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 kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
57 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
59 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
60 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
61 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
63 static const char *kAsanModuleCtorName = "asan.module_ctor";
64 static const char *kAsanModuleDtorName = "asan.module_dtor";
65 static const int kAsanCtorAndCtorPriority = 1;
66 static const char *kAsanReportErrorTemplate = "__asan_report_";
67 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
68 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
69 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
70 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
71 static const char *kAsanInitName = "__asan_init";
72 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
73 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
74 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
75 static const char *kAsanStackMallocName = "__asan_stack_malloc";
76 static const char *kAsanStackFreeName = "__asan_stack_free";
77 static const char *kAsanGenPrefix = "__asan_gen_";
78 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
79 static const char *kAsanUnpoisonStackMemoryName =
80 "__asan_unpoison_stack_memory";
82 static const int kAsanStackLeftRedzoneMagic = 0xf1;
83 static const int kAsanStackMidRedzoneMagic = 0xf2;
84 static const int kAsanStackRightRedzoneMagic = 0xf3;
85 static const int kAsanStackPartialRedzoneMagic = 0xf4;
87 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
88 static const size_t kNumberOfAccessSizes = 5;
90 // Command-line flags.
92 // This flag may need to be replaced with -f[no-]asan-reads.
93 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
94 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
95 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
96 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
97 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
98 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
99 cl::Hidden, cl::init(true));
100 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
101 cl::desc("use instrumentation with slow path for all accesses"),
102 cl::Hidden, cl::init(false));
103 // This flag limits the number of instructions to be instrumented
104 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
105 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
107 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
109 cl::desc("maximal number of instructions to instrument in any given BB"),
111 // This flag may need to be replaced with -f[no]asan-stack.
112 static cl::opt<bool> ClStack("asan-stack",
113 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
114 // This flag may need to be replaced with -f[no]asan-use-after-return.
115 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
116 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
117 // This flag may need to be replaced with -f[no]asan-globals.
118 static cl::opt<bool> ClGlobals("asan-globals",
119 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
120 static cl::opt<bool> ClInitializers("asan-initialization-order",
121 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
122 static cl::opt<bool> ClMemIntrin("asan-memintrin",
123 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
124 static cl::opt<bool> ClRealignStack("asan-realign-stack",
125 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
126 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
127 cl::desc("File containing the list of objects to ignore "
128 "during instrumentation"), cl::Hidden);
130 // These flags allow to change the shadow mapping.
131 // The shadow mapping looks like
132 // Shadow = (Mem >> scale) + (1 << offset_log)
133 static cl::opt<int> ClMappingScale("asan-mapping-scale",
134 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
135 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
136 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
137 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
138 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
139 cl::Hidden, cl::init(false));
141 // Optimization flags. Not user visible, used mostly for testing
142 // and benchmarking the tool.
143 static cl::opt<bool> ClOpt("asan-opt",
144 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
145 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
146 cl::desc("Instrument the same temp just once"), cl::Hidden,
148 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
149 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
151 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
152 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
153 cl::Hidden, cl::init(false));
156 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
158 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
159 cl::Hidden, cl::init(0));
160 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
161 cl::Hidden, cl::desc("Debug func"));
162 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
163 cl::Hidden, cl::init(-1));
164 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
165 cl::Hidden, cl::init(-1));
168 /// A set of dynamically initialized globals extracted from metadata.
169 class SetOfDynamicallyInitializedGlobals {
171 void Init(Module& M) {
172 // Clang generates metadata identifying all dynamically initialized globals.
173 NamedMDNode *DynamicGlobals =
174 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
177 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
178 MDNode *MDN = DynamicGlobals->getOperand(i);
179 assert(MDN->getNumOperands() == 1);
180 Value *VG = MDN->getOperand(0);
181 // The optimizer may optimize away a global entirely, in which case we
182 // cannot instrument access to it.
185 DynInitGlobals.insert(cast<GlobalVariable>(VG));
188 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
190 SmallSet<GlobalValue*, 32> DynInitGlobals;
193 /// This struct defines the shadow mapping using the rule:
194 /// shadow = (mem >> Scale) ADD-or-OR Offset.
195 struct ShadowMapping {
201 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
202 bool ZeroBaseShadow) {
203 llvm::Triple TargetTriple(M.getTargetTriple());
204 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
205 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
207 ShadowMapping Mapping;
209 // OR-ing shadow offset if more efficient (at least on x86),
210 // but on ppc64 we have to use add since the shadow offset is not neccesary
211 // 1/8-th of the address space.
212 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
214 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
215 (LongSize == 32 ? kDefaultShadowOffset32 :
216 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
217 if (!ZeroBaseShadow && ClShort64BitOffset && LongSize == 64) {
218 Mapping.Offset = kDefaultShort64bitShadowOffset;
219 } if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
220 // Zero offset log is the special case.
221 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
224 Mapping.Scale = kDefaultShadowScale;
225 if (ClMappingScale) {
226 Mapping.Scale = ClMappingScale;
232 static size_t RedzoneSizeForScale(int MappingScale) {
233 // Redzone used for stack and globals is at least 32 bytes.
234 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
235 return std::max(32U, 1U << MappingScale);
238 /// AddressSanitizer: instrument the code in module to find memory bugs.
239 struct AddressSanitizer : public FunctionPass {
240 AddressSanitizer(bool CheckInitOrder = false,
241 bool CheckUseAfterReturn = false,
242 bool CheckLifetime = false,
243 StringRef BlacklistFile = StringRef(),
244 bool ZeroBaseShadow = false)
246 CheckInitOrder(CheckInitOrder || ClInitializers),
247 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
248 CheckLifetime(CheckLifetime || ClCheckLifetime),
249 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
251 ZeroBaseShadow(ZeroBaseShadow) {}
252 virtual const char *getPassName() const {
253 return "AddressSanitizerFunctionPass";
255 void instrumentMop(Instruction *I);
256 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
257 Value *Addr, uint32_t TypeSize, bool IsWrite);
258 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
259 Value *ShadowValue, uint32_t TypeSize);
260 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
261 bool IsWrite, size_t AccessSizeIndex);
262 bool instrumentMemIntrinsic(MemIntrinsic *MI);
263 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
265 Instruction *InsertBefore, bool IsWrite);
266 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
267 bool runOnFunction(Function &F);
268 void createInitializerPoisonCalls(Module &M,
269 Value *FirstAddr, Value *LastAddr);
270 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
271 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
272 virtual bool doInitialization(Module &M);
273 static char ID; // Pass identification, replacement for typeid
276 void initializeCallbacks(Module &M);
278 bool ShouldInstrumentGlobal(GlobalVariable *G);
279 bool LooksLikeCodeInBug11395(Instruction *I);
280 void FindDynamicInitializers(Module &M);
283 bool CheckUseAfterReturn;
285 SmallString<64> BlacklistFile;
292 ShadowMapping Mapping;
293 Function *AsanCtorFunction;
294 Function *AsanInitFunction;
295 Function *AsanHandleNoReturnFunc;
296 OwningPtr<BlackList> BL;
297 // This array is indexed by AccessIsWrite and log2(AccessSize).
298 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
300 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
302 friend struct FunctionStackPoisoner;
305 class AddressSanitizerModule : public ModulePass {
307 AddressSanitizerModule(bool CheckInitOrder = false,
308 StringRef BlacklistFile = StringRef(),
309 bool ZeroBaseShadow = false)
311 CheckInitOrder(CheckInitOrder || ClInitializers),
312 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
314 ZeroBaseShadow(ZeroBaseShadow) {}
315 bool runOnModule(Module &M);
316 static char ID; // Pass identification, replacement for typeid
317 virtual const char *getPassName() const {
318 return "AddressSanitizerModule";
322 void initializeCallbacks(Module &M);
324 bool ShouldInstrumentGlobal(GlobalVariable *G);
325 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
327 size_t RedzoneSize() const {
328 return RedzoneSizeForScale(Mapping.Scale);
332 SmallString<64> BlacklistFile;
335 OwningPtr<BlackList> BL;
336 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
340 ShadowMapping Mapping;
341 Function *AsanPoisonGlobals;
342 Function *AsanUnpoisonGlobals;
343 Function *AsanRegisterGlobals;
344 Function *AsanUnregisterGlobals;
347 // Stack poisoning does not play well with exception handling.
348 // When an exception is thrown, we essentially bypass the code
349 // that unpoisones the stack. This is why the run-time library has
350 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
351 // stack in the interceptor. This however does not work inside the
352 // actual function which catches the exception. Most likely because the
353 // compiler hoists the load of the shadow value somewhere too high.
354 // This causes asan to report a non-existing bug on 453.povray.
355 // It sounds like an LLVM bug.
356 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
358 AddressSanitizer &ASan;
363 ShadowMapping Mapping;
365 SmallVector<AllocaInst*, 16> AllocaVec;
366 SmallVector<Instruction*, 8> RetVec;
367 uint64_t TotalStackSize;
368 unsigned StackAlignment;
370 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
371 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
373 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
374 struct AllocaPoisonCall {
375 IntrinsicInst *InsBefore;
379 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
381 // Maps Value to an AllocaInst from which the Value is originated.
382 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
383 AllocaForValueMapTy AllocaForValue;
385 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
386 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
387 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
388 Mapping(ASan.Mapping),
389 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
391 bool runOnFunction() {
392 if (!ClStack) return false;
393 // Collect alloca, ret, lifetime instructions etc.
394 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
395 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
396 BasicBlock *BB = *DI;
399 if (AllocaVec.empty()) return false;
401 initializeCallbacks(*F.getParent());
411 // Finds all static Alloca instructions and puts
412 // poisoned red zones around all of them.
413 // Then unpoison everything back before the function returns.
416 // ----------------------- Visitors.
417 /// \brief Collect all Ret instructions.
418 void visitReturnInst(ReturnInst &RI) {
419 RetVec.push_back(&RI);
422 /// \brief Collect Alloca instructions we want (and can) handle.
423 void visitAllocaInst(AllocaInst &AI) {
424 if (!isInterestingAlloca(AI)) return;
426 StackAlignment = std::max(StackAlignment, AI.getAlignment());
427 AllocaVec.push_back(&AI);
428 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
429 TotalStackSize += AlignedSize;
432 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
434 void visitIntrinsicInst(IntrinsicInst &II) {
435 if (!ASan.CheckLifetime) return;
436 Intrinsic::ID ID = II.getIntrinsicID();
437 if (ID != Intrinsic::lifetime_start &&
438 ID != Intrinsic::lifetime_end)
440 // Found lifetime intrinsic, add ASan instrumentation if necessary.
441 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
442 // If size argument is undefined, don't do anything.
443 if (Size->isMinusOne()) return;
444 // Check that size doesn't saturate uint64_t and can
445 // be stored in IntptrTy.
446 const uint64_t SizeValue = Size->getValue().getLimitedValue();
447 if (SizeValue == ~0ULL ||
448 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
450 // Find alloca instruction that corresponds to llvm.lifetime argument.
451 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
453 bool DoPoison = (ID == Intrinsic::lifetime_end);
454 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
455 AllocaPoisonCallVec.push_back(APC);
458 // ---------------------- Helpers.
459 void initializeCallbacks(Module &M);
461 // Check if we want (and can) handle this alloca.
462 bool isInterestingAlloca(AllocaInst &AI) {
463 return (!AI.isArrayAllocation() &&
464 AI.isStaticAlloca() &&
465 AI.getAllocatedType()->isSized());
468 size_t RedzoneSize() const {
469 return RedzoneSizeForScale(Mapping.Scale);
471 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
472 Type *Ty = AI->getAllocatedType();
473 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
476 uint64_t getAlignedSize(uint64_t SizeInBytes) {
477 size_t RZ = RedzoneSize();
478 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
480 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
481 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
482 return getAlignedSize(SizeInBytes);
484 /// Finds alloca where the value comes from.
485 AllocaInst *findAllocaForValue(Value *V);
486 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
487 Value *ShadowBase, bool DoPoison);
488 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
493 char AddressSanitizer::ID = 0;
494 INITIALIZE_PASS(AddressSanitizer, "asan",
495 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
497 FunctionPass *llvm::createAddressSanitizerFunctionPass(
498 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
499 StringRef BlacklistFile, bool ZeroBaseShadow) {
500 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
501 CheckLifetime, BlacklistFile, ZeroBaseShadow);
504 char AddressSanitizerModule::ID = 0;
505 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
506 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
507 "ModulePass", false, false)
508 ModulePass *llvm::createAddressSanitizerModulePass(
509 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
510 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
514 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
515 size_t Res = CountTrailingZeros_32(TypeSize / 8);
516 assert(Res < kNumberOfAccessSizes);
520 // Create a constant for Str so that we can pass it to the run-time lib.
521 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
522 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
523 return new GlobalVariable(M, StrConst->getType(), true,
524 GlobalValue::PrivateLinkage, StrConst,
528 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
529 return G->getName().find(kAsanGenPrefix) == 0;
532 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
534 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
535 if (Mapping.Offset == 0)
537 // (Shadow >> scale) | offset
538 if (Mapping.OrShadowOffset)
539 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
541 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
544 void AddressSanitizer::instrumentMemIntrinsicParam(
545 Instruction *OrigIns,
546 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
547 // Check the first byte.
549 IRBuilder<> IRB(InsertBefore);
550 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
552 // Check the last byte.
554 IRBuilder<> IRB(InsertBefore);
555 Value *SizeMinusOne = IRB.CreateSub(
556 Size, ConstantInt::get(Size->getType(), 1));
557 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
558 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
559 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
560 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
564 // Instrument memset/memmove/memcpy
565 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
566 Value *Dst = MI->getDest();
567 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
568 Value *Src = MemTran ? MemTran->getSource() : 0;
569 Value *Length = MI->getLength();
571 Constant *ConstLength = dyn_cast<Constant>(Length);
572 Instruction *InsertBefore = MI;
574 if (ConstLength->isNullValue()) return false;
576 // The size is not a constant so it could be zero -- check at run-time.
577 IRBuilder<> IRB(InsertBefore);
579 Value *Cmp = IRB.CreateICmpNE(Length,
580 Constant::getNullValue(Length->getType()));
581 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
584 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
586 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
590 // If I is an interesting memory access, return the PointerOperand
591 // and set IsWrite. Otherwise return NULL.
592 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
593 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
594 if (!ClInstrumentReads) return NULL;
596 return LI->getPointerOperand();
598 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
599 if (!ClInstrumentWrites) return NULL;
601 return SI->getPointerOperand();
603 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
604 if (!ClInstrumentAtomics) return NULL;
606 return RMW->getPointerOperand();
608 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
609 if (!ClInstrumentAtomics) return NULL;
611 return XCHG->getPointerOperand();
616 void AddressSanitizer::instrumentMop(Instruction *I) {
617 bool IsWrite = false;
618 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
620 if (ClOpt && ClOptGlobals) {
621 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
622 // If initialization order checking is disabled, a simple access to a
623 // dynamically initialized global is always valid.
626 // If a global variable does not have dynamic initialization we don't
627 // have to instrument it. However, if a global does not have initailizer
628 // at all, we assume it has dynamic initializer (in other TU).
629 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
634 Type *OrigPtrTy = Addr->getType();
635 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
637 assert(OrigTy->isSized());
638 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
640 if (TypeSize != 8 && TypeSize != 16 &&
641 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
642 // Ignore all unusual sizes.
647 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
650 // Validate the result of Module::getOrInsertFunction called for an interface
651 // function of AddressSanitizer. If the instrumented module defines a function
652 // with the same name, their prototypes must match, otherwise
653 // getOrInsertFunction returns a bitcast.
654 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
655 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
656 FuncOrBitcast->dump();
657 report_fatal_error("trying to redefine an AddressSanitizer "
658 "interface function");
661 Instruction *AddressSanitizer::generateCrashCode(
662 Instruction *InsertBefore, Value *Addr,
663 bool IsWrite, size_t AccessSizeIndex) {
664 IRBuilder<> IRB(InsertBefore);
665 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
667 // We don't do Call->setDoesNotReturn() because the BB already has
668 // UnreachableInst at the end.
669 // This EmptyAsm is required to avoid callback merge.
670 IRB.CreateCall(EmptyAsm);
674 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
677 size_t Granularity = 1 << Mapping.Scale;
678 // Addr & (Granularity - 1)
679 Value *LastAccessedByte = IRB.CreateAnd(
680 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
681 // (Addr & (Granularity - 1)) + size - 1
682 if (TypeSize / 8 > 1)
683 LastAccessedByte = IRB.CreateAdd(
684 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
685 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
686 LastAccessedByte = IRB.CreateIntCast(
687 LastAccessedByte, ShadowValue->getType(), false);
688 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
689 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
692 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
693 IRBuilder<> &IRB, Value *Addr,
694 uint32_t TypeSize, bool IsWrite) {
695 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
697 Type *ShadowTy = IntegerType::get(
698 *C, std::max(8U, TypeSize >> Mapping.Scale));
699 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
700 Value *ShadowPtr = memToShadow(AddrLong, IRB);
701 Value *CmpVal = Constant::getNullValue(ShadowTy);
702 Value *ShadowValue = IRB.CreateLoad(
703 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
705 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
706 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
707 size_t Granularity = 1 << Mapping.Scale;
708 TerminatorInst *CrashTerm = 0;
710 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
711 TerminatorInst *CheckTerm =
712 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
713 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
714 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
715 IRB.SetInsertPoint(CheckTerm);
716 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
717 BasicBlock *CrashBlock =
718 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
719 CrashTerm = new UnreachableInst(*C, CrashBlock);
720 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
721 ReplaceInstWithInst(CheckTerm, NewTerm);
723 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
727 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
728 Crash->setDebugLoc(OrigIns->getDebugLoc());
731 void AddressSanitizerModule::createInitializerPoisonCalls(
732 Module &M, Value *FirstAddr, Value *LastAddr) {
733 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
734 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
735 // If that function is not present, this TU contains no globals, or they have
736 // all been optimized away
740 // Set up the arguments to our poison/unpoison functions.
741 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
743 // Add a call to poison all external globals before the given function starts.
744 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
746 // Add calls to unpoison all globals before each return instruction.
747 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
749 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
750 CallInst::Create(AsanUnpoisonGlobals, "", RI);
755 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
756 Type *Ty = cast<PointerType>(G->getType())->getElementType();
757 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
759 if (BL->isIn(*G)) return false;
760 if (!Ty->isSized()) return false;
761 if (!G->hasInitializer()) return false;
762 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
763 // Touch only those globals that will not be defined in other modules.
764 // Don't handle ODR type linkages since other modules may be built w/o asan.
765 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
766 G->getLinkage() != GlobalVariable::PrivateLinkage &&
767 G->getLinkage() != GlobalVariable::InternalLinkage)
769 // Two problems with thread-locals:
770 // - The address of the main thread's copy can't be computed at link-time.
771 // - Need to poison all copies, not just the main thread's one.
772 if (G->isThreadLocal())
774 // For now, just ignore this Alloca if the alignment is large.
775 if (G->getAlignment() > RedzoneSize()) return false;
777 // Ignore all the globals with the names starting with "\01L_OBJC_".
778 // Many of those are put into the .cstring section. The linker compresses
779 // that section by removing the spare \0s after the string terminator, so
780 // our redzones get broken.
781 if ((G->getName().find("\01L_OBJC_") == 0) ||
782 (G->getName().find("\01l_OBJC_") == 0)) {
783 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
787 if (G->hasSection()) {
788 StringRef Section(G->getSection());
789 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
790 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
792 if ((Section.find("__OBJC,") == 0) ||
793 (Section.find("__DATA, __objc_") == 0)) {
794 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
797 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
798 // Constant CFString instances are compiled in the following way:
799 // -- the string buffer is emitted into
800 // __TEXT,__cstring,cstring_literals
801 // -- the constant NSConstantString structure referencing that buffer
802 // is placed into __DATA,__cfstring
803 // Therefore there's no point in placing redzones into __DATA,__cfstring.
804 // Moreover, it causes the linker to crash on OS X 10.7
805 if (Section.find("__DATA,__cfstring") == 0) {
806 DEBUG(dbgs() << "Ignoring CFString: " << *G);
814 void AddressSanitizerModule::initializeCallbacks(Module &M) {
816 // Declare our poisoning and unpoisoning functions.
817 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
818 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
819 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
820 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
821 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
822 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
823 // Declare functions that register/unregister globals.
824 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
825 kAsanRegisterGlobalsName, IRB.getVoidTy(),
826 IntptrTy, IntptrTy, NULL));
827 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
828 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
829 kAsanUnregisterGlobalsName,
830 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
831 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
834 // This function replaces all global variables with new variables that have
835 // trailing redzones. It also creates a function that poisons
836 // redzones and inserts this function into llvm.global_ctors.
837 bool AddressSanitizerModule::runOnModule(Module &M) {
838 if (!ClGlobals) return false;
839 TD = getAnalysisIfAvailable<DataLayout>();
842 BL.reset(new BlackList(BlacklistFile));
843 if (BL->isIn(M)) return false;
844 C = &(M.getContext());
845 int LongSize = TD->getPointerSizeInBits();
846 IntptrTy = Type::getIntNTy(*C, LongSize);
847 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
848 initializeCallbacks(M);
849 DynamicallyInitializedGlobals.Init(M);
851 SmallVector<GlobalVariable *, 16> GlobalsToChange;
853 for (Module::GlobalListType::iterator G = M.global_begin(),
854 E = M.global_end(); G != E; ++G) {
855 if (ShouldInstrumentGlobal(G))
856 GlobalsToChange.push_back(G);
859 size_t n = GlobalsToChange.size();
860 if (n == 0) return false;
862 // A global is described by a structure
865 // size_t size_with_redzone;
867 // size_t has_dynamic_init;
868 // We initialize an array of such structures and pass it to a run-time call.
869 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
872 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
875 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
877 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
879 // The addresses of the first and last dynamically initialized globals in
880 // this TU. Used in initialization order checking.
881 Value *FirstDynamic = 0, *LastDynamic = 0;
883 for (size_t i = 0; i < n; i++) {
884 static const uint64_t kMaxGlobalRedzone = 1 << 18;
885 GlobalVariable *G = GlobalsToChange[i];
886 PointerType *PtrTy = cast<PointerType>(G->getType());
887 Type *Ty = PtrTy->getElementType();
888 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
889 uint64_t MinRZ = RedzoneSize();
890 // MinRZ <= RZ <= kMaxGlobalRedzone
891 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
892 uint64_t RZ = std::max(MinRZ,
893 std::min(kMaxGlobalRedzone,
894 (SizeInBytes / MinRZ / 4) * MinRZ));
895 uint64_t RightRedzoneSize = RZ;
897 if (SizeInBytes % MinRZ)
898 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
899 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
900 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
901 // Determine whether this global should be poisoned in initialization.
902 bool GlobalHasDynamicInitializer =
903 DynamicallyInitializedGlobals.Contains(G);
904 // Don't check initialization order if this global is blacklisted.
905 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
907 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
908 Constant *NewInitializer = ConstantStruct::get(
909 NewTy, G->getInitializer(),
910 Constant::getNullValue(RightRedZoneTy), NULL);
912 SmallString<2048> DescriptionOfGlobal = G->getName();
913 DescriptionOfGlobal += " (";
914 DescriptionOfGlobal += M.getModuleIdentifier();
915 DescriptionOfGlobal += ")";
916 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
918 // Create a new global variable with enough space for a redzone.
919 GlobalVariable *NewGlobal = new GlobalVariable(
920 M, NewTy, G->isConstant(), G->getLinkage(),
921 NewInitializer, "", G, G->getThreadLocalMode());
922 NewGlobal->copyAttributesFrom(G);
923 NewGlobal->setAlignment(MinRZ);
926 Indices2[0] = IRB.getInt32(0);
927 Indices2[1] = IRB.getInt32(0);
929 G->replaceAllUsesWith(
930 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
931 NewGlobal->takeName(G);
932 G->eraseFromParent();
934 Initializers[i] = ConstantStruct::get(
936 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
937 ConstantInt::get(IntptrTy, SizeInBytes),
938 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
939 ConstantExpr::getPointerCast(Name, IntptrTy),
940 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
943 // Populate the first and last globals declared in this TU.
944 if (CheckInitOrder && GlobalHasDynamicInitializer) {
945 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
946 if (FirstDynamic == 0)
947 FirstDynamic = LastDynamic;
950 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
953 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
954 GlobalVariable *AllGlobals = new GlobalVariable(
955 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
956 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
958 // Create calls for poisoning before initializers run and unpoisoning after.
959 if (CheckInitOrder && FirstDynamic && LastDynamic)
960 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
961 IRB.CreateCall2(AsanRegisterGlobals,
962 IRB.CreatePointerCast(AllGlobals, IntptrTy),
963 ConstantInt::get(IntptrTy, n));
965 // We also need to unregister globals at the end, e.g. when a shared library
967 Function *AsanDtorFunction = Function::Create(
968 FunctionType::get(Type::getVoidTy(*C), false),
969 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
970 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
971 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
972 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
973 IRB.CreatePointerCast(AllGlobals, IntptrTy),
974 ConstantInt::get(IntptrTy, n));
975 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
981 void AddressSanitizer::initializeCallbacks(Module &M) {
983 // Create __asan_report* callbacks.
984 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
985 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
987 // IsWrite and TypeSize are encoded in the function name.
988 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
989 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
990 // If we are merging crash callbacks, they have two parameters.
991 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
992 checkInterfaceFunction(M.getOrInsertFunction(
993 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
997 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
998 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
999 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1000 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1001 StringRef(""), StringRef(""),
1002 /*hasSideEffects=*/true);
1005 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1006 // Tell the values of mapping offset and scale to the run-time.
1007 GlobalValue *asan_mapping_offset =
1008 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1009 ConstantInt::get(IntptrTy, Mapping.Offset),
1010 kAsanMappingOffsetName);
1011 // Read the global, otherwise it may be optimized away.
1012 IRB.CreateLoad(asan_mapping_offset, true);
1014 GlobalValue *asan_mapping_scale =
1015 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1016 ConstantInt::get(IntptrTy, Mapping.Scale),
1017 kAsanMappingScaleName);
1018 // Read the global, otherwise it may be optimized away.
1019 IRB.CreateLoad(asan_mapping_scale, true);
1023 bool AddressSanitizer::doInitialization(Module &M) {
1024 // Initialize the private fields. No one has accessed them before.
1025 TD = getAnalysisIfAvailable<DataLayout>();
1029 BL.reset(new BlackList(BlacklistFile));
1030 DynamicallyInitializedGlobals.Init(M);
1032 C = &(M.getContext());
1033 LongSize = TD->getPointerSizeInBits();
1034 IntptrTy = Type::getIntNTy(*C, LongSize);
1036 AsanCtorFunction = Function::Create(
1037 FunctionType::get(Type::getVoidTy(*C), false),
1038 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1039 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1040 // call __asan_init in the module ctor.
1041 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1042 AsanInitFunction = checkInterfaceFunction(
1043 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1044 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1045 IRB.CreateCall(AsanInitFunction);
1047 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1048 emitShadowMapping(M, IRB);
1050 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1054 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1055 // For each NSObject descendant having a +load method, this method is invoked
1056 // by the ObjC runtime before any of the static constructors is called.
1057 // Therefore we need to instrument such methods with a call to __asan_init
1058 // at the beginning in order to initialize our runtime before any access to
1059 // the shadow memory.
1060 // We cannot just ignore these methods, because they may call other
1061 // instrumented functions.
1062 if (F.getName().find(" load]") != std::string::npos) {
1063 IRBuilder<> IRB(F.begin()->begin());
1064 IRB.CreateCall(AsanInitFunction);
1070 bool AddressSanitizer::runOnFunction(Function &F) {
1071 if (BL->isIn(F)) return false;
1072 if (&F == AsanCtorFunction) return false;
1073 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1074 initializeCallbacks(*F.getParent());
1076 // If needed, insert __asan_init before checking for AddressSafety attr.
1077 maybeInsertAsanInitAtFunctionEntry(F);
1079 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1080 Attribute::AddressSafety))
1083 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1086 // We want to instrument every address only once per basic block (unless there
1087 // are calls between uses).
1088 SmallSet<Value*, 16> TempsToInstrument;
1089 SmallVector<Instruction*, 16> ToInstrument;
1090 SmallVector<Instruction*, 8> NoReturnCalls;
1093 // Fill the set of memory operations to instrument.
1094 for (Function::iterator FI = F.begin(), FE = F.end();
1096 TempsToInstrument.clear();
1097 int NumInsnsPerBB = 0;
1098 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1100 if (LooksLikeCodeInBug11395(BI)) return false;
1101 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1102 if (ClOpt && ClOptSameTemp) {
1103 if (!TempsToInstrument.insert(Addr))
1104 continue; // We've seen this temp in the current BB.
1106 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1109 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1110 // A call inside BB.
1111 TempsToInstrument.clear();
1112 if (CI->doesNotReturn()) {
1113 NoReturnCalls.push_back(CI);
1118 ToInstrument.push_back(BI);
1120 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1126 int NumInstrumented = 0;
1127 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1128 Instruction *Inst = ToInstrument[i];
1129 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1130 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1131 if (isInterestingMemoryAccess(Inst, &IsWrite))
1132 instrumentMop(Inst);
1134 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1139 FunctionStackPoisoner FSP(F, *this);
1140 bool ChangedStack = FSP.runOnFunction();
1142 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1143 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1144 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1145 Instruction *CI = NoReturnCalls[i];
1146 IRBuilder<> IRB(CI);
1147 IRB.CreateCall(AsanHandleNoReturnFunc);
1149 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1151 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1154 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1155 if (ShadowRedzoneSize == 1) return PoisonByte;
1156 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1157 if (ShadowRedzoneSize == 4)
1158 return (PoisonByte << 24) + (PoisonByte << 16) +
1159 (PoisonByte << 8) + (PoisonByte);
1160 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1163 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1166 size_t ShadowGranularity,
1168 for (size_t i = 0; i < RZSize;
1169 i+= ShadowGranularity, Shadow++) {
1170 if (i + ShadowGranularity <= Size) {
1171 *Shadow = 0; // fully addressable
1172 } else if (i >= Size) {
1173 *Shadow = Magic; // unaddressable
1175 *Shadow = Size - i; // first Size-i bytes are addressable
1180 // Workaround for bug 11395: we don't want to instrument stack in functions
1181 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1182 // FIXME: remove once the bug 11395 is fixed.
1183 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1184 if (LongSize != 32) return false;
1185 CallInst *CI = dyn_cast<CallInst>(I);
1186 if (!CI || !CI->isInlineAsm()) return false;
1187 if (CI->getNumArgOperands() <= 5) return false;
1188 // We have inline assembly with quite a few arguments.
1192 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1193 IRBuilder<> IRB(*C);
1194 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1195 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1196 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1197 kAsanStackFreeName, IRB.getVoidTy(),
1198 IntptrTy, IntptrTy, IntptrTy, NULL));
1199 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1200 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1201 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1202 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1205 void FunctionStackPoisoner::poisonRedZones(
1206 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1208 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1209 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1210 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1211 Type *RZPtrTy = PointerType::get(RZTy, 0);
1213 Value *PoisonLeft = ConstantInt::get(RZTy,
1214 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1215 Value *PoisonMid = ConstantInt::get(RZTy,
1216 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1217 Value *PoisonRight = ConstantInt::get(RZTy,
1218 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1220 // poison the first red zone.
1221 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1223 // poison all other red zones.
1224 uint64_t Pos = RedzoneSize();
1225 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1226 AllocaInst *AI = AllocaVec[i];
1227 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1228 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1229 assert(AlignedSize - SizeInBytes < RedzoneSize());
1234 assert(ShadowBase->getType() == IntptrTy);
1235 if (SizeInBytes < AlignedSize) {
1236 // Poison the partial redzone at right
1237 Ptr = IRB.CreateAdd(
1238 ShadowBase, ConstantInt::get(IntptrTy,
1239 (Pos >> Mapping.Scale) - ShadowRZSize));
1240 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1241 uint32_t Poison = 0;
1243 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1245 1ULL << Mapping.Scale,
1246 kAsanStackPartialRedzoneMagic);
1248 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1249 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1252 // Poison the full redzone at right.
1253 Ptr = IRB.CreateAdd(ShadowBase,
1254 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1255 bool LastAlloca = (i == AllocaVec.size() - 1);
1256 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1257 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1259 Pos += RedzoneSize();
1263 void FunctionStackPoisoner::poisonStack() {
1264 uint64_t LocalStackSize = TotalStackSize +
1265 (AllocaVec.size() + 1) * RedzoneSize();
1267 bool DoStackMalloc = ASan.CheckUseAfterReturn
1268 && LocalStackSize <= kMaxStackMallocSize;
1270 assert(AllocaVec.size() > 0);
1271 Instruction *InsBefore = AllocaVec[0];
1272 IRBuilder<> IRB(InsBefore);
1275 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1276 AllocaInst *MyAlloca =
1277 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1278 if (ClRealignStack && StackAlignment < RedzoneSize())
1279 StackAlignment = RedzoneSize();
1280 MyAlloca->setAlignment(StackAlignment);
1281 assert(MyAlloca->isStaticAlloca());
1282 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1283 Value *LocalStackBase = OrigStackBase;
1285 if (DoStackMalloc) {
1286 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1287 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1290 // This string will be parsed by the run-time (DescribeStackAddress).
1291 SmallString<2048> StackDescriptionStorage;
1292 raw_svector_ostream StackDescription(StackDescriptionStorage);
1293 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1295 // Insert poison calls for lifetime intrinsics for alloca.
1296 bool HavePoisonedAllocas = false;
1297 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1298 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1299 IntrinsicInst *II = APC.InsBefore;
1300 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1302 IRBuilder<> IRB(II);
1303 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1304 HavePoisonedAllocas |= APC.DoPoison;
1307 uint64_t Pos = RedzoneSize();
1308 // Replace Alloca instructions with base+offset.
1309 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1310 AllocaInst *AI = AllocaVec[i];
1311 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1312 StringRef Name = AI->getName();
1313 StackDescription << Pos << " " << SizeInBytes << " "
1314 << Name.size() << " " << Name << " ";
1315 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1316 assert((AlignedSize % RedzoneSize()) == 0);
1317 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1318 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1320 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1321 AI->replaceAllUsesWith(NewAllocaPtr);
1322 Pos += AlignedSize + RedzoneSize();
1324 assert(Pos == LocalStackSize);
1326 // Write the Magic value and the frame description constant to the redzone.
1327 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1328 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1330 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1331 ConstantInt::get(IntptrTy,
1333 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1334 GlobalVariable *StackDescriptionGlobal =
1335 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1336 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1338 IRB.CreateStore(Description, BasePlus1);
1340 // Poison the stack redzones at the entry.
1341 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1342 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1344 // Unpoison the stack before all ret instructions.
1345 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1346 Instruction *Ret = RetVec[i];
1347 IRBuilder<> IRBRet(Ret);
1348 // Mark the current frame as retired.
1349 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1351 // Unpoison the stack.
1352 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1353 if (DoStackMalloc) {
1354 // In use-after-return mode, mark the whole stack frame unaddressable.
1355 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1356 ConstantInt::get(IntptrTy, LocalStackSize),
1358 } else if (HavePoisonedAllocas) {
1359 // If we poisoned some allocas in llvm.lifetime analysis,
1360 // unpoison whole stack frame now.
1361 assert(LocalStackBase == OrigStackBase);
1362 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1366 // We are done. Remove the old unused alloca instructions.
1367 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1368 AllocaVec[i]->eraseFromParent();
1371 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1372 IRBuilder<> IRB, bool DoPoison) {
1373 // For now just insert the call to ASan runtime.
1374 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1375 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1376 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1377 : AsanUnpoisonStackMemoryFunc,
1381 // Handling llvm.lifetime intrinsics for a given %alloca:
1382 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1383 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1384 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1385 // could be poisoned by previous llvm.lifetime.end instruction, as the
1386 // variable may go in and out of scope several times, e.g. in loops).
1387 // (3) if we poisoned at least one %alloca in a function,
1388 // unpoison the whole stack frame at function exit.
1390 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1391 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1392 // We're intested only in allocas we can handle.
1393 return isInterestingAlloca(*AI) ? AI : 0;
1394 // See if we've already calculated (or started to calculate) alloca for a
1396 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1397 if (I != AllocaForValue.end())
1399 // Store 0 while we're calculating alloca for value V to avoid
1400 // infinite recursion if the value references itself.
1401 AllocaForValue[V] = 0;
1402 AllocaInst *Res = 0;
1403 if (CastInst *CI = dyn_cast<CastInst>(V))
1404 Res = findAllocaForValue(CI->getOperand(0));
1405 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1406 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1407 Value *IncValue = PN->getIncomingValue(i);
1408 // Allow self-referencing phi-nodes.
1409 if (IncValue == PN) continue;
1410 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1411 // AI for incoming values should exist and should all be equal.
1412 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1418 AllocaForValue[V] = Res;