFormatMachO()) {
1538 StringRef ParsedSegment, ParsedSection;
1539 unsigned TAA = 0, StubSize = 0;
1541 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1542 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1543 assert(ErrorCode.empty() && "Invalid section specifier.");
1545 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1546 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1548 if (ParsedSegment == "__OBJC" ||
1549 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1550 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1553 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1554 // Constant CFString instances are compiled in the following way:
1555 // -- the string buffer is emitted into
1556 // __TEXT,__cstring,cstring_literals
1557 // -- the constant NSConstantString structure referencing that buffer
1558 // is placed into __DATA,__cfstring
1559 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1560 // Moreover, it causes the linker to crash on OS X 10.7
1561 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1562 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1565 // The linker merges the contents of cstring_literals and removes the
1567 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1568 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1577 // On Mach-O platforms, we emit global metadata in a separate section of the
1578 // binary in order to allow the linker to properly dead strip. This is only
1579 // supported on recent versions of ld64.
1580 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1581 if (!TargetTriple.isOSBinFormatMachO())
1584 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1586 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1588 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1594 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1595 switch (TargetTriple.getObjectFormat()) {
1596 case Triple::COFF: return ".ASAN$GL";
1597 case Triple::ELF: return "asan_globals";
1598 case Triple::MachO: return "__DATA,__asan_globals,regular";
1601 llvm_unreachable("unsupported object format");
1604 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1605 IRBuilder<> IRB(*C);
1607 // Declare our poisoning and unpoisoning functions.
1608 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1609 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy));
1610 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1611 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1612 kAsanUnpoisonGlobalsName, IRB.getVoidTy()));
1613 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1615 // Declare functions that register/unregister globals.
1616 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1617 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy));
1618 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1619 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1620 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1621 IntptrTy, IntptrTy));
1622 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1624 // Declare the functions that find globals in a shared object and then invoke
1625 // the (un)register function on them.
1626 AsanRegisterImageGlobals =
1627 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1628 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
1629 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1631 AsanUnregisterImageGlobals =
1632 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1633 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
1634 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1636 AsanRegisterElfGlobals = checkSanitizerInterfaceFunction(
1637 M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
1638 IntptrTy, IntptrTy, IntptrTy));
1639 AsanRegisterElfGlobals->setLinkage(Function::ExternalLinkage);
1641 AsanUnregisterElfGlobals = checkSanitizerInterfaceFunction(
1642 M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
1643 IntptrTy, IntptrTy, IntptrTy));
1644 AsanUnregisterElfGlobals->setLinkage(Function::ExternalLinkage);
1647 // Put the metadata and the instrumented global in the same group. This ensures
1648 // that the metadata is discarded if the instrumented global is discarded.
1649 void AddressSanitizerModule::SetComdatForGlobalMetadata(
1650 GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
1651 Module &M = *G->getParent();
1652 Comdat *C = G->getComdat();
1654 if (!G->hasName()) {
1655 // If G is unnamed, it must be internal. Give it an artificial name
1656 // so we can put it in a comdat.
1657 assert(G->hasLocalLinkage());
1658 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1661 if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
1662 std::string Name = G->getName();
1663 Name += InternalSuffix;
1664 C = M.getOrInsertComdat(Name);
1666 C = M.getOrInsertComdat(G->getName());
1669 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1670 if (TargetTriple.isOSBinFormatCOFF())
1671 C->setSelectionKind(Comdat::NoDuplicates);
1675 assert(G->hasComdat());
1676 Metadata->setComdat(G->getComdat());
1679 // Create a separate metadata global and put it in the appropriate ASan
1680 // global registration section.
1682 AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
1683 StringRef OriginalName) {
1684 auto Linkage = TargetTriple.isOSBinFormatMachO()
1685 ? GlobalVariable::InternalLinkage
1686 : GlobalVariable::PrivateLinkage;
1687 GlobalVariable *Metadata = new GlobalVariable(
1688 M, Initializer->getType(), false, Linkage, Initializer,
1689 Twine("__asan_global_") + GlobalValue::dropLLVMManglingEscape(OriginalName));
1690 Metadata->setSection(getGlobalMetadataSection());
1694 IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) {
1696 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1697 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1698 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1700 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
1703 void AddressSanitizerModule::InstrumentGlobalsCOFF(
1704 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1705 ArrayRef<Constant *> MetadataInitializers) {
1706 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1707 auto &DL = M.getDataLayout();
1709 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1710 Constant *Initializer = MetadataInitializers[i];
1711 GlobalVariable *G = ExtendedGlobals[i];
1712 GlobalVariable *Metadata =
1713 CreateMetadataGlobal(M, Initializer, G->getName());
1715 // The MSVC linker always inserts padding when linking incrementally. We
1716 // cope with that by aligning each struct to its size, which must be a power
1718 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
1719 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
1720 "global metadata will not be padded appropriately");
1721 Metadata->setAlignment(SizeOfGlobalStruct);
1723 SetComdatForGlobalMetadata(G, Metadata, "");
1727 void AddressSanitizerModule::InstrumentGlobalsELF(
1728 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1729 ArrayRef<Constant *> MetadataInitializers,
1730 const std::string &UniqueModuleId) {
1731 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1733 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
1734 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1735 GlobalVariable *G = ExtendedGlobals[i];
1736 GlobalVariable *Metadata =
1737 CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
1738 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
1739 Metadata->setMetadata(LLVMContext::MD_associated, MD);
1740 MetadataGlobals[i] = Metadata;
1742 SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
1745 // Update llvm.compiler.used, adding the new metadata globals. This is
1746 // needed so that during LTO these variables stay alive.
1747 if (!MetadataGlobals.empty())
1748 appendToCompilerUsed(M, MetadataGlobals);
1750 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1751 // to look up the loaded image that contains it. Second, we can store in it
1752 // whether registration has already occurred, to prevent duplicate
1755 // Common linkage ensures that there is only one global per shared library.
1756 GlobalVariable *RegisteredFlag = new GlobalVariable(
1757 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1758 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1759 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1761 // Create start and stop symbols.
1762 GlobalVariable *StartELFMetadata = new GlobalVariable(
1763 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
1764 "__start_" + getGlobalMetadataSection());
1765 StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
1766 GlobalVariable *StopELFMetadata = new GlobalVariable(
1767 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
1768 "__stop_" + getGlobalMetadataSection());
1769 StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
1771 // Create a call to register the globals with the runtime.
1772 IRB.CreateCall(AsanRegisterElfGlobals,
1773 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
1774 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
1775 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
1777 // We also need to unregister globals at the end, e.g., when a shared library
1779 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1780 IRB_Dtor.CreateCall(AsanUnregisterElfGlobals,
1781 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
1782 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
1783 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
1786 void AddressSanitizerModule::InstrumentGlobalsMachO(
1787 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1788 ArrayRef<Constant *> MetadataInitializers) {
1789 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1791 // On recent Mach-O platforms, use a structure which binds the liveness of
1792 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1793 // created to be added to llvm.compiler.used
1794 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy);
1795 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
1797 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1798 Constant *Initializer = MetadataInitializers[i];
1799 GlobalVariable *G = ExtendedGlobals[i];
1800 GlobalVariable *Metadata =
1801 CreateMetadataGlobal(M, Initializer, G->getName());
1803 // On recent Mach-O platforms, we emit the global metadata in a way that
1804 // allows the linker to properly strip dead globals.
1805 auto LivenessBinder =
1806 ConstantStruct::get(LivenessTy, Initializer->getAggregateElement(0u),
1807 ConstantExpr::getPointerCast(Metadata, IntptrTy));
1808 GlobalVariable *Liveness = new GlobalVariable(
1809 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1810 Twine("__asan_binder_") + G->getName());
1811 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1812 LivenessGlobals[i] = Liveness;
1815 // Update llvm.compiler.used, adding the new liveness globals. This is
1816 // needed so that during LTO these variables stay alive. The alternative
1817 // would be to have the linker handling the LTO symbols, but libLTO
1818 // current API does not expose access to the section for each symbol.
1819 if (!LivenessGlobals.empty())
1820 appendToCompilerUsed(M, LivenessGlobals);
1822 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1823 // to look up the loaded image that contains it. Second, we can store in it
1824 // whether registration has already occurred, to prevent duplicate
1827 // common linkage ensures that there is only one global per shared library.
1828 GlobalVariable *RegisteredFlag = new GlobalVariable(
1829 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1830 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1831 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1833 IRB.CreateCall(AsanRegisterImageGlobals,
1834 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1836 // We also need to unregister globals at the end, e.g., when a shared library
1838 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1839 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1840 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1843 void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
1844 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1845 ArrayRef<Constant *> MetadataInitializers) {
1846 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1847 unsigned N = ExtendedGlobals.size();
1850 // On platforms that don't have a custom metadata section, we emit an array
1851 // of global metadata structures.
1852 ArrayType *ArrayOfGlobalStructTy =
1853 ArrayType::get(MetadataInitializers[0]->getType(), N);
1854 auto AllGlobals = new GlobalVariable(
1855 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1856 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
1858 IRB.CreateCall(AsanRegisterGlobals,
1859 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1860 ConstantInt::get(IntptrTy, N)});
1862 // We also need to unregister globals at the end, e.g., when a shared library
1864 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1865 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1866 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1867 ConstantInt::get(IntptrTy, N)});
1870 // This function replaces all global variables with new variables that have
1871 // trailing redzones. It also creates a function that poisons
1872 // redzones and inserts this function into llvm.global_ctors.
1873 // Sets *CtorComdat to true if the global registration code emitted into the
1874 // asan constructor is comdat-compatible.
1875 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat) {
1876 *CtorComdat = false;
1879 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1881 for (auto &G : M.globals()) {
1882 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1885 size_t n = GlobalsToChange.size();
1891 auto &DL = M.getDataLayout();
1893 // A global is described by a structure
1896 // size_t size_with_redzone;
1897 // const char *name;
1898 // const char *module_name;
1899 // size_t has_dynamic_init;
1900 // void *source_location;
1901 // size_t odr_indicator;
1902 // We initialize an array of such structures and pass it to a run-time call.
1903 StructType *GlobalStructTy =
1904 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1905 IntptrTy, IntptrTy, IntptrTy);
1906 SmallVector<GlobalVariable *, 16> NewGlobals(n);
1907 SmallVector<Constant *, 16> Initializers(n);
1909 bool HasDynamicallyInitializedGlobals = false;
1911 // We shouldn't merge same module names, as this string serves as unique
1912 // module ID in runtime.
1913 GlobalVariable *ModuleName = createPrivateGlobalForString(
1914 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1916 for (size_t i = 0; i < n; i++) {
1917 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1918 GlobalVariable *G = GlobalsToChange[i];
1920 auto MD = GlobalsMD.get(G);
1921 StringRef NameForGlobal = G->getName();
1922 // Create string holding the global name (use global name from metadata
1923 // if it's available, otherwise just write the name of global variable).
1924 GlobalVariable *Name = createPrivateGlobalForString(
1925 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1926 /*AllowMerging*/ true);
1928 Type *Ty = G->getValueType();
1929 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1930 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1931 // MinRZ <= RZ <= kMaxGlobalRedzone
1932 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1933 uint64_t RZ = std::max(
1934 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1935 uint64_t RightRedzoneSize = RZ;
1936 // Round up to MinRZ
1937 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1938 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1939 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1941 StructType *NewTy = StructType::get(Ty, RightRedZoneTy);
1942 Constant *NewInitializer = ConstantStruct::get(
1943 NewTy, G->getInitializer(), Constant::getNullValue(RightRedZoneTy));
1945 // Create a new global variable with enough space for a redzone.
1946 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1947 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1948 Linkage = GlobalValue::InternalLinkage;
1949 GlobalVariable *NewGlobal =
1950 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1951 "", G, G->getThreadLocalMode());
1952 NewGlobal->copyAttributesFrom(G);
1953 NewGlobal->setAlignment(MinRZ);
1955 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1956 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1958 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1959 if (Seq && Seq->isCString())
1960 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1963 // Transfer the debug info. The payload starts at offset zero so we can
1964 // copy the debug info over as is.
1965 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1966 G->getDebugInfo(GVs);
1967 for (auto *GV : GVs)
1968 NewGlobal->addDebugInfo(GV);
1971 Indices2[0] = IRB.getInt32(0);
1972 Indices2[1] = IRB.getInt32(0);
1974 G->replaceAllUsesWith(
1975 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1976 NewGlobal->takeName(G);
1977 G->eraseFromParent();
1978 NewGlobals[i] = NewGlobal;
1980 Constant *SourceLoc;
1981 if (!MD.SourceLoc.empty()) {
1982 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1983 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1985 SourceLoc = ConstantInt::get(IntptrTy, 0);
1988 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
1989 GlobalValue *InstrumentedGlobal = NewGlobal;
1991 bool CanUsePrivateAliases =
1992 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
1993 TargetTriple.isOSBinFormatWasm();
1994 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
1995 // Create local alias for NewGlobal to avoid crash on ODR between
1996 // instrumented and non-instrumented libraries.
1997 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
1998 NameForGlobal + M.getName(), NewGlobal);
2000 // With local aliases, we need to provide another externally visible
2001 // symbol __odr_asan_XXX to detect ODR violation.
2002 auto *ODRIndicatorSym =
2003 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
2004 Constant::getNullValue(IRB.getInt8Ty()),
2005 kODRGenPrefix + NameForGlobal, nullptr,
2006 NewGlobal->getThreadLocalMode());
2008 // Set meaningful attributes for indicator symbol.
2009 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
2010 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
2011 ODRIndicatorSym->setAlignment(1);
2012 ODRIndicator = ODRIndicatorSym;
2013 InstrumentedGlobal = GA;
2016 Constant *Initializer = ConstantStruct::get(
2018 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
2019 ConstantInt::get(IntptrTy, SizeInBytes),
2020 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
2021 ConstantExpr::getPointerCast(Name, IntptrTy),
2022 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
2023 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
2024 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy));
2026 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
2028 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
2030 Initializers[i] = Initializer;
2033 std::string ELFUniqueModuleId =
2034 (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
2037 if (!ELFUniqueModuleId.empty()) {
2038 InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
2040 } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
2041 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
2042 } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
2043 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
2045 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
2048 // Create calls for poisoning before initializers run and unpoisoning after.
2049 if (HasDynamicallyInitializedGlobals)
2050 createInitializerPoisonCalls(M, ModuleName);
2056 bool AddressSanitizerModule::runOnModule(Module &M) {
2057 C = &(M.getContext());
2058 int LongSize = M.getDataLayout().getPointerSizeInBits();
2059 IntptrTy = Type::getIntNTy(*C, LongSize);
2060 TargetTriple = Triple(M.getTargetTriple());
2061 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2062 initializeCallbacks(M);
2067 // Create a module constructor. A destructor is created lazily because not all
2068 // platforms, and not all modules need it.
2069 std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
2070 M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
2071 /*InitArgs=*/{}, kAsanVersionCheckName);
2073 bool CtorComdat = true;
2074 bool Changed = false;
2075 // TODO(glider): temporarily disabled globals instrumentation for KASan.
2077 IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
2078 Changed |= InstrumentGlobals(IRB, M, &CtorComdat);
2081 // Put the constructor and destructor in comdat if both
2082 // (1) global instrumentation is not TU-specific
2083 // (2) target is ELF.
2084 if (UseCtorComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
2085 AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
2086 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority,
2088 if (AsanDtorFunction) {
2089 AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
2090 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority,
2094 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
2095 if (AsanDtorFunction)
2096 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
2102 void AddressSanitizer::initializeCallbacks(Module &M) {
2103 IRBuilder<> IRB(*C);
2104 // Create __asan_report* callbacks.
2105 // IsWrite, TypeSize and Exp are encoded in the function name.
2106 for (int Exp = 0; Exp < 2; Exp++) {
2107 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
2108 const std::string TypeStr = AccessIsWrite ? "store" : "load";
2109 const std::string ExpStr = Exp ? "exp_" : "";
2110 const std::string SuffixStr = CompileKernel ? "N" : "_n";
2111 const std::string EndingStr = Recover ? "_noabort" : "";
2113 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
2114 SmallVector<Type *, 2> Args1{1, IntptrTy};
2116 Type *ExpType = Type::getInt32Ty(*C);
2117 Args2.push_back(ExpType);
2118 Args1.push_back(ExpType);
2120 AsanErrorCallbackSized[AccessIsWrite][Exp] =
2121 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2122 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr +
2124 FunctionType::get(IRB.getVoidTy(), Args2, false)));
2126 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
2127 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2128 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
2129 FunctionType::get(IRB.getVoidTy(), Args2, false)));
2131 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
2132 AccessSizeIndex++) {
2133 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
2134 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2135 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2136 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
2137 FunctionType::get(IRB.getVoidTy(), Args1, false)));
2139 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2140 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2141 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
2142 FunctionType::get(IRB.getVoidTy(), Args1, false)));
2147 const std::string MemIntrinCallbackPrefix =
2148 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
2149 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2150 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
2151 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy));
2152 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2153 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
2154 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy));
2155 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2156 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
2157 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy));
2159 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
2160 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy()));
2162 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2163 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy));
2164 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2165 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy));
2166 // We insert an empty inline asm after __asan_report* to avoid callback merge.
2167 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
2168 StringRef(""), StringRef(""),
2169 /*hasSideEffects=*/true);
2173 bool AddressSanitizer::doInitialization(Module &M) {
2174 // Initialize the private fields. No one has accessed them before.
2177 C = &(M.getContext());
2178 LongSize = M.getDataLayout().getPointerSizeInBits();
2179 IntptrTy = Type::getIntNTy(*C, LongSize);
2180 TargetTriple = Triple(M.getTargetTriple());
2182 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2186 bool AddressSanitizer::doFinalization(Module &M) {
2191 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2192 // For each NSObject descendant having a +load method, this method is invoked
2193 // by the ObjC runtime before any of the static constructors is called.
2194 // Therefore we need to instrument such methods with a call to __asan_init
2195 // at the beginning in order to initialize our runtime before any access to
2196 // the shadow memory.
2197 // We cannot just ignore these methods, because they may call other
2198 // instrumented functions.
2199 if (F.getName().find(" load]") != std::string::npos) {
2200 Function *AsanInitFunction =
2201 declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
2202 IRBuilder<> IRB(&F.front(), F.front().begin());
2203 IRB.CreateCall(AsanInitFunction, {});
2209 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2210 // Generate code only when dynamic addressing is needed.
2211 if (Mapping.Offset != kDynamicShadowSentinel)
2214 IRBuilder<> IRB(&F.front().front());
2215 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2216 kAsanShadowMemoryDynamicAddress, IntptrTy);
2217 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
2220 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2221 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2222 // to it as uninteresting. This assumes we haven't started processing allocas
2223 // yet. This check is done up front because iterating the use list in
2224 // isInterestingAlloca would be algorithmically slower.
2225 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2227 // Try to get the declaration of llvm.localescape. If it's not in the module,
2228 // we can exit early.
2229 if (!F.getParent()->getFunction("llvm.localescape")) return;
2231 // Look for a call to llvm.localescape call in the entry block. It can't be in
2233 for (Instruction &I : F.getEntryBlock()) {
2234 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2235 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2236 // We found a call. Mark all the allocas passed in as uninteresting.
2237 for (Value *Arg : II->arg_operands()) {
2238 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2239 assert(AI && AI->isStaticAlloca() &&
2240 "non-static alloca arg to localescape");
2241 ProcessedAllocas[AI] = false;
2248 bool AddressSanitizer::runOnFunction(Function &F) {
2249 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2250 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2251 if (F.getName().startswith("__asan_")) return false;
2253 bool FunctionModified = false;
2255 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2256 // This function needs to be called even if the function body is not
2258 if (maybeInsertAsanInitAtFunctionEntry(F))
2259 FunctionModified = true;
2261 // Leave if the function doesn't need instrumentation.
2262 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2264 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2266 initializeCallbacks(*F.getParent());
2267 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2269 FunctionStateRAII CleanupObj(this);
2271 maybeInsertDynamicShadowAtFunctionEntry(F);
2273 // We can't instrument allocas used with llvm.localescape. Only static allocas
2274 // can be passed to that intrinsic.
2275 markEscapedLocalAllocas(F);
2277 // We want to instrument every address only once per basic block (unless there
2278 // are calls between uses).
2279 SmallSet<Value *, 16> TempsToInstrument;
2280 SmallVector<Instruction *, 16> ToInstrument;
2281 SmallVector<Instruction *, 8> NoReturnCalls;
2282 SmallVector<BasicBlock *, 16> AllBlocks;
2283 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2288 const TargetLibraryInfo *TLI =
2289 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2291 // Fill the set of memory operations to instrument.
2292 for (auto &BB : F) {
2293 AllBlocks.push_back(&BB);
2294 TempsToInstrument.clear();
2295 int NumInsnsPerBB = 0;
2296 for (auto &Inst : BB) {
2297 if (LooksLikeCodeInBug11395(&Inst)) return false;
2298 Value *MaybeMask = nullptr;
2299 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2300 &Alignment, &MaybeMask)) {
2301 if (ClOpt && ClOptSameTemp) {
2302 // If we have a mask, skip instrumentation if we've already
2303 // instrumented the full object. But don't add to TempsToInstrument
2304 // because we might get another load/store with a different mask.
2306 if (TempsToInstrument.count(Addr))
2307 continue; // We've seen this (whole) temp in the current BB.
2309 if (!TempsToInstrument.insert(Addr).second)
2310 continue; // We've seen this temp in the current BB.
2313 } else if (ClInvalidPointerPairs &&
2314 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2315 PointerComparisonsOrSubtracts.push_back(&Inst);
2317 } else if (isa<MemIntrinsic>(Inst)) {
2320 if (isa<AllocaInst>(Inst)) NumAllocas++;
2323 // A call inside BB.
2324 TempsToInstrument.clear();
2325 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2327 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2328 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2331 ToInstrument.push_back(&Inst);
2333 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2339 (ClInstrumentationWithCallsThreshold >= 0 &&
2340 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2341 const DataLayout &DL = F.getParent()->getDataLayout();
2342 ObjectSizeOpts ObjSizeOpts;
2343 ObjSizeOpts.RoundToAlign = true;
2344 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
2347 int NumInstrumented = 0;
2348 for (auto Inst : ToInstrument) {
2349 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2350 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2351 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2352 instrumentMop(ObjSizeVis, Inst, UseCalls,
2353 F.getParent()->getDataLayout());
2355 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2360 FunctionStackPoisoner FSP(F, *this);
2361 bool ChangedStack = FSP.runOnFunction();
2363 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2364 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2365 for (auto CI : NoReturnCalls) {
2366 IRBuilder<> IRB(CI);
2367 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2370 for (auto Inst : PointerComparisonsOrSubtracts) {
2371 instrumentPointerComparisonOrSubtraction(Inst);
2375 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2376 FunctionModified = true;
2378 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2381 return FunctionModified;
2384 // Workaround for bug 11395: we don't want to instrument stack in functions
2385 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2386 // FIXME: remove once the bug 11395 is fixed.
2387 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2388 if (LongSize != 32) return false;
2389 CallInst *CI = dyn_cast<CallInst>(I);
2390 if (!CI || !CI->isInlineAsm()) return false;
2391 if (CI->getNumArgOperands() <= 5) return false;
2392 // We have inline assembly with quite a few arguments.
2396 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2397 IRBuilder<> IRB(*C);
2398 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2399 std::string Suffix = itostr(i);
2400 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2401 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2403 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2404 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2405 IRB.getVoidTy(), IntptrTy, IntptrTy));
2407 if (ASan.UseAfterScope) {
2408 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2409 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2410 IntptrTy, IntptrTy));
2411 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2412 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2413 IntptrTy, IntptrTy));
2416 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2417 std::ostringstream Name;
2418 Name << kAsanSetShadowPrefix;
2419 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2420 AsanSetShadowFunc[Val] =
2421 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2422 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy));
2425 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2426 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy));
2427 AsanAllocasUnpoisonFunc =
2428 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2429 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy));
2432 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2433 ArrayRef<uint8_t> ShadowBytes,
2434 size_t Begin, size_t End,
2436 Value *ShadowBase) {
2440 const size_t LargestStoreSizeInBytes =
2441 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2443 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2445 // Poison given range in shadow using larges store size with out leading and
2446 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2447 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2448 // middle of a store.
2449 for (size_t i = Begin; i < End;) {
2450 if (!ShadowMask[i]) {
2451 assert(!ShadowBytes[i]);
2456 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2457 // Fit store size into the range.
2458 while (StoreSizeInBytes > End - i)
2459 StoreSizeInBytes /= 2;
2461 // Minimize store size by trimming trailing zeros.
2462 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2463 while (j <= StoreSizeInBytes / 2)
2464 StoreSizeInBytes /= 2;
2468 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2470 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2472 Val = (Val << 8) | ShadowBytes[i + j];
2475 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2476 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2477 IRB.CreateAlignedStore(
2478 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2480 i += StoreSizeInBytes;
2484 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2485 ArrayRef<uint8_t> ShadowBytes,
2486 IRBuilder<> &IRB, Value *ShadowBase) {
2487 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2490 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2491 ArrayRef<uint8_t> ShadowBytes,
2492 size_t Begin, size_t End,
2493 IRBuilder<> &IRB, Value *ShadowBase) {
2494 assert(ShadowMask.size() == ShadowBytes.size());
2495 size_t Done = Begin;
2496 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2497 if (!ShadowMask[i]) {
2498 assert(!ShadowBytes[i]);
2501 uint8_t Val = ShadowBytes[i];
2502 if (!AsanSetShadowFunc[Val])
2505 // Skip same values.
2506 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2509 if (j - i >= ClMaxInlinePoisoningSize) {
2510 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2511 IRB.CreateCall(AsanSetShadowFunc[Val],
2512 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2513 ConstantInt::get(IntptrTy, j - i)});
2518 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2521 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2522 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2523 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2524 assert(LocalStackSize <= kMaxStackMallocSize);
2525 uint64_t MaxSize = kMinStackMallocSize;
2526 for (int i = 0;; i++, MaxSize *= 2)
2527 if (LocalStackSize <= MaxSize) return i;
2528 llvm_unreachable("impossible LocalStackSize");
2531 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2533 Instruction *ThenTerm,
2534 Value *ValueIfFalse) {
2535 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2536 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2537 PHI->addIncoming(ValueIfFalse, CondBlock);
2538 BasicBlock *ThenBlock = ThenTerm->getParent();
2539 PHI->addIncoming(ValueIfTrue, ThenBlock);
2543 Value *FunctionStackPoisoner::createAllocaForLayout(
2544 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2547 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2548 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2551 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2552 nullptr, "MyAlloca");
2553 assert(Alloca->isStaticAlloca());
2555 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2556 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2557 Alloca->setAlignment(FrameAlignment);
2558 return IRB.CreatePointerCast(Alloca, IntptrTy);
2561 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2562 BasicBlock &FirstBB = *F.begin();
2563 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2564 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2565 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2566 DynamicAllocaLayout->setAlignment(32);
2569 void FunctionStackPoisoner::processDynamicAllocas() {
2570 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2571 assert(DynamicAllocaPoisonCallVec.empty());
2575 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2576 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2577 assert(APC.InsBefore);
2579 assert(ASan.isInterestingAlloca(*APC.AI));
2580 assert(!APC.AI->isStaticAlloca());
2582 IRBuilder<> IRB(APC.InsBefore);
2583 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2584 // Dynamic allocas will be unpoisoned unconditionally below in
2585 // unpoisonDynamicAllocas.
2586 // Flag that we need unpoison static allocas.
2589 // Handle dynamic allocas.
2590 createDynamicAllocasInitStorage();
2591 for (auto &AI : DynamicAllocaVec)
2592 handleDynamicAllocaCall(AI);
2593 unpoisonDynamicAllocas();
2596 void FunctionStackPoisoner::processStaticAllocas() {
2597 if (AllocaVec.empty()) {
2598 assert(StaticAllocaPoisonCallVec.empty());
2602 int StackMallocIdx = -1;
2603 DebugLoc EntryDebugLocation;
2604 if (auto SP = F.getSubprogram())
2605 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2607 Instruction *InsBefore = AllocaVec[0];
2608 IRBuilder<> IRB(InsBefore);
2609 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2611 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2612 // debug info is broken, because only entry-block allocas are treated as
2613 // regular stack slots.
2614 auto InsBeforeB = InsBefore->getParent();
2615 assert(InsBeforeB == &F.getEntryBlock());
2616 for (auto *AI : StaticAllocasToMoveUp)
2617 if (AI->getParent() == InsBeforeB)
2618 AI->moveBefore(InsBefore);
2620 // If we have a call to llvm.localescape, keep it in the entry block.
2621 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2623 SmallVector<ASanStackVariableDescription, 16> SVD;
2624 SVD.reserve(AllocaVec.size());
2625 for (AllocaInst *AI : AllocaVec) {
2626 ASanStackVariableDescription D = {AI->getName().data(),
2627 ASan.getAllocaSizeInBytes(*AI),
2636 // Minimal header size (left redzone) is 4 pointers,
2637 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2638 size_t MinHeaderSize = ASan.LongSize / 2;
2639 const ASanStackFrameLayout &L =
2640 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2642 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2643 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2644 for (auto &Desc : SVD)
2645 AllocaToSVDMap[Desc.AI] = &Desc;
2647 // Update SVD with information from lifetime intrinsics.
2648 for (const auto &APC : StaticAllocaPoisonCallVec) {
2649 assert(APC.InsBefore);
2651 assert(ASan.isInterestingAlloca(*APC.AI));
2652 assert(APC.AI->isStaticAlloca());
2654 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2655 Desc.LifetimeSize = Desc.Size;
2656 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2657 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2658 if (LifetimeLoc->getFile() == FnLoc->getFile())
2659 if (unsigned Line = LifetimeLoc->getLine())
2660 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2665 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2666 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2667 uint64_t LocalStackSize = L.FrameSize;
2668 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2669 LocalStackSize <= kMaxStackMallocSize;
2670 bool DoDynamicAlloca = ClDynamicAllocaStack;
2671 // Don't do dynamic alloca or stack malloc if:
2672 // 1) There is inline asm: too often it makes assumptions on which registers
2674 // 2) There is a returns_twice call (typically setjmp), which is
2675 // optimization-hostile, and doesn't play well with introduced indirect
2676 // register-relative calculation of local variable addresses.
2677 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2678 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2680 Value *StaticAlloca =
2681 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2684 Value *LocalStackBase;
2686 if (DoStackMalloc) {
2687 // void *FakeStack = __asan_option_detect_stack_use_after_return
2688 // ? __asan_stack_malloc_N(LocalStackSize)
2690 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2691 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2692 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2693 Value *UseAfterReturnIsEnabled =
2694 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2695 Constant::getNullValue(IRB.getInt32Ty()));
2697 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2698 IRBuilder<> IRBIf(Term);
2699 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2700 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2701 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2702 Value *FakeStackValue =
2703 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2704 ConstantInt::get(IntptrTy, LocalStackSize));
2705 IRB.SetInsertPoint(InsBefore);
2706 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2707 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2708 ConstantInt::get(IntptrTy, 0));
2710 Value *NoFakeStack =
2711 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2712 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2713 IRBIf.SetInsertPoint(Term);
2714 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2715 Value *AllocaValue =
2716 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2717 IRB.SetInsertPoint(InsBefore);
2718 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2719 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2721 // void *FakeStack = nullptr;
2722 // void *LocalStackBase = alloca(LocalStackSize);
2723 FakeStack = ConstantInt::get(IntptrTy, 0);
2725 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2728 // Replace Alloca instructions with base+offset.
2729 for (const auto &Desc : SVD) {
2730 AllocaInst *AI = Desc.AI;
2731 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2732 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2734 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, DIExpression::NoDeref);
2735 AI->replaceAllUsesWith(NewAllocaPtr);
2738 // The left-most redzone has enough space for at least 4 pointers.
2739 // Write the Magic value to redzone[0].
2740 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2741 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2743 // Write the frame description constant to redzone[1].
2744 Value *BasePlus1 = IRB.CreateIntToPtr(
2745 IRB.CreateAdd(LocalStackBase,
2746 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2748 GlobalVariable *StackDescriptionGlobal =
2749 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2750 /*AllowMerging*/ true);
2751 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2752 IRB.CreateStore(Description, BasePlus1);
2753 // Write the PC to redzone[2].
2754 Value *BasePlus2 = IRB.CreateIntToPtr(
2755 IRB.CreateAdd(LocalStackBase,
2756 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2758 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2760 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2762 // Poison the stack red zones at the entry.
2763 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2764 // As mask we must use most poisoned case: red zones and after scope.
2765 // As bytes we can use either the same or just red zones only.
2766 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2768 if (!StaticAllocaPoisonCallVec.empty()) {
2769 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2771 // Poison static allocas near lifetime intrinsics.
2772 for (const auto &APC : StaticAllocaPoisonCallVec) {
2773 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2774 assert(Desc.Offset % L.Granularity == 0);
2775 size_t Begin = Desc.Offset / L.Granularity;
2776 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2778 IRBuilder<> IRB(APC.InsBefore);
2779 copyToShadow(ShadowAfterScope,
2780 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2785 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2786 SmallVector<uint8_t, 64> ShadowAfterReturn;
2788 // (Un)poison the stack before all ret instructions.
2789 for (auto Ret : RetVec) {
2790 IRBuilder<> IRBRet(Ret);
2791 // Mark the current frame as retired.
2792 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2794 if (DoStackMalloc) {
2795 assert(StackMallocIdx >= 0);
2796 // if FakeStack != 0 // LocalStackBase == FakeStack
2797 // // In use-after-return mode, poison the whole stack frame.
2798 // if StackMallocIdx <= 4
2799 // // For small sizes inline the whole thing:
2800 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2801 // **SavedFlagPtr(FakeStack) = 0
2803 // __asan_stack_free_N(FakeStack, LocalStackSize)
2805 // <This is not a fake stack; unpoison the redzones>
2807 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2808 TerminatorInst *ThenTerm, *ElseTerm;
2809 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2811 IRBuilder<> IRBPoison(ThenTerm);
2812 if (StackMallocIdx <= 4) {
2813 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2814 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2815 kAsanStackUseAfterReturnMagic);
2816 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2818 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2820 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2821 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2822 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2823 IRBPoison.CreateStore(
2824 Constant::getNullValue(IRBPoison.getInt8Ty()),
2825 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2827 // For larger frames call __asan_stack_free_*.
2828 IRBPoison.CreateCall(
2829 AsanStackFreeFunc[StackMallocIdx],
2830 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2833 IRBuilder<> IRBElse(ElseTerm);
2834 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2836 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2840 // We are done. Remove the old unused alloca instructions.
2841 for (auto AI : AllocaVec) AI->eraseFromParent();
2844 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2845 IRBuilder<> &IRB, bool DoPoison) {
2846 // For now just insert the call to ASan runtime.
2847 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2848 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2850 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2851 {AddrArg, SizeArg});
2854 // Handling llvm.lifetime intrinsics for a given %alloca:
2855 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2856 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2857 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2858 // could be poisoned by previous llvm.lifetime.end instruction, as the
2859 // variable may go in and out of scope several times, e.g. in loops).
2860 // (3) if we poisoned at least one %alloca in a function,
2861 // unpoison the whole stack frame at function exit.
2863 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2864 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2865 // We're interested only in allocas we can handle.
2866 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2867 // See if we've already calculated (or started to calculate) alloca for a
2869 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2870 if (I != AllocaForValue.end()) return I->second;
2871 // Store 0 while we're calculating alloca for value V to avoid
2872 // infinite recursion if the value references itself.
2873 AllocaForValue[V] = nullptr;
2874 AllocaInst *Res = nullptr;
2875 if (CastInst *CI = dyn_cast<CastInst>(V))
2876 Res = findAllocaForValue(CI->getOperand(0));
2877 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2878 for (Value *IncValue : PN->incoming_values()) {
2879 // Allow self-referencing phi-nodes.
2880 if (IncValue == PN) continue;
2881 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2882 // AI for incoming values should exist and should all be equal.
2883 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2887 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2888 Res = findAllocaForValue(EP->getPointerOperand());
2890 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2892 if (Res) AllocaForValue[V] = Res;
2896 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2897 IRBuilder<> IRB(AI);
2899 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2900 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2902 Value *Zero = Constant::getNullValue(IntptrTy);
2903 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2904 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2906 // Since we need to extend alloca with additional memory to locate
2907 // redzones, and OldSize is number of allocated blocks with
2908 // ElementSize size, get allocated memory size in bytes by
2909 // OldSize * ElementSize.
2910 const unsigned ElementSize =
2911 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2913 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2914 ConstantInt::get(IntptrTy, ElementSize));
2916 // PartialSize = OldSize % 32
2917 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2919 // Misalign = kAllocaRzSize - PartialSize;
2920 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2922 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2923 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2924 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2926 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2927 // Align is added to locate left redzone, PartialPadding for possible
2928 // partial redzone and kAllocaRzSize for right redzone respectively.
2929 Value *AdditionalChunkSize = IRB.CreateAdd(
2930 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2932 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2934 // Insert new alloca with new NewSize and Align params.
2935 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2936 NewAlloca->setAlignment(Align);
2938 // NewAddress = Address + Align
2939 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2940 ConstantInt::get(IntptrTy, Align));
2942 // Insert __asan_alloca_poison call for new created alloca.
2943 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2945 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2946 // for unpoisoning stuff.
2947 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2949 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2951 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2952 AI->replaceAllUsesWith(NewAddressPtr);
2954 // We are done. Erase old alloca from parent.
2955 AI->eraseFromParent();
2958 // isSafeAccess returns true if Addr is always inbounds with respect to its
2959 // base object. For example, it is a field access or an array access with
2960 // constant inbounds index.
2961 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2962 Value *Addr, uint64_t TypeSize) const {
2963 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2964 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2965 uint64_t Size = SizeOffset.first.getZExtValue();
2966 int64_t Offset = SizeOffset.second.getSExtValue();
2967 // Three checks are required to ensure safety:
2968 // . Offset >= 0 (since the offset is given from the base ptr)
2969 // . Size >= Offset (unsigned)
2970 // . Size - Offset >= NeededSize (unsigned)
2971 return Offset >= 0 && Size >= uint64_t(Offset) &&
2972 Size - uint64_t(Offset) >= TypeSize / 8;