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 "FunctionBlackList.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/OwningPtr.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/StringExtras.h"
25 #include "llvm/Function.h"
26 #include "llvm/IntrinsicInst.h"
27 #include "llvm/LLVMContext.h"
28 #include "llvm/Module.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/DataTypes.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/IRBuilder.h"
33 #include "llvm/Support/raw_ostream.h"
34 #include "llvm/Support/system_error.h"
35 #include "llvm/Target/TargetData.h"
36 #include "llvm/Target/TargetMachine.h"
37 #include "llvm/Transforms/Instrumentation.h"
38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
39 #include "llvm/Transforms/Utils/ModuleUtils.h"
40 #include "llvm/Type.h"
47 static const uint64_t kDefaultShadowScale = 3;
48 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
49 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
51 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
52 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
53 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
55 static const char *kAsanModuleCtorName = "asan.module_ctor";
56 static const char *kAsanModuleDtorName = "asan.module_dtor";
57 static const int kAsanCtorAndCtorPriority = 1;
58 static const char *kAsanReportErrorTemplate = "__asan_report_";
59 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
60 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
61 static const char *kAsanInitName = "__asan_init";
62 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
63 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
64 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
65 static const char *kAsanStackMallocName = "__asan_stack_malloc";
66 static const char *kAsanStackFreeName = "__asan_stack_free";
68 static const int kAsanStackLeftRedzoneMagic = 0xf1;
69 static const int kAsanStackMidRedzoneMagic = 0xf2;
70 static const int kAsanStackRightRedzoneMagic = 0xf3;
71 static const int kAsanStackPartialRedzoneMagic = 0xf4;
73 // Command-line flags.
75 // This flag may need to be replaced with -f[no-]asan-reads.
76 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
77 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
78 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
79 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
80 // This flag may need to be replaced with -f[no]asan-stack.
81 static cl::opt<bool> ClStack("asan-stack",
82 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
83 // This flag may need to be replaced with -f[no]asan-use-after-return.
84 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
85 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
86 // This flag may need to be replaced with -f[no]asan-globals.
87 static cl::opt<bool> ClGlobals("asan-globals",
88 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
89 static cl::opt<bool> ClMemIntrin("asan-memintrin",
90 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
91 // This flag may need to be replaced with -fasan-blacklist.
92 static cl::opt<std::string> ClBlackListFile("asan-blacklist",
93 cl::desc("File containing the list of functions to ignore "
94 "during instrumentation"), cl::Hidden);
96 // These flags allow to change the shadow mapping.
97 // The shadow mapping looks like
98 // Shadow = (Mem >> scale) + (1 << offset_log)
99 static cl::opt<int> ClMappingScale("asan-mapping-scale",
100 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
101 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
102 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
104 // Optimization flags. Not user visible, used mostly for testing
105 // and benchmarking the tool.
106 static cl::opt<bool> ClOpt("asan-opt",
107 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
108 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
109 cl::desc("Instrument the same temp just once"), cl::Hidden,
111 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
112 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
115 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
117 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
118 cl::Hidden, cl::init(0));
119 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
120 cl::Hidden, cl::desc("Debug func"));
121 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
122 cl::Hidden, cl::init(-1));
123 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
124 cl::Hidden, cl::init(-1));
128 /// AddressSanitizer: instrument the code in module to find memory bugs.
129 struct AddressSanitizer : public ModulePass {
131 virtual const char *getPassName() const;
132 void instrumentMop(Instruction *I);
133 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
134 Value *Addr, uint32_t TypeSize, bool IsWrite);
135 Instruction *generateCrashCode(IRBuilder<> &IRB, Value *Addr,
136 bool IsWrite, uint32_t TypeSize);
137 bool instrumentMemIntrinsic(MemIntrinsic *MI);
138 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
140 Instruction *InsertBefore, bool IsWrite);
141 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
142 bool handleFunction(Module &M, Function &F);
143 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
144 bool poisonStackInFunction(Module &M, Function &F);
145 virtual bool runOnModule(Module &M);
146 bool insertGlobalRedzones(Module &M);
147 BranchInst *splitBlockAndInsertIfThen(Instruction *SplitBefore, Value *Cmp);
148 static char ID; // Pass identification, replacement for typeid
152 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
153 Type *Ty = AI->getAllocatedType();
154 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
157 uint64_t getAlignedSize(uint64_t SizeInBytes) {
158 return ((SizeInBytes + RedzoneSize - 1)
159 / RedzoneSize) * RedzoneSize;
161 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
162 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
163 return getAlignedSize(SizeInBytes);
166 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
167 Value *ShadowBase, bool DoPoison);
168 bool LooksLikeCodeInBug11395(Instruction *I);
170 Module *CurrentModule;
173 uint64_t MappingOffset;
179 Function *AsanCtorFunction;
180 Function *AsanInitFunction;
181 Instruction *CtorInsertBefore;
182 OwningPtr<FunctionBlackList> BL;
186 char AddressSanitizer::ID = 0;
187 INITIALIZE_PASS(AddressSanitizer, "asan",
188 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
190 AddressSanitizer::AddressSanitizer() : ModulePass(ID) { }
191 ModulePass *llvm::createAddressSanitizerPass() {
192 return new AddressSanitizer();
195 const char *AddressSanitizer::getPassName() const {
196 return "AddressSanitizer";
199 // Create a constant for Str so that we can pass it to the run-time lib.
200 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
201 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
202 return new GlobalVariable(M, StrConst->getType(), true,
203 GlobalValue::PrivateLinkage, StrConst, "");
206 // Split the basic block and insert an if-then code.
218 // Returns the NewBasicBlock's terminator.
219 BranchInst *AddressSanitizer::splitBlockAndInsertIfThen(
220 Instruction *SplitBefore, Value *Cmp) {
221 BasicBlock *Head = SplitBefore->getParent();
222 BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
223 TerminatorInst *HeadOldTerm = Head->getTerminator();
224 BasicBlock *NewBasicBlock =
225 BasicBlock::Create(*C, "", Head->getParent());
226 BranchInst *HeadNewTerm = BranchInst::Create(/*ifTrue*/NewBasicBlock,
229 ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
231 BranchInst *CheckTerm = BranchInst::Create(Tail, NewBasicBlock);
235 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
237 Shadow = IRB.CreateLShr(Shadow, MappingScale);
238 if (MappingOffset == 0)
240 // (Shadow >> scale) | offset
241 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
245 void AddressSanitizer::instrumentMemIntrinsicParam(Instruction *OrigIns,
246 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
247 // Check the first byte.
249 IRBuilder<> IRB(InsertBefore);
250 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
252 // Check the last byte.
254 IRBuilder<> IRB(InsertBefore);
255 Value *SizeMinusOne = IRB.CreateSub(
256 Size, ConstantInt::get(Size->getType(), 1));
257 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
258 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
259 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
260 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
264 // Instrument memset/memmove/memcpy
265 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
266 Value *Dst = MI->getDest();
267 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
268 Value *Src = MemTran ? MemTran->getSource() : NULL;
269 Value *Length = MI->getLength();
271 Constant *ConstLength = dyn_cast<Constant>(Length);
272 Instruction *InsertBefore = MI;
274 if (ConstLength->isNullValue()) return false;
276 // The size is not a constant so it could be zero -- check at run-time.
277 IRBuilder<> IRB(InsertBefore);
279 Value *Cmp = IRB.CreateICmpNE(Length,
280 Constant::getNullValue(Length->getType()));
281 InsertBefore = splitBlockAndInsertIfThen(InsertBefore, Cmp);
284 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
286 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
290 static Value *getLDSTOperand(Instruction *I) {
291 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
292 return LI->getPointerOperand();
294 return cast<StoreInst>(*I).getPointerOperand();
297 void AddressSanitizer::instrumentMop(Instruction *I) {
298 int IsWrite = isa<StoreInst>(*I);
299 Value *Addr = getLDSTOperand(I);
300 if (ClOpt && ClOptGlobals && isa<GlobalVariable>(Addr)) {
301 // We are accessing a global scalar variable. Nothing to catch here.
304 Type *OrigPtrTy = Addr->getType();
305 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
307 assert(OrigTy->isSized());
308 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
310 if (TypeSize != 8 && TypeSize != 16 &&
311 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
312 // Ignore all unusual sizes.
317 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
320 Instruction *AddressSanitizer::generateCrashCode(
321 IRBuilder<> &IRB, Value *Addr, bool IsWrite, uint32_t TypeSize) {
322 // IsWrite and TypeSize are encoded in the function name.
323 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
324 (IsWrite ? "store" : "load") + itostr(TypeSize / 8);
325 Value *ReportWarningFunc = CurrentModule->getOrInsertFunction(
326 FunctionName, IRB.getVoidTy(), IntptrTy, NULL);
327 CallInst *Call = IRB.CreateCall(ReportWarningFunc, Addr);
328 Call->setDoesNotReturn();
332 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
333 IRBuilder<> &IRB, Value *Addr,
334 uint32_t TypeSize, bool IsWrite) {
335 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
337 Type *ShadowTy = IntegerType::get(
338 *C, std::max(8U, TypeSize >> MappingScale));
339 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
340 Value *ShadowPtr = memToShadow(AddrLong, IRB);
341 Value *CmpVal = Constant::getNullValue(ShadowTy);
342 Value *ShadowValue = IRB.CreateLoad(
343 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
345 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
347 Instruction *CheckTerm = splitBlockAndInsertIfThen(
348 cast<Instruction>(Cmp)->getNextNode(), Cmp);
349 IRBuilder<> IRB2(CheckTerm);
351 size_t Granularity = 1 << MappingScale;
352 if (TypeSize < 8 * Granularity) {
353 // Addr & (Granularity - 1)
354 Value *Lower3Bits = IRB2.CreateAnd(
355 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
356 // (Addr & (Granularity - 1)) + size - 1
357 Value *LastAccessedByte = IRB2.CreateAdd(
358 Lower3Bits, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
359 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
360 LastAccessedByte = IRB2.CreateIntCast(
361 LastAccessedByte, IRB.getInt8Ty(), false);
362 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
363 Value *Cmp2 = IRB2.CreateICmpSGE(LastAccessedByte, ShadowValue);
365 CheckTerm = splitBlockAndInsertIfThen(CheckTerm, Cmp2);
368 IRBuilder<> IRB1(CheckTerm);
369 Instruction *Crash = generateCrashCode(IRB1, AddrLong, IsWrite, TypeSize);
370 Crash->setDebugLoc(OrigIns->getDebugLoc());
371 ReplaceInstWithInst(CheckTerm, new UnreachableInst(*C));
374 // This function replaces all global variables with new variables that have
375 // trailing redzones. It also creates a function that poisons
376 // redzones and inserts this function into llvm.global_ctors.
377 bool AddressSanitizer::insertGlobalRedzones(Module &M) {
378 SmallVector<GlobalVariable *, 16> GlobalsToChange;
380 for (Module::GlobalListType::iterator G = M.getGlobalList().begin(),
381 E = M.getGlobalList().end(); G != E; ++G) {
382 Type *Ty = cast<PointerType>(G->getType())->getElementType();
383 DEBUG(dbgs() << "GLOBAL: " << *G);
385 if (!Ty->isSized()) continue;
386 if (!G->hasInitializer()) continue;
387 // Touch only those globals that will not be defined in other modules.
388 // Don't handle ODR type linkages since other modules may be built w/o asan.
389 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
390 G->getLinkage() != GlobalVariable::PrivateLinkage &&
391 G->getLinkage() != GlobalVariable::InternalLinkage)
393 // Two problems with thread-locals:
394 // - The address of the main thread's copy can't be computed at link-time.
395 // - Need to poison all copies, not just the main thread's one.
396 if (G->isThreadLocal())
398 // For now, just ignore this Alloca if the alignment is large.
399 if (G->getAlignment() > RedzoneSize) continue;
401 // Ignore all the globals with the names starting with "\01L_OBJC_".
402 // Many of those are put into the .cstring section. The linker compresses
403 // that section by removing the spare \0s after the string terminator, so
404 // our redzones get broken.
405 if ((G->getName().find("\01L_OBJC_") == 0) ||
406 (G->getName().find("\01l_OBJC_") == 0)) {
407 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
411 if (G->hasSection()) {
412 StringRef Section(G->getSection());
413 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
414 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
416 if ((Section.find("__OBJC,") == 0) ||
417 (Section.find("__DATA, __objc_") == 0)) {
418 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
421 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
422 // Constant CFString instances are compiled in the following way:
423 // -- the string buffer is emitted into
424 // __TEXT,__cstring,cstring_literals
425 // -- the constant NSConstantString structure referencing that buffer
426 // is placed into __DATA,__cfstring
427 // Therefore there's no point in placing redzones into __DATA,__cfstring.
428 // Moreover, it causes the linker to crash on OS X 10.7
429 if (Section.find("__DATA,__cfstring") == 0) {
430 DEBUG(dbgs() << "Ignoring CFString: " << *G);
435 GlobalsToChange.push_back(G);
438 size_t n = GlobalsToChange.size();
439 if (n == 0) return false;
441 // A global is described by a structure
444 // size_t size_with_redzone;
446 // We initialize an array of such structures and pass it to a run-time call.
447 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
448 IntptrTy, IntptrTy, NULL);
449 SmallVector<Constant *, 16> Initializers(n);
451 IRBuilder<> IRB(CtorInsertBefore);
453 for (size_t i = 0; i < n; i++) {
454 GlobalVariable *G = GlobalsToChange[i];
455 PointerType *PtrTy = cast<PointerType>(G->getType());
456 Type *Ty = PtrTy->getElementType();
457 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
458 uint64_t RightRedzoneSize = RedzoneSize +
459 (RedzoneSize - (SizeInBytes % RedzoneSize));
460 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
462 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
463 Constant *NewInitializer = ConstantStruct::get(
464 NewTy, G->getInitializer(),
465 Constant::getNullValue(RightRedZoneTy), NULL);
467 SmallString<2048> DescriptionOfGlobal = G->getName();
468 DescriptionOfGlobal += " (";
469 DescriptionOfGlobal += M.getModuleIdentifier();
470 DescriptionOfGlobal += ")";
471 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
473 // Create a new global variable with enough space for a redzone.
474 GlobalVariable *NewGlobal = new GlobalVariable(
475 M, NewTy, G->isConstant(), G->getLinkage(),
476 NewInitializer, "", G, G->isThreadLocal());
477 NewGlobal->copyAttributesFrom(G);
478 NewGlobal->setAlignment(RedzoneSize);
481 Indices2[0] = IRB.getInt32(0);
482 Indices2[1] = IRB.getInt32(0);
484 G->replaceAllUsesWith(
485 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
486 NewGlobal->takeName(G);
487 G->eraseFromParent();
489 Initializers[i] = ConstantStruct::get(
491 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
492 ConstantInt::get(IntptrTy, SizeInBytes),
493 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
494 ConstantExpr::getPointerCast(Name, IntptrTy),
496 DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
499 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
500 GlobalVariable *AllGlobals = new GlobalVariable(
501 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
502 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
504 Function *AsanRegisterGlobals = cast<Function>(M.getOrInsertFunction(
505 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
506 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
508 IRB.CreateCall2(AsanRegisterGlobals,
509 IRB.CreatePointerCast(AllGlobals, IntptrTy),
510 ConstantInt::get(IntptrTy, n));
512 // We also need to unregister globals at the end, e.g. when a shared library
514 Function *AsanDtorFunction = Function::Create(
515 FunctionType::get(Type::getVoidTy(*C), false),
516 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
517 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
518 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
519 Function *AsanUnregisterGlobals = cast<Function>(M.getOrInsertFunction(
520 kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
521 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
523 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
524 IRB.CreatePointerCast(AllGlobals, IntptrTy),
525 ConstantInt::get(IntptrTy, n));
526 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
533 bool AddressSanitizer::runOnModule(Module &M) {
534 // Initialize the private fields. No one has accessed them before.
535 TD = getAnalysisIfAvailable<TargetData>();
538 BL.reset(new FunctionBlackList(ClBlackListFile));
541 C = &(M.getContext());
542 LongSize = TD->getPointerSizeInBits();
543 IntptrTy = Type::getIntNTy(*C, LongSize);
544 IntptrPtrTy = PointerType::get(IntptrTy, 0);
546 AsanCtorFunction = Function::Create(
547 FunctionType::get(Type::getVoidTy(*C), false),
548 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
549 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
550 CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB);
552 // call __asan_init in the module ctor.
553 IRBuilder<> IRB(CtorInsertBefore);
554 AsanInitFunction = cast<Function>(
555 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
556 AsanInitFunction->setLinkage(Function::ExternalLinkage);
557 IRB.CreateCall(AsanInitFunction);
559 MappingOffset = LongSize == 32
560 ? kDefaultShadowOffset32 : kDefaultShadowOffset64;
561 if (ClMappingOffsetLog >= 0) {
562 if (ClMappingOffsetLog == 0) {
566 MappingOffset = 1ULL << ClMappingOffsetLog;
569 MappingScale = kDefaultShadowScale;
570 if (ClMappingScale) {
571 MappingScale = ClMappingScale;
573 // Redzone used for stack and globals is at least 32 bytes.
574 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
575 RedzoneSize = std::max(32, (int)(1 << MappingScale));
580 Res |= insertGlobalRedzones(M);
582 if (ClMappingOffsetLog >= 0) {
583 // Tell the run-time the current values of mapping offset and scale.
584 GlobalValue *asan_mapping_offset =
585 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
586 ConstantInt::get(IntptrTy, MappingOffset),
587 kAsanMappingOffsetName);
588 // Read the global, otherwise it may be optimized away.
589 IRB.CreateLoad(asan_mapping_offset, true);
591 if (ClMappingScale) {
592 GlobalValue *asan_mapping_scale =
593 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
594 ConstantInt::get(IntptrTy, MappingScale),
595 kAsanMappingScaleName);
596 // Read the global, otherwise it may be optimized away.
597 IRB.CreateLoad(asan_mapping_scale, true);
601 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
602 if (F->isDeclaration()) continue;
603 Res |= handleFunction(M, *F);
606 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
611 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
612 // For each NSObject descendant having a +load method, this method is invoked
613 // by the ObjC runtime before any of the static constructors is called.
614 // Therefore we need to instrument such methods with a call to __asan_init
615 // at the beginning in order to initialize our runtime before any access to
616 // the shadow memory.
617 // We cannot just ignore these methods, because they may call other
618 // instrumented functions.
619 if (F.getName().find(" load]") != std::string::npos) {
620 IRBuilder<> IRB(F.begin()->begin());
621 IRB.CreateCall(AsanInitFunction);
627 bool AddressSanitizer::handleFunction(Module &M, Function &F) {
628 if (BL->isIn(F)) return false;
629 if (&F == AsanCtorFunction) return false;
631 // If needed, insert __asan_init before checking for AddressSafety attr.
632 maybeInsertAsanInitAtFunctionEntry(F);
634 if (!F.hasFnAttr(Attribute::AddressSafety)) return false;
636 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
638 // We want to instrument every address only once per basic block
639 // (unless there are calls between uses).
640 SmallSet<Value*, 16> TempsToInstrument;
641 SmallVector<Instruction*, 16> ToInstrument;
642 SmallVector<Instruction*, 8> NoReturnCalls;
644 // Fill the set of memory operations to instrument.
645 for (Function::iterator FI = F.begin(), FE = F.end();
647 TempsToInstrument.clear();
648 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
650 if (LooksLikeCodeInBug11395(BI)) return false;
651 if ((isa<LoadInst>(BI) && ClInstrumentReads) ||
652 (isa<StoreInst>(BI) && ClInstrumentWrites)) {
653 Value *Addr = getLDSTOperand(BI);
654 if (ClOpt && ClOptSameTemp) {
655 if (!TempsToInstrument.insert(Addr))
656 continue; // We've seen this temp in the current BB.
658 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
661 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
663 TempsToInstrument.clear();
664 if (CI->doesNotReturn()) {
665 NoReturnCalls.push_back(CI);
670 ToInstrument.push_back(BI);
675 int NumInstrumented = 0;
676 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
677 Instruction *Inst = ToInstrument[i];
678 if (ClDebugMin < 0 || ClDebugMax < 0 ||
679 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
680 if (isa<StoreInst>(Inst) || isa<LoadInst>(Inst))
683 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
690 bool ChangedStack = poisonStackInFunction(M, F);
692 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
693 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
694 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
695 Instruction *CI = NoReturnCalls[i];
697 IRB.CreateCall(M.getOrInsertFunction(kAsanHandleNoReturnName,
698 IRB.getVoidTy(), NULL));
701 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
704 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
705 if (ShadowRedzoneSize == 1) return PoisonByte;
706 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
707 if (ShadowRedzoneSize == 4)
708 return (PoisonByte << 24) + (PoisonByte << 16) +
709 (PoisonByte << 8) + (PoisonByte);
710 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
713 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
716 size_t ShadowGranularity,
718 for (size_t i = 0; i < RedzoneSize;
719 i+= ShadowGranularity, Shadow++) {
720 if (i + ShadowGranularity <= Size) {
721 *Shadow = 0; // fully addressable
722 } else if (i >= Size) {
723 *Shadow = Magic; // unaddressable
725 *Shadow = Size - i; // first Size-i bytes are addressable
730 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
732 Value *ShadowBase, bool DoPoison) {
733 size_t ShadowRZSize = RedzoneSize >> MappingScale;
734 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
735 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
736 Type *RZPtrTy = PointerType::get(RZTy, 0);
738 Value *PoisonLeft = ConstantInt::get(RZTy,
739 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
740 Value *PoisonMid = ConstantInt::get(RZTy,
741 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
742 Value *PoisonRight = ConstantInt::get(RZTy,
743 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
745 // poison the first red zone.
746 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
748 // poison all other red zones.
749 uint64_t Pos = RedzoneSize;
750 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
751 AllocaInst *AI = AllocaVec[i];
752 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
753 uint64_t AlignedSize = getAlignedAllocaSize(AI);
754 assert(AlignedSize - SizeInBytes < RedzoneSize);
759 assert(ShadowBase->getType() == IntptrTy);
760 if (SizeInBytes < AlignedSize) {
761 // Poison the partial redzone at right
763 ShadowBase, ConstantInt::get(IntptrTy,
764 (Pos >> MappingScale) - ShadowRZSize));
765 size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes);
768 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
770 1ULL << MappingScale,
771 kAsanStackPartialRedzoneMagic);
773 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
774 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
777 // Poison the full redzone at right.
778 Ptr = IRB.CreateAdd(ShadowBase,
779 ConstantInt::get(IntptrTy, Pos >> MappingScale));
780 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
781 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
787 // Workaround for bug 11395: we don't want to instrument stack in functions
788 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
789 // FIXME: remove once the bug 11395 is fixed.
790 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
791 if (LongSize != 32) return false;
792 CallInst *CI = dyn_cast<CallInst>(I);
793 if (!CI || !CI->isInlineAsm()) return false;
794 if (CI->getNumArgOperands() <= 5) return false;
795 // We have inline assembly with quite a few arguments.
799 // Find all static Alloca instructions and put
800 // poisoned red zones around all of them.
801 // Then unpoison everything back before the function returns.
803 // Stack poisoning does not play well with exception handling.
804 // When an exception is thrown, we essentially bypass the code
805 // that unpoisones the stack. This is why the run-time library has
806 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
807 // stack in the interceptor. This however does not work inside the
808 // actual function which catches the exception. Most likely because the
809 // compiler hoists the load of the shadow value somewhere too high.
810 // This causes asan to report a non-existing bug on 453.povray.
811 // It sounds like an LLVM bug.
812 bool AddressSanitizer::poisonStackInFunction(Module &M, Function &F) {
813 if (!ClStack) return false;
814 SmallVector<AllocaInst*, 16> AllocaVec;
815 SmallVector<Instruction*, 8> RetVec;
816 uint64_t TotalSize = 0;
818 // Filter out Alloca instructions we want (and can) handle.
819 // Collect Ret instructions.
820 for (Function::iterator FI = F.begin(), FE = F.end();
822 BasicBlock &BB = *FI;
823 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
825 if (isa<ReturnInst>(BI)) {
826 RetVec.push_back(BI);
830 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
832 if (AI->isArrayAllocation()) continue;
833 if (!AI->isStaticAlloca()) continue;
834 if (!AI->getAllocatedType()->isSized()) continue;
835 if (AI->getAlignment() > RedzoneSize) continue;
836 AllocaVec.push_back(AI);
837 uint64_t AlignedSize = getAlignedAllocaSize(AI);
838 TotalSize += AlignedSize;
842 if (AllocaVec.empty()) return false;
844 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize;
846 bool DoStackMalloc = ClUseAfterReturn
847 && LocalStackSize <= kMaxStackMallocSize;
849 Instruction *InsBefore = AllocaVec[0];
850 IRBuilder<> IRB(InsBefore);
853 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
854 AllocaInst *MyAlloca =
855 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
856 MyAlloca->setAlignment(RedzoneSize);
857 assert(MyAlloca->isStaticAlloca());
858 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
859 Value *LocalStackBase = OrigStackBase;
862 Value *AsanStackMallocFunc = M.getOrInsertFunction(
863 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL);
864 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
865 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
868 // This string will be parsed by the run-time (DescribeStackAddress).
869 SmallString<2048> StackDescriptionStorage;
870 raw_svector_ostream StackDescription(StackDescriptionStorage);
871 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
873 uint64_t Pos = RedzoneSize;
874 // Replace Alloca instructions with base+offset.
875 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
876 AllocaInst *AI = AllocaVec[i];
877 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
878 StringRef Name = AI->getName();
879 StackDescription << Pos << " " << SizeInBytes << " "
880 << Name.size() << " " << Name << " ";
881 uint64_t AlignedSize = getAlignedAllocaSize(AI);
882 assert((AlignedSize % RedzoneSize) == 0);
883 AI->replaceAllUsesWith(
885 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
887 Pos += AlignedSize + RedzoneSize;
889 assert(Pos == LocalStackSize);
891 // Write the Magic value and the frame description constant to the redzone.
892 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
893 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
895 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
896 ConstantInt::get(IntptrTy, LongSize/8));
897 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
898 Value *Description = IRB.CreatePointerCast(
899 createPrivateGlobalForString(M, StackDescription.str()),
901 IRB.CreateStore(Description, BasePlus1);
903 // Poison the stack redzones at the entry.
904 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
905 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
907 Value *AsanStackFreeFunc = NULL;
909 AsanStackFreeFunc = M.getOrInsertFunction(
910 kAsanStackFreeName, IRB.getVoidTy(),
911 IntptrTy, IntptrTy, IntptrTy, NULL);
914 // Unpoison the stack before all ret instructions.
915 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
916 Instruction *Ret = RetVec[i];
917 IRBuilder<> IRBRet(Ret);
919 // Mark the current frame as retired.
920 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
922 // Unpoison the stack.
923 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
926 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
927 ConstantInt::get(IntptrTy, LocalStackSize),