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 #define DEBUG_TYPE "asan"
18 #include "BlackList.h"
19 #include "llvm/Function.h"
20 #include "llvm/IRBuilder.h"
21 #include "llvm/InlineAsm.h"
22 #include "llvm/IntrinsicInst.h"
23 #include "llvm/LLVMContext.h"
24 #include "llvm/Module.h"
25 #include "llvm/Type.h"
26 #include "llvm/ADT/ArrayRef.h"
27 #include "llvm/ADT/OwningPtr.h"
28 #include "llvm/ADT/SmallSet.h"
29 #include "llvm/ADT/SmallString.h"
30 #include "llvm/ADT/SmallVector.h"
31 #include "llvm/ADT/StringExtras.h"
32 #include "llvm/ADT/Triple.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/DataTypes.h"
35 #include "llvm/Support/Debug.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Support/system_error.h"
38 #include "llvm/Target/TargetData.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "llvm/Transforms/Instrumentation.h"
41 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
42 #include "llvm/Transforms/Utils/ModuleUtils.h"
49 static const uint64_t kDefaultShadowScale = 3;
50 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
51 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
52 static const uint64_t kDefaultShadowOffsetAndroid = 0;
54 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
55 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
56 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
58 static const char *kAsanModuleCtorName = "asan.module_ctor";
59 static const char *kAsanModuleDtorName = "asan.module_dtor";
60 static const int kAsanCtorAndCtorPriority = 1;
61 static const char *kAsanReportErrorTemplate = "__asan_report_";
62 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
63 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
64 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
65 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
66 static const char *kAsanInitName = "__asan_init";
67 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
68 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
69 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
70 static const char *kAsanStackMallocName = "__asan_stack_malloc";
71 static const char *kAsanStackFreeName = "__asan_stack_free";
73 static const int kAsanStackLeftRedzoneMagic = 0xf1;
74 static const int kAsanStackMidRedzoneMagic = 0xf2;
75 static const int kAsanStackRightRedzoneMagic = 0xf3;
76 static const int kAsanStackPartialRedzoneMagic = 0xf4;
78 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
79 static const size_t kNumberOfAccessSizes = 5;
81 // Command-line flags.
83 // This flag may need to be replaced with -f[no-]asan-reads.
84 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
85 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
86 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
87 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
88 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
89 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
90 cl::Hidden, cl::init(true));
91 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
92 cl::desc("use instrumentation with slow path for all accesses"),
93 cl::Hidden, cl::init(false));
94 // This flag limits the number of instructions to be instrumented
95 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
96 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
98 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
100 cl::desc("maximal number of instructions to instrument in any given BB"),
102 // This flag may need to be replaced with -f[no]asan-stack.
103 static cl::opt<bool> ClStack("asan-stack",
104 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
105 // This flag may need to be replaced with -f[no]asan-use-after-return.
106 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
107 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
108 // This flag may need to be replaced with -f[no]asan-globals.
109 static cl::opt<bool> ClGlobals("asan-globals",
110 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
111 static cl::opt<bool> ClInitializers("asan-initialization-order",
112 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
113 static cl::opt<bool> ClMemIntrin("asan-memintrin",
114 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
115 // This flag may need to be replaced with -fasan-blacklist.
116 static cl::opt<std::string> ClBlackListFile("asan-blacklist",
117 cl::desc("File containing the list of functions to ignore "
118 "during instrumentation"), cl::Hidden);
120 // These flags allow to change the shadow mapping.
121 // The shadow mapping looks like
122 // Shadow = (Mem >> scale) + (1 << offset_log)
123 static cl::opt<int> ClMappingScale("asan-mapping-scale",
124 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
125 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
126 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
128 // Optimization flags. Not user visible, used mostly for testing
129 // and benchmarking the tool.
130 static cl::opt<bool> ClOpt("asan-opt",
131 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
132 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
133 cl::desc("Instrument the same temp just once"), cl::Hidden,
135 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
136 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
139 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
141 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
142 cl::Hidden, cl::init(0));
143 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
144 cl::Hidden, cl::desc("Debug func"));
145 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
146 cl::Hidden, cl::init(-1));
147 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
148 cl::Hidden, cl::init(-1));
152 /// An object of this type is created while instrumenting every function.
153 struct AsanFunctionContext {
154 AsanFunctionContext(Function &Function) : F(Function) { }
159 /// AddressSanitizer: instrument the code in module to find memory bugs.
160 struct AddressSanitizer : public ModulePass {
162 virtual const char *getPassName() const;
163 void instrumentMop(AsanFunctionContext &AFC, Instruction *I);
164 void instrumentAddress(AsanFunctionContext &AFC,
165 Instruction *OrigIns, IRBuilder<> &IRB,
166 Value *Addr, uint32_t TypeSize, bool IsWrite);
167 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
168 Value *ShadowValue, uint32_t TypeSize);
169 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
170 bool IsWrite, size_t AccessSizeIndex);
171 bool instrumentMemIntrinsic(AsanFunctionContext &AFC, MemIntrinsic *MI);
172 void instrumentMemIntrinsicParam(AsanFunctionContext &AFC,
173 Instruction *OrigIns, Value *Addr,
175 Instruction *InsertBefore, bool IsWrite);
176 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
177 bool handleFunction(Module &M, Function &F);
178 void createInitializerPoisonCalls(Module &M,
179 Value *FirstAddr, Value *LastAddr);
180 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
181 bool poisonStackInFunction(Module &M, Function &F);
182 virtual bool runOnModule(Module &M);
183 bool insertGlobalRedzones(Module &M);
184 static char ID; // Pass identification, replacement for typeid
187 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
188 Type *Ty = AI->getAllocatedType();
189 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
192 uint64_t getAlignedSize(uint64_t SizeInBytes) {
193 return ((SizeInBytes + RedzoneSize - 1)
194 / RedzoneSize) * RedzoneSize;
196 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
197 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
198 return getAlignedSize(SizeInBytes);
201 Function *checkInterfaceFunction(Constant *FuncOrBitcast);
202 bool ShouldInstrumentGlobal(GlobalVariable *G);
203 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
204 Value *ShadowBase, bool DoPoison);
205 bool LooksLikeCodeInBug11395(Instruction *I);
206 void FindDynamicInitializers(Module &M);
207 bool HasDynamicInitializer(GlobalVariable *G);
211 uint64_t MappingOffset;
217 Function *AsanCtorFunction;
218 Function *AsanInitFunction;
219 Instruction *CtorInsertBefore;
220 OwningPtr<BlackList> BL;
221 // This array is indexed by AccessIsWrite and log2(AccessSize).
222 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
224 SmallSet<GlobalValue*, 32> DynamicallyInitializedGlobals;
229 char AddressSanitizer::ID = 0;
230 INITIALIZE_PASS(AddressSanitizer, "asan",
231 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
233 AddressSanitizer::AddressSanitizer() : ModulePass(ID) { }
234 ModulePass *llvm::createAddressSanitizerPass() {
235 return new AddressSanitizer();
238 const char *AddressSanitizer::getPassName() const {
239 return "AddressSanitizer";
242 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
243 size_t Res = CountTrailingZeros_32(TypeSize / 8);
244 assert(Res < kNumberOfAccessSizes);
248 // Create a constant for Str so that we can pass it to the run-time lib.
249 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
250 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
251 return new GlobalVariable(M, StrConst->getType(), true,
252 GlobalValue::PrivateLinkage, StrConst, "");
255 // Split the basic block and insert an if-then code.
266 // ThenBlock block is created and its terminator is returned.
267 // If Unreachable, ThenBlock is terminated with UnreachableInst, otherwise
268 // it is terminated with BranchInst to Tail.
269 static TerminatorInst *splitBlockAndInsertIfThen(Value *Cmp, bool Unreachable) {
270 Instruction *SplitBefore = cast<Instruction>(Cmp)->getNextNode();
271 BasicBlock *Head = SplitBefore->getParent();
272 BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
273 TerminatorInst *HeadOldTerm = Head->getTerminator();
274 LLVMContext &C = Head->getParent()->getParent()->getContext();
275 BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
276 TerminatorInst *CheckTerm;
278 CheckTerm = new UnreachableInst(C, ThenBlock);
280 CheckTerm = BranchInst::Create(Tail, ThenBlock);
281 BranchInst *HeadNewTerm =
282 BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cmp);
283 ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
287 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
289 Shadow = IRB.CreateLShr(Shadow, MappingScale);
290 if (MappingOffset == 0)
292 // (Shadow >> scale) | offset
293 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
297 void AddressSanitizer::instrumentMemIntrinsicParam(
298 AsanFunctionContext &AFC, Instruction *OrigIns,
299 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
300 // Check the first byte.
302 IRBuilder<> IRB(InsertBefore);
303 instrumentAddress(AFC, OrigIns, IRB, Addr, 8, IsWrite);
305 // Check the last byte.
307 IRBuilder<> IRB(InsertBefore);
308 Value *SizeMinusOne = IRB.CreateSub(
309 Size, ConstantInt::get(Size->getType(), 1));
310 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
311 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
312 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
313 instrumentAddress(AFC, OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
317 // Instrument memset/memmove/memcpy
318 bool AddressSanitizer::instrumentMemIntrinsic(AsanFunctionContext &AFC,
320 Value *Dst = MI->getDest();
321 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
322 Value *Src = MemTran ? MemTran->getSource() : 0;
323 Value *Length = MI->getLength();
325 Constant *ConstLength = dyn_cast<Constant>(Length);
326 Instruction *InsertBefore = MI;
328 if (ConstLength->isNullValue()) return false;
330 // The size is not a constant so it could be zero -- check at run-time.
331 IRBuilder<> IRB(InsertBefore);
333 Value *Cmp = IRB.CreateICmpNE(Length,
334 Constant::getNullValue(Length->getType()));
335 InsertBefore = splitBlockAndInsertIfThen(Cmp, false);
338 instrumentMemIntrinsicParam(AFC, MI, Dst, Length, InsertBefore, true);
340 instrumentMemIntrinsicParam(AFC, MI, Src, Length, InsertBefore, false);
344 // If I is an interesting memory access, return the PointerOperand
345 // and set IsWrite. Otherwise return NULL.
346 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
347 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
348 if (!ClInstrumentReads) return NULL;
350 return LI->getPointerOperand();
352 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
353 if (!ClInstrumentWrites) return NULL;
355 return SI->getPointerOperand();
357 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
358 if (!ClInstrumentAtomics) return NULL;
360 return RMW->getPointerOperand();
362 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
363 if (!ClInstrumentAtomics) return NULL;
365 return XCHG->getPointerOperand();
370 void AddressSanitizer::FindDynamicInitializers(Module& M) {
371 // Clang generates metadata identifying all dynamically initialized globals.
372 NamedMDNode *DynamicGlobals =
373 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
376 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
377 MDNode *MDN = DynamicGlobals->getOperand(i);
378 assert(MDN->getNumOperands() == 1);
379 Value *VG = MDN->getOperand(0);
380 // The optimizer may optimize away a global entirely, in which case we
381 // cannot instrument access to it.
385 GlobalVariable *G = cast<GlobalVariable>(VG);
386 DynamicallyInitializedGlobals.insert(G);
389 // Returns true if a global variable is initialized dynamically in this TU.
390 bool AddressSanitizer::HasDynamicInitializer(GlobalVariable *G) {
391 return DynamicallyInitializedGlobals.count(G);
394 void AddressSanitizer::instrumentMop(AsanFunctionContext &AFC, Instruction *I) {
396 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
398 if (ClOpt && ClOptGlobals) {
399 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
400 // If initialization order checking is disabled, a simple access to a
401 // dynamically initialized global is always valid.
404 // If a global variable does not have dynamic initialization we don't
405 // have to instrument it. However, if a global has external linkage, we
406 // assume it has dynamic initialization, as it may have an initializer
407 // in a different TU.
408 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
409 !HasDynamicInitializer(G))
414 Type *OrigPtrTy = Addr->getType();
415 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
417 assert(OrigTy->isSized());
418 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
420 if (TypeSize != 8 && TypeSize != 16 &&
421 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
422 // Ignore all unusual sizes.
427 instrumentAddress(AFC, I, IRB, Addr, TypeSize, IsWrite);
430 // Validate the result of Module::getOrInsertFunction called for an interface
431 // function of AddressSanitizer. If the instrumented module defines a function
432 // with the same name, their prototypes must match, otherwise
433 // getOrInsertFunction returns a bitcast.
434 Function *AddressSanitizer::checkInterfaceFunction(Constant *FuncOrBitcast) {
435 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
436 FuncOrBitcast->dump();
437 report_fatal_error("trying to redefine an AddressSanitizer "
438 "interface function");
441 Instruction *AddressSanitizer::generateCrashCode(
442 Instruction *InsertBefore, Value *Addr,
443 bool IsWrite, size_t AccessSizeIndex) {
444 IRBuilder<> IRB(InsertBefore);
445 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
447 // We don't do Call->setDoesNotReturn() because the BB already has
448 // UnreachableInst at the end.
449 // This EmptyAsm is required to avoid callback merge.
450 IRB.CreateCall(EmptyAsm);
454 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
457 size_t Granularity = 1 << MappingScale;
458 // Addr & (Granularity - 1)
459 Value *LastAccessedByte = IRB.CreateAnd(
460 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
461 // (Addr & (Granularity - 1)) + size - 1
462 if (TypeSize / 8 > 1)
463 LastAccessedByte = IRB.CreateAdd(
464 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
465 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
466 LastAccessedByte = IRB.CreateIntCast(
467 LastAccessedByte, ShadowValue->getType(), false);
468 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
469 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
472 void AddressSanitizer::instrumentAddress(AsanFunctionContext &AFC,
473 Instruction *OrigIns,
474 IRBuilder<> &IRB, Value *Addr,
475 uint32_t TypeSize, bool IsWrite) {
476 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
478 Type *ShadowTy = IntegerType::get(
479 *C, std::max(8U, TypeSize >> MappingScale));
480 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
481 Value *ShadowPtr = memToShadow(AddrLong, IRB);
482 Value *CmpVal = Constant::getNullValue(ShadowTy);
483 Value *ShadowValue = IRB.CreateLoad(
484 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
486 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
487 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
488 size_t Granularity = 1 << MappingScale;
489 TerminatorInst *CrashTerm = 0;
491 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
492 TerminatorInst *CheckTerm = splitBlockAndInsertIfThen(Cmp, false);
493 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
494 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
495 IRB.SetInsertPoint(CheckTerm);
496 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
497 BasicBlock *CrashBlock = BasicBlock::Create(*C, "", &AFC.F, NextBB);
498 CrashTerm = new UnreachableInst(*C, CrashBlock);
499 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
500 ReplaceInstWithInst(CheckTerm, NewTerm);
502 CrashTerm = splitBlockAndInsertIfThen(Cmp, true);
506 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
507 Crash->setDebugLoc(OrigIns->getDebugLoc());
510 void AddressSanitizer::createInitializerPoisonCalls(Module &M,
513 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
514 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
515 // If that function is not present, this TU contains no globals, or they have
516 // all been optimized away
520 // Set up the arguments to our poison/unpoison functions.
521 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
523 // Declare our poisoning and unpoisoning functions.
524 Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
525 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
526 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
527 Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
528 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
529 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
531 // Add a call to poison all external globals before the given function starts.
532 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
534 // Add calls to unpoison all globals before each return instruction.
535 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
537 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
538 CallInst::Create(AsanUnpoisonGlobals, "", RI);
543 bool AddressSanitizer::ShouldInstrumentGlobal(GlobalVariable *G) {
544 Type *Ty = cast<PointerType>(G->getType())->getElementType();
545 DEBUG(dbgs() << "GLOBAL: " << *G);
547 if (!Ty->isSized()) return false;
548 if (!G->hasInitializer()) return false;
549 // Touch only those globals that will not be defined in other modules.
550 // Don't handle ODR type linkages since other modules may be built w/o asan.
551 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
552 G->getLinkage() != GlobalVariable::PrivateLinkage &&
553 G->getLinkage() != GlobalVariable::InternalLinkage)
555 // Two problems with thread-locals:
556 // - The address of the main thread's copy can't be computed at link-time.
557 // - Need to poison all copies, not just the main thread's one.
558 if (G->isThreadLocal())
560 // For now, just ignore this Alloca if the alignment is large.
561 if (G->getAlignment() > RedzoneSize) return false;
563 // Ignore all the globals with the names starting with "\01L_OBJC_".
564 // Many of those are put into the .cstring section. The linker compresses
565 // that section by removing the spare \0s after the string terminator, so
566 // our redzones get broken.
567 if ((G->getName().find("\01L_OBJC_") == 0) ||
568 (G->getName().find("\01l_OBJC_") == 0)) {
569 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
573 if (G->hasSection()) {
574 StringRef Section(G->getSection());
575 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
576 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
578 if ((Section.find("__OBJC,") == 0) ||
579 (Section.find("__DATA, __objc_") == 0)) {
580 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
583 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
584 // Constant CFString instances are compiled in the following way:
585 // -- the string buffer is emitted into
586 // __TEXT,__cstring,cstring_literals
587 // -- the constant NSConstantString structure referencing that buffer
588 // is placed into __DATA,__cfstring
589 // Therefore there's no point in placing redzones into __DATA,__cfstring.
590 // Moreover, it causes the linker to crash on OS X 10.7
591 if (Section.find("__DATA,__cfstring") == 0) {
592 DEBUG(dbgs() << "Ignoring CFString: " << *G);
600 // This function replaces all global variables with new variables that have
601 // trailing redzones. It also creates a function that poisons
602 // redzones and inserts this function into llvm.global_ctors.
603 bool AddressSanitizer::insertGlobalRedzones(Module &M) {
604 SmallVector<GlobalVariable *, 16> GlobalsToChange;
606 for (Module::GlobalListType::iterator G = M.global_begin(),
607 E = M.global_end(); G != E; ++G) {
608 if (ShouldInstrumentGlobal(G))
609 GlobalsToChange.push_back(G);
612 size_t n = GlobalsToChange.size();
613 if (n == 0) return false;
615 // A global is described by a structure
618 // size_t size_with_redzone;
620 // size_t has_dynamic_init;
621 // We initialize an array of such structures and pass it to a run-time call.
622 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
625 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
627 IRBuilder<> IRB(CtorInsertBefore);
630 FindDynamicInitializers(M);
632 // The addresses of the first and last dynamically initialized globals in
633 // this TU. Used in initialization order checking.
634 Value *FirstDynamic = 0, *LastDynamic = 0;
636 for (size_t i = 0; i < n; i++) {
637 GlobalVariable *G = GlobalsToChange[i];
638 PointerType *PtrTy = cast<PointerType>(G->getType());
639 Type *Ty = PtrTy->getElementType();
640 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
641 uint64_t RightRedzoneSize = RedzoneSize +
642 (RedzoneSize - (SizeInBytes % RedzoneSize));
643 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
644 // Determine whether this global should be poisoned in initialization.
645 bool GlobalHasDynamicInitializer = HasDynamicInitializer(G);
647 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
648 Constant *NewInitializer = ConstantStruct::get(
649 NewTy, G->getInitializer(),
650 Constant::getNullValue(RightRedZoneTy), NULL);
652 SmallString<2048> DescriptionOfGlobal = G->getName();
653 DescriptionOfGlobal += " (";
654 DescriptionOfGlobal += M.getModuleIdentifier();
655 DescriptionOfGlobal += ")";
656 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
658 // Create a new global variable with enough space for a redzone.
659 GlobalVariable *NewGlobal = new GlobalVariable(
660 M, NewTy, G->isConstant(), G->getLinkage(),
661 NewInitializer, "", G, G->getThreadLocalMode());
662 NewGlobal->copyAttributesFrom(G);
663 NewGlobal->setAlignment(RedzoneSize);
666 Indices2[0] = IRB.getInt32(0);
667 Indices2[1] = IRB.getInt32(0);
669 G->replaceAllUsesWith(
670 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
671 NewGlobal->takeName(G);
672 G->eraseFromParent();
674 Initializers[i] = ConstantStruct::get(
676 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
677 ConstantInt::get(IntptrTy, SizeInBytes),
678 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
679 ConstantExpr::getPointerCast(Name, IntptrTy),
680 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
683 // Populate the first and last globals declared in this TU.
684 if (ClInitializers && GlobalHasDynamicInitializer) {
685 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
686 if (FirstDynamic == 0)
687 FirstDynamic = LastDynamic;
690 DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
693 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
694 GlobalVariable *AllGlobals = new GlobalVariable(
695 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
696 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
698 // Create calls for poisoning before initializers run and unpoisoning after.
699 if (ClInitializers && FirstDynamic && LastDynamic)
700 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
702 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
703 kAsanRegisterGlobalsName, IRB.getVoidTy(),
704 IntptrTy, IntptrTy, NULL));
705 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
707 IRB.CreateCall2(AsanRegisterGlobals,
708 IRB.CreatePointerCast(AllGlobals, IntptrTy),
709 ConstantInt::get(IntptrTy, n));
711 // We also need to unregister globals at the end, e.g. when a shared library
713 Function *AsanDtorFunction = Function::Create(
714 FunctionType::get(Type::getVoidTy(*C), false),
715 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
716 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
717 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
718 Function *AsanUnregisterGlobals =
719 checkInterfaceFunction(M.getOrInsertFunction(
720 kAsanUnregisterGlobalsName,
721 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
722 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
724 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
725 IRB.CreatePointerCast(AllGlobals, IntptrTy),
726 ConstantInt::get(IntptrTy, n));
727 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
734 bool AddressSanitizer::runOnModule(Module &M) {
735 // Initialize the private fields. No one has accessed them before.
736 TD = getAnalysisIfAvailable<TargetData>();
739 BL.reset(new BlackList(ClBlackListFile));
741 C = &(M.getContext());
742 LongSize = TD->getPointerSizeInBits();
743 IntptrTy = Type::getIntNTy(*C, LongSize);
744 IntptrPtrTy = PointerType::get(IntptrTy, 0);
746 AsanCtorFunction = Function::Create(
747 FunctionType::get(Type::getVoidTy(*C), false),
748 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
749 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
750 CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB);
752 // call __asan_init in the module ctor.
753 IRBuilder<> IRB(CtorInsertBefore);
754 AsanInitFunction = checkInterfaceFunction(
755 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
756 AsanInitFunction->setLinkage(Function::ExternalLinkage);
757 IRB.CreateCall(AsanInitFunction);
759 // Create __asan_report* callbacks.
760 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
761 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
763 // IsWrite and TypeSize are encoded in the function name.
764 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
765 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
766 // If we are merging crash callbacks, they have two parameters.
767 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] = cast<Function>(
768 M.getOrInsertFunction(FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
771 // We insert an empty inline asm after __asan_report* to avoid callback merge.
772 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
773 StringRef(""), StringRef(""),
774 /*hasSideEffects=*/true);
776 llvm::Triple targetTriple(M.getTargetTriple());
777 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::ANDROIDEABI;
779 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
780 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
781 if (ClMappingOffsetLog >= 0) {
782 if (ClMappingOffsetLog == 0) {
786 MappingOffset = 1ULL << ClMappingOffsetLog;
789 MappingScale = kDefaultShadowScale;
790 if (ClMappingScale) {
791 MappingScale = ClMappingScale;
793 // Redzone used for stack and globals is at least 32 bytes.
794 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
795 RedzoneSize = std::max(32, (int)(1 << MappingScale));
800 Res |= insertGlobalRedzones(M);
802 if (ClMappingOffsetLog >= 0) {
803 // Tell the run-time the current values of mapping offset and scale.
804 GlobalValue *asan_mapping_offset =
805 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
806 ConstantInt::get(IntptrTy, MappingOffset),
807 kAsanMappingOffsetName);
808 // Read the global, otherwise it may be optimized away.
809 IRB.CreateLoad(asan_mapping_offset, true);
811 if (ClMappingScale) {
812 GlobalValue *asan_mapping_scale =
813 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
814 ConstantInt::get(IntptrTy, MappingScale),
815 kAsanMappingScaleName);
816 // Read the global, otherwise it may be optimized away.
817 IRB.CreateLoad(asan_mapping_scale, true);
821 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
822 if (F->isDeclaration()) continue;
823 Res |= handleFunction(M, *F);
826 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
831 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
832 // For each NSObject descendant having a +load method, this method is invoked
833 // by the ObjC runtime before any of the static constructors is called.
834 // Therefore we need to instrument such methods with a call to __asan_init
835 // at the beginning in order to initialize our runtime before any access to
836 // the shadow memory.
837 // We cannot just ignore these methods, because they may call other
838 // instrumented functions.
839 if (F.getName().find(" load]") != std::string::npos) {
840 IRBuilder<> IRB(F.begin()->begin());
841 IRB.CreateCall(AsanInitFunction);
847 bool AddressSanitizer::handleFunction(Module &M, Function &F) {
848 if (BL->isIn(F)) return false;
849 if (&F == AsanCtorFunction) return false;
851 // If needed, insert __asan_init before checking for AddressSafety attr.
852 maybeInsertAsanInitAtFunctionEntry(F);
854 if (!F.hasFnAttr(Attribute::AddressSafety)) return false;
856 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
858 // We want to instrument every address only once per basic block
859 // (unless there are calls between uses).
860 SmallSet<Value*, 16> TempsToInstrument;
861 SmallVector<Instruction*, 16> ToInstrument;
862 SmallVector<Instruction*, 8> NoReturnCalls;
865 // Fill the set of memory operations to instrument.
866 for (Function::iterator FI = F.begin(), FE = F.end();
868 TempsToInstrument.clear();
869 int NumInsnsPerBB = 0;
870 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
872 if (LooksLikeCodeInBug11395(BI)) return false;
873 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
874 if (ClOpt && ClOptSameTemp) {
875 if (!TempsToInstrument.insert(Addr))
876 continue; // We've seen this temp in the current BB.
878 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
881 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
883 TempsToInstrument.clear();
884 if (CI->doesNotReturn()) {
885 NoReturnCalls.push_back(CI);
890 ToInstrument.push_back(BI);
892 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
897 AsanFunctionContext AFC(F);
900 int NumInstrumented = 0;
901 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
902 Instruction *Inst = ToInstrument[i];
903 if (ClDebugMin < 0 || ClDebugMax < 0 ||
904 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
905 if (isInterestingMemoryAccess(Inst, &IsWrite))
906 instrumentMop(AFC, Inst);
908 instrumentMemIntrinsic(AFC, cast<MemIntrinsic>(Inst));
915 bool ChangedStack = poisonStackInFunction(M, F);
917 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
918 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
919 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
920 Instruction *CI = NoReturnCalls[i];
922 IRB.CreateCall(M.getOrInsertFunction(kAsanHandleNoReturnName,
923 IRB.getVoidTy(), NULL));
926 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
929 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
930 if (ShadowRedzoneSize == 1) return PoisonByte;
931 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
932 if (ShadowRedzoneSize == 4)
933 return (PoisonByte << 24) + (PoisonByte << 16) +
934 (PoisonByte << 8) + (PoisonByte);
935 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
938 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
941 size_t ShadowGranularity,
943 for (size_t i = 0; i < RedzoneSize;
944 i+= ShadowGranularity, Shadow++) {
945 if (i + ShadowGranularity <= Size) {
946 *Shadow = 0; // fully addressable
947 } else if (i >= Size) {
948 *Shadow = Magic; // unaddressable
950 *Shadow = Size - i; // first Size-i bytes are addressable
955 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
957 Value *ShadowBase, bool DoPoison) {
958 size_t ShadowRZSize = RedzoneSize >> MappingScale;
959 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
960 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
961 Type *RZPtrTy = PointerType::get(RZTy, 0);
963 Value *PoisonLeft = ConstantInt::get(RZTy,
964 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
965 Value *PoisonMid = ConstantInt::get(RZTy,
966 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
967 Value *PoisonRight = ConstantInt::get(RZTy,
968 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
970 // poison the first red zone.
971 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
973 // poison all other red zones.
974 uint64_t Pos = RedzoneSize;
975 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
976 AllocaInst *AI = AllocaVec[i];
977 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
978 uint64_t AlignedSize = getAlignedAllocaSize(AI);
979 assert(AlignedSize - SizeInBytes < RedzoneSize);
984 assert(ShadowBase->getType() == IntptrTy);
985 if (SizeInBytes < AlignedSize) {
986 // Poison the partial redzone at right
988 ShadowBase, ConstantInt::get(IntptrTy,
989 (Pos >> MappingScale) - ShadowRZSize));
990 size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes);
993 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
995 1ULL << MappingScale,
996 kAsanStackPartialRedzoneMagic);
998 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
999 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1002 // Poison the full redzone at right.
1003 Ptr = IRB.CreateAdd(ShadowBase,
1004 ConstantInt::get(IntptrTy, Pos >> MappingScale));
1005 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1006 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1012 // Workaround for bug 11395: we don't want to instrument stack in functions
1013 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1014 // FIXME: remove once the bug 11395 is fixed.
1015 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1016 if (LongSize != 32) return false;
1017 CallInst *CI = dyn_cast<CallInst>(I);
1018 if (!CI || !CI->isInlineAsm()) return false;
1019 if (CI->getNumArgOperands() <= 5) return false;
1020 // We have inline assembly with quite a few arguments.
1024 // Find all static Alloca instructions and put
1025 // poisoned red zones around all of them.
1026 // Then unpoison everything back before the function returns.
1028 // Stack poisoning does not play well with exception handling.
1029 // When an exception is thrown, we essentially bypass the code
1030 // that unpoisones the stack. This is why the run-time library has
1031 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1032 // stack in the interceptor. This however does not work inside the
1033 // actual function which catches the exception. Most likely because the
1034 // compiler hoists the load of the shadow value somewhere too high.
1035 // This causes asan to report a non-existing bug on 453.povray.
1036 // It sounds like an LLVM bug.
1037 bool AddressSanitizer::poisonStackInFunction(Module &M, Function &F) {
1038 if (!ClStack) return false;
1039 SmallVector<AllocaInst*, 16> AllocaVec;
1040 SmallVector<Instruction*, 8> RetVec;
1041 uint64_t TotalSize = 0;
1043 // Filter out Alloca instructions we want (and can) handle.
1044 // Collect Ret instructions.
1045 for (Function::iterator FI = F.begin(), FE = F.end();
1047 BasicBlock &BB = *FI;
1048 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1050 if (isa<ReturnInst>(BI)) {
1051 RetVec.push_back(BI);
1055 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1057 if (AI->isArrayAllocation()) continue;
1058 if (!AI->isStaticAlloca()) continue;
1059 if (!AI->getAllocatedType()->isSized()) continue;
1060 if (AI->getAlignment() > RedzoneSize) continue;
1061 AllocaVec.push_back(AI);
1062 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1063 TotalSize += AlignedSize;
1067 if (AllocaVec.empty()) return false;
1069 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize;
1071 bool DoStackMalloc = ClUseAfterReturn
1072 && LocalStackSize <= kMaxStackMallocSize;
1074 Instruction *InsBefore = AllocaVec[0];
1075 IRBuilder<> IRB(InsBefore);
1078 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1079 AllocaInst *MyAlloca =
1080 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1081 MyAlloca->setAlignment(RedzoneSize);
1082 assert(MyAlloca->isStaticAlloca());
1083 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1084 Value *LocalStackBase = OrigStackBase;
1086 if (DoStackMalloc) {
1087 Value *AsanStackMallocFunc = M.getOrInsertFunction(
1088 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL);
1089 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1090 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1093 // This string will be parsed by the run-time (DescribeStackAddress).
1094 SmallString<2048> StackDescriptionStorage;
1095 raw_svector_ostream StackDescription(StackDescriptionStorage);
1096 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1098 uint64_t Pos = RedzoneSize;
1099 // Replace Alloca instructions with base+offset.
1100 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1101 AllocaInst *AI = AllocaVec[i];
1102 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1103 StringRef Name = AI->getName();
1104 StackDescription << Pos << " " << SizeInBytes << " "
1105 << Name.size() << " " << Name << " ";
1106 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1107 assert((AlignedSize % RedzoneSize) == 0);
1108 AI->replaceAllUsesWith(
1110 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1112 Pos += AlignedSize + RedzoneSize;
1114 assert(Pos == LocalStackSize);
1116 // Write the Magic value and the frame description constant to the redzone.
1117 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1118 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1120 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1121 ConstantInt::get(IntptrTy, LongSize/8));
1122 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1123 Value *Description = IRB.CreatePointerCast(
1124 createPrivateGlobalForString(M, StackDescription.str()),
1126 IRB.CreateStore(Description, BasePlus1);
1128 // Poison the stack redzones at the entry.
1129 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1130 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1132 Value *AsanStackFreeFunc = NULL;
1133 if (DoStackMalloc) {
1134 AsanStackFreeFunc = M.getOrInsertFunction(
1135 kAsanStackFreeName, IRB.getVoidTy(),
1136 IntptrTy, IntptrTy, IntptrTy, NULL);
1139 // Unpoison the stack before all ret instructions.
1140 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1141 Instruction *Ret = RetVec[i];
1142 IRBuilder<> IRBRet(Ret);
1144 // Mark the current frame as retired.
1145 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1147 // Unpoison the stack.
1148 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1150 if (DoStackMalloc) {
1151 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1152 ConstantInt::get(IntptrTy, LocalStackSize),