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/CallSite.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/DataTypes.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/Endian.h"
43 #include "llvm/Support/raw_ostream.h"
44 #include "llvm/Support/system_error.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/BlackList.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/Transforms/Utils/ModuleUtils.h"
54 static const uint64_t kDefaultShadowScale = 3;
55 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
56 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
57 static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
58 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
59 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
61 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
62 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
63 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
65 static const char *kAsanModuleCtorName = "asan.module_ctor";
66 static const char *kAsanModuleDtorName = "asan.module_dtor";
67 static const int kAsanCtorAndCtorPriority = 1;
68 static const char *kAsanReportErrorTemplate = "__asan_report_";
69 static const char *kAsanReportLoadN = "__asan_report_load_n";
70 static const char *kAsanReportStoreN = "__asan_report_store_n";
71 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
72 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
73 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
74 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
75 static const char *kAsanInitName = "__asan_init_v3";
76 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
77 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
78 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
79 static const char *kAsanStackMallocName = "__asan_stack_malloc";
80 static const char *kAsanStackFreeName = "__asan_stack_free";
81 static const char *kAsanGenPrefix = "__asan_gen_";
82 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
83 static const char *kAsanUnpoisonStackMemoryName =
84 "__asan_unpoison_stack_memory";
86 static const int kAsanStackLeftRedzoneMagic = 0xf1;
87 static const int kAsanStackMidRedzoneMagic = 0xf2;
88 static const int kAsanStackRightRedzoneMagic = 0xf3;
89 static const int kAsanStackPartialRedzoneMagic = 0xf4;
91 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
92 static const size_t kNumberOfAccessSizes = 5;
94 // Command-line flags.
96 // This flag may need to be replaced with -f[no-]asan-reads.
97 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
98 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
99 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
100 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
101 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
102 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
103 cl::Hidden, cl::init(true));
104 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
105 cl::desc("use instrumentation with slow path for all accesses"),
106 cl::Hidden, cl::init(false));
107 // This flag limits the number of instructions to be instrumented
108 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
109 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
111 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
113 cl::desc("maximal number of instructions to instrument in any given BB"),
115 // This flag may need to be replaced with -f[no]asan-stack.
116 static cl::opt<bool> ClStack("asan-stack",
117 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
118 // This flag may need to be replaced with -f[no]asan-use-after-return.
119 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
120 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
121 // This flag may need to be replaced with -f[no]asan-globals.
122 static cl::opt<bool> ClGlobals("asan-globals",
123 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
124 static cl::opt<bool> ClInitializers("asan-initialization-order",
125 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
126 static cl::opt<bool> ClMemIntrin("asan-memintrin",
127 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
128 static cl::opt<bool> ClRealignStack("asan-realign-stack",
129 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
130 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
131 cl::desc("File containing the list of objects to ignore "
132 "during instrumentation"), cl::Hidden);
134 // These flags allow to change the shadow mapping.
135 // The shadow mapping looks like
136 // Shadow = (Mem >> scale) + (1 << offset_log)
137 static cl::opt<int> ClMappingScale("asan-mapping-scale",
138 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
139 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
140 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
141 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
142 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
143 cl::Hidden, cl::init(true));
145 // Optimization flags. Not user visible, used mostly for testing
146 // and benchmarking the tool.
147 static cl::opt<bool> ClOpt("asan-opt",
148 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
149 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
150 cl::desc("Instrument the same temp just once"), cl::Hidden,
152 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
153 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
155 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
156 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
157 cl::Hidden, cl::init(false));
160 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
162 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
163 cl::Hidden, cl::init(0));
164 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
165 cl::Hidden, cl::desc("Debug func"));
166 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
167 cl::Hidden, cl::init(-1));
168 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
169 cl::Hidden, cl::init(-1));
172 /// A set of dynamically initialized globals extracted from metadata.
173 class SetOfDynamicallyInitializedGlobals {
175 void Init(Module& M) {
176 // Clang generates metadata identifying all dynamically initialized globals.
177 NamedMDNode *DynamicGlobals =
178 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
181 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
182 MDNode *MDN = DynamicGlobals->getOperand(i);
183 assert(MDN->getNumOperands() == 1);
184 Value *VG = MDN->getOperand(0);
185 // The optimizer may optimize away a global entirely, in which case we
186 // cannot instrument access to it.
189 DynInitGlobals.insert(cast<GlobalVariable>(VG));
192 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
194 SmallSet<GlobalValue*, 32> DynInitGlobals;
197 /// This struct defines the shadow mapping using the rule:
198 /// shadow = (mem >> Scale) ADD-or-OR Offset.
199 struct ShadowMapping {
205 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
206 bool ZeroBaseShadow) {
207 llvm::Triple TargetTriple(M.getTargetTriple());
208 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
209 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
210 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
211 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
212 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
213 TargetTriple.getArch() == llvm::Triple::mipsel;
215 ShadowMapping Mapping;
217 // OR-ing shadow offset if more efficient (at least on x86),
218 // but on ppc64 we have to use add since the shadow offset is not neccesary
219 // 1/8-th of the address space.
220 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
222 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
224 (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
225 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
226 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
227 assert(LongSize == 64);
228 Mapping.Offset = kDefaultShort64bitShadowOffset;
230 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
231 // Zero offset log is the special case.
232 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
235 Mapping.Scale = kDefaultShadowScale;
236 if (ClMappingScale) {
237 Mapping.Scale = ClMappingScale;
243 static size_t RedzoneSizeForScale(int MappingScale) {
244 // Redzone used for stack and globals is at least 32 bytes.
245 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
246 return std::max(32U, 1U << MappingScale);
249 /// AddressSanitizer: instrument the code in module to find memory bugs.
250 struct AddressSanitizer : public FunctionPass {
251 AddressSanitizer(bool CheckInitOrder = true,
252 bool CheckUseAfterReturn = false,
253 bool CheckLifetime = false,
254 StringRef BlacklistFile = StringRef(),
255 bool ZeroBaseShadow = false)
257 CheckInitOrder(CheckInitOrder || ClInitializers),
258 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
259 CheckLifetime(CheckLifetime || ClCheckLifetime),
260 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
262 ZeroBaseShadow(ZeroBaseShadow) {}
263 virtual const char *getPassName() const {
264 return "AddressSanitizerFunctionPass";
266 void instrumentMop(Instruction *I);
267 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
268 Value *Addr, uint32_t TypeSize, bool IsWrite,
269 Value *SizeArgument);
270 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
271 Value *ShadowValue, uint32_t TypeSize);
272 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
273 bool IsWrite, size_t AccessSizeIndex,
274 Value *SizeArgument);
275 bool instrumentMemIntrinsic(MemIntrinsic *MI);
276 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
278 Instruction *InsertBefore, bool IsWrite);
279 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
280 bool runOnFunction(Function &F);
281 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
282 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
283 virtual bool doInitialization(Module &M);
284 static char ID; // Pass identification, replacement for typeid
287 void initializeCallbacks(Module &M);
289 bool ShouldInstrumentGlobal(GlobalVariable *G);
290 bool LooksLikeCodeInBug11395(Instruction *I);
291 void FindDynamicInitializers(Module &M);
294 bool CheckUseAfterReturn;
296 SmallString<64> BlacklistFile;
303 ShadowMapping Mapping;
304 Function *AsanCtorFunction;
305 Function *AsanInitFunction;
306 Function *AsanHandleNoReturnFunc;
307 OwningPtr<BlackList> BL;
308 // This array is indexed by AccessIsWrite and log2(AccessSize).
309 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
310 // This array is indexed by AccessIsWrite.
311 Function *AsanErrorCallbackSized[2];
313 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
315 friend struct FunctionStackPoisoner;
318 class AddressSanitizerModule : public ModulePass {
320 AddressSanitizerModule(bool CheckInitOrder = true,
321 StringRef BlacklistFile = StringRef(),
322 bool ZeroBaseShadow = false)
324 CheckInitOrder(CheckInitOrder || ClInitializers),
325 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
327 ZeroBaseShadow(ZeroBaseShadow) {}
328 bool runOnModule(Module &M);
329 static char ID; // Pass identification, replacement for typeid
330 virtual const char *getPassName() const {
331 return "AddressSanitizerModule";
335 void initializeCallbacks(Module &M);
337 bool ShouldInstrumentGlobal(GlobalVariable *G);
338 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
339 size_t RedzoneSize() const {
340 return RedzoneSizeForScale(Mapping.Scale);
344 SmallString<64> BlacklistFile;
347 OwningPtr<BlackList> BL;
348 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
352 ShadowMapping Mapping;
353 Function *AsanPoisonGlobals;
354 Function *AsanUnpoisonGlobals;
355 Function *AsanRegisterGlobals;
356 Function *AsanUnregisterGlobals;
359 // Stack poisoning does not play well with exception handling.
360 // When an exception is thrown, we essentially bypass the code
361 // that unpoisones the stack. This is why the run-time library has
362 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
363 // stack in the interceptor. This however does not work inside the
364 // actual function which catches the exception. Most likely because the
365 // compiler hoists the load of the shadow value somewhere too high.
366 // This causes asan to report a non-existing bug on 453.povray.
367 // It sounds like an LLVM bug.
368 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
370 AddressSanitizer &ASan;
375 ShadowMapping Mapping;
377 SmallVector<AllocaInst*, 16> AllocaVec;
378 SmallVector<Instruction*, 8> RetVec;
379 uint64_t TotalStackSize;
380 unsigned StackAlignment;
382 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
383 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
385 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
386 struct AllocaPoisonCall {
387 IntrinsicInst *InsBefore;
391 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
393 // Maps Value to an AllocaInst from which the Value is originated.
394 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
395 AllocaForValueMapTy AllocaForValue;
397 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
398 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
399 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
400 Mapping(ASan.Mapping),
401 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
403 bool runOnFunction() {
404 if (!ClStack) return false;
405 // Collect alloca, ret, lifetime instructions etc.
406 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
407 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
408 BasicBlock *BB = *DI;
411 if (AllocaVec.empty()) return false;
413 initializeCallbacks(*F.getParent());
423 // Finds all static Alloca instructions and puts
424 // poisoned red zones around all of them.
425 // Then unpoison everything back before the function returns.
428 // ----------------------- Visitors.
429 /// \brief Collect all Ret instructions.
430 void visitReturnInst(ReturnInst &RI) {
431 RetVec.push_back(&RI);
434 /// \brief Collect Alloca instructions we want (and can) handle.
435 void visitAllocaInst(AllocaInst &AI) {
436 if (!isInterestingAlloca(AI)) return;
438 StackAlignment = std::max(StackAlignment, AI.getAlignment());
439 AllocaVec.push_back(&AI);
440 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
441 TotalStackSize += AlignedSize;
444 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
446 void visitIntrinsicInst(IntrinsicInst &II) {
447 if (!ASan.CheckLifetime) return;
448 Intrinsic::ID ID = II.getIntrinsicID();
449 if (ID != Intrinsic::lifetime_start &&
450 ID != Intrinsic::lifetime_end)
452 // Found lifetime intrinsic, add ASan instrumentation if necessary.
453 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
454 // If size argument is undefined, don't do anything.
455 if (Size->isMinusOne()) return;
456 // Check that size doesn't saturate uint64_t and can
457 // be stored in IntptrTy.
458 const uint64_t SizeValue = Size->getValue().getLimitedValue();
459 if (SizeValue == ~0ULL ||
460 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
462 // Find alloca instruction that corresponds to llvm.lifetime argument.
463 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
465 bool DoPoison = (ID == Intrinsic::lifetime_end);
466 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
467 AllocaPoisonCallVec.push_back(APC);
470 // ---------------------- Helpers.
471 void initializeCallbacks(Module &M);
473 // Check if we want (and can) handle this alloca.
474 bool isInterestingAlloca(AllocaInst &AI) {
475 return (!AI.isArrayAllocation() &&
476 AI.isStaticAlloca() &&
477 AI.getAllocatedType()->isSized());
480 size_t RedzoneSize() const {
481 return RedzoneSizeForScale(Mapping.Scale);
483 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
484 Type *Ty = AI->getAllocatedType();
485 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
488 uint64_t getAlignedSize(uint64_t SizeInBytes) {
489 size_t RZ = RedzoneSize();
490 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
492 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
493 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
494 return getAlignedSize(SizeInBytes);
496 /// Finds alloca where the value comes from.
497 AllocaInst *findAllocaForValue(Value *V);
498 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
499 Value *ShadowBase, bool DoPoison);
500 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
505 char AddressSanitizer::ID = 0;
506 INITIALIZE_PASS(AddressSanitizer, "asan",
507 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
509 FunctionPass *llvm::createAddressSanitizerFunctionPass(
510 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
511 StringRef BlacklistFile, bool ZeroBaseShadow) {
512 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
513 CheckLifetime, BlacklistFile, ZeroBaseShadow);
516 char AddressSanitizerModule::ID = 0;
517 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
518 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
519 "ModulePass", false, false)
520 ModulePass *llvm::createAddressSanitizerModulePass(
521 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
522 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
526 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
527 size_t Res = countTrailingZeros(TypeSize / 8);
528 assert(Res < kNumberOfAccessSizes);
532 // Create a constant for Str so that we can pass it to the run-time lib.
533 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
534 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
535 GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
536 GlobalValue::PrivateLinkage, StrConst,
538 GV->setUnnamedAddr(true); // Ok to merge these.
539 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
543 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
544 return G->getName().find(kAsanGenPrefix) == 0;
547 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
549 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
550 if (Mapping.Offset == 0)
552 // (Shadow >> scale) | offset
553 if (Mapping.OrShadowOffset)
554 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
556 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
559 void AddressSanitizer::instrumentMemIntrinsicParam(
560 Instruction *OrigIns,
561 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
562 IRBuilder<> IRB(InsertBefore);
563 if (Size->getType() != IntptrTy)
564 Size = IRB.CreateIntCast(Size, IntptrTy, false);
565 // Check the first byte.
566 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
567 // Check the last byte.
568 IRB.SetInsertPoint(InsertBefore);
569 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
570 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
571 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
572 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
575 // Instrument memset/memmove/memcpy
576 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
577 Value *Dst = MI->getDest();
578 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
579 Value *Src = MemTran ? MemTran->getSource() : 0;
580 Value *Length = MI->getLength();
582 Constant *ConstLength = dyn_cast<Constant>(Length);
583 Instruction *InsertBefore = MI;
585 if (ConstLength->isNullValue()) return false;
587 // The size is not a constant so it could be zero -- check at run-time.
588 IRBuilder<> IRB(InsertBefore);
590 Value *Cmp = IRB.CreateICmpNE(Length,
591 Constant::getNullValue(Length->getType()));
592 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
595 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
597 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
601 // If I is an interesting memory access, return the PointerOperand
602 // and set IsWrite. Otherwise return NULL.
603 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
604 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
605 if (!ClInstrumentReads) return NULL;
607 return LI->getPointerOperand();
609 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
610 if (!ClInstrumentWrites) return NULL;
612 return SI->getPointerOperand();
614 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
615 if (!ClInstrumentAtomics) return NULL;
617 return RMW->getPointerOperand();
619 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
620 if (!ClInstrumentAtomics) return NULL;
622 return XCHG->getPointerOperand();
627 void AddressSanitizer::instrumentMop(Instruction *I) {
628 bool IsWrite = false;
629 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
631 if (ClOpt && ClOptGlobals) {
632 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
633 // If initialization order checking is disabled, a simple access to a
634 // dynamically initialized global is always valid.
637 // If a global variable does not have dynamic initialization we don't
638 // have to instrument it. However, if a global does not have initailizer
639 // at all, we assume it has dynamic initializer (in other TU).
640 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
645 Type *OrigPtrTy = Addr->getType();
646 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
648 assert(OrigTy->isSized());
649 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
651 assert((TypeSize % 8) == 0);
653 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
654 if (TypeSize == 8 || TypeSize == 16 ||
655 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
656 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
657 // Instrument unusual size (but still multiple of 8).
658 // We can not do it with a single check, so we do 1-byte check for the first
659 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
660 // to report the actual access size.
662 Value *LastByte = IRB.CreateIntToPtr(
663 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
664 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
666 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
667 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
668 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
671 // Validate the result of Module::getOrInsertFunction called for an interface
672 // function of AddressSanitizer. If the instrumented module defines a function
673 // with the same name, their prototypes must match, otherwise
674 // getOrInsertFunction returns a bitcast.
675 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
676 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
677 FuncOrBitcast->dump();
678 report_fatal_error("trying to redefine an AddressSanitizer "
679 "interface function");
682 Instruction *AddressSanitizer::generateCrashCode(
683 Instruction *InsertBefore, Value *Addr,
684 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
685 IRBuilder<> IRB(InsertBefore);
686 CallInst *Call = SizeArgument
687 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
688 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
690 // We don't do Call->setDoesNotReturn() because the BB already has
691 // UnreachableInst at the end.
692 // This EmptyAsm is required to avoid callback merge.
693 IRB.CreateCall(EmptyAsm);
697 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
700 size_t Granularity = 1 << Mapping.Scale;
701 // Addr & (Granularity - 1)
702 Value *LastAccessedByte = IRB.CreateAnd(
703 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
704 // (Addr & (Granularity - 1)) + size - 1
705 if (TypeSize / 8 > 1)
706 LastAccessedByte = IRB.CreateAdd(
707 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
708 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
709 LastAccessedByte = IRB.CreateIntCast(
710 LastAccessedByte, ShadowValue->getType(), false);
711 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
712 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
715 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
716 Instruction *InsertBefore,
717 Value *Addr, uint32_t TypeSize,
718 bool IsWrite, Value *SizeArgument) {
719 IRBuilder<> IRB(InsertBefore);
720 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
722 Type *ShadowTy = IntegerType::get(
723 *C, std::max(8U, TypeSize >> Mapping.Scale));
724 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
725 Value *ShadowPtr = memToShadow(AddrLong, IRB);
726 Value *CmpVal = Constant::getNullValue(ShadowTy);
727 Value *ShadowValue = IRB.CreateLoad(
728 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
730 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
731 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
732 size_t Granularity = 1 << Mapping.Scale;
733 TerminatorInst *CrashTerm = 0;
735 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
736 TerminatorInst *CheckTerm =
737 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
738 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
739 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
740 IRB.SetInsertPoint(CheckTerm);
741 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
742 BasicBlock *CrashBlock =
743 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
744 CrashTerm = new UnreachableInst(*C, CrashBlock);
745 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
746 ReplaceInstWithInst(CheckTerm, NewTerm);
748 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
751 Instruction *Crash = generateCrashCode(
752 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
753 Crash->setDebugLoc(OrigIns->getDebugLoc());
756 void AddressSanitizerModule::createInitializerPoisonCalls(
757 Module &M, GlobalValue *ModuleName) {
758 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
759 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
760 // If that function is not present, this TU contains no globals, or they have
761 // all been optimized away
765 // Set up the arguments to our poison/unpoison functions.
766 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
768 // Add a call to poison all external globals before the given function starts.
769 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
770 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
772 // Add calls to unpoison all globals before each return instruction.
773 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
775 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
776 CallInst::Create(AsanUnpoisonGlobals, "", RI);
781 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
782 Type *Ty = cast<PointerType>(G->getType())->getElementType();
783 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
785 if (BL->isIn(*G)) return false;
786 if (!Ty->isSized()) return false;
787 if (!G->hasInitializer()) return false;
788 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
789 // Touch only those globals that will not be defined in other modules.
790 // Don't handle ODR type linkages since other modules may be built w/o asan.
791 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
792 G->getLinkage() != GlobalVariable::PrivateLinkage &&
793 G->getLinkage() != GlobalVariable::InternalLinkage)
795 // Two problems with thread-locals:
796 // - The address of the main thread's copy can't be computed at link-time.
797 // - Need to poison all copies, not just the main thread's one.
798 if (G->isThreadLocal())
800 // For now, just ignore this Alloca if the alignment is large.
801 if (G->getAlignment() > RedzoneSize()) return false;
803 // Ignore all the globals with the names starting with "\01L_OBJC_".
804 // Many of those are put into the .cstring section. The linker compresses
805 // that section by removing the spare \0s after the string terminator, so
806 // our redzones get broken.
807 if ((G->getName().find("\01L_OBJC_") == 0) ||
808 (G->getName().find("\01l_OBJC_") == 0)) {
809 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
813 if (G->hasSection()) {
814 StringRef Section(G->getSection());
815 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
816 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
818 if ((Section.find("__OBJC,") == 0) ||
819 (Section.find("__DATA, __objc_") == 0)) {
820 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
823 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
824 // Constant CFString instances are compiled in the following way:
825 // -- the string buffer is emitted into
826 // __TEXT,__cstring,cstring_literals
827 // -- the constant NSConstantString structure referencing that buffer
828 // is placed into __DATA,__cfstring
829 // Therefore there's no point in placing redzones into __DATA,__cfstring.
830 // Moreover, it causes the linker to crash on OS X 10.7
831 if (Section.find("__DATA,__cfstring") == 0) {
832 DEBUG(dbgs() << "Ignoring CFString: " << *G);
840 void AddressSanitizerModule::initializeCallbacks(Module &M) {
842 // Declare our poisoning and unpoisoning functions.
843 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
844 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
845 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
846 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
847 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
848 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
849 // Declare functions that register/unregister globals.
850 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
851 kAsanRegisterGlobalsName, IRB.getVoidTy(),
852 IntptrTy, IntptrTy, NULL));
853 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
854 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
855 kAsanUnregisterGlobalsName,
856 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
857 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
860 // This function replaces all global variables with new variables that have
861 // trailing redzones. It also creates a function that poisons
862 // redzones and inserts this function into llvm.global_ctors.
863 bool AddressSanitizerModule::runOnModule(Module &M) {
864 if (!ClGlobals) return false;
865 TD = getAnalysisIfAvailable<DataLayout>();
868 BL.reset(new BlackList(BlacklistFile));
869 if (BL->isIn(M)) return false;
870 C = &(M.getContext());
871 int LongSize = TD->getPointerSizeInBits();
872 IntptrTy = Type::getIntNTy(*C, LongSize);
873 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
874 initializeCallbacks(M);
875 DynamicallyInitializedGlobals.Init(M);
877 SmallVector<GlobalVariable *, 16> GlobalsToChange;
879 for (Module::GlobalListType::iterator G = M.global_begin(),
880 E = M.global_end(); G != E; ++G) {
881 if (ShouldInstrumentGlobal(G))
882 GlobalsToChange.push_back(G);
885 size_t n = GlobalsToChange.size();
886 if (n == 0) return false;
888 // A global is described by a structure
891 // size_t size_with_redzone;
893 // const char *module_name;
894 // size_t has_dynamic_init;
895 // We initialize an array of such structures and pass it to a run-time call.
896 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
898 IntptrTy, IntptrTy, NULL);
899 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
902 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
904 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
906 bool HasDynamicallyInitializedGlobals = false;
908 GlobalVariable *ModuleName = createPrivateGlobalForString(
909 M, M.getModuleIdentifier());
910 // We shouldn't merge same module names, as this string serves as unique
911 // module ID in runtime.
912 ModuleName->setUnnamedAddr(false);
914 for (size_t i = 0; i < n; i++) {
915 static const uint64_t kMaxGlobalRedzone = 1 << 18;
916 GlobalVariable *G = GlobalsToChange[i];
917 PointerType *PtrTy = cast<PointerType>(G->getType());
918 Type *Ty = PtrTy->getElementType();
919 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
920 uint64_t MinRZ = RedzoneSize();
921 // MinRZ <= RZ <= kMaxGlobalRedzone
922 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
923 uint64_t RZ = std::max(MinRZ,
924 std::min(kMaxGlobalRedzone,
925 (SizeInBytes / MinRZ / 4) * MinRZ));
926 uint64_t RightRedzoneSize = RZ;
928 if (SizeInBytes % MinRZ)
929 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
930 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
931 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
932 // Determine whether this global should be poisoned in initialization.
933 bool GlobalHasDynamicInitializer =
934 DynamicallyInitializedGlobals.Contains(G);
935 // Don't check initialization order if this global is blacklisted.
936 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
938 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
939 Constant *NewInitializer = ConstantStruct::get(
940 NewTy, G->getInitializer(),
941 Constant::getNullValue(RightRedZoneTy), NULL);
943 GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
945 // Create a new global variable with enough space for a redzone.
946 GlobalVariable *NewGlobal = new GlobalVariable(
947 M, NewTy, G->isConstant(), G->getLinkage(),
948 NewInitializer, "", G, G->getThreadLocalMode());
949 NewGlobal->copyAttributesFrom(G);
950 NewGlobal->setAlignment(MinRZ);
953 Indices2[0] = IRB.getInt32(0);
954 Indices2[1] = IRB.getInt32(0);
956 G->replaceAllUsesWith(
957 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
958 NewGlobal->takeName(G);
959 G->eraseFromParent();
961 Initializers[i] = ConstantStruct::get(
963 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
964 ConstantInt::get(IntptrTy, SizeInBytes),
965 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
966 ConstantExpr::getPointerCast(Name, IntptrTy),
967 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
968 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
971 // Populate the first and last globals declared in this TU.
972 if (CheckInitOrder && GlobalHasDynamicInitializer)
973 HasDynamicallyInitializedGlobals = true;
975 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
978 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
979 GlobalVariable *AllGlobals = new GlobalVariable(
980 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
981 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
983 // Create calls for poisoning before initializers run and unpoisoning after.
984 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
985 createInitializerPoisonCalls(M, ModuleName);
986 IRB.CreateCall2(AsanRegisterGlobals,
987 IRB.CreatePointerCast(AllGlobals, IntptrTy),
988 ConstantInt::get(IntptrTy, n));
990 // We also need to unregister globals at the end, e.g. when a shared library
992 Function *AsanDtorFunction = Function::Create(
993 FunctionType::get(Type::getVoidTy(*C), false),
994 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
995 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
996 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
997 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
998 IRB.CreatePointerCast(AllGlobals, IntptrTy),
999 ConstantInt::get(IntptrTy, n));
1000 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1006 void AddressSanitizer::initializeCallbacks(Module &M) {
1007 IRBuilder<> IRB(*C);
1008 // Create __asan_report* callbacks.
1009 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1010 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1011 AccessSizeIndex++) {
1012 // IsWrite and TypeSize are encoded in the function name.
1013 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1014 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1015 // If we are merging crash callbacks, they have two parameters.
1016 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1017 checkInterfaceFunction(M.getOrInsertFunction(
1018 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1021 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1022 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1023 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1024 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1026 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1027 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1028 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1029 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1030 StringRef(""), StringRef(""),
1031 /*hasSideEffects=*/true);
1034 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1035 // Tell the values of mapping offset and scale to the run-time.
1036 GlobalValue *asan_mapping_offset =
1037 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1038 ConstantInt::get(IntptrTy, Mapping.Offset),
1039 kAsanMappingOffsetName);
1040 // Read the global, otherwise it may be optimized away.
1041 IRB.CreateLoad(asan_mapping_offset, true);
1043 GlobalValue *asan_mapping_scale =
1044 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1045 ConstantInt::get(IntptrTy, Mapping.Scale),
1046 kAsanMappingScaleName);
1047 // Read the global, otherwise it may be optimized away.
1048 IRB.CreateLoad(asan_mapping_scale, true);
1052 bool AddressSanitizer::doInitialization(Module &M) {
1053 // Initialize the private fields. No one has accessed them before.
1054 TD = getAnalysisIfAvailable<DataLayout>();
1058 BL.reset(new BlackList(BlacklistFile));
1059 DynamicallyInitializedGlobals.Init(M);
1061 C = &(M.getContext());
1062 LongSize = TD->getPointerSizeInBits();
1063 IntptrTy = Type::getIntNTy(*C, LongSize);
1065 AsanCtorFunction = Function::Create(
1066 FunctionType::get(Type::getVoidTy(*C), false),
1067 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1068 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1069 // call __asan_init in the module ctor.
1070 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1071 AsanInitFunction = checkInterfaceFunction(
1072 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1073 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1074 IRB.CreateCall(AsanInitFunction);
1076 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1077 emitShadowMapping(M, IRB);
1079 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1083 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1084 // For each NSObject descendant having a +load method, this method is invoked
1085 // by the ObjC runtime before any of the static constructors is called.
1086 // Therefore we need to instrument such methods with a call to __asan_init
1087 // at the beginning in order to initialize our runtime before any access to
1088 // the shadow memory.
1089 // We cannot just ignore these methods, because they may call other
1090 // instrumented functions.
1091 if (F.getName().find(" load]") != std::string::npos) {
1092 IRBuilder<> IRB(F.begin()->begin());
1093 IRB.CreateCall(AsanInitFunction);
1099 bool AddressSanitizer::runOnFunction(Function &F) {
1100 if (BL->isIn(F)) return false;
1101 if (&F == AsanCtorFunction) return false;
1102 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1103 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1104 initializeCallbacks(*F.getParent());
1106 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1107 maybeInsertAsanInitAtFunctionEntry(F);
1109 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1110 Attribute::SanitizeAddress))
1113 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1116 // We want to instrument every address only once per basic block (unless there
1117 // are calls between uses).
1118 SmallSet<Value*, 16> TempsToInstrument;
1119 SmallVector<Instruction*, 16> ToInstrument;
1120 SmallVector<Instruction*, 8> NoReturnCalls;
1123 // Fill the set of memory operations to instrument.
1124 for (Function::iterator FI = F.begin(), FE = F.end();
1126 TempsToInstrument.clear();
1127 int NumInsnsPerBB = 0;
1128 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1130 if (LooksLikeCodeInBug11395(BI)) return false;
1131 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1132 if (ClOpt && ClOptSameTemp) {
1133 if (!TempsToInstrument.insert(Addr))
1134 continue; // We've seen this temp in the current BB.
1136 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1141 // A call inside BB.
1142 TempsToInstrument.clear();
1143 if (CS.doesNotReturn())
1144 NoReturnCalls.push_back(CS.getInstruction());
1148 ToInstrument.push_back(BI);
1150 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1156 int NumInstrumented = 0;
1157 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1158 Instruction *Inst = ToInstrument[i];
1159 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1160 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1161 if (isInterestingMemoryAccess(Inst, &IsWrite))
1162 instrumentMop(Inst);
1164 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1169 FunctionStackPoisoner FSP(F, *this);
1170 bool ChangedStack = FSP.runOnFunction();
1172 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1173 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1174 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1175 Instruction *CI = NoReturnCalls[i];
1176 IRBuilder<> IRB(CI);
1177 IRB.CreateCall(AsanHandleNoReturnFunc);
1179 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1181 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1184 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1185 if (ShadowRedzoneSize == 1) return PoisonByte;
1186 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1187 if (ShadowRedzoneSize == 4)
1188 return (PoisonByte << 24) + (PoisonByte << 16) +
1189 (PoisonByte << 8) + (PoisonByte);
1190 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1193 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1196 size_t ShadowGranularity,
1198 for (size_t i = 0; i < RZSize;
1199 i+= ShadowGranularity, Shadow++) {
1200 if (i + ShadowGranularity <= Size) {
1201 *Shadow = 0; // fully addressable
1202 } else if (i >= Size) {
1203 *Shadow = Magic; // unaddressable
1205 *Shadow = Size - i; // first Size-i bytes are addressable
1210 // Workaround for bug 11395: we don't want to instrument stack in functions
1211 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1212 // FIXME: remove once the bug 11395 is fixed.
1213 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1214 if (LongSize != 32) return false;
1215 CallInst *CI = dyn_cast<CallInst>(I);
1216 if (!CI || !CI->isInlineAsm()) return false;
1217 if (CI->getNumArgOperands() <= 5) return false;
1218 // We have inline assembly with quite a few arguments.
1222 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1223 IRBuilder<> IRB(*C);
1224 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1225 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1226 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1227 kAsanStackFreeName, IRB.getVoidTy(),
1228 IntptrTy, IntptrTy, IntptrTy, NULL));
1229 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1230 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1231 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1232 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1235 void FunctionStackPoisoner::poisonRedZones(
1236 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1238 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1239 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1240 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1241 Type *RZPtrTy = PointerType::get(RZTy, 0);
1243 Value *PoisonLeft = ConstantInt::get(RZTy,
1244 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1245 Value *PoisonMid = ConstantInt::get(RZTy,
1246 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1247 Value *PoisonRight = ConstantInt::get(RZTy,
1248 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1250 // poison the first red zone.
1251 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1253 // poison all other red zones.
1254 uint64_t Pos = RedzoneSize();
1255 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1256 AllocaInst *AI = AllocaVec[i];
1257 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1258 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1259 assert(AlignedSize - SizeInBytes < RedzoneSize());
1264 assert(ShadowBase->getType() == IntptrTy);
1265 if (SizeInBytes < AlignedSize) {
1266 // Poison the partial redzone at right
1267 Ptr = IRB.CreateAdd(
1268 ShadowBase, ConstantInt::get(IntptrTy,
1269 (Pos >> Mapping.Scale) - ShadowRZSize));
1270 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1271 uint32_t Poison = 0;
1273 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1275 1ULL << Mapping.Scale,
1276 kAsanStackPartialRedzoneMagic);
1278 ASan.TD->isLittleEndian()
1279 ? support::endian::byte_swap<uint32_t, support::little>(Poison)
1280 : support::endian::byte_swap<uint32_t, support::big>(Poison);
1282 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1283 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1286 // Poison the full redzone at right.
1287 Ptr = IRB.CreateAdd(ShadowBase,
1288 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1289 bool LastAlloca = (i == AllocaVec.size() - 1);
1290 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1291 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1293 Pos += RedzoneSize();
1297 void FunctionStackPoisoner::poisonStack() {
1298 uint64_t LocalStackSize = TotalStackSize +
1299 (AllocaVec.size() + 1) * RedzoneSize();
1301 bool DoStackMalloc = ASan.CheckUseAfterReturn
1302 && LocalStackSize <= kMaxStackMallocSize;
1304 assert(AllocaVec.size() > 0);
1305 Instruction *InsBefore = AllocaVec[0];
1306 IRBuilder<> IRB(InsBefore);
1309 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1310 AllocaInst *MyAlloca =
1311 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1312 if (ClRealignStack && StackAlignment < RedzoneSize())
1313 StackAlignment = RedzoneSize();
1314 MyAlloca->setAlignment(StackAlignment);
1315 assert(MyAlloca->isStaticAlloca());
1316 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1317 Value *LocalStackBase = OrigStackBase;
1319 if (DoStackMalloc) {
1320 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1321 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1324 // This string will be parsed by the run-time (DescribeAddressIfStack).
1325 SmallString<2048> StackDescriptionStorage;
1326 raw_svector_ostream StackDescription(StackDescriptionStorage);
1327 StackDescription << AllocaVec.size() << " ";
1329 // Insert poison calls for lifetime intrinsics for alloca.
1330 bool HavePoisonedAllocas = false;
1331 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1332 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1333 IntrinsicInst *II = APC.InsBefore;
1334 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1336 IRBuilder<> IRB(II);
1337 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1338 HavePoisonedAllocas |= APC.DoPoison;
1341 uint64_t Pos = RedzoneSize();
1342 // Replace Alloca instructions with base+offset.
1343 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1344 AllocaInst *AI = AllocaVec[i];
1345 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1346 StringRef Name = AI->getName();
1347 StackDescription << Pos << " " << SizeInBytes << " "
1348 << Name.size() << " " << Name << " ";
1349 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1350 assert((AlignedSize % RedzoneSize()) == 0);
1351 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1352 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1354 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1355 AI->replaceAllUsesWith(NewAllocaPtr);
1356 Pos += AlignedSize + RedzoneSize();
1358 assert(Pos == LocalStackSize);
1360 // The left-most redzone has enough space for at least 4 pointers.
1361 // Write the Magic value to redzone[0].
1362 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1363 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1365 // Write the frame description constant to redzone[1].
1366 Value *BasePlus1 = IRB.CreateIntToPtr(
1367 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1369 GlobalVariable *StackDescriptionGlobal =
1370 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1371 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1373 IRB.CreateStore(Description, BasePlus1);
1374 // Write the PC to redzone[2].
1375 Value *BasePlus2 = IRB.CreateIntToPtr(
1376 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1377 2 * ASan.LongSize/8)),
1379 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1381 // Poison the stack redzones at the entry.
1382 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1383 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1385 // Unpoison the stack before all ret instructions.
1386 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1387 Instruction *Ret = RetVec[i];
1388 IRBuilder<> IRBRet(Ret);
1389 // Mark the current frame as retired.
1390 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1392 // Unpoison the stack.
1393 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1394 if (DoStackMalloc) {
1395 // In use-after-return mode, mark the whole stack frame unaddressable.
1396 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1397 ConstantInt::get(IntptrTy, LocalStackSize),
1399 } else if (HavePoisonedAllocas) {
1400 // If we poisoned some allocas in llvm.lifetime analysis,
1401 // unpoison whole stack frame now.
1402 assert(LocalStackBase == OrigStackBase);
1403 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1407 // We are done. Remove the old unused alloca instructions.
1408 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1409 AllocaVec[i]->eraseFromParent();
1412 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1413 IRBuilder<> IRB, bool DoPoison) {
1414 // For now just insert the call to ASan runtime.
1415 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1416 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1417 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1418 : AsanUnpoisonStackMemoryFunc,
1422 // Handling llvm.lifetime intrinsics for a given %alloca:
1423 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1424 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1425 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1426 // could be poisoned by previous llvm.lifetime.end instruction, as the
1427 // variable may go in and out of scope several times, e.g. in loops).
1428 // (3) if we poisoned at least one %alloca in a function,
1429 // unpoison the whole stack frame at function exit.
1431 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1432 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1433 // We're intested only in allocas we can handle.
1434 return isInterestingAlloca(*AI) ? AI : 0;
1435 // See if we've already calculated (or started to calculate) alloca for a
1437 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1438 if (I != AllocaForValue.end())
1440 // Store 0 while we're calculating alloca for value V to avoid
1441 // infinite recursion if the value references itself.
1442 AllocaForValue[V] = 0;
1443 AllocaInst *Res = 0;
1444 if (CastInst *CI = dyn_cast<CastInst>(V))
1445 Res = findAllocaForValue(CI->getOperand(0));
1446 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1447 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1448 Value *IncValue = PN->getIncomingValue(i);
1449 // Allow self-referencing phi-nodes.
1450 if (IncValue == PN) continue;
1451 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1452 // AI for incoming values should exist and should all be equal.
1453 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1459 AllocaForValue[V] = Res;