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/Statistic.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/DIBuilder.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/Function.h"
32 #include "llvm/IR/IRBuilder.h"
33 #include "llvm/IR/InlineAsm.h"
34 #include "llvm/IR/IntrinsicInst.h"
35 #include "llvm/IR/LLVMContext.h"
36 #include "llvm/IR/Module.h"
37 #include "llvm/IR/Type.h"
38 #include "llvm/InstVisitor.h"
39 #include "llvm/Support/CallSite.h"
40 #include "llvm/Support/CommandLine.h"
41 #include "llvm/Support/DataTypes.h"
42 #include "llvm/Support/Debug.h"
43 #include "llvm/Support/Endian.h"
44 #include "llvm/Support/raw_ostream.h"
45 #include "llvm/Support/system_error.h"
46 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
47 #include "llvm/Transforms/Utils/Cloning.h"
48 #include "llvm/Transforms/Utils/Local.h"
49 #include "llvm/Transforms/Utils/ModuleUtils.h"
50 #include "llvm/Transforms/Utils/SpecialCaseList.h"
56 static const uint64_t kDefaultShadowScale = 3;
57 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
58 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
59 static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
60 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
61 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
63 static const size_t kMinStackMallocSize = 1 << 6; // 64B
64 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
65 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
66 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
68 static const char *const kAsanModuleCtorName = "asan.module_ctor";
69 static const char *const kAsanModuleDtorName = "asan.module_dtor";
70 static const int kAsanCtorAndCtorPriority = 1;
71 static const char *const kAsanReportErrorTemplate = "__asan_report_";
72 static const char *const kAsanReportLoadN = "__asan_report_load_n";
73 static const char *const kAsanReportStoreN = "__asan_report_store_n";
74 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
75 static const char *const kAsanUnregisterGlobalsName =
76 "__asan_unregister_globals";
77 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
78 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
79 static const char *const kAsanInitName = "__asan_init_v3";
80 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
81 static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
82 static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
83 static const int kMaxAsanStackMallocSizeClass = 10;
84 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
85 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
86 static const char *const kAsanGenPrefix = "__asan_gen_";
87 static const char *const kAsanPoisonStackMemoryName =
88 "__asan_poison_stack_memory";
89 static const char *const kAsanUnpoisonStackMemoryName =
90 "__asan_unpoison_stack_memory";
92 static const char *const kAsanOptionDetectUAR =
93 "__asan_option_detect_stack_use_after_return";
95 // These constants must match the definitions in the run-time library.
96 static const int kAsanStackLeftRedzoneMagic = 0xf1;
97 static const int kAsanStackMidRedzoneMagic = 0xf2;
98 static const int kAsanStackRightRedzoneMagic = 0xf3;
99 static const int kAsanStackPartialRedzoneMagic = 0xf4;
101 static const int kAsanStackAfterReturnMagic = 0xf5;
104 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105 static const size_t kNumberOfAccessSizes = 5;
107 // Command-line flags.
109 // This flag may need to be replaced with -f[no-]asan-reads.
110 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
111 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
112 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
113 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
114 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
115 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
116 cl::Hidden, cl::init(true));
117 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
118 cl::desc("use instrumentation with slow path for all accesses"),
119 cl::Hidden, cl::init(false));
120 // This flag limits the number of instructions to be instrumented
121 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
122 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
124 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
126 cl::desc("maximal number of instructions to instrument in any given BB"),
128 // This flag may need to be replaced with -f[no]asan-stack.
129 static cl::opt<bool> ClStack("asan-stack",
130 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
131 // This flag may need to be replaced with -f[no]asan-use-after-return.
132 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
134 // This flag may need to be replaced with -f[no]asan-globals.
135 static cl::opt<bool> ClGlobals("asan-globals",
136 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
137 static cl::opt<bool> ClInitializers("asan-initialization-order",
138 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
139 static cl::opt<bool> ClMemIntrin("asan-memintrin",
140 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
141 static cl::opt<bool> ClRealignStack("asan-realign-stack",
142 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
143 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
144 cl::desc("File containing the list of objects to ignore "
145 "during instrumentation"), cl::Hidden);
147 // This is an experimental feature that will allow to choose between
148 // instrumented and non-instrumented code at link-time.
149 // If this option is on, just before instrumenting a function we create its
150 // clone; if the function is not changed by asan the clone is deleted.
151 // If we end up with a clone, we put the instrumented function into a section
152 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
154 // This is still a prototype, we need to figure out a way to keep two copies of
155 // a function so that the linker can easily choose one of them.
156 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
157 cl::desc("Keep uninstrumented copies of functions"),
158 cl::Hidden, cl::init(false));
160 // These flags allow to change the shadow mapping.
161 // The shadow mapping looks like
162 // Shadow = (Mem >> scale) + (1 << offset_log)
163 static cl::opt<int> ClMappingScale("asan-mapping-scale",
164 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
165 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
166 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
167 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
168 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
169 cl::Hidden, cl::init(true));
171 // Optimization flags. Not user visible, used mostly for testing
172 // and benchmarking the tool.
173 static cl::opt<bool> ClOpt("asan-opt",
174 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
175 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
176 cl::desc("Instrument the same temp just once"), cl::Hidden,
178 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
179 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
181 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
182 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
183 cl::Hidden, cl::init(false));
186 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
188 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
189 cl::Hidden, cl::init(0));
190 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
191 cl::Hidden, cl::desc("Debug func"));
192 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
193 cl::Hidden, cl::init(-1));
194 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
195 cl::Hidden, cl::init(-1));
197 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
198 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
199 STATISTIC(NumOptimizedAccessesToGlobalArray,
200 "Number of optimized accesses to global arrays");
201 STATISTIC(NumOptimizedAccessesToGlobalVar,
202 "Number of optimized accesses to global vars");
205 /// A set of dynamically initialized globals extracted from metadata.
206 class SetOfDynamicallyInitializedGlobals {
208 void Init(Module& M) {
209 // Clang generates metadata identifying all dynamically initialized globals.
210 NamedMDNode *DynamicGlobals =
211 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
214 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
215 MDNode *MDN = DynamicGlobals->getOperand(i);
216 assert(MDN->getNumOperands() == 1);
217 Value *VG = MDN->getOperand(0);
218 // The optimizer may optimize away a global entirely, in which case we
219 // cannot instrument access to it.
222 DynInitGlobals.insert(cast<GlobalVariable>(VG));
225 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
227 SmallSet<GlobalValue*, 32> DynInitGlobals;
230 /// This struct defines the shadow mapping using the rule:
231 /// shadow = (mem >> Scale) ADD-or-OR Offset.
232 struct ShadowMapping {
238 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
239 bool ZeroBaseShadow) {
240 llvm::Triple TargetTriple(M.getTargetTriple());
241 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
242 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
243 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
244 TargetTriple.getArch() == llvm::Triple::ppc64le;
245 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
246 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
247 TargetTriple.getArch() == llvm::Triple::mipsel;
249 ShadowMapping Mapping;
251 // OR-ing shadow offset if more efficient (at least on x86),
252 // but on ppc64 we have to use add since the shadow offset is not neccesary
253 // 1/8-th of the address space.
254 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
256 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
258 (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
259 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
260 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
261 assert(LongSize == 64);
262 Mapping.Offset = kDefaultShort64bitShadowOffset;
264 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
265 // Zero offset log is the special case.
266 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
269 Mapping.Scale = kDefaultShadowScale;
270 if (ClMappingScale) {
271 Mapping.Scale = ClMappingScale;
277 static size_t RedzoneSizeForScale(int MappingScale) {
278 // Redzone used for stack and globals is at least 32 bytes.
279 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
280 return std::max(32U, 1U << MappingScale);
283 /// AddressSanitizer: instrument the code in module to find memory bugs.
284 struct AddressSanitizer : public FunctionPass {
285 AddressSanitizer(bool CheckInitOrder = true,
286 bool CheckUseAfterReturn = false,
287 bool CheckLifetime = false,
288 StringRef BlacklistFile = StringRef(),
289 bool ZeroBaseShadow = false)
291 CheckInitOrder(CheckInitOrder || ClInitializers),
292 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
293 CheckLifetime(CheckLifetime || ClCheckLifetime),
294 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
296 ZeroBaseShadow(ZeroBaseShadow) {}
297 virtual const char *getPassName() const {
298 return "AddressSanitizerFunctionPass";
300 void instrumentMop(Instruction *I);
301 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
302 Value *Addr, uint32_t TypeSize, bool IsWrite,
303 Value *SizeArgument);
304 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
305 Value *ShadowValue, uint32_t TypeSize);
306 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
307 bool IsWrite, size_t AccessSizeIndex,
308 Value *SizeArgument);
309 bool instrumentMemIntrinsic(MemIntrinsic *MI);
310 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
312 Instruction *InsertBefore, bool IsWrite);
313 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
314 bool runOnFunction(Function &F);
315 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
316 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
317 virtual bool doInitialization(Module &M);
318 static char ID; // Pass identification, replacement for typeid
321 void initializeCallbacks(Module &M);
323 bool ShouldInstrumentGlobal(GlobalVariable *G);
324 bool LooksLikeCodeInBug11395(Instruction *I);
325 void FindDynamicInitializers(Module &M);
326 bool GlobalIsLinkerInitialized(GlobalVariable *G);
329 bool CheckUseAfterReturn;
331 SmallString<64> BlacklistFile;
338 ShadowMapping Mapping;
339 Function *AsanCtorFunction;
340 Function *AsanInitFunction;
341 Function *AsanHandleNoReturnFunc;
342 OwningPtr<SpecialCaseList> BL;
343 // This array is indexed by AccessIsWrite and log2(AccessSize).
344 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
345 // This array is indexed by AccessIsWrite.
346 Function *AsanErrorCallbackSized[2];
348 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
350 friend struct FunctionStackPoisoner;
353 class AddressSanitizerModule : public ModulePass {
355 AddressSanitizerModule(bool CheckInitOrder = true,
356 StringRef BlacklistFile = StringRef(),
357 bool ZeroBaseShadow = false)
359 CheckInitOrder(CheckInitOrder || ClInitializers),
360 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
362 ZeroBaseShadow(ZeroBaseShadow) {}
363 bool runOnModule(Module &M);
364 static char ID; // Pass identification, replacement for typeid
365 virtual const char *getPassName() const {
366 return "AddressSanitizerModule";
370 void initializeCallbacks(Module &M);
372 bool ShouldInstrumentGlobal(GlobalVariable *G);
373 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
374 size_t RedzoneSize() const {
375 return RedzoneSizeForScale(Mapping.Scale);
379 SmallString<64> BlacklistFile;
382 OwningPtr<SpecialCaseList> BL;
383 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
387 ShadowMapping Mapping;
388 Function *AsanPoisonGlobals;
389 Function *AsanUnpoisonGlobals;
390 Function *AsanRegisterGlobals;
391 Function *AsanUnregisterGlobals;
394 // Stack poisoning does not play well with exception handling.
395 // When an exception is thrown, we essentially bypass the code
396 // that unpoisones the stack. This is why the run-time library has
397 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
398 // stack in the interceptor. This however does not work inside the
399 // actual function which catches the exception. Most likely because the
400 // compiler hoists the load of the shadow value somewhere too high.
401 // This causes asan to report a non-existing bug on 453.povray.
402 // It sounds like an LLVM bug.
403 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
405 AddressSanitizer &ASan;
410 ShadowMapping Mapping;
412 SmallVector<AllocaInst*, 16> AllocaVec;
413 SmallVector<Instruction*, 8> RetVec;
414 uint64_t TotalStackSize;
415 unsigned StackAlignment;
417 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
418 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
419 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
421 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
422 struct AllocaPoisonCall {
423 IntrinsicInst *InsBefore;
427 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
429 // Maps Value to an AllocaInst from which the Value is originated.
430 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
431 AllocaForValueMapTy AllocaForValue;
433 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
434 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
435 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
436 Mapping(ASan.Mapping),
437 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
439 bool runOnFunction() {
440 if (!ClStack) return false;
441 // Collect alloca, ret, lifetime instructions etc.
442 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
443 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
444 BasicBlock *BB = *DI;
447 if (AllocaVec.empty()) return false;
449 initializeCallbacks(*F.getParent());
459 // Finds all static Alloca instructions and puts
460 // poisoned red zones around all of them.
461 // Then unpoison everything back before the function returns.
464 // ----------------------- Visitors.
465 /// \brief Collect all Ret instructions.
466 void visitReturnInst(ReturnInst &RI) {
467 RetVec.push_back(&RI);
470 /// \brief Collect Alloca instructions we want (and can) handle.
471 void visitAllocaInst(AllocaInst &AI) {
472 if (!isInterestingAlloca(AI)) return;
474 StackAlignment = std::max(StackAlignment, AI.getAlignment());
475 AllocaVec.push_back(&AI);
476 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
477 TotalStackSize += AlignedSize;
480 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
482 void visitIntrinsicInst(IntrinsicInst &II) {
483 if (!ASan.CheckLifetime) return;
484 Intrinsic::ID ID = II.getIntrinsicID();
485 if (ID != Intrinsic::lifetime_start &&
486 ID != Intrinsic::lifetime_end)
488 // Found lifetime intrinsic, add ASan instrumentation if necessary.
489 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
490 // If size argument is undefined, don't do anything.
491 if (Size->isMinusOne()) return;
492 // Check that size doesn't saturate uint64_t and can
493 // be stored in IntptrTy.
494 const uint64_t SizeValue = Size->getValue().getLimitedValue();
495 if (SizeValue == ~0ULL ||
496 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
498 // Find alloca instruction that corresponds to llvm.lifetime argument.
499 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
501 bool DoPoison = (ID == Intrinsic::lifetime_end);
502 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
503 AllocaPoisonCallVec.push_back(APC);
506 // ---------------------- Helpers.
507 void initializeCallbacks(Module &M);
509 // Check if we want (and can) handle this alloca.
510 bool isInterestingAlloca(AllocaInst &AI) const {
511 return (!AI.isArrayAllocation() &&
512 AI.isStaticAlloca() &&
513 AI.getAlignment() <= RedzoneSize() &&
514 AI.getAllocatedType()->isSized());
517 size_t RedzoneSize() const {
518 return RedzoneSizeForScale(Mapping.Scale);
520 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
521 Type *Ty = AI->getAllocatedType();
522 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
525 uint64_t getAlignedSize(uint64_t SizeInBytes) const {
526 size_t RZ = RedzoneSize();
527 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
529 uint64_t getAlignedAllocaSize(AllocaInst *AI) const {
530 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
531 return getAlignedSize(SizeInBytes);
533 /// Finds alloca where the value comes from.
534 AllocaInst *findAllocaForValue(Value *V);
535 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB,
536 Value *ShadowBase, bool DoPoison);
537 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
539 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
545 char AddressSanitizer::ID = 0;
546 INITIALIZE_PASS(AddressSanitizer, "asan",
547 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
549 FunctionPass *llvm::createAddressSanitizerFunctionPass(
550 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
551 StringRef BlacklistFile, bool ZeroBaseShadow) {
552 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
553 CheckLifetime, BlacklistFile, ZeroBaseShadow);
556 char AddressSanitizerModule::ID = 0;
557 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
558 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
559 "ModulePass", false, false)
560 ModulePass *llvm::createAddressSanitizerModulePass(
561 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
562 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
566 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
567 size_t Res = countTrailingZeros(TypeSize / 8);
568 assert(Res < kNumberOfAccessSizes);
572 // \brief Create a constant for Str so that we can pass it to the run-time lib.
573 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
574 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
575 GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
576 GlobalValue::InternalLinkage, StrConst,
578 GV->setUnnamedAddr(true); // Ok to merge these.
579 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
583 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
584 return G->getName().find(kAsanGenPrefix) == 0;
587 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
589 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
590 if (Mapping.Offset == 0)
592 // (Shadow >> scale) | offset
593 if (Mapping.OrShadowOffset)
594 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
596 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
599 void AddressSanitizer::instrumentMemIntrinsicParam(
600 Instruction *OrigIns,
601 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
602 IRBuilder<> IRB(InsertBefore);
603 if (Size->getType() != IntptrTy)
604 Size = IRB.CreateIntCast(Size, IntptrTy, false);
605 // Check the first byte.
606 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
607 // Check the last byte.
608 IRB.SetInsertPoint(InsertBefore);
609 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
610 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
611 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
612 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
615 // Instrument memset/memmove/memcpy
616 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
617 Value *Dst = MI->getDest();
618 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
619 Value *Src = MemTran ? MemTran->getSource() : 0;
620 Value *Length = MI->getLength();
622 Constant *ConstLength = dyn_cast<Constant>(Length);
623 Instruction *InsertBefore = MI;
625 if (ConstLength->isNullValue()) return false;
627 // The size is not a constant so it could be zero -- check at run-time.
628 IRBuilder<> IRB(InsertBefore);
630 Value *Cmp = IRB.CreateICmpNE(Length,
631 Constant::getNullValue(Length->getType()));
632 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
635 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
637 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
641 // If I is an interesting memory access, return the PointerOperand
642 // and set IsWrite. Otherwise return NULL.
643 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
644 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
645 if (!ClInstrumentReads) return NULL;
647 return LI->getPointerOperand();
649 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
650 if (!ClInstrumentWrites) return NULL;
652 return SI->getPointerOperand();
654 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
655 if (!ClInstrumentAtomics) return NULL;
657 return RMW->getPointerOperand();
659 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
660 if (!ClInstrumentAtomics) return NULL;
662 return XCHG->getPointerOperand();
667 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
668 // If a global variable does not have dynamic initialization we don't
669 // have to instrument it. However, if a global does not have initializer
670 // at all, we assume it has dynamic initializer (in other TU).
671 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
674 void AddressSanitizer::instrumentMop(Instruction *I) {
675 bool IsWrite = false;
676 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
678 if (ClOpt && ClOptGlobals) {
679 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
680 // If initialization order checking is disabled, a simple access to a
681 // dynamically initialized global is always valid.
682 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
683 NumOptimizedAccessesToGlobalVar++;
687 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
688 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
689 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
690 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
691 NumOptimizedAccessesToGlobalArray++;
698 Type *OrigPtrTy = Addr->getType();
699 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
701 assert(OrigTy->isSized());
702 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
704 assert((TypeSize % 8) == 0);
707 NumInstrumentedWrites++;
709 NumInstrumentedReads++;
711 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
712 if (TypeSize == 8 || TypeSize == 16 ||
713 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
714 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
715 // Instrument unusual size (but still multiple of 8).
716 // We can not do it with a single check, so we do 1-byte check for the first
717 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
718 // to report the actual access size.
720 Value *LastByte = IRB.CreateIntToPtr(
721 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
722 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
724 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
725 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
726 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
729 // Validate the result of Module::getOrInsertFunction called for an interface
730 // function of AddressSanitizer. If the instrumented module defines a function
731 // with the same name, their prototypes must match, otherwise
732 // getOrInsertFunction returns a bitcast.
733 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
734 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
735 FuncOrBitcast->dump();
736 report_fatal_error("trying to redefine an AddressSanitizer "
737 "interface function");
740 Instruction *AddressSanitizer::generateCrashCode(
741 Instruction *InsertBefore, Value *Addr,
742 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
743 IRBuilder<> IRB(InsertBefore);
744 CallInst *Call = SizeArgument
745 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
746 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
748 // We don't do Call->setDoesNotReturn() because the BB already has
749 // UnreachableInst at the end.
750 // This EmptyAsm is required to avoid callback merge.
751 IRB.CreateCall(EmptyAsm);
755 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
758 size_t Granularity = 1 << Mapping.Scale;
759 // Addr & (Granularity - 1)
760 Value *LastAccessedByte = IRB.CreateAnd(
761 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
762 // (Addr & (Granularity - 1)) + size - 1
763 if (TypeSize / 8 > 1)
764 LastAccessedByte = IRB.CreateAdd(
765 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
766 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
767 LastAccessedByte = IRB.CreateIntCast(
768 LastAccessedByte, ShadowValue->getType(), false);
769 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
770 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
773 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
774 Instruction *InsertBefore,
775 Value *Addr, uint32_t TypeSize,
776 bool IsWrite, Value *SizeArgument) {
777 IRBuilder<> IRB(InsertBefore);
778 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
780 Type *ShadowTy = IntegerType::get(
781 *C, std::max(8U, TypeSize >> Mapping.Scale));
782 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
783 Value *ShadowPtr = memToShadow(AddrLong, IRB);
784 Value *CmpVal = Constant::getNullValue(ShadowTy);
785 Value *ShadowValue = IRB.CreateLoad(
786 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
788 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
789 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
790 size_t Granularity = 1 << Mapping.Scale;
791 TerminatorInst *CrashTerm = 0;
793 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
794 TerminatorInst *CheckTerm =
795 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
796 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
797 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
798 IRB.SetInsertPoint(CheckTerm);
799 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
800 BasicBlock *CrashBlock =
801 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
802 CrashTerm = new UnreachableInst(*C, CrashBlock);
803 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
804 ReplaceInstWithInst(CheckTerm, NewTerm);
806 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
809 Instruction *Crash = generateCrashCode(
810 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
811 Crash->setDebugLoc(OrigIns->getDebugLoc());
814 void AddressSanitizerModule::createInitializerPoisonCalls(
815 Module &M, GlobalValue *ModuleName) {
816 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
817 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
818 // If that function is not present, this TU contains no globals, or they have
819 // all been optimized away
823 // Set up the arguments to our poison/unpoison functions.
824 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
826 // Add a call to poison all external globals before the given function starts.
827 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
828 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
830 // Add calls to unpoison all globals before each return instruction.
831 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
833 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
834 CallInst::Create(AsanUnpoisonGlobals, "", RI);
839 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
840 Type *Ty = cast<PointerType>(G->getType())->getElementType();
841 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
843 if (BL->isIn(*G)) return false;
844 if (!Ty->isSized()) return false;
845 if (!G->hasInitializer()) return false;
846 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
847 // Touch only those globals that will not be defined in other modules.
848 // Don't handle ODR type linkages since other modules may be built w/o asan.
849 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
850 G->getLinkage() != GlobalVariable::PrivateLinkage &&
851 G->getLinkage() != GlobalVariable::InternalLinkage)
853 // Two problems with thread-locals:
854 // - The address of the main thread's copy can't be computed at link-time.
855 // - Need to poison all copies, not just the main thread's one.
856 if (G->isThreadLocal())
858 // For now, just ignore this Alloca if the alignment is large.
859 if (G->getAlignment() > RedzoneSize()) return false;
861 // Ignore all the globals with the names starting with "\01L_OBJC_".
862 // Many of those are put into the .cstring section. The linker compresses
863 // that section by removing the spare \0s after the string terminator, so
864 // our redzones get broken.
865 if ((G->getName().find("\01L_OBJC_") == 0) ||
866 (G->getName().find("\01l_OBJC_") == 0)) {
867 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
871 if (G->hasSection()) {
872 StringRef Section(G->getSection());
873 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
874 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
876 if ((Section.find("__OBJC,") == 0) ||
877 (Section.find("__DATA, __objc_") == 0)) {
878 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
881 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
882 // Constant CFString instances are compiled in the following way:
883 // -- the string buffer is emitted into
884 // __TEXT,__cstring,cstring_literals
885 // -- the constant NSConstantString structure referencing that buffer
886 // is placed into __DATA,__cfstring
887 // Therefore there's no point in placing redzones into __DATA,__cfstring.
888 // Moreover, it causes the linker to crash on OS X 10.7
889 if (Section.find("__DATA,__cfstring") == 0) {
890 DEBUG(dbgs() << "Ignoring CFString: " << *G);
898 void AddressSanitizerModule::initializeCallbacks(Module &M) {
900 // Declare our poisoning and unpoisoning functions.
901 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
902 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
903 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
904 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
905 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
906 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
907 // Declare functions that register/unregister globals.
908 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
909 kAsanRegisterGlobalsName, IRB.getVoidTy(),
910 IntptrTy, IntptrTy, NULL));
911 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
912 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
913 kAsanUnregisterGlobalsName,
914 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
915 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
918 // This function replaces all global variables with new variables that have
919 // trailing redzones. It also creates a function that poisons
920 // redzones and inserts this function into llvm.global_ctors.
921 bool AddressSanitizerModule::runOnModule(Module &M) {
922 if (!ClGlobals) return false;
923 TD = getAnalysisIfAvailable<DataLayout>();
926 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
927 if (BL->isIn(M)) return false;
928 C = &(M.getContext());
929 int LongSize = TD->getPointerSizeInBits();
930 IntptrTy = Type::getIntNTy(*C, LongSize);
931 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
932 initializeCallbacks(M);
933 DynamicallyInitializedGlobals.Init(M);
935 SmallVector<GlobalVariable *, 16> GlobalsToChange;
937 for (Module::GlobalListType::iterator G = M.global_begin(),
938 E = M.global_end(); G != E; ++G) {
939 if (ShouldInstrumentGlobal(G))
940 GlobalsToChange.push_back(G);
943 size_t n = GlobalsToChange.size();
944 if (n == 0) return false;
946 // A global is described by a structure
949 // size_t size_with_redzone;
951 // const char *module_name;
952 // size_t has_dynamic_init;
953 // We initialize an array of such structures and pass it to a run-time call.
954 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
956 IntptrTy, IntptrTy, NULL);
957 SmallVector<Constant *, 16> Initializers(n);
959 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
961 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
963 bool HasDynamicallyInitializedGlobals = false;
965 GlobalVariable *ModuleName = createPrivateGlobalForString(
966 M, M.getModuleIdentifier());
967 // We shouldn't merge same module names, as this string serves as unique
968 // module ID in runtime.
969 ModuleName->setUnnamedAddr(false);
971 for (size_t i = 0; i < n; i++) {
972 static const uint64_t kMaxGlobalRedzone = 1 << 18;
973 GlobalVariable *G = GlobalsToChange[i];
974 PointerType *PtrTy = cast<PointerType>(G->getType());
975 Type *Ty = PtrTy->getElementType();
976 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
977 uint64_t MinRZ = RedzoneSize();
978 // MinRZ <= RZ <= kMaxGlobalRedzone
979 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
980 uint64_t RZ = std::max(MinRZ,
981 std::min(kMaxGlobalRedzone,
982 (SizeInBytes / MinRZ / 4) * MinRZ));
983 uint64_t RightRedzoneSize = RZ;
985 if (SizeInBytes % MinRZ)
986 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
987 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
988 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
989 // Determine whether this global should be poisoned in initialization.
990 bool GlobalHasDynamicInitializer =
991 DynamicallyInitializedGlobals.Contains(G);
992 // Don't check initialization order if this global is blacklisted.
993 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
995 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
996 Constant *NewInitializer = ConstantStruct::get(
997 NewTy, G->getInitializer(),
998 Constant::getNullValue(RightRedZoneTy), NULL);
1000 GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
1002 // Create a new global variable with enough space for a redzone.
1003 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1004 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1005 Linkage = GlobalValue::InternalLinkage;
1006 GlobalVariable *NewGlobal = new GlobalVariable(
1007 M, NewTy, G->isConstant(), Linkage,
1008 NewInitializer, "", G, G->getThreadLocalMode());
1009 NewGlobal->copyAttributesFrom(G);
1010 NewGlobal->setAlignment(MinRZ);
1013 Indices2[0] = IRB.getInt32(0);
1014 Indices2[1] = IRB.getInt32(0);
1016 G->replaceAllUsesWith(
1017 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1018 NewGlobal->takeName(G);
1019 G->eraseFromParent();
1021 Initializers[i] = ConstantStruct::get(
1023 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1024 ConstantInt::get(IntptrTy, SizeInBytes),
1025 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1026 ConstantExpr::getPointerCast(Name, IntptrTy),
1027 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1028 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1031 // Populate the first and last globals declared in this TU.
1032 if (CheckInitOrder && GlobalHasDynamicInitializer)
1033 HasDynamicallyInitializedGlobals = true;
1035 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1038 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1039 GlobalVariable *AllGlobals = new GlobalVariable(
1040 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1041 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1043 // Create calls for poisoning before initializers run and unpoisoning after.
1044 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1045 createInitializerPoisonCalls(M, ModuleName);
1046 IRB.CreateCall2(AsanRegisterGlobals,
1047 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1048 ConstantInt::get(IntptrTy, n));
1050 // We also need to unregister globals at the end, e.g. when a shared library
1052 Function *AsanDtorFunction = Function::Create(
1053 FunctionType::get(Type::getVoidTy(*C), false),
1054 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1055 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1056 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1057 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1058 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1059 ConstantInt::get(IntptrTy, n));
1060 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1066 void AddressSanitizer::initializeCallbacks(Module &M) {
1067 IRBuilder<> IRB(*C);
1068 // Create __asan_report* callbacks.
1069 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1070 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1071 AccessSizeIndex++) {
1072 // IsWrite and TypeSize are encoded in the function name.
1073 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1074 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1075 // If we are merging crash callbacks, they have two parameters.
1076 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1077 checkInterfaceFunction(M.getOrInsertFunction(
1078 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1081 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1082 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1083 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1084 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1086 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1087 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1088 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1089 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1090 StringRef(""), StringRef(""),
1091 /*hasSideEffects=*/true);
1094 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1095 // Tell the values of mapping offset and scale to the run-time.
1096 GlobalValue *asan_mapping_offset =
1097 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1098 ConstantInt::get(IntptrTy, Mapping.Offset),
1099 kAsanMappingOffsetName);
1100 // Read the global, otherwise it may be optimized away.
1101 IRB.CreateLoad(asan_mapping_offset, true);
1103 GlobalValue *asan_mapping_scale =
1104 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1105 ConstantInt::get(IntptrTy, Mapping.Scale),
1106 kAsanMappingScaleName);
1107 // Read the global, otherwise it may be optimized away.
1108 IRB.CreateLoad(asan_mapping_scale, true);
1112 bool AddressSanitizer::doInitialization(Module &M) {
1113 // Initialize the private fields. No one has accessed them before.
1114 TD = getAnalysisIfAvailable<DataLayout>();
1118 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1119 DynamicallyInitializedGlobals.Init(M);
1121 C = &(M.getContext());
1122 LongSize = TD->getPointerSizeInBits();
1123 IntptrTy = Type::getIntNTy(*C, LongSize);
1125 AsanCtorFunction = Function::Create(
1126 FunctionType::get(Type::getVoidTy(*C), false),
1127 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1128 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1129 // call __asan_init in the module ctor.
1130 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1131 AsanInitFunction = checkInterfaceFunction(
1132 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1133 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1134 IRB.CreateCall(AsanInitFunction);
1136 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1137 emitShadowMapping(M, IRB);
1139 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1143 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1144 // For each NSObject descendant having a +load method, this method is invoked
1145 // by the ObjC runtime before any of the static constructors is called.
1146 // Therefore we need to instrument such methods with a call to __asan_init
1147 // at the beginning in order to initialize our runtime before any access to
1148 // the shadow memory.
1149 // We cannot just ignore these methods, because they may call other
1150 // instrumented functions.
1151 if (F.getName().find(" load]") != std::string::npos) {
1152 IRBuilder<> IRB(F.begin()->begin());
1153 IRB.CreateCall(AsanInitFunction);
1159 bool AddressSanitizer::runOnFunction(Function &F) {
1160 if (BL->isIn(F)) return false;
1161 if (&F == AsanCtorFunction) return false;
1162 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1163 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1164 initializeCallbacks(*F.getParent());
1166 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1167 maybeInsertAsanInitAtFunctionEntry(F);
1169 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1172 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1175 // We want to instrument every address only once per basic block (unless there
1176 // are calls between uses).
1177 SmallSet<Value*, 16> TempsToInstrument;
1178 SmallVector<Instruction*, 16> ToInstrument;
1179 SmallVector<Instruction*, 8> NoReturnCalls;
1183 // Fill the set of memory operations to instrument.
1184 for (Function::iterator FI = F.begin(), FE = F.end();
1186 TempsToInstrument.clear();
1187 int NumInsnsPerBB = 0;
1188 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1190 if (LooksLikeCodeInBug11395(BI)) return false;
1191 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1192 if (ClOpt && ClOptSameTemp) {
1193 if (!TempsToInstrument.insert(Addr))
1194 continue; // We've seen this temp in the current BB.
1196 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1199 if (isa<AllocaInst>(BI))
1203 // A call inside BB.
1204 TempsToInstrument.clear();
1205 if (CS.doesNotReturn())
1206 NoReturnCalls.push_back(CS.getInstruction());
1210 ToInstrument.push_back(BI);
1212 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1217 Function *UninstrumentedDuplicate = 0;
1218 bool LikelyToInstrument =
1219 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1220 if (ClKeepUninstrumented && LikelyToInstrument) {
1221 ValueToValueMapTy VMap;
1222 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1223 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1224 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1225 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1229 int NumInstrumented = 0;
1230 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1231 Instruction *Inst = ToInstrument[i];
1232 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1233 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1234 if (isInterestingMemoryAccess(Inst, &IsWrite))
1235 instrumentMop(Inst);
1237 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1242 FunctionStackPoisoner FSP(F, *this);
1243 bool ChangedStack = FSP.runOnFunction();
1245 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1246 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1247 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1248 Instruction *CI = NoReturnCalls[i];
1249 IRBuilder<> IRB(CI);
1250 IRB.CreateCall(AsanHandleNoReturnFunc);
1253 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1254 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1256 if (ClKeepUninstrumented) {
1258 // No instrumentation is done, no need for the duplicate.
1259 if (UninstrumentedDuplicate)
1260 UninstrumentedDuplicate->eraseFromParent();
1262 // The function was instrumented. We must have the duplicate.
1263 assert(UninstrumentedDuplicate);
1264 UninstrumentedDuplicate->setSection("NOASAN");
1265 assert(!F.hasSection());
1266 F.setSection("ASAN");
1273 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1274 if (ShadowRedzoneSize == 1) return PoisonByte;
1275 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1276 if (ShadowRedzoneSize == 4)
1277 return (PoisonByte << 24) + (PoisonByte << 16) +
1278 (PoisonByte << 8) + (PoisonByte);
1279 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1282 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1285 size_t ShadowGranularity,
1287 for (size_t i = 0; i < RZSize;
1288 i+= ShadowGranularity, Shadow++) {
1289 if (i + ShadowGranularity <= Size) {
1290 *Shadow = 0; // fully addressable
1291 } else if (i >= Size) {
1292 *Shadow = Magic; // unaddressable
1294 *Shadow = Size - i; // first Size-i bytes are addressable
1299 // Workaround for bug 11395: we don't want to instrument stack in functions
1300 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1301 // FIXME: remove once the bug 11395 is fixed.
1302 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1303 if (LongSize != 32) return false;
1304 CallInst *CI = dyn_cast<CallInst>(I);
1305 if (!CI || !CI->isInlineAsm()) return false;
1306 if (CI->getNumArgOperands() <= 5) return false;
1307 // We have inline assembly with quite a few arguments.
1311 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1312 IRBuilder<> IRB(*C);
1313 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1314 std::string Suffix = itostr(i);
1315 AsanStackMallocFunc[i] = checkInterfaceFunction(
1316 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1317 IntptrTy, IntptrTy, NULL));
1318 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1319 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1320 IntptrTy, IntptrTy, NULL));
1322 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1323 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1324 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1325 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1328 void FunctionStackPoisoner::poisonRedZones(
1329 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB, Value *ShadowBase,
1331 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1332 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1333 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1334 Type *RZPtrTy = PointerType::get(RZTy, 0);
1336 Value *PoisonLeft = ConstantInt::get(RZTy,
1337 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1338 Value *PoisonMid = ConstantInt::get(RZTy,
1339 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1340 Value *PoisonRight = ConstantInt::get(RZTy,
1341 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1343 // poison the first red zone.
1344 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1346 // poison all other red zones.
1347 uint64_t Pos = RedzoneSize();
1348 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1349 AllocaInst *AI = AllocaVec[i];
1350 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1351 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1352 assert(AlignedSize - SizeInBytes < RedzoneSize());
1357 assert(ShadowBase->getType() == IntptrTy);
1358 if (SizeInBytes < AlignedSize) {
1359 // Poison the partial redzone at right
1360 Ptr = IRB.CreateAdd(
1361 ShadowBase, ConstantInt::get(IntptrTy,
1362 (Pos >> Mapping.Scale) - ShadowRZSize));
1363 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1364 uint32_t Poison = 0;
1366 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1368 1ULL << Mapping.Scale,
1369 kAsanStackPartialRedzoneMagic);
1371 ASan.TD->isLittleEndian()
1372 ? support::endian::byte_swap<uint32_t, support::little>(Poison)
1373 : support::endian::byte_swap<uint32_t, support::big>(Poison);
1375 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1376 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1379 // Poison the full redzone at right.
1380 Ptr = IRB.CreateAdd(ShadowBase,
1381 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1382 bool LastAlloca = (i == AllocaVec.size() - 1);
1383 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1384 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1386 Pos += RedzoneSize();
1390 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1391 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1392 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1393 assert(LocalStackSize <= kMaxStackMallocSize);
1394 uint64_t MaxSize = kMinStackMallocSize;
1395 for (int i = 0; ; i++, MaxSize *= 2)
1396 if (LocalStackSize <= MaxSize)
1398 llvm_unreachable("impossible LocalStackSize");
1401 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1402 // We can not use MemSet intrinsic because it may end up calling the actual
1403 // memset. Size is a multiple of 8.
1404 // Currently this generates 8-byte stores on x86_64; it may be better to
1405 // generate wider stores.
1406 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1407 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1408 assert(!(Size % 8));
1409 assert(kAsanStackAfterReturnMagic == 0xf5);
1410 for (int i = 0; i < Size; i += 8) {
1411 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1412 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1413 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1417 void FunctionStackPoisoner::poisonStack() {
1418 uint64_t LocalStackSize = TotalStackSize +
1419 (AllocaVec.size() + 1) * RedzoneSize();
1421 bool DoStackMalloc = ASan.CheckUseAfterReturn
1422 && LocalStackSize <= kMaxStackMallocSize;
1423 int StackMallocIdx = -1;
1425 assert(AllocaVec.size() > 0);
1426 Instruction *InsBefore = AllocaVec[0];
1427 IRBuilder<> IRB(InsBefore);
1430 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1431 AllocaInst *MyAlloca =
1432 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1433 if (ClRealignStack && StackAlignment < RedzoneSize())
1434 StackAlignment = RedzoneSize();
1435 MyAlloca->setAlignment(StackAlignment);
1436 assert(MyAlloca->isStaticAlloca());
1437 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1438 Value *LocalStackBase = OrigStackBase;
1440 if (DoStackMalloc) {
1441 // LocalStackBase = OrigStackBase
1442 // if (__asan_option_detect_stack_use_after_return)
1443 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1444 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1445 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1446 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1447 kAsanOptionDetectUAR, IRB.getInt32Ty());
1448 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1449 Constant::getNullValue(IRB.getInt32Ty()));
1451 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
1452 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1453 IRBuilder<> IRBIf(Term);
1454 LocalStackBase = IRBIf.CreateCall2(
1455 AsanStackMallocFunc[StackMallocIdx],
1456 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1457 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1458 IRB.SetInsertPoint(InsBefore);
1459 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1460 Phi->addIncoming(OrigStackBase, CmpBlock);
1461 Phi->addIncoming(LocalStackBase, SetBlock);
1462 LocalStackBase = Phi;
1465 // This string will be parsed by the run-time (DescribeAddressIfStack).
1466 SmallString<2048> StackDescriptionStorage;
1467 raw_svector_ostream StackDescription(StackDescriptionStorage);
1468 StackDescription << AllocaVec.size() << " ";
1470 // Insert poison calls for lifetime intrinsics for alloca.
1471 bool HavePoisonedAllocas = false;
1472 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1473 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1474 IntrinsicInst *II = APC.InsBefore;
1475 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1477 IRBuilder<> IRB(II);
1478 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1479 HavePoisonedAllocas |= APC.DoPoison;
1482 uint64_t Pos = RedzoneSize();
1483 // Replace Alloca instructions with base+offset.
1484 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1485 AllocaInst *AI = AllocaVec[i];
1486 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1487 StringRef Name = AI->getName();
1488 StackDescription << Pos << " " << SizeInBytes << " "
1489 << Name.size() << " " << Name << " ";
1490 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1491 assert((AlignedSize % RedzoneSize()) == 0);
1492 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1493 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1495 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1496 AI->replaceAllUsesWith(NewAllocaPtr);
1497 Pos += AlignedSize + RedzoneSize();
1499 assert(Pos == LocalStackSize);
1501 // The left-most redzone has enough space for at least 4 pointers.
1502 // Write the Magic value to redzone[0].
1503 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1504 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1506 // Write the frame description constant to redzone[1].
1507 Value *BasePlus1 = IRB.CreateIntToPtr(
1508 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1510 GlobalVariable *StackDescriptionGlobal =
1511 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1512 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1514 IRB.CreateStore(Description, BasePlus1);
1515 // Write the PC to redzone[2].
1516 Value *BasePlus2 = IRB.CreateIntToPtr(
1517 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1518 2 * ASan.LongSize/8)),
1520 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1522 // Poison the stack redzones at the entry.
1523 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1524 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1526 // Unpoison the stack before all ret instructions.
1527 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1528 Instruction *Ret = RetVec[i];
1529 IRBuilder<> IRBRet(Ret);
1530 // Mark the current frame as retired.
1531 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1533 // Unpoison the stack.
1534 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1535 if (DoStackMalloc) {
1536 assert(StackMallocIdx >= 0);
1537 // In use-after-return mode, mark the whole stack frame unaddressable.
1538 if (StackMallocIdx <= 4) {
1539 // For small sizes inline the whole thing:
1540 // if LocalStackBase != OrigStackBase:
1541 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1542 // **SavedFlagPtr(LocalStackBase) = 0
1543 // FIXME: if LocalStackBase != OrigStackBase don't call poisonRedZones.
1544 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1545 TerminatorInst *PoisonTerm =
1546 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
1547 IRBuilder<> IRBPoison(PoisonTerm);
1548 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1549 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1550 ClassSize >> Mapping.Scale);
1551 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1553 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1554 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1555 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1556 IRBPoison.CreateStore(
1557 Constant::getNullValue(IRBPoison.getInt8Ty()),
1558 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1560 // For larger frames call __asan_stack_free_*.
1561 IRBRet.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1562 ConstantInt::get(IntptrTy, LocalStackSize),
1565 } else if (HavePoisonedAllocas) {
1566 // If we poisoned some allocas in llvm.lifetime analysis,
1567 // unpoison whole stack frame now.
1568 assert(LocalStackBase == OrigStackBase);
1569 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1573 // We are done. Remove the old unused alloca instructions.
1574 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1575 AllocaVec[i]->eraseFromParent();
1578 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1579 IRBuilder<> &IRB, bool DoPoison) {
1580 // For now just insert the call to ASan runtime.
1581 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1582 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1583 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1584 : AsanUnpoisonStackMemoryFunc,
1588 // Handling llvm.lifetime intrinsics for a given %alloca:
1589 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1590 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1591 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1592 // could be poisoned by previous llvm.lifetime.end instruction, as the
1593 // variable may go in and out of scope several times, e.g. in loops).
1594 // (3) if we poisoned at least one %alloca in a function,
1595 // unpoison the whole stack frame at function exit.
1597 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1598 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1599 // We're intested only in allocas we can handle.
1600 return isInterestingAlloca(*AI) ? AI : 0;
1601 // See if we've already calculated (or started to calculate) alloca for a
1603 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1604 if (I != AllocaForValue.end())
1606 // Store 0 while we're calculating alloca for value V to avoid
1607 // infinite recursion if the value references itself.
1608 AllocaForValue[V] = 0;
1609 AllocaInst *Res = 0;
1610 if (CastInst *CI = dyn_cast<CastInst>(V))
1611 Res = findAllocaForValue(CI->getOperand(0));
1612 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1613 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1614 Value *IncValue = PN->getIncomingValue(i);
1615 // Allow self-referencing phi-nodes.
1616 if (IncValue == PN) continue;
1617 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1618 // AI for incoming values should exist and should all be equal.
1619 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1625 AllocaForValue[V] = Res;