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/raw_ostream.h"
43 #include "llvm/Support/system_error.h"
44 #include "llvm/Target/TargetMachine.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;
60 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
61 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
62 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
64 static const char *kAsanModuleCtorName = "asan.module_ctor";
65 static const char *kAsanModuleDtorName = "asan.module_dtor";
66 static const int kAsanCtorAndCtorPriority = 1;
67 static const char *kAsanReportErrorTemplate = "__asan_report_";
68 static const char *kAsanReportLoadN = "__asan_report_load_n";
69 static const char *kAsanReportStoreN = "__asan_report_store_n";
70 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
71 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
72 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
73 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
74 static const char *kAsanInitName = "__asan_init_v2";
75 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
76 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
77 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
78 static const char *kAsanStackMallocName = "__asan_stack_malloc";
79 static const char *kAsanStackFreeName = "__asan_stack_free";
80 static const char *kAsanGenPrefix = "__asan_gen_";
81 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
82 static const char *kAsanUnpoisonStackMemoryName =
83 "__asan_unpoison_stack_memory";
85 static const int kAsanStackLeftRedzoneMagic = 0xf1;
86 static const int kAsanStackMidRedzoneMagic = 0xf2;
87 static const int kAsanStackRightRedzoneMagic = 0xf3;
88 static const int kAsanStackPartialRedzoneMagic = 0xf4;
90 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
91 static const size_t kNumberOfAccessSizes = 5;
93 // Command-line flags.
95 // This flag may need to be replaced with -f[no-]asan-reads.
96 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
97 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
98 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
99 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
100 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
101 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
102 cl::Hidden, cl::init(true));
103 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
104 cl::desc("use instrumentation with slow path for all accesses"),
105 cl::Hidden, cl::init(false));
106 // This flag limits the number of instructions to be instrumented
107 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
108 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
110 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
112 cl::desc("maximal number of instructions to instrument in any given BB"),
114 // This flag may need to be replaced with -f[no]asan-stack.
115 static cl::opt<bool> ClStack("asan-stack",
116 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
117 // This flag may need to be replaced with -f[no]asan-use-after-return.
118 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
119 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
120 // This flag may need to be replaced with -f[no]asan-globals.
121 static cl::opt<bool> ClGlobals("asan-globals",
122 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClInitializers("asan-initialization-order",
124 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
125 static cl::opt<bool> ClMemIntrin("asan-memintrin",
126 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
127 static cl::opt<bool> ClRealignStack("asan-realign-stack",
128 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
129 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
130 cl::desc("File containing the list of objects to ignore "
131 "during instrumentation"), cl::Hidden);
133 // These flags allow to change the shadow mapping.
134 // The shadow mapping looks like
135 // Shadow = (Mem >> scale) + (1 << offset_log)
136 static cl::opt<int> ClMappingScale("asan-mapping-scale",
137 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
138 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
139 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
140 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
141 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
142 cl::Hidden, cl::init(true));
144 // Optimization flags. Not user visible, used mostly for testing
145 // and benchmarking the tool.
146 static cl::opt<bool> ClOpt("asan-opt",
147 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
148 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
149 cl::desc("Instrument the same temp just once"), cl::Hidden,
151 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
152 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
154 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
155 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
156 cl::Hidden, cl::init(false));
159 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
161 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
162 cl::Hidden, cl::init(0));
163 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
164 cl::Hidden, cl::desc("Debug func"));
165 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
166 cl::Hidden, cl::init(-1));
167 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
168 cl::Hidden, cl::init(-1));
171 /// A set of dynamically initialized globals extracted from metadata.
172 class SetOfDynamicallyInitializedGlobals {
174 void Init(Module& M) {
175 // Clang generates metadata identifying all dynamically initialized globals.
176 NamedMDNode *DynamicGlobals =
177 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
180 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
181 MDNode *MDN = DynamicGlobals->getOperand(i);
182 assert(MDN->getNumOperands() == 1);
183 Value *VG = MDN->getOperand(0);
184 // The optimizer may optimize away a global entirely, in which case we
185 // cannot instrument access to it.
188 DynInitGlobals.insert(cast<GlobalVariable>(VG));
191 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
193 SmallSet<GlobalValue*, 32> DynInitGlobals;
196 /// This struct defines the shadow mapping using the rule:
197 /// shadow = (mem >> Scale) ADD-or-OR Offset.
198 struct ShadowMapping {
204 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
205 bool ZeroBaseShadow) {
206 llvm::Triple TargetTriple(M.getTargetTriple());
207 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
208 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
209 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
210 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
212 ShadowMapping Mapping;
214 // OR-ing shadow offset if more efficient (at least on x86),
215 // but on ppc64 we have to use add since the shadow offset is not neccesary
216 // 1/8-th of the address space.
217 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
219 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
220 (LongSize == 32 ? kDefaultShadowOffset32 :
221 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
222 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
223 assert(LongSize == 64);
224 Mapping.Offset = kDefaultShort64bitShadowOffset;
226 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
227 // Zero offset log is the special case.
228 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
231 Mapping.Scale = kDefaultShadowScale;
232 if (ClMappingScale) {
233 Mapping.Scale = ClMappingScale;
239 static size_t RedzoneSizeForScale(int MappingScale) {
240 // Redzone used for stack and globals is at least 32 bytes.
241 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
242 return std::max(32U, 1U << MappingScale);
245 /// AddressSanitizer: instrument the code in module to find memory bugs.
246 struct AddressSanitizer : public FunctionPass {
247 AddressSanitizer(bool CheckInitOrder = true,
248 bool CheckUseAfterReturn = false,
249 bool CheckLifetime = false,
250 StringRef BlacklistFile = StringRef(),
251 bool ZeroBaseShadow = false)
253 CheckInitOrder(CheckInitOrder || ClInitializers),
254 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
255 CheckLifetime(CheckLifetime || ClCheckLifetime),
256 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
258 ZeroBaseShadow(ZeroBaseShadow) {}
259 virtual const char *getPassName() const {
260 return "AddressSanitizerFunctionPass";
262 void instrumentMop(Instruction *I);
263 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
264 Value *Addr, uint32_t TypeSize, bool IsWrite,
265 Value *SizeArgument);
266 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
267 Value *ShadowValue, uint32_t TypeSize);
268 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
269 bool IsWrite, size_t AccessSizeIndex,
270 Value *SizeArgument);
271 bool instrumentMemIntrinsic(MemIntrinsic *MI);
272 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
274 Instruction *InsertBefore, bool IsWrite);
275 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
276 bool runOnFunction(Function &F);
277 void createInitializerPoisonCalls(Module &M,
278 Value *FirstAddr, Value *LastAddr);
279 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
280 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
281 virtual bool doInitialization(Module &M);
282 static char ID; // Pass identification, replacement for typeid
285 void initializeCallbacks(Module &M);
287 bool ShouldInstrumentGlobal(GlobalVariable *G);
288 bool LooksLikeCodeInBug11395(Instruction *I);
289 void FindDynamicInitializers(Module &M);
292 bool CheckUseAfterReturn;
294 SmallString<64> BlacklistFile;
301 ShadowMapping Mapping;
302 Function *AsanCtorFunction;
303 Function *AsanInitFunction;
304 Function *AsanHandleNoReturnFunc;
305 OwningPtr<BlackList> BL;
306 // This array is indexed by AccessIsWrite and log2(AccessSize).
307 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
308 // This array is indexed by AccessIsWrite.
309 Function *AsanErrorCallbackSized[2];
311 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
313 friend struct FunctionStackPoisoner;
316 class AddressSanitizerModule : public ModulePass {
318 AddressSanitizerModule(bool CheckInitOrder = true,
319 StringRef BlacklistFile = StringRef(),
320 bool ZeroBaseShadow = false)
322 CheckInitOrder(CheckInitOrder || ClInitializers),
323 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
325 ZeroBaseShadow(ZeroBaseShadow) {}
326 bool runOnModule(Module &M);
327 static char ID; // Pass identification, replacement for typeid
328 virtual const char *getPassName() const {
329 return "AddressSanitizerModule";
333 void initializeCallbacks(Module &M);
335 bool ShouldInstrumentGlobal(GlobalVariable *G);
336 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
338 size_t RedzoneSize() const {
339 return RedzoneSizeForScale(Mapping.Scale);
343 SmallString<64> BlacklistFile;
346 OwningPtr<BlackList> BL;
347 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
351 ShadowMapping Mapping;
352 Function *AsanPoisonGlobals;
353 Function *AsanUnpoisonGlobals;
354 Function *AsanRegisterGlobals;
355 Function *AsanUnregisterGlobals;
358 // Stack poisoning does not play well with exception handling.
359 // When an exception is thrown, we essentially bypass the code
360 // that unpoisones the stack. This is why the run-time library has
361 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
362 // stack in the interceptor. This however does not work inside the
363 // actual function which catches the exception. Most likely because the
364 // compiler hoists the load of the shadow value somewhere too high.
365 // This causes asan to report a non-existing bug on 453.povray.
366 // It sounds like an LLVM bug.
367 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
369 AddressSanitizer &ASan;
374 ShadowMapping Mapping;
376 SmallVector<AllocaInst*, 16> AllocaVec;
377 SmallVector<Instruction*, 8> RetVec;
378 uint64_t TotalStackSize;
379 unsigned StackAlignment;
381 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
382 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
384 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
385 struct AllocaPoisonCall {
386 IntrinsicInst *InsBefore;
390 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
392 // Maps Value to an AllocaInst from which the Value is originated.
393 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
394 AllocaForValueMapTy AllocaForValue;
396 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
397 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
398 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
399 Mapping(ASan.Mapping),
400 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
402 bool runOnFunction() {
403 if (!ClStack) return false;
404 // Collect alloca, ret, lifetime instructions etc.
405 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
406 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
407 BasicBlock *BB = *DI;
410 if (AllocaVec.empty()) return false;
412 initializeCallbacks(*F.getParent());
422 // Finds all static Alloca instructions and puts
423 // poisoned red zones around all of them.
424 // Then unpoison everything back before the function returns.
427 // ----------------------- Visitors.
428 /// \brief Collect all Ret instructions.
429 void visitReturnInst(ReturnInst &RI) {
430 RetVec.push_back(&RI);
433 /// \brief Collect Alloca instructions we want (and can) handle.
434 void visitAllocaInst(AllocaInst &AI) {
435 if (!isInterestingAlloca(AI)) return;
437 StackAlignment = std::max(StackAlignment, AI.getAlignment());
438 AllocaVec.push_back(&AI);
439 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
440 TotalStackSize += AlignedSize;
443 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
445 void visitIntrinsicInst(IntrinsicInst &II) {
446 if (!ASan.CheckLifetime) return;
447 Intrinsic::ID ID = II.getIntrinsicID();
448 if (ID != Intrinsic::lifetime_start &&
449 ID != Intrinsic::lifetime_end)
451 // Found lifetime intrinsic, add ASan instrumentation if necessary.
452 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
453 // If size argument is undefined, don't do anything.
454 if (Size->isMinusOne()) return;
455 // Check that size doesn't saturate uint64_t and can
456 // be stored in IntptrTy.
457 const uint64_t SizeValue = Size->getValue().getLimitedValue();
458 if (SizeValue == ~0ULL ||
459 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
461 // Find alloca instruction that corresponds to llvm.lifetime argument.
462 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
464 bool DoPoison = (ID == Intrinsic::lifetime_end);
465 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
466 AllocaPoisonCallVec.push_back(APC);
469 // ---------------------- Helpers.
470 void initializeCallbacks(Module &M);
472 // Check if we want (and can) handle this alloca.
473 bool isInterestingAlloca(AllocaInst &AI) {
474 return (!AI.isArrayAllocation() &&
475 AI.isStaticAlloca() &&
476 AI.getAllocatedType()->isSized());
479 size_t RedzoneSize() const {
480 return RedzoneSizeForScale(Mapping.Scale);
482 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
483 Type *Ty = AI->getAllocatedType();
484 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
487 uint64_t getAlignedSize(uint64_t SizeInBytes) {
488 size_t RZ = RedzoneSize();
489 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
491 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
492 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
493 return getAlignedSize(SizeInBytes);
495 /// Finds alloca where the value comes from.
496 AllocaInst *findAllocaForValue(Value *V);
497 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
498 Value *ShadowBase, bool DoPoison);
499 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
504 char AddressSanitizer::ID = 0;
505 INITIALIZE_PASS(AddressSanitizer, "asan",
506 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
508 FunctionPass *llvm::createAddressSanitizerFunctionPass(
509 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
510 StringRef BlacklistFile, bool ZeroBaseShadow) {
511 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
512 CheckLifetime, BlacklistFile, ZeroBaseShadow);
515 char AddressSanitizerModule::ID = 0;
516 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
517 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
518 "ModulePass", false, false)
519 ModulePass *llvm::createAddressSanitizerModulePass(
520 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
521 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
525 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
526 size_t Res = CountTrailingZeros_32(TypeSize / 8);
527 assert(Res < kNumberOfAccessSizes);
531 // Create a constant for Str so that we can pass it to the run-time lib.
532 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
533 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
534 return new GlobalVariable(M, StrConst->getType(), true,
535 GlobalValue::PrivateLinkage, StrConst,
539 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
540 return G->getName().find(kAsanGenPrefix) == 0;
543 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
545 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
546 if (Mapping.Offset == 0)
548 // (Shadow >> scale) | offset
549 if (Mapping.OrShadowOffset)
550 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
552 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
555 void AddressSanitizer::instrumentMemIntrinsicParam(
556 Instruction *OrigIns,
557 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
558 IRBuilder<> IRB(InsertBefore);
559 if (Size->getType() != IntptrTy)
560 Size = IRB.CreateIntCast(Size, IntptrTy, false);
561 // Check the first byte.
562 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
563 // Check the last byte.
564 IRB.SetInsertPoint(InsertBefore);
565 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
566 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
567 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
568 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
571 // Instrument memset/memmove/memcpy
572 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
573 Value *Dst = MI->getDest();
574 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
575 Value *Src = MemTran ? MemTran->getSource() : 0;
576 Value *Length = MI->getLength();
578 Constant *ConstLength = dyn_cast<Constant>(Length);
579 Instruction *InsertBefore = MI;
581 if (ConstLength->isNullValue()) return false;
583 // The size is not a constant so it could be zero -- check at run-time.
584 IRBuilder<> IRB(InsertBefore);
586 Value *Cmp = IRB.CreateICmpNE(Length,
587 Constant::getNullValue(Length->getType()));
588 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
591 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
593 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
597 // If I is an interesting memory access, return the PointerOperand
598 // and set IsWrite. Otherwise return NULL.
599 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
600 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
601 if (!ClInstrumentReads) return NULL;
603 return LI->getPointerOperand();
605 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
606 if (!ClInstrumentWrites) return NULL;
608 return SI->getPointerOperand();
610 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
611 if (!ClInstrumentAtomics) return NULL;
613 return RMW->getPointerOperand();
615 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
616 if (!ClInstrumentAtomics) return NULL;
618 return XCHG->getPointerOperand();
623 void AddressSanitizer::instrumentMop(Instruction *I) {
624 bool IsWrite = false;
625 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
627 if (ClOpt && ClOptGlobals) {
628 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
629 // If initialization order checking is disabled, a simple access to a
630 // dynamically initialized global is always valid.
633 // If a global variable does not have dynamic initialization we don't
634 // have to instrument it. However, if a global does not have initailizer
635 // at all, we assume it has dynamic initializer (in other TU).
636 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
641 Type *OrigPtrTy = Addr->getType();
642 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
644 assert(OrigTy->isSized());
645 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
647 assert((TypeSize % 8) == 0);
649 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
650 if (TypeSize == 8 || TypeSize == 16 ||
651 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
652 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
653 // Instrument unusual size (but still multiple of 8).
654 // We can not do it with a single check, so we do 1-byte check for the first
655 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
656 // to report the actual access size.
658 Value *LastByte = IRB.CreateIntToPtr(
659 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
660 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
662 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
663 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
664 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
667 // Validate the result of Module::getOrInsertFunction called for an interface
668 // function of AddressSanitizer. If the instrumented module defines a function
669 // with the same name, their prototypes must match, otherwise
670 // getOrInsertFunction returns a bitcast.
671 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
672 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
673 FuncOrBitcast->dump();
674 report_fatal_error("trying to redefine an AddressSanitizer "
675 "interface function");
678 Instruction *AddressSanitizer::generateCrashCode(
679 Instruction *InsertBefore, Value *Addr,
680 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
681 IRBuilder<> IRB(InsertBefore);
682 CallInst *Call = SizeArgument
683 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
684 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
686 // We don't do Call->setDoesNotReturn() because the BB already has
687 // UnreachableInst at the end.
688 // This EmptyAsm is required to avoid callback merge.
689 IRB.CreateCall(EmptyAsm);
693 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
696 size_t Granularity = 1 << Mapping.Scale;
697 // Addr & (Granularity - 1)
698 Value *LastAccessedByte = IRB.CreateAnd(
699 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
700 // (Addr & (Granularity - 1)) + size - 1
701 if (TypeSize / 8 > 1)
702 LastAccessedByte = IRB.CreateAdd(
703 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
704 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
705 LastAccessedByte = IRB.CreateIntCast(
706 LastAccessedByte, ShadowValue->getType(), false);
707 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
708 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
711 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
712 Instruction *InsertBefore,
713 Value *Addr, uint32_t TypeSize,
714 bool IsWrite, Value *SizeArgument) {
715 IRBuilder<> IRB(InsertBefore);
716 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
718 Type *ShadowTy = IntegerType::get(
719 *C, std::max(8U, TypeSize >> Mapping.Scale));
720 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
721 Value *ShadowPtr = memToShadow(AddrLong, IRB);
722 Value *CmpVal = Constant::getNullValue(ShadowTy);
723 Value *ShadowValue = IRB.CreateLoad(
724 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
726 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
727 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
728 size_t Granularity = 1 << Mapping.Scale;
729 TerminatorInst *CrashTerm = 0;
731 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
732 TerminatorInst *CheckTerm =
733 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
734 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
735 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
736 IRB.SetInsertPoint(CheckTerm);
737 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
738 BasicBlock *CrashBlock =
739 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
740 CrashTerm = new UnreachableInst(*C, CrashBlock);
741 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
742 ReplaceInstWithInst(CheckTerm, NewTerm);
744 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
747 Instruction *Crash = generateCrashCode(
748 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
749 Crash->setDebugLoc(OrigIns->getDebugLoc());
752 void AddressSanitizerModule::createInitializerPoisonCalls(
753 Module &M, Value *FirstAddr, Value *LastAddr) {
754 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
755 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
756 // If that function is not present, this TU contains no globals, or they have
757 // all been optimized away
761 // Set up the arguments to our poison/unpoison functions.
762 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
764 // Add a call to poison all external globals before the given function starts.
765 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
767 // Add calls to unpoison all globals before each return instruction.
768 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
770 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
771 CallInst::Create(AsanUnpoisonGlobals, "", RI);
776 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
777 Type *Ty = cast<PointerType>(G->getType())->getElementType();
778 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
780 if (BL->isIn(*G)) return false;
781 if (!Ty->isSized()) return false;
782 if (!G->hasInitializer()) return false;
783 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
784 // Touch only those globals that will not be defined in other modules.
785 // Don't handle ODR type linkages since other modules may be built w/o asan.
786 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
787 G->getLinkage() != GlobalVariable::PrivateLinkage &&
788 G->getLinkage() != GlobalVariable::InternalLinkage)
790 // Two problems with thread-locals:
791 // - The address of the main thread's copy can't be computed at link-time.
792 // - Need to poison all copies, not just the main thread's one.
793 if (G->isThreadLocal())
795 // For now, just ignore this Alloca if the alignment is large.
796 if (G->getAlignment() > RedzoneSize()) return false;
798 // Ignore all the globals with the names starting with "\01L_OBJC_".
799 // Many of those are put into the .cstring section. The linker compresses
800 // that section by removing the spare \0s after the string terminator, so
801 // our redzones get broken.
802 if ((G->getName().find("\01L_OBJC_") == 0) ||
803 (G->getName().find("\01l_OBJC_") == 0)) {
804 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
808 if (G->hasSection()) {
809 StringRef Section(G->getSection());
810 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
811 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
813 if ((Section.find("__OBJC,") == 0) ||
814 (Section.find("__DATA, __objc_") == 0)) {
815 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
818 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
819 // Constant CFString instances are compiled in the following way:
820 // -- the string buffer is emitted into
821 // __TEXT,__cstring,cstring_literals
822 // -- the constant NSConstantString structure referencing that buffer
823 // is placed into __DATA,__cfstring
824 // Therefore there's no point in placing redzones into __DATA,__cfstring.
825 // Moreover, it causes the linker to crash on OS X 10.7
826 if (Section.find("__DATA,__cfstring") == 0) {
827 DEBUG(dbgs() << "Ignoring CFString: " << *G);
835 void AddressSanitizerModule::initializeCallbacks(Module &M) {
837 // Declare our poisoning and unpoisoning functions.
838 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
839 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
840 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
841 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
842 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
843 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
844 // Declare functions that register/unregister globals.
845 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
846 kAsanRegisterGlobalsName, IRB.getVoidTy(),
847 IntptrTy, IntptrTy, NULL));
848 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
849 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
850 kAsanUnregisterGlobalsName,
851 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
852 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
855 // This function replaces all global variables with new variables that have
856 // trailing redzones. It also creates a function that poisons
857 // redzones and inserts this function into llvm.global_ctors.
858 bool AddressSanitizerModule::runOnModule(Module &M) {
859 if (!ClGlobals) return false;
860 TD = getAnalysisIfAvailable<DataLayout>();
863 BL.reset(new BlackList(BlacklistFile));
864 if (BL->isIn(M)) return false;
865 C = &(M.getContext());
866 int LongSize = TD->getPointerSizeInBits();
867 IntptrTy = Type::getIntNTy(*C, LongSize);
868 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
869 initializeCallbacks(M);
870 DynamicallyInitializedGlobals.Init(M);
872 SmallVector<GlobalVariable *, 16> GlobalsToChange;
874 for (Module::GlobalListType::iterator G = M.global_begin(),
875 E = M.global_end(); G != E; ++G) {
876 if (ShouldInstrumentGlobal(G))
877 GlobalsToChange.push_back(G);
880 size_t n = GlobalsToChange.size();
881 if (n == 0) return false;
883 // A global is described by a structure
886 // size_t size_with_redzone;
888 // const char *module_name;
889 // size_t has_dynamic_init;
890 // We initialize an array of such structures and pass it to a run-time call.
891 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
893 IntptrTy, IntptrTy, NULL);
894 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
897 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
899 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
901 // The addresses of the first and last dynamically initialized globals in
902 // this TU. Used in initialization order checking.
903 Value *FirstDynamic = 0, *LastDynamic = 0;
905 GlobalVariable *ModuleName = createPrivateGlobalForString(
906 M, M.getModuleIdentifier());
908 for (size_t i = 0; i < n; i++) {
909 static const uint64_t kMaxGlobalRedzone = 1 << 18;
910 GlobalVariable *G = GlobalsToChange[i];
911 PointerType *PtrTy = cast<PointerType>(G->getType());
912 Type *Ty = PtrTy->getElementType();
913 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
914 uint64_t MinRZ = RedzoneSize();
915 // MinRZ <= RZ <= kMaxGlobalRedzone
916 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
917 uint64_t RZ = std::max(MinRZ,
918 std::min(kMaxGlobalRedzone,
919 (SizeInBytes / MinRZ / 4) * MinRZ));
920 uint64_t RightRedzoneSize = RZ;
922 if (SizeInBytes % MinRZ)
923 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
924 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
925 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
926 // Determine whether this global should be poisoned in initialization.
927 bool GlobalHasDynamicInitializer =
928 DynamicallyInitializedGlobals.Contains(G);
929 // Don't check initialization order if this global is blacklisted.
930 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
932 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
933 Constant *NewInitializer = ConstantStruct::get(
934 NewTy, G->getInitializer(),
935 Constant::getNullValue(RightRedZoneTy), NULL);
937 GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
939 // Create a new global variable with enough space for a redzone.
940 GlobalVariable *NewGlobal = new GlobalVariable(
941 M, NewTy, G->isConstant(), G->getLinkage(),
942 NewInitializer, "", G, G->getThreadLocalMode());
943 NewGlobal->copyAttributesFrom(G);
944 NewGlobal->setAlignment(MinRZ);
947 Indices2[0] = IRB.getInt32(0);
948 Indices2[1] = IRB.getInt32(0);
950 G->replaceAllUsesWith(
951 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
952 NewGlobal->takeName(G);
953 G->eraseFromParent();
955 Initializers[i] = ConstantStruct::get(
957 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
958 ConstantInt::get(IntptrTy, SizeInBytes),
959 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
960 ConstantExpr::getPointerCast(Name, IntptrTy),
961 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
962 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
965 // Populate the first and last globals declared in this TU.
966 if (CheckInitOrder && GlobalHasDynamicInitializer) {
967 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
968 if (FirstDynamic == 0)
969 FirstDynamic = LastDynamic;
972 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
975 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
976 GlobalVariable *AllGlobals = new GlobalVariable(
977 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
978 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
980 // Create calls for poisoning before initializers run and unpoisoning after.
981 if (CheckInitOrder && FirstDynamic && LastDynamic)
982 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
983 IRB.CreateCall2(AsanRegisterGlobals,
984 IRB.CreatePointerCast(AllGlobals, IntptrTy),
985 ConstantInt::get(IntptrTy, n));
987 // We also need to unregister globals at the end, e.g. when a shared library
989 Function *AsanDtorFunction = Function::Create(
990 FunctionType::get(Type::getVoidTy(*C), false),
991 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
992 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
993 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
994 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
995 IRB.CreatePointerCast(AllGlobals, IntptrTy),
996 ConstantInt::get(IntptrTy, n));
997 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1003 void AddressSanitizer::initializeCallbacks(Module &M) {
1004 IRBuilder<> IRB(*C);
1005 // Create __asan_report* callbacks.
1006 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1007 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1008 AccessSizeIndex++) {
1009 // IsWrite and TypeSize are encoded in the function name.
1010 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1011 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1012 // If we are merging crash callbacks, they have two parameters.
1013 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1014 checkInterfaceFunction(M.getOrInsertFunction(
1015 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1018 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1019 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1020 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1021 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1023 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1024 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1025 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1026 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1027 StringRef(""), StringRef(""),
1028 /*hasSideEffects=*/true);
1031 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1032 // Tell the values of mapping offset and scale to the run-time.
1033 GlobalValue *asan_mapping_offset =
1034 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1035 ConstantInt::get(IntptrTy, Mapping.Offset),
1036 kAsanMappingOffsetName);
1037 // Read the global, otherwise it may be optimized away.
1038 IRB.CreateLoad(asan_mapping_offset, true);
1040 GlobalValue *asan_mapping_scale =
1041 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1042 ConstantInt::get(IntptrTy, Mapping.Scale),
1043 kAsanMappingScaleName);
1044 // Read the global, otherwise it may be optimized away.
1045 IRB.CreateLoad(asan_mapping_scale, true);
1049 bool AddressSanitizer::doInitialization(Module &M) {
1050 // Initialize the private fields. No one has accessed them before.
1051 TD = getAnalysisIfAvailable<DataLayout>();
1055 BL.reset(new BlackList(BlacklistFile));
1056 DynamicallyInitializedGlobals.Init(M);
1058 C = &(M.getContext());
1059 LongSize = TD->getPointerSizeInBits();
1060 IntptrTy = Type::getIntNTy(*C, LongSize);
1062 AsanCtorFunction = Function::Create(
1063 FunctionType::get(Type::getVoidTy(*C), false),
1064 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1065 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1066 // call __asan_init in the module ctor.
1067 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1068 AsanInitFunction = checkInterfaceFunction(
1069 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1070 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1071 IRB.CreateCall(AsanInitFunction);
1073 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1074 emitShadowMapping(M, IRB);
1076 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1080 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1081 // For each NSObject descendant having a +load method, this method is invoked
1082 // by the ObjC runtime before any of the static constructors is called.
1083 // Therefore we need to instrument such methods with a call to __asan_init
1084 // at the beginning in order to initialize our runtime before any access to
1085 // the shadow memory.
1086 // We cannot just ignore these methods, because they may call other
1087 // instrumented functions.
1088 if (F.getName().find(" load]") != std::string::npos) {
1089 IRBuilder<> IRB(F.begin()->begin());
1090 IRB.CreateCall(AsanInitFunction);
1096 bool AddressSanitizer::runOnFunction(Function &F) {
1097 if (BL->isIn(F)) return false;
1098 if (&F == AsanCtorFunction) return false;
1099 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1100 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1101 initializeCallbacks(*F.getParent());
1103 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1104 maybeInsertAsanInitAtFunctionEntry(F);
1106 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1107 Attribute::SanitizeAddress))
1110 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1113 // We want to instrument every address only once per basic block (unless there
1114 // are calls between uses).
1115 SmallSet<Value*, 16> TempsToInstrument;
1116 SmallVector<Instruction*, 16> ToInstrument;
1117 SmallVector<Instruction*, 8> NoReturnCalls;
1120 // Fill the set of memory operations to instrument.
1121 for (Function::iterator FI = F.begin(), FE = F.end();
1123 TempsToInstrument.clear();
1124 int NumInsnsPerBB = 0;
1125 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1127 if (LooksLikeCodeInBug11395(BI)) return false;
1128 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1129 if (ClOpt && ClOptSameTemp) {
1130 if (!TempsToInstrument.insert(Addr))
1131 continue; // We've seen this temp in the current BB.
1133 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1138 // A call inside BB.
1139 TempsToInstrument.clear();
1140 if (CS.doesNotReturn())
1141 NoReturnCalls.push_back(CS.getInstruction());
1145 ToInstrument.push_back(BI);
1147 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1153 int NumInstrumented = 0;
1154 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1155 Instruction *Inst = ToInstrument[i];
1156 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1157 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1158 if (isInterestingMemoryAccess(Inst, &IsWrite))
1159 instrumentMop(Inst);
1161 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1166 FunctionStackPoisoner FSP(F, *this);
1167 bool ChangedStack = FSP.runOnFunction();
1169 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1170 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1171 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1172 Instruction *CI = NoReturnCalls[i];
1173 IRBuilder<> IRB(CI);
1174 IRB.CreateCall(AsanHandleNoReturnFunc);
1176 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1178 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1181 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1182 if (ShadowRedzoneSize == 1) return PoisonByte;
1183 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1184 if (ShadowRedzoneSize == 4)
1185 return (PoisonByte << 24) + (PoisonByte << 16) +
1186 (PoisonByte << 8) + (PoisonByte);
1187 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1190 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1193 size_t ShadowGranularity,
1195 for (size_t i = 0; i < RZSize;
1196 i+= ShadowGranularity, Shadow++) {
1197 if (i + ShadowGranularity <= Size) {
1198 *Shadow = 0; // fully addressable
1199 } else if (i >= Size) {
1200 *Shadow = Magic; // unaddressable
1202 *Shadow = Size - i; // first Size-i bytes are addressable
1207 // Workaround for bug 11395: we don't want to instrument stack in functions
1208 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1209 // FIXME: remove once the bug 11395 is fixed.
1210 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1211 if (LongSize != 32) return false;
1212 CallInst *CI = dyn_cast<CallInst>(I);
1213 if (!CI || !CI->isInlineAsm()) return false;
1214 if (CI->getNumArgOperands() <= 5) return false;
1215 // We have inline assembly with quite a few arguments.
1219 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1220 IRBuilder<> IRB(*C);
1221 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1222 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1223 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1224 kAsanStackFreeName, IRB.getVoidTy(),
1225 IntptrTy, IntptrTy, IntptrTy, NULL));
1226 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1227 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1228 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1229 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1232 void FunctionStackPoisoner::poisonRedZones(
1233 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1235 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1236 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1237 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1238 Type *RZPtrTy = PointerType::get(RZTy, 0);
1240 Value *PoisonLeft = ConstantInt::get(RZTy,
1241 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1242 Value *PoisonMid = ConstantInt::get(RZTy,
1243 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1244 Value *PoisonRight = ConstantInt::get(RZTy,
1245 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1247 // poison the first red zone.
1248 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1250 // poison all other red zones.
1251 uint64_t Pos = RedzoneSize();
1252 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1253 AllocaInst *AI = AllocaVec[i];
1254 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1255 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1256 assert(AlignedSize - SizeInBytes < RedzoneSize());
1261 assert(ShadowBase->getType() == IntptrTy);
1262 if (SizeInBytes < AlignedSize) {
1263 // Poison the partial redzone at right
1264 Ptr = IRB.CreateAdd(
1265 ShadowBase, ConstantInt::get(IntptrTy,
1266 (Pos >> Mapping.Scale) - ShadowRZSize));
1267 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1268 uint32_t Poison = 0;
1270 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1272 1ULL << Mapping.Scale,
1273 kAsanStackPartialRedzoneMagic);
1275 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1276 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1279 // Poison the full redzone at right.
1280 Ptr = IRB.CreateAdd(ShadowBase,
1281 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1282 bool LastAlloca = (i == AllocaVec.size() - 1);
1283 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1284 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1286 Pos += RedzoneSize();
1290 void FunctionStackPoisoner::poisonStack() {
1291 uint64_t LocalStackSize = TotalStackSize +
1292 (AllocaVec.size() + 1) * RedzoneSize();
1294 bool DoStackMalloc = ASan.CheckUseAfterReturn
1295 && LocalStackSize <= kMaxStackMallocSize;
1297 assert(AllocaVec.size() > 0);
1298 Instruction *InsBefore = AllocaVec[0];
1299 IRBuilder<> IRB(InsBefore);
1302 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1303 AllocaInst *MyAlloca =
1304 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1305 if (ClRealignStack && StackAlignment < RedzoneSize())
1306 StackAlignment = RedzoneSize();
1307 MyAlloca->setAlignment(StackAlignment);
1308 assert(MyAlloca->isStaticAlloca());
1309 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1310 Value *LocalStackBase = OrigStackBase;
1312 if (DoStackMalloc) {
1313 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1314 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1317 // This string will be parsed by the run-time (DescribeStackAddress).
1318 SmallString<2048> StackDescriptionStorage;
1319 raw_svector_ostream StackDescription(StackDescriptionStorage);
1320 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1322 // Insert poison calls for lifetime intrinsics for alloca.
1323 bool HavePoisonedAllocas = false;
1324 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1325 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1326 IntrinsicInst *II = APC.InsBefore;
1327 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1329 IRBuilder<> IRB(II);
1330 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1331 HavePoisonedAllocas |= APC.DoPoison;
1334 uint64_t Pos = RedzoneSize();
1335 // Replace Alloca instructions with base+offset.
1336 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1337 AllocaInst *AI = AllocaVec[i];
1338 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1339 StringRef Name = AI->getName();
1340 StackDescription << Pos << " " << SizeInBytes << " "
1341 << Name.size() << " " << Name << " ";
1342 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1343 assert((AlignedSize % RedzoneSize()) == 0);
1344 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1345 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1347 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1348 AI->replaceAllUsesWith(NewAllocaPtr);
1349 Pos += AlignedSize + RedzoneSize();
1351 assert(Pos == LocalStackSize);
1353 // Write the Magic value and the frame description constant to the redzone.
1354 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1355 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1357 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1358 ConstantInt::get(IntptrTy,
1360 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1361 GlobalVariable *StackDescriptionGlobal =
1362 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1363 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1365 IRB.CreateStore(Description, BasePlus1);
1367 // Poison the stack redzones at the entry.
1368 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1369 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1371 // Unpoison the stack before all ret instructions.
1372 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1373 Instruction *Ret = RetVec[i];
1374 IRBuilder<> IRBRet(Ret);
1375 // Mark the current frame as retired.
1376 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1378 // Unpoison the stack.
1379 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1380 if (DoStackMalloc) {
1381 // In use-after-return mode, mark the whole stack frame unaddressable.
1382 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1383 ConstantInt::get(IntptrTy, LocalStackSize),
1385 } else if (HavePoisonedAllocas) {
1386 // If we poisoned some allocas in llvm.lifetime analysis,
1387 // unpoison whole stack frame now.
1388 assert(LocalStackBase == OrigStackBase);
1389 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1393 // We are done. Remove the old unused alloca instructions.
1394 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1395 AllocaVec[i]->eraseFromParent();
1398 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1399 IRBuilder<> IRB, bool DoPoison) {
1400 // For now just insert the call to ASan runtime.
1401 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1402 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1403 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1404 : AsanUnpoisonStackMemoryFunc,
1408 // Handling llvm.lifetime intrinsics for a given %alloca:
1409 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1410 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1411 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1412 // could be poisoned by previous llvm.lifetime.end instruction, as the
1413 // variable may go in and out of scope several times, e.g. in loops).
1414 // (3) if we poisoned at least one %alloca in a function,
1415 // unpoison the whole stack frame at function exit.
1417 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1418 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1419 // We're intested only in allocas we can handle.
1420 return isInterestingAlloca(*AI) ? AI : 0;
1421 // See if we've already calculated (or started to calculate) alloca for a
1423 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1424 if (I != AllocaForValue.end())
1426 // Store 0 while we're calculating alloca for value V to avoid
1427 // infinite recursion if the value references itself.
1428 AllocaForValue[V] = 0;
1429 AllocaInst *Res = 0;
1430 if (CastInst *CI = dyn_cast<CastInst>(V))
1431 Res = findAllocaForValue(CI->getOperand(0));
1432 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1433 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1434 Value *IncValue = PN->getIncomingValue(i);
1435 // Allow self-referencing phi-nodes.
1436 if (IncValue == PN) continue;
1437 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1438 // AI for incoming values should exist and should all be equal.
1439 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1445 AllocaForValue[V] = Res;