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 "llvm/Transforms/Instrumentation.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DepthFirstIterator.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/SmallSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/IR/Type.h"
37 #include "llvm/InstVisitor.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/DataTypes.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include "llvm/Support/system_error.h"
43 #include "llvm/Target/TargetMachine.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/BlackList.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
53 static const uint64_t kDefaultShadowScale = 3;
54 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
55 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
56 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
58 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
59 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
60 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
62 static const char *kAsanModuleCtorName = "asan.module_ctor";
63 static const char *kAsanModuleDtorName = "asan.module_dtor";
64 static const int kAsanCtorAndCtorPriority = 1;
65 static const char *kAsanReportErrorTemplate = "__asan_report_";
66 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
67 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
68 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
69 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
70 static const char *kAsanInitName = "__asan_init";
71 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
72 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
73 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
74 static const char *kAsanStackMallocName = "__asan_stack_malloc";
75 static const char *kAsanStackFreeName = "__asan_stack_free";
76 static const char *kAsanGenPrefix = "__asan_gen_";
77 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
78 static const char *kAsanUnpoisonStackMemoryName =
79 "__asan_unpoison_stack_memory";
81 static const int kAsanStackLeftRedzoneMagic = 0xf1;
82 static const int kAsanStackMidRedzoneMagic = 0xf2;
83 static const int kAsanStackRightRedzoneMagic = 0xf3;
84 static const int kAsanStackPartialRedzoneMagic = 0xf4;
86 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
87 static const size_t kNumberOfAccessSizes = 5;
89 // Command-line flags.
91 // This flag may need to be replaced with -f[no-]asan-reads.
92 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
93 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
94 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
95 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
96 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
97 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
98 cl::Hidden, cl::init(true));
99 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
100 cl::desc("use instrumentation with slow path for all accesses"),
101 cl::Hidden, cl::init(false));
102 // This flag limits the number of instructions to be instrumented
103 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
104 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
106 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
108 cl::desc("maximal number of instructions to instrument in any given BB"),
110 // This flag may need to be replaced with -f[no]asan-stack.
111 static cl::opt<bool> ClStack("asan-stack",
112 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
113 // This flag may need to be replaced with -f[no]asan-use-after-return.
114 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
115 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
116 // This flag may need to be replaced with -f[no]asan-globals.
117 static cl::opt<bool> ClGlobals("asan-globals",
118 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
119 static cl::opt<bool> ClInitializers("asan-initialization-order",
120 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
121 static cl::opt<bool> ClMemIntrin("asan-memintrin",
122 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClRealignStack("asan-realign-stack",
124 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
125 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
126 cl::desc("File containing the list of objects to ignore "
127 "during instrumentation"), cl::Hidden);
129 // These flags allow to change the shadow mapping.
130 // The shadow mapping looks like
131 // Shadow = (Mem >> scale) + (1 << offset_log)
132 static cl::opt<int> ClMappingScale("asan-mapping-scale",
133 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
134 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
135 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
137 // Optimization flags. Not user visible, used mostly for testing
138 // and benchmarking the tool.
139 static cl::opt<bool> ClOpt("asan-opt",
140 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
141 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
142 cl::desc("Instrument the same temp just once"), cl::Hidden,
144 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
145 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
147 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
148 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
149 cl::Hidden, cl::init(false));
152 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
154 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
155 cl::Hidden, cl::init(0));
156 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
157 cl::Hidden, cl::desc("Debug func"));
158 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
159 cl::Hidden, cl::init(-1));
160 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
161 cl::Hidden, cl::init(-1));
164 /// A set of dynamically initialized globals extracted from metadata.
165 class SetOfDynamicallyInitializedGlobals {
167 void Init(Module& M) {
168 // Clang generates metadata identifying all dynamically initialized globals.
169 NamedMDNode *DynamicGlobals =
170 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
173 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
174 MDNode *MDN = DynamicGlobals->getOperand(i);
175 assert(MDN->getNumOperands() == 1);
176 Value *VG = MDN->getOperand(0);
177 // The optimizer may optimize away a global entirely, in which case we
178 // cannot instrument access to it.
181 DynInitGlobals.insert(cast<GlobalVariable>(VG));
184 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
186 SmallSet<GlobalValue*, 32> DynInitGlobals;
189 /// This struct defines the shadow mapping using the rule:
190 /// shadow = (mem >> Scale) ADD-or-OR Offset.
191 struct ShadowMapping {
197 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
198 bool ZeroBaseShadow) {
199 llvm::Triple TargetTriple(M.getTargetTriple());
200 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
201 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
203 ShadowMapping Mapping;
205 // OR-ing shadow offset if more efficient (at least on x86),
206 // but on ppc64 we have to use add since the shadow offset is not neccesary
207 // 1/8-th of the address space.
208 Mapping.OrShadowOffset = !IsPPC64;
210 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
211 (LongSize == 32 ? kDefaultShadowOffset32 :
212 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
213 if (ClMappingOffsetLog >= 0) {
214 // Zero offset log is the special case.
215 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
218 Mapping.Scale = kDefaultShadowScale;
219 if (ClMappingScale) {
220 Mapping.Scale = ClMappingScale;
226 static size_t RedzoneSizeForScale(int MappingScale) {
227 // Redzone used for stack and globals is at least 32 bytes.
228 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
229 return std::max(32U, 1U << MappingScale);
232 /// AddressSanitizer: instrument the code in module to find memory bugs.
233 struct AddressSanitizer : public FunctionPass {
234 AddressSanitizer(bool CheckInitOrder = false,
235 bool CheckUseAfterReturn = false,
236 bool CheckLifetime = false,
237 StringRef BlacklistFile = StringRef(),
238 bool ZeroBaseShadow = false)
240 CheckInitOrder(CheckInitOrder || ClInitializers),
241 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
242 CheckLifetime(CheckLifetime || ClCheckLifetime),
243 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
245 ZeroBaseShadow(ZeroBaseShadow) {}
246 virtual const char *getPassName() const {
247 return "AddressSanitizerFunctionPass";
249 void instrumentMop(Instruction *I);
250 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
251 Value *Addr, uint32_t TypeSize, bool IsWrite);
252 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
253 Value *ShadowValue, uint32_t TypeSize);
254 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
255 bool IsWrite, size_t AccessSizeIndex);
256 bool instrumentMemIntrinsic(MemIntrinsic *MI);
257 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
259 Instruction *InsertBefore, bool IsWrite);
260 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
261 bool runOnFunction(Function &F);
262 void createInitializerPoisonCalls(Module &M,
263 Value *FirstAddr, Value *LastAddr);
264 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
265 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
266 virtual bool doInitialization(Module &M);
267 static char ID; // Pass identification, replacement for typeid
270 void initializeCallbacks(Module &M);
272 bool ShouldInstrumentGlobal(GlobalVariable *G);
273 bool LooksLikeCodeInBug11395(Instruction *I);
274 void FindDynamicInitializers(Module &M);
277 bool CheckUseAfterReturn;
279 SmallString<64> BlacklistFile;
286 ShadowMapping Mapping;
287 Function *AsanCtorFunction;
288 Function *AsanInitFunction;
289 Function *AsanHandleNoReturnFunc;
290 OwningPtr<BlackList> BL;
291 // This array is indexed by AccessIsWrite and log2(AccessSize).
292 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
294 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
296 friend struct FunctionStackPoisoner;
299 class AddressSanitizerModule : public ModulePass {
301 AddressSanitizerModule(bool CheckInitOrder = false,
302 StringRef BlacklistFile = StringRef(),
303 bool ZeroBaseShadow = false)
305 CheckInitOrder(CheckInitOrder || ClInitializers),
306 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
308 ZeroBaseShadow(ZeroBaseShadow) {}
309 bool runOnModule(Module &M);
310 static char ID; // Pass identification, replacement for typeid
311 virtual const char *getPassName() const {
312 return "AddressSanitizerModule";
316 void initializeCallbacks(Module &M);
318 bool ShouldInstrumentGlobal(GlobalVariable *G);
319 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
321 size_t RedzoneSize() const {
322 return RedzoneSizeForScale(Mapping.Scale);
326 SmallString<64> BlacklistFile;
329 OwningPtr<BlackList> BL;
330 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
334 ShadowMapping Mapping;
335 Function *AsanPoisonGlobals;
336 Function *AsanUnpoisonGlobals;
337 Function *AsanRegisterGlobals;
338 Function *AsanUnregisterGlobals;
341 // Stack poisoning does not play well with exception handling.
342 // When an exception is thrown, we essentially bypass the code
343 // that unpoisones the stack. This is why the run-time library has
344 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
345 // stack in the interceptor. This however does not work inside the
346 // actual function which catches the exception. Most likely because the
347 // compiler hoists the load of the shadow value somewhere too high.
348 // This causes asan to report a non-existing bug on 453.povray.
349 // It sounds like an LLVM bug.
350 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
352 AddressSanitizer &ASan;
357 ShadowMapping Mapping;
359 SmallVector<AllocaInst*, 16> AllocaVec;
360 SmallVector<Instruction*, 8> RetVec;
361 uint64_t TotalStackSize;
362 unsigned StackAlignment;
364 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
365 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
367 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
368 struct AllocaPoisonCall {
369 IntrinsicInst *InsBefore;
373 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
375 // Maps Value to an AllocaInst from which the Value is originated.
376 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
377 AllocaForValueMapTy AllocaForValue;
379 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
380 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
381 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
382 Mapping(ASan.Mapping),
383 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
385 bool runOnFunction() {
386 if (!ClStack) return false;
387 // Collect alloca, ret, lifetime instructions etc.
388 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
389 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
390 BasicBlock *BB = *DI;
393 if (AllocaVec.empty()) return false;
395 initializeCallbacks(*F.getParent());
405 // Finds all static Alloca instructions and puts
406 // poisoned red zones around all of them.
407 // Then unpoison everything back before the function returns.
410 // ----------------------- Visitors.
411 /// \brief Collect all Ret instructions.
412 void visitReturnInst(ReturnInst &RI) {
413 RetVec.push_back(&RI);
416 /// \brief Collect Alloca instructions we want (and can) handle.
417 void visitAllocaInst(AllocaInst &AI) {
418 if (!isInterestingAlloca(AI)) return;
420 StackAlignment = std::max(StackAlignment, AI.getAlignment());
421 AllocaVec.push_back(&AI);
422 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
423 TotalStackSize += AlignedSize;
426 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
428 void visitIntrinsicInst(IntrinsicInst &II) {
429 if (!ASan.CheckLifetime) return;
430 Intrinsic::ID ID = II.getIntrinsicID();
431 if (ID != Intrinsic::lifetime_start &&
432 ID != Intrinsic::lifetime_end)
434 // Found lifetime intrinsic, add ASan instrumentation if necessary.
435 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
436 // If size argument is undefined, don't do anything.
437 if (Size->isMinusOne()) return;
438 // Check that size doesn't saturate uint64_t and can
439 // be stored in IntptrTy.
440 const uint64_t SizeValue = Size->getValue().getLimitedValue();
441 if (SizeValue == ~0ULL ||
442 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
444 // Find alloca instruction that corresponds to llvm.lifetime argument.
445 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
447 bool DoPoison = (ID == Intrinsic::lifetime_end);
448 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
449 AllocaPoisonCallVec.push_back(APC);
452 // ---------------------- Helpers.
453 void initializeCallbacks(Module &M);
455 // Check if we want (and can) handle this alloca.
456 bool isInterestingAlloca(AllocaInst &AI) {
457 return (!AI.isArrayAllocation() &&
458 AI.isStaticAlloca() &&
459 AI.getAllocatedType()->isSized());
462 size_t RedzoneSize() const {
463 return RedzoneSizeForScale(Mapping.Scale);
465 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
466 Type *Ty = AI->getAllocatedType();
467 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
470 uint64_t getAlignedSize(uint64_t SizeInBytes) {
471 size_t RZ = RedzoneSize();
472 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
474 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
475 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
476 return getAlignedSize(SizeInBytes);
478 /// Finds alloca where the value comes from.
479 AllocaInst *findAllocaForValue(Value *V);
480 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
481 Value *ShadowBase, bool DoPoison);
482 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
487 char AddressSanitizer::ID = 0;
488 INITIALIZE_PASS(AddressSanitizer, "asan",
489 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
491 FunctionPass *llvm::createAddressSanitizerFunctionPass(
492 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
493 StringRef BlacklistFile, bool ZeroBaseShadow) {
494 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
495 CheckLifetime, BlacklistFile, ZeroBaseShadow);
498 char AddressSanitizerModule::ID = 0;
499 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
500 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
501 "ModulePass", false, false)
502 ModulePass *llvm::createAddressSanitizerModulePass(
503 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
504 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
508 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
509 size_t Res = CountTrailingZeros_32(TypeSize / 8);
510 assert(Res < kNumberOfAccessSizes);
514 // Create a constant for Str so that we can pass it to the run-time lib.
515 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
516 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
517 return new GlobalVariable(M, StrConst->getType(), true,
518 GlobalValue::PrivateLinkage, StrConst,
522 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
523 return G->getName().find(kAsanGenPrefix) == 0;
526 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
528 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
529 if (Mapping.Offset == 0)
531 // (Shadow >> scale) | offset
532 if (Mapping.OrShadowOffset)
533 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
535 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
538 void AddressSanitizer::instrumentMemIntrinsicParam(
539 Instruction *OrigIns,
540 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
541 // Check the first byte.
543 IRBuilder<> IRB(InsertBefore);
544 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
546 // Check the last byte.
548 IRBuilder<> IRB(InsertBefore);
549 Value *SizeMinusOne = IRB.CreateSub(
550 Size, ConstantInt::get(Size->getType(), 1));
551 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
552 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
553 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
554 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
558 // Instrument memset/memmove/memcpy
559 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
560 Value *Dst = MI->getDest();
561 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
562 Value *Src = MemTran ? MemTran->getSource() : 0;
563 Value *Length = MI->getLength();
565 Constant *ConstLength = dyn_cast<Constant>(Length);
566 Instruction *InsertBefore = MI;
568 if (ConstLength->isNullValue()) return false;
570 // The size is not a constant so it could be zero -- check at run-time.
571 IRBuilder<> IRB(InsertBefore);
573 Value *Cmp = IRB.CreateICmpNE(Length,
574 Constant::getNullValue(Length->getType()));
575 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
578 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
580 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
584 // If I is an interesting memory access, return the PointerOperand
585 // and set IsWrite. Otherwise return NULL.
586 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
587 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
588 if (!ClInstrumentReads) return NULL;
590 return LI->getPointerOperand();
592 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
593 if (!ClInstrumentWrites) return NULL;
595 return SI->getPointerOperand();
597 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
598 if (!ClInstrumentAtomics) return NULL;
600 return RMW->getPointerOperand();
602 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
603 if (!ClInstrumentAtomics) return NULL;
605 return XCHG->getPointerOperand();
610 void AddressSanitizer::instrumentMop(Instruction *I) {
611 bool IsWrite = false;
612 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
614 if (ClOpt && ClOptGlobals) {
615 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
616 // If initialization order checking is disabled, a simple access to a
617 // dynamically initialized global is always valid.
620 // If a global variable does not have dynamic initialization we don't
621 // have to instrument it. However, if a global does not have initailizer
622 // at all, we assume it has dynamic initializer (in other TU).
623 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
628 Type *OrigPtrTy = Addr->getType();
629 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
631 assert(OrigTy->isSized());
632 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
634 if (TypeSize != 8 && TypeSize != 16 &&
635 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
636 // Ignore all unusual sizes.
641 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
644 // Validate the result of Module::getOrInsertFunction called for an interface
645 // function of AddressSanitizer. If the instrumented module defines a function
646 // with the same name, their prototypes must match, otherwise
647 // getOrInsertFunction returns a bitcast.
648 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
649 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
650 FuncOrBitcast->dump();
651 report_fatal_error("trying to redefine an AddressSanitizer "
652 "interface function");
655 Instruction *AddressSanitizer::generateCrashCode(
656 Instruction *InsertBefore, Value *Addr,
657 bool IsWrite, size_t AccessSizeIndex) {
658 IRBuilder<> IRB(InsertBefore);
659 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
661 // We don't do Call->setDoesNotReturn() because the BB already has
662 // UnreachableInst at the end.
663 // This EmptyAsm is required to avoid callback merge.
664 IRB.CreateCall(EmptyAsm);
668 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
671 size_t Granularity = 1 << Mapping.Scale;
672 // Addr & (Granularity - 1)
673 Value *LastAccessedByte = IRB.CreateAnd(
674 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
675 // (Addr & (Granularity - 1)) + size - 1
676 if (TypeSize / 8 > 1)
677 LastAccessedByte = IRB.CreateAdd(
678 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
679 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
680 LastAccessedByte = IRB.CreateIntCast(
681 LastAccessedByte, ShadowValue->getType(), false);
682 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
683 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
686 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
687 IRBuilder<> &IRB, Value *Addr,
688 uint32_t TypeSize, bool IsWrite) {
689 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
691 Type *ShadowTy = IntegerType::get(
692 *C, std::max(8U, TypeSize >> Mapping.Scale));
693 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
694 Value *ShadowPtr = memToShadow(AddrLong, IRB);
695 Value *CmpVal = Constant::getNullValue(ShadowTy);
696 Value *ShadowValue = IRB.CreateLoad(
697 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
699 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
700 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
701 size_t Granularity = 1 << Mapping.Scale;
702 TerminatorInst *CrashTerm = 0;
704 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
705 TerminatorInst *CheckTerm =
706 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
707 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
708 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
709 IRB.SetInsertPoint(CheckTerm);
710 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
711 BasicBlock *CrashBlock =
712 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
713 CrashTerm = new UnreachableInst(*C, CrashBlock);
714 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
715 ReplaceInstWithInst(CheckTerm, NewTerm);
717 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
721 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
722 Crash->setDebugLoc(OrigIns->getDebugLoc());
725 void AddressSanitizerModule::createInitializerPoisonCalls(
726 Module &M, Value *FirstAddr, Value *LastAddr) {
727 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
728 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
729 // If that function is not present, this TU contains no globals, or they have
730 // all been optimized away
734 // Set up the arguments to our poison/unpoison functions.
735 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
737 // Add a call to poison all external globals before the given function starts.
738 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
740 // Add calls to unpoison all globals before each return instruction.
741 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
743 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
744 CallInst::Create(AsanUnpoisonGlobals, "", RI);
749 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
750 Type *Ty = cast<PointerType>(G->getType())->getElementType();
751 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
753 if (BL->isIn(*G)) return false;
754 if (!Ty->isSized()) return false;
755 if (!G->hasInitializer()) return false;
756 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
757 // Touch only those globals that will not be defined in other modules.
758 // Don't handle ODR type linkages since other modules may be built w/o asan.
759 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
760 G->getLinkage() != GlobalVariable::PrivateLinkage &&
761 G->getLinkage() != GlobalVariable::InternalLinkage)
763 // Two problems with thread-locals:
764 // - The address of the main thread's copy can't be computed at link-time.
765 // - Need to poison all copies, not just the main thread's one.
766 if (G->isThreadLocal())
768 // For now, just ignore this Alloca if the alignment is large.
769 if (G->getAlignment() > RedzoneSize()) return false;
771 // Ignore all the globals with the names starting with "\01L_OBJC_".
772 // Many of those are put into the .cstring section. The linker compresses
773 // that section by removing the spare \0s after the string terminator, so
774 // our redzones get broken.
775 if ((G->getName().find("\01L_OBJC_") == 0) ||
776 (G->getName().find("\01l_OBJC_") == 0)) {
777 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
781 if (G->hasSection()) {
782 StringRef Section(G->getSection());
783 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
784 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
786 if ((Section.find("__OBJC,") == 0) ||
787 (Section.find("__DATA, __objc_") == 0)) {
788 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
791 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
792 // Constant CFString instances are compiled in the following way:
793 // -- the string buffer is emitted into
794 // __TEXT,__cstring,cstring_literals
795 // -- the constant NSConstantString structure referencing that buffer
796 // is placed into __DATA,__cfstring
797 // Therefore there's no point in placing redzones into __DATA,__cfstring.
798 // Moreover, it causes the linker to crash on OS X 10.7
799 if (Section.find("__DATA,__cfstring") == 0) {
800 DEBUG(dbgs() << "Ignoring CFString: " << *G);
808 void AddressSanitizerModule::initializeCallbacks(Module &M) {
810 // Declare our poisoning and unpoisoning functions.
811 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
812 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
813 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
814 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
815 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
816 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
817 // Declare functions that register/unregister globals.
818 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
819 kAsanRegisterGlobalsName, IRB.getVoidTy(),
820 IntptrTy, IntptrTy, NULL));
821 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
822 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
823 kAsanUnregisterGlobalsName,
824 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
825 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
828 // This function replaces all global variables with new variables that have
829 // trailing redzones. It also creates a function that poisons
830 // redzones and inserts this function into llvm.global_ctors.
831 bool AddressSanitizerModule::runOnModule(Module &M) {
832 if (!ClGlobals) return false;
833 TD = getAnalysisIfAvailable<DataLayout>();
836 BL.reset(new BlackList(BlacklistFile));
837 if (BL->isIn(M)) return false;
838 C = &(M.getContext());
839 int LongSize = TD->getPointerSizeInBits();
840 IntptrTy = Type::getIntNTy(*C, LongSize);
841 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
842 initializeCallbacks(M);
843 DynamicallyInitializedGlobals.Init(M);
845 SmallVector<GlobalVariable *, 16> GlobalsToChange;
847 for (Module::GlobalListType::iterator G = M.global_begin(),
848 E = M.global_end(); G != E; ++G) {
849 if (ShouldInstrumentGlobal(G))
850 GlobalsToChange.push_back(G);
853 size_t n = GlobalsToChange.size();
854 if (n == 0) return false;
856 // A global is described by a structure
859 // size_t size_with_redzone;
861 // size_t has_dynamic_init;
862 // We initialize an array of such structures and pass it to a run-time call.
863 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
866 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
869 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
871 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
873 // The addresses of the first and last dynamically initialized globals in
874 // this TU. Used in initialization order checking.
875 Value *FirstDynamic = 0, *LastDynamic = 0;
877 for (size_t i = 0; i < n; i++) {
878 static const uint64_t kMaxGlobalRedzone = 1 << 18;
879 GlobalVariable *G = GlobalsToChange[i];
880 PointerType *PtrTy = cast<PointerType>(G->getType());
881 Type *Ty = PtrTy->getElementType();
882 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
883 uint64_t MinRZ = RedzoneSize();
884 // MinRZ <= RZ <= kMaxGlobalRedzone
885 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
886 uint64_t RZ = std::max(MinRZ,
887 std::min(kMaxGlobalRedzone,
888 (SizeInBytes / MinRZ / 4) * MinRZ));
889 uint64_t RightRedzoneSize = RZ;
891 if (SizeInBytes % MinRZ)
892 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
893 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
894 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
895 // Determine whether this global should be poisoned in initialization.
896 bool GlobalHasDynamicInitializer =
897 DynamicallyInitializedGlobals.Contains(G);
898 // Don't check initialization order if this global is blacklisted.
899 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
901 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
902 Constant *NewInitializer = ConstantStruct::get(
903 NewTy, G->getInitializer(),
904 Constant::getNullValue(RightRedZoneTy), NULL);
906 SmallString<2048> DescriptionOfGlobal = G->getName();
907 DescriptionOfGlobal += " (";
908 DescriptionOfGlobal += M.getModuleIdentifier();
909 DescriptionOfGlobal += ")";
910 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
912 // Create a new global variable with enough space for a redzone.
913 GlobalVariable *NewGlobal = new GlobalVariable(
914 M, NewTy, G->isConstant(), G->getLinkage(),
915 NewInitializer, "", G, G->getThreadLocalMode());
916 NewGlobal->copyAttributesFrom(G);
917 NewGlobal->setAlignment(MinRZ);
920 Indices2[0] = IRB.getInt32(0);
921 Indices2[1] = IRB.getInt32(0);
923 G->replaceAllUsesWith(
924 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
925 NewGlobal->takeName(G);
926 G->eraseFromParent();
928 Initializers[i] = ConstantStruct::get(
930 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
931 ConstantInt::get(IntptrTy, SizeInBytes),
932 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
933 ConstantExpr::getPointerCast(Name, IntptrTy),
934 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
937 // Populate the first and last globals declared in this TU.
938 if (CheckInitOrder && GlobalHasDynamicInitializer) {
939 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
940 if (FirstDynamic == 0)
941 FirstDynamic = LastDynamic;
944 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
947 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
948 GlobalVariable *AllGlobals = new GlobalVariable(
949 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
950 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
952 // Create calls for poisoning before initializers run and unpoisoning after.
953 if (CheckInitOrder && FirstDynamic && LastDynamic)
954 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
955 IRB.CreateCall2(AsanRegisterGlobals,
956 IRB.CreatePointerCast(AllGlobals, IntptrTy),
957 ConstantInt::get(IntptrTy, n));
959 // We also need to unregister globals at the end, e.g. when a shared library
961 Function *AsanDtorFunction = Function::Create(
962 FunctionType::get(Type::getVoidTy(*C), false),
963 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
964 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
965 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
966 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
967 IRB.CreatePointerCast(AllGlobals, IntptrTy),
968 ConstantInt::get(IntptrTy, n));
969 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
975 void AddressSanitizer::initializeCallbacks(Module &M) {
977 // Create __asan_report* callbacks.
978 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
979 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
981 // IsWrite and TypeSize are encoded in the function name.
982 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
983 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
984 // If we are merging crash callbacks, they have two parameters.
985 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
986 checkInterfaceFunction(M.getOrInsertFunction(
987 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
991 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
992 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
993 // We insert an empty inline asm after __asan_report* to avoid callback merge.
994 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
995 StringRef(""), StringRef(""),
996 /*hasSideEffects=*/true);
999 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1000 // Tell the values of mapping offset and scale to the run-time.
1001 GlobalValue *asan_mapping_offset =
1002 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1003 ConstantInt::get(IntptrTy, Mapping.Offset),
1004 kAsanMappingOffsetName);
1005 // Read the global, otherwise it may be optimized away.
1006 IRB.CreateLoad(asan_mapping_offset, true);
1008 GlobalValue *asan_mapping_scale =
1009 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1010 ConstantInt::get(IntptrTy, Mapping.Scale),
1011 kAsanMappingScaleName);
1012 // Read the global, otherwise it may be optimized away.
1013 IRB.CreateLoad(asan_mapping_scale, true);
1017 bool AddressSanitizer::doInitialization(Module &M) {
1018 // Initialize the private fields. No one has accessed them before.
1019 TD = getAnalysisIfAvailable<DataLayout>();
1023 BL.reset(new BlackList(BlacklistFile));
1024 DynamicallyInitializedGlobals.Init(M);
1026 C = &(M.getContext());
1027 LongSize = TD->getPointerSizeInBits();
1028 IntptrTy = Type::getIntNTy(*C, LongSize);
1030 AsanCtorFunction = Function::Create(
1031 FunctionType::get(Type::getVoidTy(*C), false),
1032 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1033 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1034 // call __asan_init in the module ctor.
1035 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1036 AsanInitFunction = checkInterfaceFunction(
1037 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1038 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1039 IRB.CreateCall(AsanInitFunction);
1041 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1042 emitShadowMapping(M, IRB);
1044 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1048 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1049 // For each NSObject descendant having a +load method, this method is invoked
1050 // by the ObjC runtime before any of the static constructors is called.
1051 // Therefore we need to instrument such methods with a call to __asan_init
1052 // at the beginning in order to initialize our runtime before any access to
1053 // the shadow memory.
1054 // We cannot just ignore these methods, because they may call other
1055 // instrumented functions.
1056 if (F.getName().find(" load]") != std::string::npos) {
1057 IRBuilder<> IRB(F.begin()->begin());
1058 IRB.CreateCall(AsanInitFunction);
1064 bool AddressSanitizer::runOnFunction(Function &F) {
1065 if (BL->isIn(F)) return false;
1066 if (&F == AsanCtorFunction) return false;
1067 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1068 initializeCallbacks(*F.getParent());
1070 // If needed, insert __asan_init before checking for AddressSafety attr.
1071 maybeInsertAsanInitAtFunctionEntry(F);
1073 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1074 Attribute::AddressSafety))
1077 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1080 // We want to instrument every address only once per basic block (unless there
1081 // are calls between uses).
1082 SmallSet<Value*, 16> TempsToInstrument;
1083 SmallVector<Instruction*, 16> ToInstrument;
1084 SmallVector<Instruction*, 8> NoReturnCalls;
1087 // Fill the set of memory operations to instrument.
1088 for (Function::iterator FI = F.begin(), FE = F.end();
1090 TempsToInstrument.clear();
1091 int NumInsnsPerBB = 0;
1092 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1094 if (LooksLikeCodeInBug11395(BI)) return false;
1095 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1096 if (ClOpt && ClOptSameTemp) {
1097 if (!TempsToInstrument.insert(Addr))
1098 continue; // We've seen this temp in the current BB.
1100 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1103 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1104 // A call inside BB.
1105 TempsToInstrument.clear();
1106 if (CI->doesNotReturn()) {
1107 NoReturnCalls.push_back(CI);
1112 ToInstrument.push_back(BI);
1114 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1120 int NumInstrumented = 0;
1121 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1122 Instruction *Inst = ToInstrument[i];
1123 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1124 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1125 if (isInterestingMemoryAccess(Inst, &IsWrite))
1126 instrumentMop(Inst);
1128 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1133 FunctionStackPoisoner FSP(F, *this);
1134 bool ChangedStack = FSP.runOnFunction();
1136 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1137 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1138 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1139 Instruction *CI = NoReturnCalls[i];
1140 IRBuilder<> IRB(CI);
1141 IRB.CreateCall(AsanHandleNoReturnFunc);
1143 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1145 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1148 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1149 if (ShadowRedzoneSize == 1) return PoisonByte;
1150 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1151 if (ShadowRedzoneSize == 4)
1152 return (PoisonByte << 24) + (PoisonByte << 16) +
1153 (PoisonByte << 8) + (PoisonByte);
1154 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1157 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1160 size_t ShadowGranularity,
1162 for (size_t i = 0; i < RZSize;
1163 i+= ShadowGranularity, Shadow++) {
1164 if (i + ShadowGranularity <= Size) {
1165 *Shadow = 0; // fully addressable
1166 } else if (i >= Size) {
1167 *Shadow = Magic; // unaddressable
1169 *Shadow = Size - i; // first Size-i bytes are addressable
1174 // Workaround for bug 11395: we don't want to instrument stack in functions
1175 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1176 // FIXME: remove once the bug 11395 is fixed.
1177 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1178 if (LongSize != 32) return false;
1179 CallInst *CI = dyn_cast<CallInst>(I);
1180 if (!CI || !CI->isInlineAsm()) return false;
1181 if (CI->getNumArgOperands() <= 5) return false;
1182 // We have inline assembly with quite a few arguments.
1186 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1187 IRBuilder<> IRB(*C);
1188 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1189 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1190 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1191 kAsanStackFreeName, IRB.getVoidTy(),
1192 IntptrTy, IntptrTy, IntptrTy, NULL));
1193 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1194 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1195 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1196 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1199 void FunctionStackPoisoner::poisonRedZones(
1200 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1202 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1203 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1204 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1205 Type *RZPtrTy = PointerType::get(RZTy, 0);
1207 Value *PoisonLeft = ConstantInt::get(RZTy,
1208 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1209 Value *PoisonMid = ConstantInt::get(RZTy,
1210 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1211 Value *PoisonRight = ConstantInt::get(RZTy,
1212 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1214 // poison the first red zone.
1215 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1217 // poison all other red zones.
1218 uint64_t Pos = RedzoneSize();
1219 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1220 AllocaInst *AI = AllocaVec[i];
1221 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1222 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1223 assert(AlignedSize - SizeInBytes < RedzoneSize());
1228 assert(ShadowBase->getType() == IntptrTy);
1229 if (SizeInBytes < AlignedSize) {
1230 // Poison the partial redzone at right
1231 Ptr = IRB.CreateAdd(
1232 ShadowBase, ConstantInt::get(IntptrTy,
1233 (Pos >> Mapping.Scale) - ShadowRZSize));
1234 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1235 uint32_t Poison = 0;
1237 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1239 1ULL << Mapping.Scale,
1240 kAsanStackPartialRedzoneMagic);
1242 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1243 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1246 // Poison the full redzone at right.
1247 Ptr = IRB.CreateAdd(ShadowBase,
1248 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1249 bool LastAlloca = (i == AllocaVec.size() - 1);
1250 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1251 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1253 Pos += RedzoneSize();
1257 void FunctionStackPoisoner::poisonStack() {
1258 uint64_t LocalStackSize = TotalStackSize +
1259 (AllocaVec.size() + 1) * RedzoneSize();
1261 bool DoStackMalloc = ASan.CheckUseAfterReturn
1262 && LocalStackSize <= kMaxStackMallocSize;
1264 assert(AllocaVec.size() > 0);
1265 Instruction *InsBefore = AllocaVec[0];
1266 IRBuilder<> IRB(InsBefore);
1269 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1270 AllocaInst *MyAlloca =
1271 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1272 if (ClRealignStack && StackAlignment < RedzoneSize())
1273 StackAlignment = RedzoneSize();
1274 MyAlloca->setAlignment(StackAlignment);
1275 assert(MyAlloca->isStaticAlloca());
1276 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1277 Value *LocalStackBase = OrigStackBase;
1279 if (DoStackMalloc) {
1280 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1281 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1284 // This string will be parsed by the run-time (DescribeStackAddress).
1285 SmallString<2048> StackDescriptionStorage;
1286 raw_svector_ostream StackDescription(StackDescriptionStorage);
1287 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1289 // Insert poison calls for lifetime intrinsics for alloca.
1290 bool HavePoisonedAllocas = false;
1291 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1292 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1293 IntrinsicInst *II = APC.InsBefore;
1294 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1296 IRBuilder<> IRB(II);
1297 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1298 HavePoisonedAllocas |= APC.DoPoison;
1301 uint64_t Pos = RedzoneSize();
1302 // Replace Alloca instructions with base+offset.
1303 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1304 AllocaInst *AI = AllocaVec[i];
1305 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1306 StringRef Name = AI->getName();
1307 StackDescription << Pos << " " << SizeInBytes << " "
1308 << Name.size() << " " << Name << " ";
1309 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1310 assert((AlignedSize % RedzoneSize()) == 0);
1311 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1312 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1314 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1315 AI->replaceAllUsesWith(NewAllocaPtr);
1316 Pos += AlignedSize + RedzoneSize();
1318 assert(Pos == LocalStackSize);
1320 // Write the Magic value and the frame description constant to the redzone.
1321 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1322 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1324 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1325 ConstantInt::get(IntptrTy,
1327 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1328 GlobalVariable *StackDescriptionGlobal =
1329 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1330 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1332 IRB.CreateStore(Description, BasePlus1);
1334 // Poison the stack redzones at the entry.
1335 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1336 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1338 // Unpoison the stack before all ret instructions.
1339 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1340 Instruction *Ret = RetVec[i];
1341 IRBuilder<> IRBRet(Ret);
1342 // Mark the current frame as retired.
1343 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1345 // Unpoison the stack.
1346 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1347 if (DoStackMalloc) {
1348 // In use-after-return mode, mark the whole stack frame unaddressable.
1349 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1350 ConstantInt::get(IntptrTy, LocalStackSize),
1352 } else if (HavePoisonedAllocas) {
1353 // If we poisoned some allocas in llvm.lifetime analysis,
1354 // unpoison whole stack frame now.
1355 assert(LocalStackBase == OrigStackBase);
1356 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1360 // We are done. Remove the old unused alloca instructions.
1361 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1362 AllocaVec[i]->eraseFromParent();
1365 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1366 IRBuilder<> IRB, bool DoPoison) {
1367 // For now just insert the call to ASan runtime.
1368 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1369 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1370 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1371 : AsanUnpoisonStackMemoryFunc,
1375 // Handling llvm.lifetime intrinsics for a given %alloca:
1376 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1377 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1378 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1379 // could be poisoned by previous llvm.lifetime.end instruction, as the
1380 // variable may go in and out of scope several times, e.g. in loops).
1381 // (3) if we poisoned at least one %alloca in a function,
1382 // unpoison the whole stack frame at function exit.
1384 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1385 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1386 // We're intested only in allocas we can handle.
1387 return isInterestingAlloca(*AI) ? AI : 0;
1388 // See if we've already calculated (or started to calculate) alloca for a
1390 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1391 if (I != AllocaForValue.end())
1393 // Store 0 while we're calculating alloca for value V to avoid
1394 // infinite recursion if the value references itself.
1395 AllocaForValue[V] = 0;
1396 AllocaInst *Res = 0;
1397 if (CastInst *CI = dyn_cast<CastInst>(V))
1398 Res = findAllocaForValue(CI->getOperand(0));
1399 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1400 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1401 Value *IncValue = PN->getIncomingValue(i);
1402 // Allow self-referencing phi-nodes.
1403 if (IncValue == PN) continue;
1404 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1405 // AI for incoming values should exist and should all be equal.
1406 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1412 AllocaForValue[V] = Res;