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_v1";
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(true));
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;
206 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
208 ShadowMapping Mapping;
210 // OR-ing shadow offset if more efficient (at least on x86),
211 // but on ppc64 we have to use add since the shadow offset is not neccesary
212 // 1/8-th of the address space.
213 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
215 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
216 (LongSize == 32 ? kDefaultShadowOffset32 :
217 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
218 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64) {
219 assert(LongSize == 64);
220 Mapping.Offset = kDefaultShort64bitShadowOffset;
221 } if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
222 // Zero offset log is the special case.
223 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
226 Mapping.Scale = kDefaultShadowScale;
227 if (ClMappingScale) {
228 Mapping.Scale = ClMappingScale;
234 static size_t RedzoneSizeForScale(int MappingScale) {
235 // Redzone used for stack and globals is at least 32 bytes.
236 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
237 return std::max(32U, 1U << MappingScale);
240 /// AddressSanitizer: instrument the code in module to find memory bugs.
241 struct AddressSanitizer : public FunctionPass {
242 AddressSanitizer(bool CheckInitOrder = false,
243 bool CheckUseAfterReturn = false,
244 bool CheckLifetime = false,
245 StringRef BlacklistFile = StringRef(),
246 bool ZeroBaseShadow = false)
248 CheckInitOrder(CheckInitOrder || ClInitializers),
249 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
250 CheckLifetime(CheckLifetime || ClCheckLifetime),
251 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
253 ZeroBaseShadow(ZeroBaseShadow) {}
254 virtual const char *getPassName() const {
255 return "AddressSanitizerFunctionPass";
257 void instrumentMop(Instruction *I);
258 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
259 Value *Addr, uint32_t TypeSize, bool IsWrite);
260 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
261 Value *ShadowValue, uint32_t TypeSize);
262 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
263 bool IsWrite, size_t AccessSizeIndex);
264 bool instrumentMemIntrinsic(MemIntrinsic *MI);
265 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
267 Instruction *InsertBefore, bool IsWrite);
268 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
269 bool runOnFunction(Function &F);
270 void createInitializerPoisonCalls(Module &M,
271 Value *FirstAddr, Value *LastAddr);
272 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
273 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
274 virtual bool doInitialization(Module &M);
275 static char ID; // Pass identification, replacement for typeid
278 void initializeCallbacks(Module &M);
280 bool ShouldInstrumentGlobal(GlobalVariable *G);
281 bool LooksLikeCodeInBug11395(Instruction *I);
282 void FindDynamicInitializers(Module &M);
285 bool CheckUseAfterReturn;
287 SmallString<64> BlacklistFile;
294 ShadowMapping Mapping;
295 Function *AsanCtorFunction;
296 Function *AsanInitFunction;
297 Function *AsanHandleNoReturnFunc;
298 OwningPtr<BlackList> BL;
299 // This array is indexed by AccessIsWrite and log2(AccessSize).
300 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
302 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
304 friend struct FunctionStackPoisoner;
307 class AddressSanitizerModule : public ModulePass {
309 AddressSanitizerModule(bool CheckInitOrder = false,
310 StringRef BlacklistFile = StringRef(),
311 bool ZeroBaseShadow = false)
313 CheckInitOrder(CheckInitOrder || ClInitializers),
314 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
316 ZeroBaseShadow(ZeroBaseShadow) {}
317 bool runOnModule(Module &M);
318 static char ID; // Pass identification, replacement for typeid
319 virtual const char *getPassName() const {
320 return "AddressSanitizerModule";
324 void initializeCallbacks(Module &M);
326 bool ShouldInstrumentGlobal(GlobalVariable *G);
327 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
329 size_t RedzoneSize() const {
330 return RedzoneSizeForScale(Mapping.Scale);
334 SmallString<64> BlacklistFile;
337 OwningPtr<BlackList> BL;
338 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
342 ShadowMapping Mapping;
343 Function *AsanPoisonGlobals;
344 Function *AsanUnpoisonGlobals;
345 Function *AsanRegisterGlobals;
346 Function *AsanUnregisterGlobals;
349 // Stack poisoning does not play well with exception handling.
350 // When an exception is thrown, we essentially bypass the code
351 // that unpoisones the stack. This is why the run-time library has
352 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
353 // stack in the interceptor. This however does not work inside the
354 // actual function which catches the exception. Most likely because the
355 // compiler hoists the load of the shadow value somewhere too high.
356 // This causes asan to report a non-existing bug on 453.povray.
357 // It sounds like an LLVM bug.
358 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
360 AddressSanitizer &ASan;
365 ShadowMapping Mapping;
367 SmallVector<AllocaInst*, 16> AllocaVec;
368 SmallVector<Instruction*, 8> RetVec;
369 uint64_t TotalStackSize;
370 unsigned StackAlignment;
372 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
373 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
375 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
376 struct AllocaPoisonCall {
377 IntrinsicInst *InsBefore;
381 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
383 // Maps Value to an AllocaInst from which the Value is originated.
384 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
385 AllocaForValueMapTy AllocaForValue;
387 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
388 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
389 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
390 Mapping(ASan.Mapping),
391 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
393 bool runOnFunction() {
394 if (!ClStack) return false;
395 // Collect alloca, ret, lifetime instructions etc.
396 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
397 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
398 BasicBlock *BB = *DI;
401 if (AllocaVec.empty()) return false;
403 initializeCallbacks(*F.getParent());
413 // Finds all static Alloca instructions and puts
414 // poisoned red zones around all of them.
415 // Then unpoison everything back before the function returns.
418 // ----------------------- Visitors.
419 /// \brief Collect all Ret instructions.
420 void visitReturnInst(ReturnInst &RI) {
421 RetVec.push_back(&RI);
424 /// \brief Collect Alloca instructions we want (and can) handle.
425 void visitAllocaInst(AllocaInst &AI) {
426 if (!isInterestingAlloca(AI)) return;
428 StackAlignment = std::max(StackAlignment, AI.getAlignment());
429 AllocaVec.push_back(&AI);
430 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
431 TotalStackSize += AlignedSize;
434 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
436 void visitIntrinsicInst(IntrinsicInst &II) {
437 if (!ASan.CheckLifetime) return;
438 Intrinsic::ID ID = II.getIntrinsicID();
439 if (ID != Intrinsic::lifetime_start &&
440 ID != Intrinsic::lifetime_end)
442 // Found lifetime intrinsic, add ASan instrumentation if necessary.
443 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
444 // If size argument is undefined, don't do anything.
445 if (Size->isMinusOne()) return;
446 // Check that size doesn't saturate uint64_t and can
447 // be stored in IntptrTy.
448 const uint64_t SizeValue = Size->getValue().getLimitedValue();
449 if (SizeValue == ~0ULL ||
450 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
452 // Find alloca instruction that corresponds to llvm.lifetime argument.
453 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
455 bool DoPoison = (ID == Intrinsic::lifetime_end);
456 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
457 AllocaPoisonCallVec.push_back(APC);
460 // ---------------------- Helpers.
461 void initializeCallbacks(Module &M);
463 // Check if we want (and can) handle this alloca.
464 bool isInterestingAlloca(AllocaInst &AI) {
465 return (!AI.isArrayAllocation() &&
466 AI.isStaticAlloca() &&
467 AI.getAllocatedType()->isSized());
470 size_t RedzoneSize() const {
471 return RedzoneSizeForScale(Mapping.Scale);
473 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
474 Type *Ty = AI->getAllocatedType();
475 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
478 uint64_t getAlignedSize(uint64_t SizeInBytes) {
479 size_t RZ = RedzoneSize();
480 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
482 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
483 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
484 return getAlignedSize(SizeInBytes);
486 /// Finds alloca where the value comes from.
487 AllocaInst *findAllocaForValue(Value *V);
488 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
489 Value *ShadowBase, bool DoPoison);
490 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
495 char AddressSanitizer::ID = 0;
496 INITIALIZE_PASS(AddressSanitizer, "asan",
497 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
499 FunctionPass *llvm::createAddressSanitizerFunctionPass(
500 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
501 StringRef BlacklistFile, bool ZeroBaseShadow) {
502 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
503 CheckLifetime, BlacklistFile, ZeroBaseShadow);
506 char AddressSanitizerModule::ID = 0;
507 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
508 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
509 "ModulePass", false, false)
510 ModulePass *llvm::createAddressSanitizerModulePass(
511 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
512 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
516 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
517 size_t Res = CountTrailingZeros_32(TypeSize / 8);
518 assert(Res < kNumberOfAccessSizes);
522 // Create a constant for Str so that we can pass it to the run-time lib.
523 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
524 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
525 return new GlobalVariable(M, StrConst->getType(), true,
526 GlobalValue::PrivateLinkage, StrConst,
530 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
531 return G->getName().find(kAsanGenPrefix) == 0;
534 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
536 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
537 if (Mapping.Offset == 0)
539 // (Shadow >> scale) | offset
540 if (Mapping.OrShadowOffset)
541 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
543 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
546 void AddressSanitizer::instrumentMemIntrinsicParam(
547 Instruction *OrigIns,
548 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
549 // Check the first byte.
551 IRBuilder<> IRB(InsertBefore);
552 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
554 // Check the last byte.
556 IRBuilder<> IRB(InsertBefore);
557 Value *SizeMinusOne = IRB.CreateSub(
558 Size, ConstantInt::get(Size->getType(), 1));
559 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
560 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
561 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
562 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
566 // Instrument memset/memmove/memcpy
567 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
568 Value *Dst = MI->getDest();
569 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
570 Value *Src = MemTran ? MemTran->getSource() : 0;
571 Value *Length = MI->getLength();
573 Constant *ConstLength = dyn_cast<Constant>(Length);
574 Instruction *InsertBefore = MI;
576 if (ConstLength->isNullValue()) return false;
578 // The size is not a constant so it could be zero -- check at run-time.
579 IRBuilder<> IRB(InsertBefore);
581 Value *Cmp = IRB.CreateICmpNE(Length,
582 Constant::getNullValue(Length->getType()));
583 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
586 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
588 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
592 // If I is an interesting memory access, return the PointerOperand
593 // and set IsWrite. Otherwise return NULL.
594 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
595 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
596 if (!ClInstrumentReads) return NULL;
598 return LI->getPointerOperand();
600 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
601 if (!ClInstrumentWrites) return NULL;
603 return SI->getPointerOperand();
605 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
606 if (!ClInstrumentAtomics) return NULL;
608 return RMW->getPointerOperand();
610 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
611 if (!ClInstrumentAtomics) return NULL;
613 return XCHG->getPointerOperand();
618 void AddressSanitizer::instrumentMop(Instruction *I) {
619 bool IsWrite = false;
620 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
622 if (ClOpt && ClOptGlobals) {
623 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
624 // If initialization order checking is disabled, a simple access to a
625 // dynamically initialized global is always valid.
628 // If a global variable does not have dynamic initialization we don't
629 // have to instrument it. However, if a global does not have initailizer
630 // at all, we assume it has dynamic initializer (in other TU).
631 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
636 Type *OrigPtrTy = Addr->getType();
637 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
639 assert(OrigTy->isSized());
640 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
642 if (TypeSize != 8 && TypeSize != 16 &&
643 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
644 // Ignore all unusual sizes.
649 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
652 // Validate the result of Module::getOrInsertFunction called for an interface
653 // function of AddressSanitizer. If the instrumented module defines a function
654 // with the same name, their prototypes must match, otherwise
655 // getOrInsertFunction returns a bitcast.
656 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
657 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
658 FuncOrBitcast->dump();
659 report_fatal_error("trying to redefine an AddressSanitizer "
660 "interface function");
663 Instruction *AddressSanitizer::generateCrashCode(
664 Instruction *InsertBefore, Value *Addr,
665 bool IsWrite, size_t AccessSizeIndex) {
666 IRBuilder<> IRB(InsertBefore);
667 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
669 // We don't do Call->setDoesNotReturn() because the BB already has
670 // UnreachableInst at the end.
671 // This EmptyAsm is required to avoid callback merge.
672 IRB.CreateCall(EmptyAsm);
676 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
679 size_t Granularity = 1 << Mapping.Scale;
680 // Addr & (Granularity - 1)
681 Value *LastAccessedByte = IRB.CreateAnd(
682 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
683 // (Addr & (Granularity - 1)) + size - 1
684 if (TypeSize / 8 > 1)
685 LastAccessedByte = IRB.CreateAdd(
686 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
687 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
688 LastAccessedByte = IRB.CreateIntCast(
689 LastAccessedByte, ShadowValue->getType(), false);
690 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
691 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
694 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
695 IRBuilder<> &IRB, Value *Addr,
696 uint32_t TypeSize, bool IsWrite) {
697 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
699 Type *ShadowTy = IntegerType::get(
700 *C, std::max(8U, TypeSize >> Mapping.Scale));
701 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
702 Value *ShadowPtr = memToShadow(AddrLong, IRB);
703 Value *CmpVal = Constant::getNullValue(ShadowTy);
704 Value *ShadowValue = IRB.CreateLoad(
705 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
707 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
708 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
709 size_t Granularity = 1 << Mapping.Scale;
710 TerminatorInst *CrashTerm = 0;
712 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
713 TerminatorInst *CheckTerm =
714 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
715 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
716 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
717 IRB.SetInsertPoint(CheckTerm);
718 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
719 BasicBlock *CrashBlock =
720 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
721 CrashTerm = new UnreachableInst(*C, CrashBlock);
722 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
723 ReplaceInstWithInst(CheckTerm, NewTerm);
725 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
729 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
730 Crash->setDebugLoc(OrigIns->getDebugLoc());
733 void AddressSanitizerModule::createInitializerPoisonCalls(
734 Module &M, Value *FirstAddr, Value *LastAddr) {
735 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
736 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
737 // If that function is not present, this TU contains no globals, or they have
738 // all been optimized away
742 // Set up the arguments to our poison/unpoison functions.
743 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
745 // Add a call to poison all external globals before the given function starts.
746 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
748 // Add calls to unpoison all globals before each return instruction.
749 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
751 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
752 CallInst::Create(AsanUnpoisonGlobals, "", RI);
757 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
758 Type *Ty = cast<PointerType>(G->getType())->getElementType();
759 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
761 if (BL->isIn(*G)) return false;
762 if (!Ty->isSized()) return false;
763 if (!G->hasInitializer()) return false;
764 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
765 // Touch only those globals that will not be defined in other modules.
766 // Don't handle ODR type linkages since other modules may be built w/o asan.
767 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
768 G->getLinkage() != GlobalVariable::PrivateLinkage &&
769 G->getLinkage() != GlobalVariable::InternalLinkage)
771 // Two problems with thread-locals:
772 // - The address of the main thread's copy can't be computed at link-time.
773 // - Need to poison all copies, not just the main thread's one.
774 if (G->isThreadLocal())
776 // For now, just ignore this Alloca if the alignment is large.
777 if (G->getAlignment() > RedzoneSize()) return false;
779 // Ignore all the globals with the names starting with "\01L_OBJC_".
780 // Many of those are put into the .cstring section. The linker compresses
781 // that section by removing the spare \0s after the string terminator, so
782 // our redzones get broken.
783 if ((G->getName().find("\01L_OBJC_") == 0) ||
784 (G->getName().find("\01l_OBJC_") == 0)) {
785 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
789 if (G->hasSection()) {
790 StringRef Section(G->getSection());
791 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
792 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
794 if ((Section.find("__OBJC,") == 0) ||
795 (Section.find("__DATA, __objc_") == 0)) {
796 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
799 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
800 // Constant CFString instances are compiled in the following way:
801 // -- the string buffer is emitted into
802 // __TEXT,__cstring,cstring_literals
803 // -- the constant NSConstantString structure referencing that buffer
804 // is placed into __DATA,__cfstring
805 // Therefore there's no point in placing redzones into __DATA,__cfstring.
806 // Moreover, it causes the linker to crash on OS X 10.7
807 if (Section.find("__DATA,__cfstring") == 0) {
808 DEBUG(dbgs() << "Ignoring CFString: " << *G);
816 void AddressSanitizerModule::initializeCallbacks(Module &M) {
818 // Declare our poisoning and unpoisoning functions.
819 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
820 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
821 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
822 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
823 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
824 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
825 // Declare functions that register/unregister globals.
826 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
827 kAsanRegisterGlobalsName, IRB.getVoidTy(),
828 IntptrTy, IntptrTy, NULL));
829 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
830 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
831 kAsanUnregisterGlobalsName,
832 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
833 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
836 // This function replaces all global variables with new variables that have
837 // trailing redzones. It also creates a function that poisons
838 // redzones and inserts this function into llvm.global_ctors.
839 bool AddressSanitizerModule::runOnModule(Module &M) {
840 if (!ClGlobals) return false;
841 TD = getAnalysisIfAvailable<DataLayout>();
844 BL.reset(new BlackList(BlacklistFile));
845 if (BL->isIn(M)) return false;
846 C = &(M.getContext());
847 int LongSize = TD->getPointerSizeInBits();
848 IntptrTy = Type::getIntNTy(*C, LongSize);
849 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
850 initializeCallbacks(M);
851 DynamicallyInitializedGlobals.Init(M);
853 SmallVector<GlobalVariable *, 16> GlobalsToChange;
855 for (Module::GlobalListType::iterator G = M.global_begin(),
856 E = M.global_end(); G != E; ++G) {
857 if (ShouldInstrumentGlobal(G))
858 GlobalsToChange.push_back(G);
861 size_t n = GlobalsToChange.size();
862 if (n == 0) return false;
864 // A global is described by a structure
867 // size_t size_with_redzone;
869 // size_t has_dynamic_init;
870 // We initialize an array of such structures and pass it to a run-time call.
871 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
874 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
877 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
879 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
881 // The addresses of the first and last dynamically initialized globals in
882 // this TU. Used in initialization order checking.
883 Value *FirstDynamic = 0, *LastDynamic = 0;
885 for (size_t i = 0; i < n; i++) {
886 static const uint64_t kMaxGlobalRedzone = 1 << 18;
887 GlobalVariable *G = GlobalsToChange[i];
888 PointerType *PtrTy = cast<PointerType>(G->getType());
889 Type *Ty = PtrTy->getElementType();
890 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
891 uint64_t MinRZ = RedzoneSize();
892 // MinRZ <= RZ <= kMaxGlobalRedzone
893 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
894 uint64_t RZ = std::max(MinRZ,
895 std::min(kMaxGlobalRedzone,
896 (SizeInBytes / MinRZ / 4) * MinRZ));
897 uint64_t RightRedzoneSize = RZ;
899 if (SizeInBytes % MinRZ)
900 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
901 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
902 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
903 // Determine whether this global should be poisoned in initialization.
904 bool GlobalHasDynamicInitializer =
905 DynamicallyInitializedGlobals.Contains(G);
906 // Don't check initialization order if this global is blacklisted.
907 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
909 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
910 Constant *NewInitializer = ConstantStruct::get(
911 NewTy, G->getInitializer(),
912 Constant::getNullValue(RightRedZoneTy), NULL);
914 SmallString<2048> DescriptionOfGlobal = G->getName();
915 DescriptionOfGlobal += " (";
916 DescriptionOfGlobal += M.getModuleIdentifier();
917 DescriptionOfGlobal += ")";
918 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
920 // Create a new global variable with enough space for a redzone.
921 GlobalVariable *NewGlobal = new GlobalVariable(
922 M, NewTy, G->isConstant(), G->getLinkage(),
923 NewInitializer, "", G, G->getThreadLocalMode());
924 NewGlobal->copyAttributesFrom(G);
925 NewGlobal->setAlignment(MinRZ);
928 Indices2[0] = IRB.getInt32(0);
929 Indices2[1] = IRB.getInt32(0);
931 G->replaceAllUsesWith(
932 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
933 NewGlobal->takeName(G);
934 G->eraseFromParent();
936 Initializers[i] = ConstantStruct::get(
938 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
939 ConstantInt::get(IntptrTy, SizeInBytes),
940 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
941 ConstantExpr::getPointerCast(Name, IntptrTy),
942 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
945 // Populate the first and last globals declared in this TU.
946 if (CheckInitOrder && GlobalHasDynamicInitializer) {
947 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
948 if (FirstDynamic == 0)
949 FirstDynamic = LastDynamic;
952 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
955 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
956 GlobalVariable *AllGlobals = new GlobalVariable(
957 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
958 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
960 // Create calls for poisoning before initializers run and unpoisoning after.
961 if (CheckInitOrder && FirstDynamic && LastDynamic)
962 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
963 IRB.CreateCall2(AsanRegisterGlobals,
964 IRB.CreatePointerCast(AllGlobals, IntptrTy),
965 ConstantInt::get(IntptrTy, n));
967 // We also need to unregister globals at the end, e.g. when a shared library
969 Function *AsanDtorFunction = Function::Create(
970 FunctionType::get(Type::getVoidTy(*C), false),
971 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
972 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
973 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
974 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
975 IRB.CreatePointerCast(AllGlobals, IntptrTy),
976 ConstantInt::get(IntptrTy, n));
977 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
983 void AddressSanitizer::initializeCallbacks(Module &M) {
985 // Create __asan_report* callbacks.
986 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
987 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
989 // IsWrite and TypeSize are encoded in the function name.
990 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
991 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
992 // If we are merging crash callbacks, they have two parameters.
993 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
994 checkInterfaceFunction(M.getOrInsertFunction(
995 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
999 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1000 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1001 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1002 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1003 StringRef(""), StringRef(""),
1004 /*hasSideEffects=*/true);
1007 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1008 // Tell the values of mapping offset and scale to the run-time.
1009 GlobalValue *asan_mapping_offset =
1010 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1011 ConstantInt::get(IntptrTy, Mapping.Offset),
1012 kAsanMappingOffsetName);
1013 // Read the global, otherwise it may be optimized away.
1014 IRB.CreateLoad(asan_mapping_offset, true);
1016 GlobalValue *asan_mapping_scale =
1017 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1018 ConstantInt::get(IntptrTy, Mapping.Scale),
1019 kAsanMappingScaleName);
1020 // Read the global, otherwise it may be optimized away.
1021 IRB.CreateLoad(asan_mapping_scale, true);
1025 bool AddressSanitizer::doInitialization(Module &M) {
1026 // Initialize the private fields. No one has accessed them before.
1027 TD = getAnalysisIfAvailable<DataLayout>();
1031 BL.reset(new BlackList(BlacklistFile));
1032 DynamicallyInitializedGlobals.Init(M);
1034 C = &(M.getContext());
1035 LongSize = TD->getPointerSizeInBits();
1036 IntptrTy = Type::getIntNTy(*C, LongSize);
1038 AsanCtorFunction = Function::Create(
1039 FunctionType::get(Type::getVoidTy(*C), false),
1040 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1041 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1042 // call __asan_init in the module ctor.
1043 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1044 AsanInitFunction = checkInterfaceFunction(
1045 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1046 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1047 IRB.CreateCall(AsanInitFunction);
1049 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1050 emitShadowMapping(M, IRB);
1052 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1056 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1057 // For each NSObject descendant having a +load method, this method is invoked
1058 // by the ObjC runtime before any of the static constructors is called.
1059 // Therefore we need to instrument such methods with a call to __asan_init
1060 // at the beginning in order to initialize our runtime before any access to
1061 // the shadow memory.
1062 // We cannot just ignore these methods, because they may call other
1063 // instrumented functions.
1064 if (F.getName().find(" load]") != std::string::npos) {
1065 IRBuilder<> IRB(F.begin()->begin());
1066 IRB.CreateCall(AsanInitFunction);
1072 bool AddressSanitizer::runOnFunction(Function &F) {
1073 if (BL->isIn(F)) return false;
1074 if (&F == AsanCtorFunction) return false;
1075 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1076 initializeCallbacks(*F.getParent());
1078 // If needed, insert __asan_init before checking for AddressSafety attr.
1079 maybeInsertAsanInitAtFunctionEntry(F);
1081 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1082 Attribute::AddressSafety))
1085 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1088 // We want to instrument every address only once per basic block (unless there
1089 // are calls between uses).
1090 SmallSet<Value*, 16> TempsToInstrument;
1091 SmallVector<Instruction*, 16> ToInstrument;
1092 SmallVector<Instruction*, 8> NoReturnCalls;
1095 // Fill the set of memory operations to instrument.
1096 for (Function::iterator FI = F.begin(), FE = F.end();
1098 TempsToInstrument.clear();
1099 int NumInsnsPerBB = 0;
1100 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1102 if (LooksLikeCodeInBug11395(BI)) return false;
1103 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1104 if (ClOpt && ClOptSameTemp) {
1105 if (!TempsToInstrument.insert(Addr))
1106 continue; // We've seen this temp in the current BB.
1108 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1111 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1112 // A call inside BB.
1113 TempsToInstrument.clear();
1114 if (CI->doesNotReturn()) {
1115 NoReturnCalls.push_back(CI);
1120 ToInstrument.push_back(BI);
1122 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1128 int NumInstrumented = 0;
1129 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1130 Instruction *Inst = ToInstrument[i];
1131 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1132 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1133 if (isInterestingMemoryAccess(Inst, &IsWrite))
1134 instrumentMop(Inst);
1136 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1141 FunctionStackPoisoner FSP(F, *this);
1142 bool ChangedStack = FSP.runOnFunction();
1144 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1145 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1146 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1147 Instruction *CI = NoReturnCalls[i];
1148 IRBuilder<> IRB(CI);
1149 IRB.CreateCall(AsanHandleNoReturnFunc);
1151 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1153 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1156 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1157 if (ShadowRedzoneSize == 1) return PoisonByte;
1158 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1159 if (ShadowRedzoneSize == 4)
1160 return (PoisonByte << 24) + (PoisonByte << 16) +
1161 (PoisonByte << 8) + (PoisonByte);
1162 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1165 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1168 size_t ShadowGranularity,
1170 for (size_t i = 0; i < RZSize;
1171 i+= ShadowGranularity, Shadow++) {
1172 if (i + ShadowGranularity <= Size) {
1173 *Shadow = 0; // fully addressable
1174 } else if (i >= Size) {
1175 *Shadow = Magic; // unaddressable
1177 *Shadow = Size - i; // first Size-i bytes are addressable
1182 // Workaround for bug 11395: we don't want to instrument stack in functions
1183 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1184 // FIXME: remove once the bug 11395 is fixed.
1185 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1186 if (LongSize != 32) return false;
1187 CallInst *CI = dyn_cast<CallInst>(I);
1188 if (!CI || !CI->isInlineAsm()) return false;
1189 if (CI->getNumArgOperands() <= 5) return false;
1190 // We have inline assembly with quite a few arguments.
1194 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1195 IRBuilder<> IRB(*C);
1196 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1197 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1198 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1199 kAsanStackFreeName, IRB.getVoidTy(),
1200 IntptrTy, IntptrTy, IntptrTy, NULL));
1201 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1202 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1203 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1204 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1207 void FunctionStackPoisoner::poisonRedZones(
1208 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1210 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1211 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1212 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1213 Type *RZPtrTy = PointerType::get(RZTy, 0);
1215 Value *PoisonLeft = ConstantInt::get(RZTy,
1216 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1217 Value *PoisonMid = ConstantInt::get(RZTy,
1218 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1219 Value *PoisonRight = ConstantInt::get(RZTy,
1220 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1222 // poison the first red zone.
1223 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1225 // poison all other red zones.
1226 uint64_t Pos = RedzoneSize();
1227 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1228 AllocaInst *AI = AllocaVec[i];
1229 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1230 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1231 assert(AlignedSize - SizeInBytes < RedzoneSize());
1236 assert(ShadowBase->getType() == IntptrTy);
1237 if (SizeInBytes < AlignedSize) {
1238 // Poison the partial redzone at right
1239 Ptr = IRB.CreateAdd(
1240 ShadowBase, ConstantInt::get(IntptrTy,
1241 (Pos >> Mapping.Scale) - ShadowRZSize));
1242 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1243 uint32_t Poison = 0;
1245 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1247 1ULL << Mapping.Scale,
1248 kAsanStackPartialRedzoneMagic);
1250 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1251 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1254 // Poison the full redzone at right.
1255 Ptr = IRB.CreateAdd(ShadowBase,
1256 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1257 bool LastAlloca = (i == AllocaVec.size() - 1);
1258 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1259 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1261 Pos += RedzoneSize();
1265 void FunctionStackPoisoner::poisonStack() {
1266 uint64_t LocalStackSize = TotalStackSize +
1267 (AllocaVec.size() + 1) * RedzoneSize();
1269 bool DoStackMalloc = ASan.CheckUseAfterReturn
1270 && LocalStackSize <= kMaxStackMallocSize;
1272 assert(AllocaVec.size() > 0);
1273 Instruction *InsBefore = AllocaVec[0];
1274 IRBuilder<> IRB(InsBefore);
1277 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1278 AllocaInst *MyAlloca =
1279 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1280 if (ClRealignStack && StackAlignment < RedzoneSize())
1281 StackAlignment = RedzoneSize();
1282 MyAlloca->setAlignment(StackAlignment);
1283 assert(MyAlloca->isStaticAlloca());
1284 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1285 Value *LocalStackBase = OrigStackBase;
1287 if (DoStackMalloc) {
1288 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1289 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1292 // This string will be parsed by the run-time (DescribeStackAddress).
1293 SmallString<2048> StackDescriptionStorage;
1294 raw_svector_ostream StackDescription(StackDescriptionStorage);
1295 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1297 // Insert poison calls for lifetime intrinsics for alloca.
1298 bool HavePoisonedAllocas = false;
1299 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1300 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1301 IntrinsicInst *II = APC.InsBefore;
1302 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1304 IRBuilder<> IRB(II);
1305 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1306 HavePoisonedAllocas |= APC.DoPoison;
1309 uint64_t Pos = RedzoneSize();
1310 // Replace Alloca instructions with base+offset.
1311 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1312 AllocaInst *AI = AllocaVec[i];
1313 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1314 StringRef Name = AI->getName();
1315 StackDescription << Pos << " " << SizeInBytes << " "
1316 << Name.size() << " " << Name << " ";
1317 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1318 assert((AlignedSize % RedzoneSize()) == 0);
1319 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1320 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1322 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1323 AI->replaceAllUsesWith(NewAllocaPtr);
1324 Pos += AlignedSize + RedzoneSize();
1326 assert(Pos == LocalStackSize);
1328 // Write the Magic value and the frame description constant to the redzone.
1329 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1330 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1332 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1333 ConstantInt::get(IntptrTy,
1335 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1336 GlobalVariable *StackDescriptionGlobal =
1337 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1338 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1340 IRB.CreateStore(Description, BasePlus1);
1342 // Poison the stack redzones at the entry.
1343 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1344 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1346 // Unpoison the stack before all ret instructions.
1347 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1348 Instruction *Ret = RetVec[i];
1349 IRBuilder<> IRBRet(Ret);
1350 // Mark the current frame as retired.
1351 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1353 // Unpoison the stack.
1354 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1355 if (DoStackMalloc) {
1356 // In use-after-return mode, mark the whole stack frame unaddressable.
1357 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1358 ConstantInt::get(IntptrTy, LocalStackSize),
1360 } else if (HavePoisonedAllocas) {
1361 // If we poisoned some allocas in llvm.lifetime analysis,
1362 // unpoison whole stack frame now.
1363 assert(LocalStackBase == OrigStackBase);
1364 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1368 // We are done. Remove the old unused alloca instructions.
1369 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1370 AllocaVec[i]->eraseFromParent();
1373 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1374 IRBuilder<> IRB, bool DoPoison) {
1375 // For now just insert the call to ASan runtime.
1376 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1377 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1378 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1379 : AsanUnpoisonStackMemoryFunc,
1383 // Handling llvm.lifetime intrinsics for a given %alloca:
1384 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1385 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1386 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1387 // could be poisoned by previous llvm.lifetime.end instruction, as the
1388 // variable may go in and out of scope several times, e.g. in loops).
1389 // (3) if we poisoned at least one %alloca in a function,
1390 // unpoison the whole stack frame at function exit.
1392 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1393 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1394 // We're intested only in allocas we can handle.
1395 return isInterestingAlloca(*AI) ? AI : 0;
1396 // See if we've already calculated (or started to calculate) alloca for a
1398 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1399 if (I != AllocaForValue.end())
1401 // Store 0 while we're calculating alloca for value V to avoid
1402 // infinite recursion if the value references itself.
1403 AllocaForValue[V] = 0;
1404 AllocaInst *Res = 0;
1405 if (CastInst *CI = dyn_cast<CastInst>(V))
1406 Res = findAllocaForValue(CI->getOperand(0));
1407 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1408 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1409 Value *IncValue = PN->getIncomingValue(i);
1410 // Allow self-referencing phi-nodes.
1411 if (IncValue == PN) continue;
1412 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1413 // AI for incoming values should exist and should all be equal.
1414 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1420 AllocaForValue[V] = Res;