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 "BlackList.h"
20 #include "llvm/ADT/ArrayRef.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/DataLayout.h"
29 #include "llvm/DIBuilder.h"
30 #include "llvm/Function.h"
31 #include "llvm/IRBuilder.h"
32 #include "llvm/InlineAsm.h"
33 #include "llvm/InstVisitor.h"
34 #include "llvm/IntrinsicInst.h"
35 #include "llvm/LLVMContext.h"
36 #include "llvm/Module.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/DataTypes.h"
39 #include "llvm/Support/Debug.h"
40 #include "llvm/Support/raw_ostream.h"
41 #include "llvm/Support/system_error.h"
42 #include "llvm/Target/TargetMachine.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Transforms/Utils/ModuleUtils.h"
46 #include "llvm/Type.h"
52 static const uint64_t kDefaultShadowScale = 3;
53 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
54 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
55 static const uint64_t kDefaultShadowOffsetAndroid = 0;
57 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
58 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
59 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
61 static const char *kAsanModuleCtorName = "asan.module_ctor";
62 static const char *kAsanModuleDtorName = "asan.module_dtor";
63 static const int kAsanCtorAndCtorPriority = 1;
64 static const char *kAsanReportErrorTemplate = "__asan_report_";
65 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
66 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
67 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
68 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
69 static const char *kAsanInitName = "__asan_init";
70 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
71 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
72 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
73 static const char *kAsanStackMallocName = "__asan_stack_malloc";
74 static const char *kAsanStackFreeName = "__asan_stack_free";
75 static const char *kAsanGenPrefix = "__asan_gen_";
76 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
77 static const char *kAsanUnpoisonStackMemoryName =
78 "__asan_unpoison_stack_memory";
80 static const int kAsanStackLeftRedzoneMagic = 0xf1;
81 static const int kAsanStackMidRedzoneMagic = 0xf2;
82 static const int kAsanStackRightRedzoneMagic = 0xf3;
83 static const int kAsanStackPartialRedzoneMagic = 0xf4;
85 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
86 static const size_t kNumberOfAccessSizes = 5;
88 // Command-line flags.
90 // This flag may need to be replaced with -f[no-]asan-reads.
91 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
92 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
93 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
94 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
95 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
96 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
97 cl::Hidden, cl::init(true));
98 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
99 cl::desc("use instrumentation with slow path for all accesses"),
100 cl::Hidden, cl::init(false));
101 // This flag limits the number of instructions to be instrumented
102 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
103 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
105 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
107 cl::desc("maximal number of instructions to instrument in any given BB"),
109 // This flag may need to be replaced with -f[no]asan-stack.
110 static cl::opt<bool> ClStack("asan-stack",
111 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
112 // This flag may need to be replaced with -f[no]asan-use-after-return.
113 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
114 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
115 // This flag may need to be replaced with -f[no]asan-globals.
116 static cl::opt<bool> ClGlobals("asan-globals",
117 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
118 static cl::opt<bool> ClInitializers("asan-initialization-order",
119 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
120 static cl::opt<bool> ClMemIntrin("asan-memintrin",
121 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
122 static cl::opt<bool> ClRealignStack("asan-realign-stack",
123 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
124 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
125 cl::desc("File containing the list of objects to ignore "
126 "during instrumentation"), cl::Hidden);
128 // These flags allow to change the shadow mapping.
129 // The shadow mapping looks like
130 // Shadow = (Mem >> scale) + (1 << offset_log)
131 static cl::opt<int> ClMappingScale("asan-mapping-scale",
132 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
133 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
134 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
136 // Optimization flags. Not user visible, used mostly for testing
137 // and benchmarking the tool.
138 static cl::opt<bool> ClOpt("asan-opt",
139 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
140 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
141 cl::desc("Instrument the same temp just once"), cl::Hidden,
143 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
144 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
146 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
147 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
148 cl::Hidden, cl::init(false));
151 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
153 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
154 cl::Hidden, cl::init(0));
155 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
156 cl::Hidden, cl::desc("Debug func"));
157 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
158 cl::Hidden, cl::init(-1));
159 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
160 cl::Hidden, cl::init(-1));
163 /// A set of dynamically initialized globals extracted from metadata.
164 class SetOfDynamicallyInitializedGlobals {
166 void Init(Module& M) {
167 // Clang generates metadata identifying all dynamically initialized globals.
168 NamedMDNode *DynamicGlobals =
169 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
172 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
173 MDNode *MDN = DynamicGlobals->getOperand(i);
174 assert(MDN->getNumOperands() == 1);
175 Value *VG = MDN->getOperand(0);
176 // The optimizer may optimize away a global entirely, in which case we
177 // cannot instrument access to it.
180 DynInitGlobals.insert(cast<GlobalVariable>(VG));
183 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
185 SmallSet<GlobalValue*, 32> DynInitGlobals;
188 static int MappingScale() {
189 return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
192 static size_t RedzoneSize() {
193 // Redzone used for stack and globals is at least 32 bytes.
194 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
195 return std::max(32U, 1U << MappingScale());
198 /// AddressSanitizer: instrument the code in module to find memory bugs.
199 struct AddressSanitizer : public FunctionPass {
200 AddressSanitizer(bool CheckInitOrder = false,
201 bool CheckUseAfterReturn = false,
202 bool CheckLifetime = false,
203 StringRef BlacklistFile = StringRef())
205 CheckInitOrder(CheckInitOrder || ClInitializers),
206 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
207 CheckLifetime(CheckLifetime || ClCheckLifetime),
208 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
210 virtual const char *getPassName() const {
211 return "AddressSanitizerFunctionPass";
213 void instrumentMop(Instruction *I);
214 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
215 Value *Addr, uint32_t TypeSize, bool IsWrite);
216 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
217 Value *ShadowValue, uint32_t TypeSize);
218 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
219 bool IsWrite, size_t AccessSizeIndex);
220 bool instrumentMemIntrinsic(MemIntrinsic *MI);
221 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
223 Instruction *InsertBefore, bool IsWrite);
224 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
225 bool runOnFunction(Function &F);
226 void createInitializerPoisonCalls(Module &M,
227 Value *FirstAddr, Value *LastAddr);
228 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
229 virtual bool doInitialization(Module &M);
230 static char ID; // Pass identification, replacement for typeid
233 void initializeCallbacks(Module &M);
235 bool ShouldInstrumentGlobal(GlobalVariable *G);
236 bool LooksLikeCodeInBug11395(Instruction *I);
237 void FindDynamicInitializers(Module &M);
240 bool CheckUseAfterReturn;
244 uint64_t MappingOffset;
247 Function *AsanCtorFunction;
248 Function *AsanInitFunction;
249 Function *AsanHandleNoReturnFunc;
250 SmallString<64> BlacklistFile;
251 OwningPtr<BlackList> BL;
252 // This array is indexed by AccessIsWrite and log2(AccessSize).
253 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
255 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
257 friend struct FunctionStackPoisoner;
260 class AddressSanitizerModule : public ModulePass {
262 AddressSanitizerModule(bool CheckInitOrder = false,
263 StringRef BlacklistFile = StringRef())
265 CheckInitOrder(CheckInitOrder || ClInitializers),
266 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
268 bool runOnModule(Module &M);
269 static char ID; // Pass identification, replacement for typeid
270 virtual const char *getPassName() const {
271 return "AddressSanitizerModule";
275 void initializeCallbacks(Module &M);
277 bool ShouldInstrumentGlobal(GlobalVariable *G);
278 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
282 SmallString<64> BlacklistFile;
283 OwningPtr<BlackList> BL;
284 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
288 Function *AsanPoisonGlobals;
289 Function *AsanUnpoisonGlobals;
290 Function *AsanRegisterGlobals;
291 Function *AsanUnregisterGlobals;
294 // Stack poisoning does not play well with exception handling.
295 // When an exception is thrown, we essentially bypass the code
296 // that unpoisones the stack. This is why the run-time library has
297 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
298 // stack in the interceptor. This however does not work inside the
299 // actual function which catches the exception. Most likely because the
300 // compiler hoists the load of the shadow value somewhere too high.
301 // This causes asan to report a non-existing bug on 453.povray.
302 // It sounds like an LLVM bug.
303 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
305 AddressSanitizer &ASan;
311 SmallVector<AllocaInst*, 16> AllocaVec;
312 SmallVector<Instruction*, 8> RetVec;
313 uint64_t TotalStackSize;
314 unsigned StackAlignment;
316 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
317 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
319 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
320 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
321 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
322 TotalStackSize(0), StackAlignment(1 << MappingScale()) {}
324 bool runOnFunction() {
325 if (!ClStack) return false;
326 // Collect alloca, ret, lifetime instructions etc.
327 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
328 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
329 BasicBlock *BB = *DI;
332 if (AllocaVec.empty()) return false;
334 initializeCallbacks(*F.getParent());
344 // Finds all static Alloca instructions and puts
345 // poisoned red zones around all of them.
346 // Then unpoison everything back before the function returns.
349 // ----------------------- Visitors.
350 /// \brief Collect all Ret instructions.
351 void visitReturnInst(ReturnInst &RI) {
352 RetVec.push_back(&RI);
355 /// \brief Collect Alloca instructions we want (and can) handle.
356 void visitAllocaInst(AllocaInst &AI) {
357 if (AI.isArrayAllocation()) return;
358 if (!AI.isStaticAlloca()) return;
359 if (!AI.getAllocatedType()->isSized()) return;
361 StackAlignment = std::max(StackAlignment, AI.getAlignment());
362 AllocaVec.push_back(&AI);
363 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
364 TotalStackSize += AlignedSize;
367 // ---------------------- Helpers.
368 void initializeCallbacks(Module &M);
370 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
371 Type *Ty = AI->getAllocatedType();
372 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
375 uint64_t getAlignedSize(uint64_t SizeInBytes) {
376 size_t RZ = RedzoneSize();
377 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
379 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
380 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
381 return getAlignedSize(SizeInBytes);
383 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
384 Value *ShadowBase, bool DoPoison);
385 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
386 /// Analyze lifetime intrinsics for given alloca. Use Value* instead of
387 /// AllocaInst* here, as we call this method after we merge all allocas into a
388 /// single one. Returns true if ASan added some instrumentation.
389 bool handleAllocaLifetime(Value *Alloca);
390 /// Analyze lifetime intrinsics for a specific value, casted from alloca.
391 /// Returns true if if ASan added some instrumentation.
392 bool handleValueLifetime(Value *V);
397 char AddressSanitizer::ID = 0;
398 INITIALIZE_PASS(AddressSanitizer, "asan",
399 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
401 FunctionPass *llvm::createAddressSanitizerFunctionPass(
402 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
403 StringRef BlacklistFile) {
404 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
405 CheckLifetime, BlacklistFile);
408 char AddressSanitizerModule::ID = 0;
409 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
410 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
411 "ModulePass", false, false)
412 ModulePass *llvm::createAddressSanitizerModulePass(
413 bool CheckInitOrder, StringRef BlacklistFile) {
414 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
417 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
418 size_t Res = CountTrailingZeros_32(TypeSize / 8);
419 assert(Res < kNumberOfAccessSizes);
423 // Create a constant for Str so that we can pass it to the run-time lib.
424 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
425 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
426 return new GlobalVariable(M, StrConst->getType(), true,
427 GlobalValue::PrivateLinkage, StrConst,
431 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
432 return G->getName().find(kAsanGenPrefix) == 0;
435 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
437 Shadow = IRB.CreateLShr(Shadow, MappingScale());
438 if (MappingOffset == 0)
440 // (Shadow >> scale) | offset
441 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
445 void AddressSanitizer::instrumentMemIntrinsicParam(
446 Instruction *OrigIns,
447 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
448 // Check the first byte.
450 IRBuilder<> IRB(InsertBefore);
451 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
453 // Check the last byte.
455 IRBuilder<> IRB(InsertBefore);
456 Value *SizeMinusOne = IRB.CreateSub(
457 Size, ConstantInt::get(Size->getType(), 1));
458 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
459 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
460 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
461 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
465 // Instrument memset/memmove/memcpy
466 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
467 Value *Dst = MI->getDest();
468 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
469 Value *Src = MemTran ? MemTran->getSource() : 0;
470 Value *Length = MI->getLength();
472 Constant *ConstLength = dyn_cast<Constant>(Length);
473 Instruction *InsertBefore = MI;
475 if (ConstLength->isNullValue()) return false;
477 // The size is not a constant so it could be zero -- check at run-time.
478 IRBuilder<> IRB(InsertBefore);
480 Value *Cmp = IRB.CreateICmpNE(Length,
481 Constant::getNullValue(Length->getType()));
482 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
485 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
487 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
491 // If I is an interesting memory access, return the PointerOperand
492 // and set IsWrite. Otherwise return NULL.
493 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
494 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
495 if (!ClInstrumentReads) return NULL;
497 return LI->getPointerOperand();
499 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
500 if (!ClInstrumentWrites) return NULL;
502 return SI->getPointerOperand();
504 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
505 if (!ClInstrumentAtomics) return NULL;
507 return RMW->getPointerOperand();
509 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
510 if (!ClInstrumentAtomics) return NULL;
512 return XCHG->getPointerOperand();
517 void AddressSanitizer::instrumentMop(Instruction *I) {
518 bool IsWrite = false;
519 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
521 if (ClOpt && ClOptGlobals) {
522 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
523 // If initialization order checking is disabled, a simple access to a
524 // dynamically initialized global is always valid.
527 // If a global variable does not have dynamic initialization we don't
528 // have to instrument it. However, if a global does not have initailizer
529 // at all, we assume it has dynamic initializer (in other TU).
530 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
535 Type *OrigPtrTy = Addr->getType();
536 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
538 assert(OrigTy->isSized());
539 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
541 if (TypeSize != 8 && TypeSize != 16 &&
542 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
543 // Ignore all unusual sizes.
548 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
551 // Validate the result of Module::getOrInsertFunction called for an interface
552 // function of AddressSanitizer. If the instrumented module defines a function
553 // with the same name, their prototypes must match, otherwise
554 // getOrInsertFunction returns a bitcast.
555 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
556 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
557 FuncOrBitcast->dump();
558 report_fatal_error("trying to redefine an AddressSanitizer "
559 "interface function");
562 Instruction *AddressSanitizer::generateCrashCode(
563 Instruction *InsertBefore, Value *Addr,
564 bool IsWrite, size_t AccessSizeIndex) {
565 IRBuilder<> IRB(InsertBefore);
566 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
568 // We don't do Call->setDoesNotReturn() because the BB already has
569 // UnreachableInst at the end.
570 // This EmptyAsm is required to avoid callback merge.
571 IRB.CreateCall(EmptyAsm);
575 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
578 size_t Granularity = 1 << MappingScale();
579 // Addr & (Granularity - 1)
580 Value *LastAccessedByte = IRB.CreateAnd(
581 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
582 // (Addr & (Granularity - 1)) + size - 1
583 if (TypeSize / 8 > 1)
584 LastAccessedByte = IRB.CreateAdd(
585 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
586 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
587 LastAccessedByte = IRB.CreateIntCast(
588 LastAccessedByte, ShadowValue->getType(), false);
589 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
590 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
593 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
594 IRBuilder<> &IRB, Value *Addr,
595 uint32_t TypeSize, bool IsWrite) {
596 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
598 Type *ShadowTy = IntegerType::get(
599 *C, std::max(8U, TypeSize >> MappingScale()));
600 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
601 Value *ShadowPtr = memToShadow(AddrLong, IRB);
602 Value *CmpVal = Constant::getNullValue(ShadowTy);
603 Value *ShadowValue = IRB.CreateLoad(
604 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
606 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
607 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
608 size_t Granularity = 1 << MappingScale();
609 TerminatorInst *CrashTerm = 0;
611 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
612 TerminatorInst *CheckTerm =
613 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
614 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
615 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
616 IRB.SetInsertPoint(CheckTerm);
617 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
618 BasicBlock *CrashBlock =
619 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
620 CrashTerm = new UnreachableInst(*C, CrashBlock);
621 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
622 ReplaceInstWithInst(CheckTerm, NewTerm);
624 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
628 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
629 Crash->setDebugLoc(OrigIns->getDebugLoc());
632 void AddressSanitizerModule::createInitializerPoisonCalls(
633 Module &M, Value *FirstAddr, Value *LastAddr) {
634 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
635 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
636 // If that function is not present, this TU contains no globals, or they have
637 // all been optimized away
641 // Set up the arguments to our poison/unpoison functions.
642 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
644 // Add a call to poison all external globals before the given function starts.
645 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
647 // Add calls to unpoison all globals before each return instruction.
648 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
650 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
651 CallInst::Create(AsanUnpoisonGlobals, "", RI);
656 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
657 Type *Ty = cast<PointerType>(G->getType())->getElementType();
658 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
660 if (BL->isIn(*G)) return false;
661 if (!Ty->isSized()) return false;
662 if (!G->hasInitializer()) return false;
663 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
664 // Touch only those globals that will not be defined in other modules.
665 // Don't handle ODR type linkages since other modules may be built w/o asan.
666 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
667 G->getLinkage() != GlobalVariable::PrivateLinkage &&
668 G->getLinkage() != GlobalVariable::InternalLinkage)
670 // Two problems with thread-locals:
671 // - The address of the main thread's copy can't be computed at link-time.
672 // - Need to poison all copies, not just the main thread's one.
673 if (G->isThreadLocal())
675 // For now, just ignore this Alloca if the alignment is large.
676 if (G->getAlignment() > RedzoneSize()) return false;
678 // Ignore all the globals with the names starting with "\01L_OBJC_".
679 // Many of those are put into the .cstring section. The linker compresses
680 // that section by removing the spare \0s after the string terminator, so
681 // our redzones get broken.
682 if ((G->getName().find("\01L_OBJC_") == 0) ||
683 (G->getName().find("\01l_OBJC_") == 0)) {
684 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
688 if (G->hasSection()) {
689 StringRef Section(G->getSection());
690 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
691 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
693 if ((Section.find("__OBJC,") == 0) ||
694 (Section.find("__DATA, __objc_") == 0)) {
695 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
698 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
699 // Constant CFString instances are compiled in the following way:
700 // -- the string buffer is emitted into
701 // __TEXT,__cstring,cstring_literals
702 // -- the constant NSConstantString structure referencing that buffer
703 // is placed into __DATA,__cfstring
704 // Therefore there's no point in placing redzones into __DATA,__cfstring.
705 // Moreover, it causes the linker to crash on OS X 10.7
706 if (Section.find("__DATA,__cfstring") == 0) {
707 DEBUG(dbgs() << "Ignoring CFString: " << *G);
715 void AddressSanitizerModule::initializeCallbacks(Module &M) {
717 // Declare our poisoning and unpoisoning functions.
718 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
719 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
720 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
721 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
722 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
723 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
724 // Declare functions that register/unregister globals.
725 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
726 kAsanRegisterGlobalsName, IRB.getVoidTy(),
727 IntptrTy, IntptrTy, NULL));
728 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
729 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
730 kAsanUnregisterGlobalsName,
731 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
732 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
735 // This function replaces all global variables with new variables that have
736 // trailing redzones. It also creates a function that poisons
737 // redzones and inserts this function into llvm.global_ctors.
738 bool AddressSanitizerModule::runOnModule(Module &M) {
739 if (!ClGlobals) return false;
740 TD = getAnalysisIfAvailable<DataLayout>();
743 BL.reset(new BlackList(BlacklistFile));
744 if (BL->isIn(M)) return false;
745 C = &(M.getContext());
746 IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
747 initializeCallbacks(M);
748 DynamicallyInitializedGlobals.Init(M);
750 SmallVector<GlobalVariable *, 16> GlobalsToChange;
752 for (Module::GlobalListType::iterator G = M.global_begin(),
753 E = M.global_end(); G != E; ++G) {
754 if (ShouldInstrumentGlobal(G))
755 GlobalsToChange.push_back(G);
758 size_t n = GlobalsToChange.size();
759 if (n == 0) return false;
761 // A global is described by a structure
764 // size_t size_with_redzone;
766 // size_t has_dynamic_init;
767 // We initialize an array of such structures and pass it to a run-time call.
768 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
771 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
774 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
776 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
778 // The addresses of the first and last dynamically initialized globals in
779 // this TU. Used in initialization order checking.
780 Value *FirstDynamic = 0, *LastDynamic = 0;
782 for (size_t i = 0; i < n; i++) {
783 GlobalVariable *G = GlobalsToChange[i];
784 PointerType *PtrTy = cast<PointerType>(G->getType());
785 Type *Ty = PtrTy->getElementType();
786 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
787 size_t RZ = RedzoneSize();
788 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
789 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
790 // Determine whether this global should be poisoned in initialization.
791 bool GlobalHasDynamicInitializer =
792 DynamicallyInitializedGlobals.Contains(G);
793 // Don't check initialization order if this global is blacklisted.
794 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
796 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
797 Constant *NewInitializer = ConstantStruct::get(
798 NewTy, G->getInitializer(),
799 Constant::getNullValue(RightRedZoneTy), NULL);
801 SmallString<2048> DescriptionOfGlobal = G->getName();
802 DescriptionOfGlobal += " (";
803 DescriptionOfGlobal += M.getModuleIdentifier();
804 DescriptionOfGlobal += ")";
805 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
807 // Create a new global variable with enough space for a redzone.
808 GlobalVariable *NewGlobal = new GlobalVariable(
809 M, NewTy, G->isConstant(), G->getLinkage(),
810 NewInitializer, "", G, G->getThreadLocalMode());
811 NewGlobal->copyAttributesFrom(G);
812 NewGlobal->setAlignment(RZ);
815 Indices2[0] = IRB.getInt32(0);
816 Indices2[1] = IRB.getInt32(0);
818 G->replaceAllUsesWith(
819 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
820 NewGlobal->takeName(G);
821 G->eraseFromParent();
823 Initializers[i] = ConstantStruct::get(
825 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
826 ConstantInt::get(IntptrTy, SizeInBytes),
827 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
828 ConstantExpr::getPointerCast(Name, IntptrTy),
829 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
832 // Populate the first and last globals declared in this TU.
833 if (CheckInitOrder && GlobalHasDynamicInitializer) {
834 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
835 if (FirstDynamic == 0)
836 FirstDynamic = LastDynamic;
839 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
842 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
843 GlobalVariable *AllGlobals = new GlobalVariable(
844 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
845 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
847 // Create calls for poisoning before initializers run and unpoisoning after.
848 if (CheckInitOrder && FirstDynamic && LastDynamic)
849 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
850 IRB.CreateCall2(AsanRegisterGlobals,
851 IRB.CreatePointerCast(AllGlobals, IntptrTy),
852 ConstantInt::get(IntptrTy, n));
854 // We also need to unregister globals at the end, e.g. when a shared library
856 Function *AsanDtorFunction = Function::Create(
857 FunctionType::get(Type::getVoidTy(*C), false),
858 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
859 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
860 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
861 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
862 IRB.CreatePointerCast(AllGlobals, IntptrTy),
863 ConstantInt::get(IntptrTy, n));
864 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
870 void AddressSanitizer::initializeCallbacks(Module &M) {
872 // Create __asan_report* callbacks.
873 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
874 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
876 // IsWrite and TypeSize are encoded in the function name.
877 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
878 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
879 // If we are merging crash callbacks, they have two parameters.
880 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
881 checkInterfaceFunction(M.getOrInsertFunction(
882 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
886 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
887 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
888 // We insert an empty inline asm after __asan_report* to avoid callback merge.
889 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
890 StringRef(""), StringRef(""),
891 /*hasSideEffects=*/true);
895 bool AddressSanitizer::doInitialization(Module &M) {
896 // Initialize the private fields. No one has accessed them before.
897 TD = getAnalysisIfAvailable<DataLayout>();
901 BL.reset(new BlackList(BlacklistFile));
902 DynamicallyInitializedGlobals.Init(M);
904 C = &(M.getContext());
905 LongSize = TD->getPointerSizeInBits();
906 IntptrTy = Type::getIntNTy(*C, LongSize);
908 AsanCtorFunction = Function::Create(
909 FunctionType::get(Type::getVoidTy(*C), false),
910 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
911 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
912 // call __asan_init in the module ctor.
913 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
914 AsanInitFunction = checkInterfaceFunction(
915 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
916 AsanInitFunction->setLinkage(Function::ExternalLinkage);
917 IRB.CreateCall(AsanInitFunction);
919 llvm::Triple targetTriple(M.getTargetTriple());
920 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
922 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
923 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
924 if (ClMappingOffsetLog >= 0) {
925 if (ClMappingOffsetLog == 0) {
929 MappingOffset = 1ULL << ClMappingOffsetLog;
934 if (ClMappingOffsetLog >= 0) {
935 // Tell the run-time the current values of mapping offset and scale.
936 GlobalValue *asan_mapping_offset =
937 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
938 ConstantInt::get(IntptrTy, MappingOffset),
939 kAsanMappingOffsetName);
940 // Read the global, otherwise it may be optimized away.
941 IRB.CreateLoad(asan_mapping_offset, true);
943 if (ClMappingScale) {
944 GlobalValue *asan_mapping_scale =
945 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
946 ConstantInt::get(IntptrTy, MappingScale()),
947 kAsanMappingScaleName);
948 // Read the global, otherwise it may be optimized away.
949 IRB.CreateLoad(asan_mapping_scale, true);
952 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
957 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
958 // For each NSObject descendant having a +load method, this method is invoked
959 // by the ObjC runtime before any of the static constructors is called.
960 // Therefore we need to instrument such methods with a call to __asan_init
961 // at the beginning in order to initialize our runtime before any access to
962 // the shadow memory.
963 // We cannot just ignore these methods, because they may call other
964 // instrumented functions.
965 if (F.getName().find(" load]") != std::string::npos) {
966 IRBuilder<> IRB(F.begin()->begin());
967 IRB.CreateCall(AsanInitFunction);
973 bool AddressSanitizer::runOnFunction(Function &F) {
974 if (BL->isIn(F)) return false;
975 if (&F == AsanCtorFunction) return false;
976 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
977 initializeCallbacks(*F.getParent());
979 // If needed, insert __asan_init before checking for AddressSafety attr.
980 maybeInsertAsanInitAtFunctionEntry(F);
982 if (!F.getFnAttributes().hasAttribute(Attribute::AddressSafety))
985 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
988 // We want to instrument every address only once per basic block (unless there
989 // are calls between uses).
990 SmallSet<Value*, 16> TempsToInstrument;
991 SmallVector<Instruction*, 16> ToInstrument;
992 SmallVector<Instruction*, 8> NoReturnCalls;
995 // Fill the set of memory operations to instrument.
996 for (Function::iterator FI = F.begin(), FE = F.end();
998 TempsToInstrument.clear();
999 int NumInsnsPerBB = 0;
1000 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1002 if (LooksLikeCodeInBug11395(BI)) return false;
1003 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1004 if (ClOpt && ClOptSameTemp) {
1005 if (!TempsToInstrument.insert(Addr))
1006 continue; // We've seen this temp in the current BB.
1008 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1011 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1012 // A call inside BB.
1013 TempsToInstrument.clear();
1014 if (CI->doesNotReturn()) {
1015 NoReturnCalls.push_back(CI);
1020 ToInstrument.push_back(BI);
1022 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1028 int NumInstrumented = 0;
1029 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1030 Instruction *Inst = ToInstrument[i];
1031 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1032 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1033 if (isInterestingMemoryAccess(Inst, &IsWrite))
1034 instrumentMop(Inst);
1036 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1041 FunctionStackPoisoner FSP(F, *this);
1042 bool ChangedStack = FSP.runOnFunction();
1044 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1045 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1046 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1047 Instruction *CI = NoReturnCalls[i];
1048 IRBuilder<> IRB(CI);
1049 IRB.CreateCall(AsanHandleNoReturnFunc);
1051 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1053 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1056 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1057 if (ShadowRedzoneSize == 1) return PoisonByte;
1058 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1059 if (ShadowRedzoneSize == 4)
1060 return (PoisonByte << 24) + (PoisonByte << 16) +
1061 (PoisonByte << 8) + (PoisonByte);
1062 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1065 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1068 size_t ShadowGranularity,
1070 for (size_t i = 0; i < RZSize;
1071 i+= ShadowGranularity, Shadow++) {
1072 if (i + ShadowGranularity <= Size) {
1073 *Shadow = 0; // fully addressable
1074 } else if (i >= Size) {
1075 *Shadow = Magic; // unaddressable
1077 *Shadow = Size - i; // first Size-i bytes are addressable
1082 // Workaround for bug 11395: we don't want to instrument stack in functions
1083 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1084 // FIXME: remove once the bug 11395 is fixed.
1085 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1086 if (LongSize != 32) return false;
1087 CallInst *CI = dyn_cast<CallInst>(I);
1088 if (!CI || !CI->isInlineAsm()) return false;
1089 if (CI->getNumArgOperands() <= 5) return false;
1090 // We have inline assembly with quite a few arguments.
1094 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1095 IRBuilder<> IRB(*C);
1096 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1097 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1098 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1099 kAsanStackFreeName, IRB.getVoidTy(),
1100 IntptrTy, IntptrTy, IntptrTy, NULL));
1101 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1102 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1103 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1104 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1107 void FunctionStackPoisoner::poisonRedZones(
1108 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1110 size_t ShadowRZSize = RedzoneSize() >> MappingScale();
1111 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1112 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1113 Type *RZPtrTy = PointerType::get(RZTy, 0);
1115 Value *PoisonLeft = ConstantInt::get(RZTy,
1116 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1117 Value *PoisonMid = ConstantInt::get(RZTy,
1118 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1119 Value *PoisonRight = ConstantInt::get(RZTy,
1120 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1122 // poison the first red zone.
1123 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1125 // poison all other red zones.
1126 uint64_t Pos = RedzoneSize();
1127 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1128 AllocaInst *AI = AllocaVec[i];
1129 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1130 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1131 assert(AlignedSize - SizeInBytes < RedzoneSize());
1136 assert(ShadowBase->getType() == IntptrTy);
1137 if (SizeInBytes < AlignedSize) {
1138 // Poison the partial redzone at right
1139 Ptr = IRB.CreateAdd(
1140 ShadowBase, ConstantInt::get(IntptrTy,
1141 (Pos >> MappingScale()) - ShadowRZSize));
1142 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1143 uint32_t Poison = 0;
1145 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1147 1ULL << MappingScale(),
1148 kAsanStackPartialRedzoneMagic);
1150 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1151 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1154 // Poison the full redzone at right.
1155 Ptr = IRB.CreateAdd(ShadowBase,
1156 ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1157 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1158 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1160 Pos += RedzoneSize();
1164 void FunctionStackPoisoner::poisonStack() {
1165 bool HavePoisonedAllocas = false;
1166 uint64_t LocalStackSize = TotalStackSize +
1167 (AllocaVec.size() + 1) * RedzoneSize();
1169 bool DoStackMalloc = ASan.CheckUseAfterReturn
1170 && LocalStackSize <= kMaxStackMallocSize;
1172 Instruction *InsBefore = AllocaVec[0];
1173 IRBuilder<> IRB(InsBefore);
1176 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1177 AllocaInst *MyAlloca =
1178 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1179 if (ClRealignStack && StackAlignment < RedzoneSize())
1180 StackAlignment = RedzoneSize();
1181 MyAlloca->setAlignment(StackAlignment);
1182 assert(MyAlloca->isStaticAlloca());
1183 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1184 Value *LocalStackBase = OrigStackBase;
1186 if (DoStackMalloc) {
1187 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1188 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1191 // This string will be parsed by the run-time (DescribeStackAddress).
1192 SmallString<2048> StackDescriptionStorage;
1193 raw_svector_ostream StackDescription(StackDescriptionStorage);
1194 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1196 uint64_t Pos = RedzoneSize();
1197 // Replace Alloca instructions with base+offset.
1198 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1199 AllocaInst *AI = AllocaVec[i];
1200 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1201 StringRef Name = AI->getName();
1202 StackDescription << Pos << " " << SizeInBytes << " "
1203 << Name.size() << " " << Name << " ";
1204 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1205 assert((AlignedSize % RedzoneSize()) == 0);
1206 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1207 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1209 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1210 AI->replaceAllUsesWith(NewAllocaPtr);
1211 // Analyze lifetime intrinsics only for static allocas we handle.
1212 if (ASan.CheckLifetime)
1213 HavePoisonedAllocas |= handleAllocaLifetime(NewAllocaPtr);
1214 Pos += AlignedSize + RedzoneSize();
1216 assert(Pos == LocalStackSize);
1218 // Write the Magic value and the frame description constant to the redzone.
1219 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1220 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1222 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1223 ConstantInt::get(IntptrTy,
1225 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1226 GlobalVariable *StackDescriptionGlobal =
1227 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1228 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1230 IRB.CreateStore(Description, BasePlus1);
1232 // Poison the stack redzones at the entry.
1233 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1234 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1236 // Unpoison the stack before all ret instructions.
1237 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1238 Instruction *Ret = RetVec[i];
1239 IRBuilder<> IRBRet(Ret);
1240 // Mark the current frame as retired.
1241 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1243 // Unpoison the stack.
1244 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1245 if (DoStackMalloc) {
1246 // In use-after-return mode, mark the whole stack frame unaddressable.
1247 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1248 ConstantInt::get(IntptrTy, LocalStackSize),
1250 } else if (HavePoisonedAllocas) {
1251 // If we poisoned some allocas in llvm.lifetime analysis,
1252 // unpoison whole stack frame now.
1253 assert(LocalStackBase == OrigStackBase);
1254 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1258 // We are done. Remove the old unused alloca instructions.
1259 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1260 AllocaVec[i]->eraseFromParent();
1263 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1264 IRBuilder<> IRB, bool DoPoison) {
1265 // For now just insert the call to ASan runtime.
1266 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1267 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1268 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1269 : AsanUnpoisonStackMemoryFunc,
1273 // Handling llvm.lifetime intrinsics for a given %alloca:
1274 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1275 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1276 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1277 // could be poisoned by previous llvm.lifetime.end instruction, as the
1278 // variable may go in and out of scope several times, e.g. in loops).
1279 // (3) if we poisoned at least one %alloca in a function,
1280 // unpoison the whole stack frame at function exit.
1281 bool FunctionStackPoisoner::handleAllocaLifetime(Value *Alloca) {
1282 assert(ASan.CheckLifetime);
1283 Type *AllocaType = Alloca->getType();
1284 Type *Int8PtrTy = Type::getInt8PtrTy(AllocaType->getContext());
1287 // Typical code looks like this:
1288 // %alloca = alloca <type>, <alignment>
1289 // ... some code ...
1290 // %val1 = bitcast <type>* %alloca to i8*
1291 // call void @llvm.lifetime.start(i64 <size>, i8* %val1)
1292 // ... more code ...
1293 // %val2 = bitcast <type>* %alloca to i8*
1294 // call void @llvm.lifetime.start(i64 <size>, i8* %val2)
1295 // That is, to handle %alloca we must find all its casts to
1296 // i8* values, and find lifetime instructions for these values.
1297 if (AllocaType == Int8PtrTy)
1298 Res |= handleValueLifetime(Alloca);
1299 for (Value::use_iterator UI = Alloca->use_begin(), UE = Alloca->use_end();
1301 if (UI->getType() != Int8PtrTy) continue;
1302 if (UI->stripPointerCasts() != Alloca) continue;
1303 Res |= handleValueLifetime(*UI);
1308 bool FunctionStackPoisoner::handleValueLifetime(Value *V) {
1309 assert(ASan.CheckLifetime);
1311 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
1313 IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI);
1315 Intrinsic::ID ID = II->getIntrinsicID();
1316 if (ID != Intrinsic::lifetime_start &&
1317 ID != Intrinsic::lifetime_end)
1319 if (V != II->getArgOperand(1))
1321 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1322 ConstantInt *Size = dyn_cast<ConstantInt>(II->getArgOperand(0));
1323 // If size argument is undefined, don't do anything.
1324 if (Size->isMinusOne())
1326 // Check that size doesn't saturate uint64_t and can
1327 // be stored in IntptrTy.
1328 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1329 if (SizeValue == ~0ULL ||
1330 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) {
1333 IRBuilder<> IRB(II);
1334 bool DoPoison = (ID == Intrinsic::lifetime_end);
1335 poisonAlloca(V, SizeValue, IRB, DoPoison);