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/Function.h"
20 #include "llvm/IRBuilder.h"
21 #include "llvm/IntrinsicInst.h"
22 #include "llvm/LLVMContext.h"
23 #include "llvm/Module.h"
24 #include "llvm/Type.h"
25 #include "llvm/ADT/ArrayRef.h"
26 #include "llvm/ADT/OwningPtr.h"
27 #include "llvm/ADT/SmallSet.h"
28 #include "llvm/ADT/SmallString.h"
29 #include "llvm/ADT/SmallVector.h"
30 #include "llvm/ADT/StringExtras.h"
31 #include "llvm/ADT/Triple.h"
32 #include "llvm/Support/CommandLine.h"
33 #include "llvm/Support/DataTypes.h"
34 #include "llvm/Support/Debug.h"
35 #include "llvm/Support/raw_ostream.h"
36 #include "llvm/Support/system_error.h"
37 #include "llvm/Target/TargetData.h"
38 #include "llvm/Target/TargetMachine.h"
39 #include "llvm/Transforms/Instrumentation.h"
40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 #include "llvm/Transforms/Utils/ModuleUtils.h"
48 static const uint64_t kDefaultShadowScale = 3;
49 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
50 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
51 static const uint64_t kDefaultShadowOffsetAndroid = 0;
53 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
54 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
55 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
57 static const char *kAsanModuleCtorName = "asan.module_ctor";
58 static const char *kAsanModuleDtorName = "asan.module_dtor";
59 static const int kAsanCtorAndCtorPriority = 1;
60 static const char *kAsanReportErrorTemplate = "__asan_report_";
61 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
62 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
63 static const char *kAsanInitName = "__asan_init";
64 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
65 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
66 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
67 static const char *kAsanStackMallocName = "__asan_stack_malloc";
68 static const char *kAsanStackFreeName = "__asan_stack_free";
70 static const int kAsanStackLeftRedzoneMagic = 0xf1;
71 static const int kAsanStackMidRedzoneMagic = 0xf2;
72 static const int kAsanStackRightRedzoneMagic = 0xf3;
73 static const int kAsanStackPartialRedzoneMagic = 0xf4;
75 // Command-line flags.
77 // This flag may need to be replaced with -f[no-]asan-reads.
78 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
79 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
80 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
81 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
82 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
83 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
84 cl::Hidden, cl::init(true));
85 // This flags limits the number of instructions to be instrumented
86 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
87 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
89 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
91 cl::desc("maximal number of instructions to instrument in any given BB"),
93 // This flag may need to be replaced with -f[no]asan-stack.
94 static cl::opt<bool> ClStack("asan-stack",
95 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
96 // This flag may need to be replaced with -f[no]asan-use-after-return.
97 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
98 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
99 // This flag may need to be replaced with -f[no]asan-globals.
100 static cl::opt<bool> ClGlobals("asan-globals",
101 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
102 static cl::opt<bool> ClMemIntrin("asan-memintrin",
103 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
104 // This flag may need to be replaced with -fasan-blacklist.
105 static cl::opt<std::string> ClBlackListFile("asan-blacklist",
106 cl::desc("File containing the list of functions to ignore "
107 "during instrumentation"), cl::Hidden);
109 // These flags allow to change the shadow mapping.
110 // The shadow mapping looks like
111 // Shadow = (Mem >> scale) + (1 << offset_log)
112 static cl::opt<int> ClMappingScale("asan-mapping-scale",
113 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
114 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
115 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
117 // Optimization flags. Not user visible, used mostly for testing
118 // and benchmarking the tool.
119 static cl::opt<bool> ClOpt("asan-opt",
120 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
121 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
122 cl::desc("Instrument the same temp just once"), cl::Hidden,
124 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
125 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
128 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
130 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
131 cl::Hidden, cl::init(0));
132 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
133 cl::Hidden, cl::desc("Debug func"));
134 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
135 cl::Hidden, cl::init(-1));
136 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
137 cl::Hidden, cl::init(-1));
141 /// AddressSanitizer: instrument the code in module to find memory bugs.
142 struct AddressSanitizer : public ModulePass {
144 virtual const char *getPassName() const;
145 void instrumentMop(Instruction *I);
146 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
147 Value *Addr, uint32_t TypeSize, bool IsWrite);
148 Instruction *generateCrashCode(IRBuilder<> &IRB, Value *Addr,
149 bool IsWrite, uint32_t TypeSize);
150 bool instrumentMemIntrinsic(MemIntrinsic *MI);
151 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
153 Instruction *InsertBefore, bool IsWrite);
154 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
155 bool handleFunction(Module &M, Function &F);
156 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
157 bool poisonStackInFunction(Module &M, Function &F);
158 virtual bool runOnModule(Module &M);
159 bool insertGlobalRedzones(Module &M);
160 static char ID; // Pass identification, replacement for typeid
164 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
165 Type *Ty = AI->getAllocatedType();
166 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
169 uint64_t getAlignedSize(uint64_t SizeInBytes) {
170 return ((SizeInBytes + RedzoneSize - 1)
171 / RedzoneSize) * RedzoneSize;
173 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
174 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
175 return getAlignedSize(SizeInBytes);
178 Function *checkInterfaceFunction(Constant *FuncOrBitcast);
179 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
180 Value *ShadowBase, bool DoPoison);
181 bool LooksLikeCodeInBug11395(Instruction *I);
183 Module *CurrentModule;
186 uint64_t MappingOffset;
192 Function *AsanCtorFunction;
193 Function *AsanInitFunction;
194 Instruction *CtorInsertBefore;
195 OwningPtr<FunctionBlackList> BL;
199 char AddressSanitizer::ID = 0;
200 INITIALIZE_PASS(AddressSanitizer, "asan",
201 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
203 AddressSanitizer::AddressSanitizer() : ModulePass(ID) { }
204 ModulePass *llvm::createAddressSanitizerPass() {
205 return new AddressSanitizer();
208 const char *AddressSanitizer::getPassName() const {
209 return "AddressSanitizer";
212 // Create a constant for Str so that we can pass it to the run-time lib.
213 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
214 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
215 return new GlobalVariable(M, StrConst->getType(), true,
216 GlobalValue::PrivateLinkage, StrConst, "");
219 // Split the basic block and insert an if-then code.
230 // Returns the ThenBlock's terminator.
231 static BranchInst *splitBlockAndInsertIfThen(Value *Cmp) {
232 Instruction *SplitBefore = cast<Instruction>(Cmp)->getNextNode();
233 BasicBlock *Head = SplitBefore->getParent();
234 BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
235 TerminatorInst *HeadOldTerm = Head->getTerminator();
236 LLVMContext &C = Head->getParent()->getParent()->getContext();
237 BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent());
238 BranchInst *HeadNewTerm =
239 BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cmp);
240 ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
242 BranchInst *CheckTerm = BranchInst::Create(Tail, ThenBlock);
246 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
248 Shadow = IRB.CreateLShr(Shadow, MappingScale);
249 if (MappingOffset == 0)
251 // (Shadow >> scale) | offset
252 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
256 void AddressSanitizer::instrumentMemIntrinsicParam(Instruction *OrigIns,
257 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
258 // Check the first byte.
260 IRBuilder<> IRB(InsertBefore);
261 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
263 // Check the last byte.
265 IRBuilder<> IRB(InsertBefore);
266 Value *SizeMinusOne = IRB.CreateSub(
267 Size, ConstantInt::get(Size->getType(), 1));
268 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
269 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
270 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
271 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
275 // Instrument memset/memmove/memcpy
276 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
277 Value *Dst = MI->getDest();
278 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
279 Value *Src = MemTran ? MemTran->getSource() : NULL;
280 Value *Length = MI->getLength();
282 Constant *ConstLength = dyn_cast<Constant>(Length);
283 Instruction *InsertBefore = MI;
285 if (ConstLength->isNullValue()) return false;
287 // The size is not a constant so it could be zero -- check at run-time.
288 IRBuilder<> IRB(InsertBefore);
290 Value *Cmp = IRB.CreateICmpNE(Length,
291 Constant::getNullValue(Length->getType()));
292 InsertBefore = splitBlockAndInsertIfThen(Cmp);
295 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
297 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
301 // If I is an interesting memory access, return the PointerOperand
302 // and set IsWrite. Otherwise return NULL.
303 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
304 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
305 if (!ClInstrumentReads) return NULL;
307 return LI->getPointerOperand();
309 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
310 if (!ClInstrumentWrites) return NULL;
312 return SI->getPointerOperand();
314 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
315 if (!ClInstrumentAtomics) return NULL;
317 return RMW->getPointerOperand();
319 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
320 if (!ClInstrumentAtomics) return NULL;
322 return XCHG->getPointerOperand();
327 void AddressSanitizer::instrumentMop(Instruction *I) {
329 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
331 if (ClOpt && ClOptGlobals && isa<GlobalVariable>(Addr)) {
332 // We are accessing a global scalar variable. Nothing to catch here.
335 Type *OrigPtrTy = Addr->getType();
336 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
338 assert(OrigTy->isSized());
339 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
341 if (TypeSize != 8 && TypeSize != 16 &&
342 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
343 // Ignore all unusual sizes.
348 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
351 // Validate the result of Module::getOrInsertFunction called for an interface
352 // function of AddressSanitizer. If the instrumented module defines a function
353 // with the same name, their prototypes must match, otherwise
354 // getOrInsertFunction returns a bitcast.
355 Function *AddressSanitizer::checkInterfaceFunction(Constant *FuncOrBitcast) {
356 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
357 FuncOrBitcast->dump();
358 report_fatal_error("trying to redefine an AddressSanitizer "
359 "interface function");
362 Instruction *AddressSanitizer::generateCrashCode(
363 IRBuilder<> &IRB, Value *Addr, bool IsWrite, uint32_t TypeSize) {
364 // IsWrite and TypeSize are encoded in the function name.
365 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
366 (IsWrite ? "store" : "load") + itostr(TypeSize / 8);
367 Value *ReportWarningFunc = CurrentModule->getOrInsertFunction(
368 FunctionName, IRB.getVoidTy(), IntptrTy, NULL);
369 CallInst *Call = IRB.CreateCall(ReportWarningFunc, Addr);
370 Call->setDoesNotReturn();
374 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
375 IRBuilder<> &IRB, Value *Addr,
376 uint32_t TypeSize, bool IsWrite) {
377 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
379 Type *ShadowTy = IntegerType::get(
380 *C, std::max(8U, TypeSize >> MappingScale));
381 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
382 Value *ShadowPtr = memToShadow(AddrLong, IRB);
383 Value *CmpVal = Constant::getNullValue(ShadowTy);
384 Value *ShadowValue = IRB.CreateLoad(
385 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
387 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
389 Instruction *CheckTerm = splitBlockAndInsertIfThen(Cmp);
390 IRBuilder<> IRB2(CheckTerm);
392 size_t Granularity = 1 << MappingScale;
393 if (TypeSize < 8 * Granularity) {
394 // Addr & (Granularity - 1)
395 Value *LastAccessedByte = IRB2.CreateAnd(
396 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
397 // (Addr & (Granularity - 1)) + size - 1
398 if (TypeSize / 8 > 1)
399 LastAccessedByte = IRB2.CreateAdd(
400 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
401 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
402 LastAccessedByte = IRB2.CreateIntCast(
403 LastAccessedByte, IRB.getInt8Ty(), false);
404 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
405 Value *Cmp2 = IRB2.CreateICmpSGE(LastAccessedByte, ShadowValue);
407 CheckTerm = splitBlockAndInsertIfThen(Cmp2);
410 IRBuilder<> IRB1(CheckTerm);
411 Instruction *Crash = generateCrashCode(IRB1, AddrLong, IsWrite, TypeSize);
412 Crash->setDebugLoc(OrigIns->getDebugLoc());
413 ReplaceInstWithInst(CheckTerm, new UnreachableInst(*C));
416 // This function replaces all global variables with new variables that have
417 // trailing redzones. It also creates a function that poisons
418 // redzones and inserts this function into llvm.global_ctors.
419 bool AddressSanitizer::insertGlobalRedzones(Module &M) {
420 SmallVector<GlobalVariable *, 16> GlobalsToChange;
422 for (Module::GlobalListType::iterator G = M.getGlobalList().begin(),
423 E = M.getGlobalList().end(); G != E; ++G) {
424 Type *Ty = cast<PointerType>(G->getType())->getElementType();
425 DEBUG(dbgs() << "GLOBAL: " << *G);
427 if (!Ty->isSized()) continue;
428 if (!G->hasInitializer()) continue;
429 // Touch only those globals that will not be defined in other modules.
430 // Don't handle ODR type linkages since other modules may be built w/o asan.
431 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
432 G->getLinkage() != GlobalVariable::PrivateLinkage &&
433 G->getLinkage() != GlobalVariable::InternalLinkage)
435 // Two problems with thread-locals:
436 // - The address of the main thread's copy can't be computed at link-time.
437 // - Need to poison all copies, not just the main thread's one.
438 if (G->isThreadLocal())
440 // For now, just ignore this Alloca if the alignment is large.
441 if (G->getAlignment() > RedzoneSize) continue;
443 // Ignore all the globals with the names starting with "\01L_OBJC_".
444 // Many of those are put into the .cstring section. The linker compresses
445 // that section by removing the spare \0s after the string terminator, so
446 // our redzones get broken.
447 if ((G->getName().find("\01L_OBJC_") == 0) ||
448 (G->getName().find("\01l_OBJC_") == 0)) {
449 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
453 if (G->hasSection()) {
454 StringRef Section(G->getSection());
455 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
456 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
458 if ((Section.find("__OBJC,") == 0) ||
459 (Section.find("__DATA, __objc_") == 0)) {
460 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
463 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
464 // Constant CFString instances are compiled in the following way:
465 // -- the string buffer is emitted into
466 // __TEXT,__cstring,cstring_literals
467 // -- the constant NSConstantString structure referencing that buffer
468 // is placed into __DATA,__cfstring
469 // Therefore there's no point in placing redzones into __DATA,__cfstring.
470 // Moreover, it causes the linker to crash on OS X 10.7
471 if (Section.find("__DATA,__cfstring") == 0) {
472 DEBUG(dbgs() << "Ignoring CFString: " << *G);
477 GlobalsToChange.push_back(G);
480 size_t n = GlobalsToChange.size();
481 if (n == 0) return false;
483 // A global is described by a structure
486 // size_t size_with_redzone;
488 // We initialize an array of such structures and pass it to a run-time call.
489 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
490 IntptrTy, IntptrTy, NULL);
491 SmallVector<Constant *, 16> Initializers(n);
493 IRBuilder<> IRB(CtorInsertBefore);
495 for (size_t i = 0; i < n; i++) {
496 GlobalVariable *G = GlobalsToChange[i];
497 PointerType *PtrTy = cast<PointerType>(G->getType());
498 Type *Ty = PtrTy->getElementType();
499 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
500 uint64_t RightRedzoneSize = RedzoneSize +
501 (RedzoneSize - (SizeInBytes % RedzoneSize));
502 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
504 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
505 Constant *NewInitializer = ConstantStruct::get(
506 NewTy, G->getInitializer(),
507 Constant::getNullValue(RightRedZoneTy), NULL);
509 SmallString<2048> DescriptionOfGlobal = G->getName();
510 DescriptionOfGlobal += " (";
511 DescriptionOfGlobal += M.getModuleIdentifier();
512 DescriptionOfGlobal += ")";
513 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
515 // Create a new global variable with enough space for a redzone.
516 GlobalVariable *NewGlobal = new GlobalVariable(
517 M, NewTy, G->isConstant(), G->getLinkage(),
518 NewInitializer, "", G, G->getThreadLocalMode());
519 NewGlobal->copyAttributesFrom(G);
520 NewGlobal->setAlignment(RedzoneSize);
523 Indices2[0] = IRB.getInt32(0);
524 Indices2[1] = IRB.getInt32(0);
526 G->replaceAllUsesWith(
527 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
528 NewGlobal->takeName(G);
529 G->eraseFromParent();
531 Initializers[i] = ConstantStruct::get(
533 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
534 ConstantInt::get(IntptrTy, SizeInBytes),
535 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
536 ConstantExpr::getPointerCast(Name, IntptrTy),
538 DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
541 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
542 GlobalVariable *AllGlobals = new GlobalVariable(
543 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
544 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
546 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
547 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
548 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
550 IRB.CreateCall2(AsanRegisterGlobals,
551 IRB.CreatePointerCast(AllGlobals, IntptrTy),
552 ConstantInt::get(IntptrTy, n));
554 // We also need to unregister globals at the end, e.g. when a shared library
556 Function *AsanDtorFunction = Function::Create(
557 FunctionType::get(Type::getVoidTy(*C), false),
558 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
559 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
560 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
561 Function *AsanUnregisterGlobals =
562 checkInterfaceFunction(M.getOrInsertFunction(
563 kAsanUnregisterGlobalsName,
564 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
565 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
567 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
568 IRB.CreatePointerCast(AllGlobals, IntptrTy),
569 ConstantInt::get(IntptrTy, n));
570 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
577 bool AddressSanitizer::runOnModule(Module &M) {
578 // Initialize the private fields. No one has accessed them before.
579 TD = getAnalysisIfAvailable<TargetData>();
582 BL.reset(new FunctionBlackList(ClBlackListFile));
585 C = &(M.getContext());
586 LongSize = TD->getPointerSizeInBits();
587 IntptrTy = Type::getIntNTy(*C, LongSize);
588 IntptrPtrTy = PointerType::get(IntptrTy, 0);
590 AsanCtorFunction = Function::Create(
591 FunctionType::get(Type::getVoidTy(*C), false),
592 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
593 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
594 CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB);
596 // call __asan_init in the module ctor.
597 IRBuilder<> IRB(CtorInsertBefore);
598 AsanInitFunction = checkInterfaceFunction(
599 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
600 AsanInitFunction->setLinkage(Function::ExternalLinkage);
601 IRB.CreateCall(AsanInitFunction);
603 llvm::Triple targetTriple(M.getTargetTriple());
604 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::ANDROIDEABI;
606 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
607 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
608 if (ClMappingOffsetLog >= 0) {
609 if (ClMappingOffsetLog == 0) {
613 MappingOffset = 1ULL << ClMappingOffsetLog;
616 MappingScale = kDefaultShadowScale;
617 if (ClMappingScale) {
618 MappingScale = ClMappingScale;
620 // Redzone used for stack and globals is at least 32 bytes.
621 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
622 RedzoneSize = std::max(32, (int)(1 << MappingScale));
627 Res |= insertGlobalRedzones(M);
629 if (ClMappingOffsetLog >= 0) {
630 // Tell the run-time the current values of mapping offset and scale.
631 GlobalValue *asan_mapping_offset =
632 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
633 ConstantInt::get(IntptrTy, MappingOffset),
634 kAsanMappingOffsetName);
635 // Read the global, otherwise it may be optimized away.
636 IRB.CreateLoad(asan_mapping_offset, true);
638 if (ClMappingScale) {
639 GlobalValue *asan_mapping_scale =
640 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
641 ConstantInt::get(IntptrTy, MappingScale),
642 kAsanMappingScaleName);
643 // Read the global, otherwise it may be optimized away.
644 IRB.CreateLoad(asan_mapping_scale, true);
648 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
649 if (F->isDeclaration()) continue;
650 Res |= handleFunction(M, *F);
653 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
658 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
659 // For each NSObject descendant having a +load method, this method is invoked
660 // by the ObjC runtime before any of the static constructors is called.
661 // Therefore we need to instrument such methods with a call to __asan_init
662 // at the beginning in order to initialize our runtime before any access to
663 // the shadow memory.
664 // We cannot just ignore these methods, because they may call other
665 // instrumented functions.
666 if (F.getName().find(" load]") != std::string::npos) {
667 IRBuilder<> IRB(F.begin()->begin());
668 IRB.CreateCall(AsanInitFunction);
674 bool AddressSanitizer::handleFunction(Module &M, Function &F) {
675 if (BL->isIn(F)) return false;
676 if (&F == AsanCtorFunction) return false;
678 // If needed, insert __asan_init before checking for AddressSafety attr.
679 maybeInsertAsanInitAtFunctionEntry(F);
681 if (!F.hasFnAttr(Attribute::AddressSafety)) return false;
683 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
685 // We want to instrument every address only once per basic block
686 // (unless there are calls between uses).
687 SmallSet<Value*, 16> TempsToInstrument;
688 SmallVector<Instruction*, 16> ToInstrument;
689 SmallVector<Instruction*, 8> NoReturnCalls;
692 // Fill the set of memory operations to instrument.
693 for (Function::iterator FI = F.begin(), FE = F.end();
695 TempsToInstrument.clear();
696 int NumInsnsPerBB = 0;
697 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
699 if (LooksLikeCodeInBug11395(BI)) return false;
700 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
701 if (ClOpt && ClOptSameTemp) {
702 if (!TempsToInstrument.insert(Addr))
703 continue; // We've seen this temp in the current BB.
705 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
708 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
710 TempsToInstrument.clear();
711 if (CI->doesNotReturn()) {
712 NoReturnCalls.push_back(CI);
717 ToInstrument.push_back(BI);
719 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
725 int NumInstrumented = 0;
726 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
727 Instruction *Inst = ToInstrument[i];
728 if (ClDebugMin < 0 || ClDebugMax < 0 ||
729 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
730 if (isInterestingMemoryAccess(Inst, &IsWrite))
733 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
740 bool ChangedStack = poisonStackInFunction(M, F);
742 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
743 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
744 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
745 Instruction *CI = NoReturnCalls[i];
747 IRB.CreateCall(M.getOrInsertFunction(kAsanHandleNoReturnName,
748 IRB.getVoidTy(), NULL));
751 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
754 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
755 if (ShadowRedzoneSize == 1) return PoisonByte;
756 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
757 if (ShadowRedzoneSize == 4)
758 return (PoisonByte << 24) + (PoisonByte << 16) +
759 (PoisonByte << 8) + (PoisonByte);
760 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
763 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
766 size_t ShadowGranularity,
768 for (size_t i = 0; i < RedzoneSize;
769 i+= ShadowGranularity, Shadow++) {
770 if (i + ShadowGranularity <= Size) {
771 *Shadow = 0; // fully addressable
772 } else if (i >= Size) {
773 *Shadow = Magic; // unaddressable
775 *Shadow = Size - i; // first Size-i bytes are addressable
780 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
782 Value *ShadowBase, bool DoPoison) {
783 size_t ShadowRZSize = RedzoneSize >> MappingScale;
784 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
785 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
786 Type *RZPtrTy = PointerType::get(RZTy, 0);
788 Value *PoisonLeft = ConstantInt::get(RZTy,
789 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
790 Value *PoisonMid = ConstantInt::get(RZTy,
791 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
792 Value *PoisonRight = ConstantInt::get(RZTy,
793 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
795 // poison the first red zone.
796 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
798 // poison all other red zones.
799 uint64_t Pos = RedzoneSize;
800 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
801 AllocaInst *AI = AllocaVec[i];
802 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
803 uint64_t AlignedSize = getAlignedAllocaSize(AI);
804 assert(AlignedSize - SizeInBytes < RedzoneSize);
809 assert(ShadowBase->getType() == IntptrTy);
810 if (SizeInBytes < AlignedSize) {
811 // Poison the partial redzone at right
813 ShadowBase, ConstantInt::get(IntptrTy,
814 (Pos >> MappingScale) - ShadowRZSize));
815 size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes);
818 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
820 1ULL << MappingScale,
821 kAsanStackPartialRedzoneMagic);
823 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
824 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
827 // Poison the full redzone at right.
828 Ptr = IRB.CreateAdd(ShadowBase,
829 ConstantInt::get(IntptrTy, Pos >> MappingScale));
830 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
831 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
837 // Workaround for bug 11395: we don't want to instrument stack in functions
838 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
839 // FIXME: remove once the bug 11395 is fixed.
840 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
841 if (LongSize != 32) return false;
842 CallInst *CI = dyn_cast<CallInst>(I);
843 if (!CI || !CI->isInlineAsm()) return false;
844 if (CI->getNumArgOperands() <= 5) return false;
845 // We have inline assembly with quite a few arguments.
849 // Find all static Alloca instructions and put
850 // poisoned red zones around all of them.
851 // Then unpoison everything back before the function returns.
853 // Stack poisoning does not play well with exception handling.
854 // When an exception is thrown, we essentially bypass the code
855 // that unpoisones the stack. This is why the run-time library has
856 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
857 // stack in the interceptor. This however does not work inside the
858 // actual function which catches the exception. Most likely because the
859 // compiler hoists the load of the shadow value somewhere too high.
860 // This causes asan to report a non-existing bug on 453.povray.
861 // It sounds like an LLVM bug.
862 bool AddressSanitizer::poisonStackInFunction(Module &M, Function &F) {
863 if (!ClStack) return false;
864 SmallVector<AllocaInst*, 16> AllocaVec;
865 SmallVector<Instruction*, 8> RetVec;
866 uint64_t TotalSize = 0;
868 // Filter out Alloca instructions we want (and can) handle.
869 // Collect Ret instructions.
870 for (Function::iterator FI = F.begin(), FE = F.end();
872 BasicBlock &BB = *FI;
873 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
875 if (isa<ReturnInst>(BI)) {
876 RetVec.push_back(BI);
880 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
882 if (AI->isArrayAllocation()) continue;
883 if (!AI->isStaticAlloca()) continue;
884 if (!AI->getAllocatedType()->isSized()) continue;
885 if (AI->getAlignment() > RedzoneSize) continue;
886 AllocaVec.push_back(AI);
887 uint64_t AlignedSize = getAlignedAllocaSize(AI);
888 TotalSize += AlignedSize;
892 if (AllocaVec.empty()) return false;
894 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize;
896 bool DoStackMalloc = ClUseAfterReturn
897 && LocalStackSize <= kMaxStackMallocSize;
899 Instruction *InsBefore = AllocaVec[0];
900 IRBuilder<> IRB(InsBefore);
903 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
904 AllocaInst *MyAlloca =
905 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
906 MyAlloca->setAlignment(RedzoneSize);
907 assert(MyAlloca->isStaticAlloca());
908 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
909 Value *LocalStackBase = OrigStackBase;
912 Value *AsanStackMallocFunc = M.getOrInsertFunction(
913 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL);
914 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
915 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
918 // This string will be parsed by the run-time (DescribeStackAddress).
919 SmallString<2048> StackDescriptionStorage;
920 raw_svector_ostream StackDescription(StackDescriptionStorage);
921 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
923 uint64_t Pos = RedzoneSize;
924 // Replace Alloca instructions with base+offset.
925 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
926 AllocaInst *AI = AllocaVec[i];
927 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
928 StringRef Name = AI->getName();
929 StackDescription << Pos << " " << SizeInBytes << " "
930 << Name.size() << " " << Name << " ";
931 uint64_t AlignedSize = getAlignedAllocaSize(AI);
932 assert((AlignedSize % RedzoneSize) == 0);
933 AI->replaceAllUsesWith(
935 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
937 Pos += AlignedSize + RedzoneSize;
939 assert(Pos == LocalStackSize);
941 // Write the Magic value and the frame description constant to the redzone.
942 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
943 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
945 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
946 ConstantInt::get(IntptrTy, LongSize/8));
947 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
948 Value *Description = IRB.CreatePointerCast(
949 createPrivateGlobalForString(M, StackDescription.str()),
951 IRB.CreateStore(Description, BasePlus1);
953 // Poison the stack redzones at the entry.
954 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
955 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
957 Value *AsanStackFreeFunc = NULL;
959 AsanStackFreeFunc = M.getOrInsertFunction(
960 kAsanStackFreeName, IRB.getVoidTy(),
961 IntptrTy, IntptrTy, IntptrTy, NULL);
964 // Unpoison the stack before all ret instructions.
965 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
966 Instruction *Ret = RetVec[i];
967 IRBuilder<> IRBRet(Ret);
969 // Mark the current frame as retired.
970 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
972 // Unpoison the stack.
973 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
976 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
977 ConstantInt::get(IntptrTy, LocalStackSize),