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/system_error.h"
45 #include "llvm/Transforms/Utils/ASanStackFrameLayout.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 kAsanCovName = "__sanitizer_cov";
81 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
82 static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
83 static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
84 static const int kMaxAsanStackMallocSizeClass = 10;
85 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
86 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
87 static const char *const kAsanGenPrefix = "__asan_gen_";
88 static const char *const kAsanPoisonStackMemoryName =
89 "__asan_poison_stack_memory";
90 static const char *const kAsanUnpoisonStackMemoryName =
91 "__asan_unpoison_stack_memory";
93 static const char *const kAsanOptionDetectUAR =
94 "__asan_option_detect_stack_use_after_return";
97 static const int kAsanStackAfterReturnMagic = 0xf5;
100 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
101 static const size_t kNumberOfAccessSizes = 5;
103 // Command-line flags.
105 // This flag may need to be replaced with -f[no-]asan-reads.
106 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
107 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
108 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
109 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
110 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
111 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
112 cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
114 cl::desc("use instrumentation with slow path for all accesses"),
115 cl::Hidden, cl::init(false));
116 // This flag limits the number of instructions to be instrumented
117 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
118 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
120 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
122 cl::desc("maximal number of instructions to instrument in any given BB"),
124 // This flag may need to be replaced with -f[no]asan-stack.
125 static cl::opt<bool> ClStack("asan-stack",
126 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
127 // This flag may need to be replaced with -f[no]asan-use-after-return.
128 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
129 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
130 // This flag may need to be replaced with -f[no]asan-globals.
131 static cl::opt<bool> ClGlobals("asan-globals",
132 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
133 static cl::opt<bool> ClCoverage("asan-coverage",
134 cl::desc("ASan coverage"), cl::Hidden, cl::init(false));
135 static cl::opt<bool> ClInitializers("asan-initialization-order",
136 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
137 static cl::opt<bool> ClMemIntrin("asan-memintrin",
138 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
139 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
140 cl::desc("Realign stack to the value of this flag (power of two)"),
141 cl::Hidden, cl::init(32));
142 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
143 cl::desc("File containing the list of objects to ignore "
144 "during instrumentation"), cl::Hidden);
146 // This is an experimental feature that will allow to choose between
147 // instrumented and non-instrumented code at link-time.
148 // If this option is on, just before instrumenting a function we create its
149 // clone; if the function is not changed by asan the clone is deleted.
150 // If we end up with a clone, we put the instrumented function into a section
151 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
153 // This is still a prototype, we need to figure out a way to keep two copies of
154 // a function so that the linker can easily choose one of them.
155 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
156 cl::desc("Keep uninstrumented copies of functions"),
157 cl::Hidden, cl::init(false));
159 // These flags allow to change the shadow mapping.
160 // The shadow mapping looks like
161 // Shadow = (Mem >> scale) + (1 << offset_log)
162 static cl::opt<int> ClMappingScale("asan-mapping-scale",
163 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
164 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
165 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
166 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
167 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
168 cl::Hidden, cl::init(true));
170 // Optimization flags. Not user visible, used mostly for testing
171 // and benchmarking the tool.
172 static cl::opt<bool> ClOpt("asan-opt",
173 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
174 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
175 cl::desc("Instrument the same temp just once"), cl::Hidden,
177 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
178 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
180 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
181 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
182 cl::Hidden, cl::init(false));
185 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
187 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
188 cl::Hidden, cl::init(0));
189 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
190 cl::Hidden, cl::desc("Debug func"));
191 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
192 cl::Hidden, cl::init(-1));
193 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
194 cl::Hidden, cl::init(-1));
196 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
197 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
198 STATISTIC(NumOptimizedAccessesToGlobalArray,
199 "Number of optimized accesses to global arrays");
200 STATISTIC(NumOptimizedAccessesToGlobalVar,
201 "Number of optimized accesses to global vars");
204 /// A set of dynamically initialized globals extracted from metadata.
205 class SetOfDynamicallyInitializedGlobals {
207 void Init(Module& M) {
208 // Clang generates metadata identifying all dynamically initialized globals.
209 NamedMDNode *DynamicGlobals =
210 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
213 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
214 MDNode *MDN = DynamicGlobals->getOperand(i);
215 assert(MDN->getNumOperands() == 1);
216 Value *VG = MDN->getOperand(0);
217 // The optimizer may optimize away a global entirely, in which case we
218 // cannot instrument access to it.
221 DynInitGlobals.insert(cast<GlobalVariable>(VG));
224 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
226 SmallSet<GlobalValue*, 32> DynInitGlobals;
229 /// This struct defines the shadow mapping using the rule:
230 /// shadow = (mem >> Scale) ADD-or-OR Offset.
231 struct ShadowMapping {
237 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
238 llvm::Triple TargetTriple(M.getTargetTriple());
239 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
240 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
241 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
242 TargetTriple.getArch() == llvm::Triple::ppc64le;
243 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
244 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
245 TargetTriple.getArch() == llvm::Triple::mipsel;
247 ShadowMapping Mapping;
249 // OR-ing shadow offset if more efficient (at least on x86),
250 // but on ppc64 we have to use add since the shadow offset is not neccesary
251 // 1/8-th of the address space.
252 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
254 Mapping.Offset = IsAndroid ? 0 :
256 (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
257 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
258 if (!IsAndroid && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
259 assert(LongSize == 64);
260 Mapping.Offset = kDefaultShort64bitShadowOffset;
262 if (!IsAndroid && ClMappingOffsetLog >= 0) {
263 // Zero offset log is the special case.
264 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
267 Mapping.Scale = kDefaultShadowScale;
268 if (ClMappingScale) {
269 Mapping.Scale = ClMappingScale;
275 static size_t RedzoneSizeForScale(int MappingScale) {
276 // Redzone used for stack and globals is at least 32 bytes.
277 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
278 return std::max(32U, 1U << MappingScale);
281 /// AddressSanitizer: instrument the code in module to find memory bugs.
282 struct AddressSanitizer : public FunctionPass {
283 AddressSanitizer(bool CheckInitOrder = true,
284 bool CheckUseAfterReturn = false,
285 bool CheckLifetime = false,
286 StringRef BlacklistFile = StringRef())
288 CheckInitOrder(CheckInitOrder || ClInitializers),
289 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
290 CheckLifetime(CheckLifetime || ClCheckLifetime),
291 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
293 virtual const char *getPassName() const {
294 return "AddressSanitizerFunctionPass";
296 void instrumentMop(Instruction *I);
297 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
298 Value *Addr, uint32_t TypeSize, bool IsWrite,
299 Value *SizeArgument);
300 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
301 Value *ShadowValue, uint32_t TypeSize);
302 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
303 bool IsWrite, size_t AccessSizeIndex,
304 Value *SizeArgument);
305 bool instrumentMemIntrinsic(MemIntrinsic *MI);
306 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
308 Instruction *InsertBefore, bool IsWrite);
309 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
310 bool runOnFunction(Function &F);
311 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
312 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
313 virtual bool doInitialization(Module &M);
314 static char ID; // Pass identification, replacement for typeid
317 void initializeCallbacks(Module &M);
319 bool ShouldInstrumentGlobal(GlobalVariable *G);
320 bool LooksLikeCodeInBug11395(Instruction *I);
321 void FindDynamicInitializers(Module &M);
322 bool GlobalIsLinkerInitialized(GlobalVariable *G);
323 bool InjectCoverage(Function &F);
326 bool CheckUseAfterReturn;
328 SmallString<64> BlacklistFile;
334 ShadowMapping Mapping;
335 Function *AsanCtorFunction;
336 Function *AsanInitFunction;
337 Function *AsanHandleNoReturnFunc;
338 Function *AsanCovFunction;
339 OwningPtr<SpecialCaseList> BL;
340 // This array is indexed by AccessIsWrite and log2(AccessSize).
341 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
342 // This array is indexed by AccessIsWrite.
343 Function *AsanErrorCallbackSized[2];
345 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
347 friend struct FunctionStackPoisoner;
350 class AddressSanitizerModule : public ModulePass {
352 AddressSanitizerModule(bool CheckInitOrder = true,
353 StringRef BlacklistFile = StringRef())
355 CheckInitOrder(CheckInitOrder || ClInitializers),
356 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
358 bool runOnModule(Module &M);
359 static char ID; // Pass identification, replacement for typeid
360 virtual const char *getPassName() const {
361 return "AddressSanitizerModule";
365 void initializeCallbacks(Module &M);
367 bool ShouldInstrumentGlobal(GlobalVariable *G);
368 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
369 size_t MinRedzoneSizeForGlobal() const {
370 return RedzoneSizeForScale(Mapping.Scale);
374 SmallString<64> BlacklistFile;
376 OwningPtr<SpecialCaseList> BL;
377 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
381 ShadowMapping Mapping;
382 Function *AsanPoisonGlobals;
383 Function *AsanUnpoisonGlobals;
384 Function *AsanRegisterGlobals;
385 Function *AsanUnregisterGlobals;
388 // Stack poisoning does not play well with exception handling.
389 // When an exception is thrown, we essentially bypass the code
390 // that unpoisones the stack. This is why the run-time library has
391 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
392 // stack in the interceptor. This however does not work inside the
393 // actual function which catches the exception. Most likely because the
394 // compiler hoists the load of the shadow value somewhere too high.
395 // This causes asan to report a non-existing bug on 453.povray.
396 // It sounds like an LLVM bug.
397 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
399 AddressSanitizer &ASan;
404 ShadowMapping Mapping;
406 SmallVector<AllocaInst*, 16> AllocaVec;
407 SmallVector<Instruction*, 8> RetVec;
408 unsigned StackAlignment;
410 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
411 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
412 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
414 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
415 struct AllocaPoisonCall {
416 IntrinsicInst *InsBefore;
421 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
423 // Maps Value to an AllocaInst from which the Value is originated.
424 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
425 AllocaForValueMapTy AllocaForValue;
427 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
428 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
429 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
430 Mapping(ASan.Mapping),
431 StackAlignment(1 << Mapping.Scale) {}
433 bool runOnFunction() {
434 if (!ClStack) return false;
435 // Collect alloca, ret, lifetime instructions etc.
436 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
437 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
438 BasicBlock *BB = *DI;
441 if (AllocaVec.empty()) return false;
443 initializeCallbacks(*F.getParent());
453 // Finds all static Alloca instructions and puts
454 // poisoned red zones around all of them.
455 // Then unpoison everything back before the function returns.
458 // ----------------------- Visitors.
459 /// \brief Collect all Ret instructions.
460 void visitReturnInst(ReturnInst &RI) {
461 RetVec.push_back(&RI);
464 /// \brief Collect Alloca instructions we want (and can) handle.
465 void visitAllocaInst(AllocaInst &AI) {
466 if (!isInterestingAlloca(AI)) return;
468 StackAlignment = std::max(StackAlignment, AI.getAlignment());
469 AllocaVec.push_back(&AI);
472 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
474 void visitIntrinsicInst(IntrinsicInst &II) {
475 if (!ASan.CheckLifetime) return;
476 Intrinsic::ID ID = II.getIntrinsicID();
477 if (ID != Intrinsic::lifetime_start &&
478 ID != Intrinsic::lifetime_end)
480 // Found lifetime intrinsic, add ASan instrumentation if necessary.
481 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
482 // If size argument is undefined, don't do anything.
483 if (Size->isMinusOne()) return;
484 // Check that size doesn't saturate uint64_t and can
485 // be stored in IntptrTy.
486 const uint64_t SizeValue = Size->getValue().getLimitedValue();
487 if (SizeValue == ~0ULL ||
488 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
490 // Find alloca instruction that corresponds to llvm.lifetime argument.
491 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
493 bool DoPoison = (ID == Intrinsic::lifetime_end);
494 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
495 AllocaPoisonCallVec.push_back(APC);
498 // ---------------------- Helpers.
499 void initializeCallbacks(Module &M);
501 // Check if we want (and can) handle this alloca.
502 bool isInterestingAlloca(AllocaInst &AI) const {
503 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
504 AI.getAllocatedType()->isSized() &&
505 // alloca() may be called with 0 size, ignore it.
506 getAllocaSizeInBytes(&AI) > 0);
509 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
510 Type *Ty = AI->getAllocatedType();
511 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
514 /// Finds alloca where the value comes from.
515 AllocaInst *findAllocaForValue(Value *V);
516 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
517 Value *ShadowBase, bool DoPoison);
518 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
520 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
526 char AddressSanitizer::ID = 0;
527 INITIALIZE_PASS(AddressSanitizer, "asan",
528 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
530 FunctionPass *llvm::createAddressSanitizerFunctionPass(
531 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
532 StringRef BlacklistFile) {
533 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
534 CheckLifetime, BlacklistFile);
537 char AddressSanitizerModule::ID = 0;
538 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
539 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
540 "ModulePass", false, false)
541 ModulePass *llvm::createAddressSanitizerModulePass(
542 bool CheckInitOrder, StringRef BlacklistFile) {
543 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
546 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
547 size_t Res = countTrailingZeros(TypeSize / 8);
548 assert(Res < kNumberOfAccessSizes);
552 // \brief Create a constant for Str so that we can pass it to the run-time lib.
553 static GlobalVariable *createPrivateGlobalForString(
554 Module &M, StringRef Str, bool AllowMerging) {
555 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
556 // For module-local strings that can be merged with another one we set the
557 // private linkage and the unnamed_addr attribute.
558 // Non-mergeable strings are made linker_private to remove them from the
559 // symbol table. "private" linkage doesn't work for Darwin, where the
560 // "L"-prefixed globals end up in __TEXT,__const section
561 // (see http://llvm.org/bugs/show_bug.cgi?id=17976 for more info).
562 GlobalValue::LinkageTypes linkage =
563 AllowMerging ? GlobalValue::PrivateLinkage
564 : GlobalValue::LinkerPrivateLinkage;
566 new GlobalVariable(M, StrConst->getType(), true,
567 linkage, StrConst, kAsanGenPrefix);
568 if (AllowMerging) GV->setUnnamedAddr(true);
569 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
573 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
574 return G->getName().find(kAsanGenPrefix) == 0;
577 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
579 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
580 if (Mapping.Offset == 0)
582 // (Shadow >> scale) | offset
583 if (Mapping.OrShadowOffset)
584 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
586 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
589 void AddressSanitizer::instrumentMemIntrinsicParam(
590 Instruction *OrigIns,
591 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
592 IRBuilder<> IRB(InsertBefore);
593 if (Size->getType() != IntptrTy)
594 Size = IRB.CreateIntCast(Size, IntptrTy, false);
595 // Check the first byte.
596 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
597 // Check the last byte.
598 IRB.SetInsertPoint(InsertBefore);
599 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
600 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
601 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
602 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
605 // Instrument memset/memmove/memcpy
606 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
607 Value *Dst = MI->getDest();
608 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
609 Value *Src = MemTran ? MemTran->getSource() : 0;
610 Value *Length = MI->getLength();
612 Constant *ConstLength = dyn_cast<Constant>(Length);
613 Instruction *InsertBefore = MI;
615 if (ConstLength->isNullValue()) return false;
617 // The size is not a constant so it could be zero -- check at run-time.
618 IRBuilder<> IRB(InsertBefore);
620 Value *Cmp = IRB.CreateICmpNE(Length,
621 Constant::getNullValue(Length->getType()));
622 InsertBefore = SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
625 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
627 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
631 // If I is an interesting memory access, return the PointerOperand
632 // and set IsWrite. Otherwise return NULL.
633 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
634 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
635 if (!ClInstrumentReads) return NULL;
637 return LI->getPointerOperand();
639 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
640 if (!ClInstrumentWrites) return NULL;
642 return SI->getPointerOperand();
644 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
645 if (!ClInstrumentAtomics) return NULL;
647 return RMW->getPointerOperand();
649 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
650 if (!ClInstrumentAtomics) return NULL;
652 return XCHG->getPointerOperand();
657 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
658 // If a global variable does not have dynamic initialization we don't
659 // have to instrument it. However, if a global does not have initializer
660 // at all, we assume it has dynamic initializer (in other TU).
661 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
664 void AddressSanitizer::instrumentMop(Instruction *I) {
665 bool IsWrite = false;
666 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
668 if (ClOpt && ClOptGlobals) {
669 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
670 // If initialization order checking is disabled, a simple access to a
671 // dynamically initialized global is always valid.
672 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
673 NumOptimizedAccessesToGlobalVar++;
677 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
678 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
679 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
680 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
681 NumOptimizedAccessesToGlobalArray++;
688 Type *OrigPtrTy = Addr->getType();
689 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
691 assert(OrigTy->isSized());
692 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
694 assert((TypeSize % 8) == 0);
697 NumInstrumentedWrites++;
699 NumInstrumentedReads++;
701 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
702 if (TypeSize == 8 || TypeSize == 16 ||
703 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
704 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
705 // Instrument unusual size (but still multiple of 8).
706 // We can not do it with a single check, so we do 1-byte check for the first
707 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
708 // to report the actual access size.
710 Value *LastByte = IRB.CreateIntToPtr(
711 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
712 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
714 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
715 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
716 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
719 // Validate the result of Module::getOrInsertFunction called for an interface
720 // function of AddressSanitizer. If the instrumented module defines a function
721 // with the same name, their prototypes must match, otherwise
722 // getOrInsertFunction returns a bitcast.
723 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
724 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
725 FuncOrBitcast->dump();
726 report_fatal_error("trying to redefine an AddressSanitizer "
727 "interface function");
730 Instruction *AddressSanitizer::generateCrashCode(
731 Instruction *InsertBefore, Value *Addr,
732 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
733 IRBuilder<> IRB(InsertBefore);
734 CallInst *Call = SizeArgument
735 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
736 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
738 // We don't do Call->setDoesNotReturn() because the BB already has
739 // UnreachableInst at the end.
740 // This EmptyAsm is required to avoid callback merge.
741 IRB.CreateCall(EmptyAsm);
745 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
748 size_t Granularity = 1 << Mapping.Scale;
749 // Addr & (Granularity - 1)
750 Value *LastAccessedByte = IRB.CreateAnd(
751 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
752 // (Addr & (Granularity - 1)) + size - 1
753 if (TypeSize / 8 > 1)
754 LastAccessedByte = IRB.CreateAdd(
755 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
756 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
757 LastAccessedByte = IRB.CreateIntCast(
758 LastAccessedByte, ShadowValue->getType(), false);
759 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
760 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
763 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
764 Instruction *InsertBefore,
765 Value *Addr, uint32_t TypeSize,
766 bool IsWrite, Value *SizeArgument) {
767 IRBuilder<> IRB(InsertBefore);
768 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
770 Type *ShadowTy = IntegerType::get(
771 *C, std::max(8U, TypeSize >> Mapping.Scale));
772 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
773 Value *ShadowPtr = memToShadow(AddrLong, IRB);
774 Value *CmpVal = Constant::getNullValue(ShadowTy);
775 Value *ShadowValue = IRB.CreateLoad(
776 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
778 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
779 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
780 size_t Granularity = 1 << Mapping.Scale;
781 TerminatorInst *CrashTerm = 0;
783 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
784 TerminatorInst *CheckTerm =
785 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
786 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
787 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
788 IRB.SetInsertPoint(CheckTerm);
789 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
790 BasicBlock *CrashBlock =
791 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
792 CrashTerm = new UnreachableInst(*C, CrashBlock);
793 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
794 ReplaceInstWithInst(CheckTerm, NewTerm);
796 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
799 Instruction *Crash = generateCrashCode(
800 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
801 Crash->setDebugLoc(OrigIns->getDebugLoc());
804 void AddressSanitizerModule::createInitializerPoisonCalls(
805 Module &M, GlobalValue *ModuleName) {
806 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
807 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
808 // If that function is not present, this TU contains no globals, or they have
809 // all been optimized away
813 // Set up the arguments to our poison/unpoison functions.
814 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
816 // Add a call to poison all external globals before the given function starts.
817 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
818 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
820 // Add calls to unpoison all globals before each return instruction.
821 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
823 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
824 CallInst::Create(AsanUnpoisonGlobals, "", RI);
829 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
830 Type *Ty = cast<PointerType>(G->getType())->getElementType();
831 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
833 if (BL->isIn(*G)) return false;
834 if (!Ty->isSized()) return false;
835 if (!G->hasInitializer()) return false;
836 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
837 // Touch only those globals that will not be defined in other modules.
838 // Don't handle ODR type linkages since other modules may be built w/o asan.
839 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
840 G->getLinkage() != GlobalVariable::PrivateLinkage &&
841 G->getLinkage() != GlobalVariable::InternalLinkage)
843 // Two problems with thread-locals:
844 // - The address of the main thread's copy can't be computed at link-time.
845 // - Need to poison all copies, not just the main thread's one.
846 if (G->isThreadLocal())
848 // For now, just ignore this Global if the alignment is large.
849 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
851 // Ignore all the globals with the names starting with "\01L_OBJC_".
852 // Many of those are put into the .cstring section. The linker compresses
853 // that section by removing the spare \0s after the string terminator, so
854 // our redzones get broken.
855 if ((G->getName().find("\01L_OBJC_") == 0) ||
856 (G->getName().find("\01l_OBJC_") == 0)) {
857 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
861 if (G->hasSection()) {
862 StringRef Section(G->getSection());
863 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
864 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
866 if ((Section.find("__OBJC,") == 0) ||
867 (Section.find("__DATA, __objc_") == 0)) {
868 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
871 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
872 // Constant CFString instances are compiled in the following way:
873 // -- the string buffer is emitted into
874 // __TEXT,__cstring,cstring_literals
875 // -- the constant NSConstantString structure referencing that buffer
876 // is placed into __DATA,__cfstring
877 // Therefore there's no point in placing redzones into __DATA,__cfstring.
878 // Moreover, it causes the linker to crash on OS X 10.7
879 if (Section.find("__DATA,__cfstring") == 0) {
880 DEBUG(dbgs() << "Ignoring CFString: " << *G);
888 void AddressSanitizerModule::initializeCallbacks(Module &M) {
890 // Declare our poisoning and unpoisoning functions.
891 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
892 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
893 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
894 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
895 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
896 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
897 // Declare functions that register/unregister globals.
898 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
899 kAsanRegisterGlobalsName, IRB.getVoidTy(),
900 IntptrTy, IntptrTy, NULL));
901 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
902 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
903 kAsanUnregisterGlobalsName,
904 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
905 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
908 // This function replaces all global variables with new variables that have
909 // trailing redzones. It also creates a function that poisons
910 // redzones and inserts this function into llvm.global_ctors.
911 bool AddressSanitizerModule::runOnModule(Module &M) {
912 if (!ClGlobals) return false;
913 TD = getAnalysisIfAvailable<DataLayout>();
916 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
917 if (BL->isIn(M)) return false;
918 C = &(M.getContext());
919 int LongSize = TD->getPointerSizeInBits();
920 IntptrTy = Type::getIntNTy(*C, LongSize);
921 Mapping = getShadowMapping(M, LongSize);
922 initializeCallbacks(M);
923 DynamicallyInitializedGlobals.Init(M);
925 SmallVector<GlobalVariable *, 16> GlobalsToChange;
927 for (Module::GlobalListType::iterator G = M.global_begin(),
928 E = M.global_end(); G != E; ++G) {
929 if (ShouldInstrumentGlobal(G))
930 GlobalsToChange.push_back(G);
933 size_t n = GlobalsToChange.size();
934 if (n == 0) return false;
936 // A global is described by a structure
939 // size_t size_with_redzone;
941 // const char *module_name;
942 // size_t has_dynamic_init;
943 // We initialize an array of such structures and pass it to a run-time call.
944 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
946 IntptrTy, IntptrTy, NULL);
947 SmallVector<Constant *, 16> Initializers(n);
949 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
951 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
953 bool HasDynamicallyInitializedGlobals = false;
955 // We shouldn't merge same module names, as this string serves as unique
956 // module ID in runtime.
957 GlobalVariable *ModuleName = createPrivateGlobalForString(
958 M, M.getModuleIdentifier(), /*AllowMerging*/false);
960 for (size_t i = 0; i < n; i++) {
961 static const uint64_t kMaxGlobalRedzone = 1 << 18;
962 GlobalVariable *G = GlobalsToChange[i];
963 PointerType *PtrTy = cast<PointerType>(G->getType());
964 Type *Ty = PtrTy->getElementType();
965 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
966 uint64_t MinRZ = MinRedzoneSizeForGlobal();
967 // MinRZ <= RZ <= kMaxGlobalRedzone
968 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
969 uint64_t RZ = std::max(MinRZ,
970 std::min(kMaxGlobalRedzone,
971 (SizeInBytes / MinRZ / 4) * MinRZ));
972 uint64_t RightRedzoneSize = RZ;
974 if (SizeInBytes % MinRZ)
975 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
976 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
977 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
978 // Determine whether this global should be poisoned in initialization.
979 bool GlobalHasDynamicInitializer =
980 DynamicallyInitializedGlobals.Contains(G);
981 // Don't check initialization order if this global is blacklisted.
982 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
984 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
985 Constant *NewInitializer = ConstantStruct::get(
986 NewTy, G->getInitializer(),
987 Constant::getNullValue(RightRedZoneTy), NULL);
989 GlobalVariable *Name =
990 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
992 // Create a new global variable with enough space for a redzone.
993 GlobalValue::LinkageTypes Linkage = G->getLinkage();
994 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
995 Linkage = GlobalValue::InternalLinkage;
996 GlobalVariable *NewGlobal = new GlobalVariable(
997 M, NewTy, G->isConstant(), Linkage,
998 NewInitializer, "", G, G->getThreadLocalMode());
999 NewGlobal->copyAttributesFrom(G);
1000 NewGlobal->setAlignment(MinRZ);
1003 Indices2[0] = IRB.getInt32(0);
1004 Indices2[1] = IRB.getInt32(0);
1006 G->replaceAllUsesWith(
1007 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1008 NewGlobal->takeName(G);
1009 G->eraseFromParent();
1011 Initializers[i] = ConstantStruct::get(
1013 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1014 ConstantInt::get(IntptrTy, SizeInBytes),
1015 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1016 ConstantExpr::getPointerCast(Name, IntptrTy),
1017 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1018 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1021 // Populate the first and last globals declared in this TU.
1022 if (CheckInitOrder && GlobalHasDynamicInitializer)
1023 HasDynamicallyInitializedGlobals = true;
1025 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1028 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1029 GlobalVariable *AllGlobals = new GlobalVariable(
1030 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1031 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1033 // Create calls for poisoning before initializers run and unpoisoning after.
1034 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1035 createInitializerPoisonCalls(M, ModuleName);
1036 IRB.CreateCall2(AsanRegisterGlobals,
1037 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1038 ConstantInt::get(IntptrTy, n));
1040 // We also need to unregister globals at the end, e.g. when a shared library
1042 Function *AsanDtorFunction = Function::Create(
1043 FunctionType::get(Type::getVoidTy(*C), false),
1044 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1045 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1046 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1047 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1048 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1049 ConstantInt::get(IntptrTy, n));
1050 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1056 void AddressSanitizer::initializeCallbacks(Module &M) {
1057 IRBuilder<> IRB(*C);
1058 // Create __asan_report* callbacks.
1059 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1060 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1061 AccessSizeIndex++) {
1062 // IsWrite and TypeSize are encoded in the function name.
1063 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1064 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1065 // If we are merging crash callbacks, they have two parameters.
1066 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1067 checkInterfaceFunction(M.getOrInsertFunction(
1068 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1071 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1072 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1073 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1074 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1076 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1077 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1078 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1079 kAsanCovName, IRB.getVoidTy(), IntptrTy, NULL));
1080 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1081 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1082 StringRef(""), StringRef(""),
1083 /*hasSideEffects=*/true);
1086 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1087 // Tell the values of mapping offset and scale to the run-time.
1088 GlobalValue *asan_mapping_offset =
1089 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1090 ConstantInt::get(IntptrTy, Mapping.Offset),
1091 kAsanMappingOffsetName);
1092 // Read the global, otherwise it may be optimized away.
1093 IRB.CreateLoad(asan_mapping_offset, true);
1095 GlobalValue *asan_mapping_scale =
1096 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1097 ConstantInt::get(IntptrTy, Mapping.Scale),
1098 kAsanMappingScaleName);
1099 // Read the global, otherwise it may be optimized away.
1100 IRB.CreateLoad(asan_mapping_scale, true);
1104 bool AddressSanitizer::doInitialization(Module &M) {
1105 // Initialize the private fields. No one has accessed them before.
1106 TD = getAnalysisIfAvailable<DataLayout>();
1110 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1111 DynamicallyInitializedGlobals.Init(M);
1113 C = &(M.getContext());
1114 LongSize = TD->getPointerSizeInBits();
1115 IntptrTy = Type::getIntNTy(*C, LongSize);
1117 AsanCtorFunction = Function::Create(
1118 FunctionType::get(Type::getVoidTy(*C), false),
1119 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1120 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1121 // call __asan_init in the module ctor.
1122 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1123 AsanInitFunction = checkInterfaceFunction(
1124 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1125 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1126 IRB.CreateCall(AsanInitFunction);
1128 Mapping = getShadowMapping(M, LongSize);
1129 emitShadowMapping(M, IRB);
1131 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1135 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1136 // For each NSObject descendant having a +load method, this method is invoked
1137 // by the ObjC runtime before any of the static constructors is called.
1138 // Therefore we need to instrument such methods with a call to __asan_init
1139 // at the beginning in order to initialize our runtime before any access to
1140 // the shadow memory.
1141 // We cannot just ignore these methods, because they may call other
1142 // instrumented functions.
1143 if (F.getName().find(" load]") != std::string::npos) {
1144 IRBuilder<> IRB(F.begin()->begin());
1145 IRB.CreateCall(AsanInitFunction);
1151 // Poor man's coverage that works with ASan.
1152 // We create a Guard boolean variable with the same linkage
1153 // as the function and inject this code into the entry block:
1155 // __sanitizer_cov(&F);
1158 // The accesses to Guard are atomic. The rest of the logic is
1159 // in __sanitizer_cov (it's fine to call it more than once).
1161 // This coverage implementation provides very limited data:
1162 // it only tells if a given function was ever executed.
1163 // No counters, no per-basic-block or per-edge data.
1164 // But for many use cases this is what we need and the added slowdown
1165 // is negligible. This simple implementation will probably be obsoleted
1166 // by the upcoming Clang-based coverage implementation.
1167 // By having it here and now we hope to
1168 // a) get the functionality to users earlier and
1169 // b) collect usage statistics to help improve Clang coverage design.
1170 bool AddressSanitizer::InjectCoverage(Function &F) {
1171 if (!ClCoverage) return false;
1173 // Skip static allocas at the top of the entry block so they don't become
1174 // dynamic when we split the block. If we used our optimized stack layout,
1175 // then there will only be one alloca and it will come first.
1176 BasicBlock &Entry = F.getEntryBlock();
1177 BasicBlock::iterator IP = Entry.getFirstInsertionPt(), BE = Entry.end();
1178 for (; IP != BE; ++IP) {
1179 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1180 if (!AI || !AI->isStaticAlloca())
1184 IRBuilder<> IRB(IP);
1185 Type *Int8Ty = IRB.getInt8Ty();
1186 GlobalVariable *Guard = new GlobalVariable(
1187 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1188 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1189 LoadInst *Load = IRB.CreateLoad(Guard);
1190 Load->setAtomic(Monotonic);
1191 Load->setAlignment(1);
1192 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1193 Instruction *Ins = SplitBlockAndInsertIfThen(Cmp, IP, false);
1194 IRB.SetInsertPoint(Ins);
1195 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1196 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1197 IRB.CreateCall(AsanCovFunction, IRB.CreatePointerCast(&F, IntptrTy));
1198 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1199 Store->setAtomic(Monotonic);
1200 Store->setAlignment(1);
1204 bool AddressSanitizer::runOnFunction(Function &F) {
1205 if (BL->isIn(F)) return false;
1206 if (&F == AsanCtorFunction) return false;
1207 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1208 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1209 initializeCallbacks(*F.getParent());
1211 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1212 maybeInsertAsanInitAtFunctionEntry(F);
1214 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1217 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1220 // We want to instrument every address only once per basic block (unless there
1221 // are calls between uses).
1222 SmallSet<Value*, 16> TempsToInstrument;
1223 SmallVector<Instruction*, 16> ToInstrument;
1224 SmallVector<Instruction*, 8> NoReturnCalls;
1228 // Fill the set of memory operations to instrument.
1229 for (Function::iterator FI = F.begin(), FE = F.end();
1231 TempsToInstrument.clear();
1232 int NumInsnsPerBB = 0;
1233 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1235 if (LooksLikeCodeInBug11395(BI)) return false;
1236 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1237 if (ClOpt && ClOptSameTemp) {
1238 if (!TempsToInstrument.insert(Addr))
1239 continue; // We've seen this temp in the current BB.
1241 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1244 if (isa<AllocaInst>(BI))
1248 // A call inside BB.
1249 TempsToInstrument.clear();
1250 if (CS.doesNotReturn())
1251 NoReturnCalls.push_back(CS.getInstruction());
1255 ToInstrument.push_back(BI);
1257 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1262 Function *UninstrumentedDuplicate = 0;
1263 bool LikelyToInstrument =
1264 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1265 if (ClKeepUninstrumented && LikelyToInstrument) {
1266 ValueToValueMapTy VMap;
1267 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1268 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1269 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1270 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1274 int NumInstrumented = 0;
1275 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1276 Instruction *Inst = ToInstrument[i];
1277 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1278 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1279 if (isInterestingMemoryAccess(Inst, &IsWrite))
1280 instrumentMop(Inst);
1282 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1287 FunctionStackPoisoner FSP(F, *this);
1288 bool ChangedStack = FSP.runOnFunction();
1290 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1291 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1292 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1293 Instruction *CI = NoReturnCalls[i];
1294 IRBuilder<> IRB(CI);
1295 IRB.CreateCall(AsanHandleNoReturnFunc);
1298 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1300 if (InjectCoverage(F))
1303 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1305 if (ClKeepUninstrumented) {
1307 // No instrumentation is done, no need for the duplicate.
1308 if (UninstrumentedDuplicate)
1309 UninstrumentedDuplicate->eraseFromParent();
1311 // The function was instrumented. We must have the duplicate.
1312 assert(UninstrumentedDuplicate);
1313 UninstrumentedDuplicate->setSection("NOASAN");
1314 assert(!F.hasSection());
1315 F.setSection("ASAN");
1322 // Workaround for bug 11395: we don't want to instrument stack in functions
1323 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1324 // FIXME: remove once the bug 11395 is fixed.
1325 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1326 if (LongSize != 32) return false;
1327 CallInst *CI = dyn_cast<CallInst>(I);
1328 if (!CI || !CI->isInlineAsm()) return false;
1329 if (CI->getNumArgOperands() <= 5) return false;
1330 // We have inline assembly with quite a few arguments.
1334 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1335 IRBuilder<> IRB(*C);
1336 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1337 std::string Suffix = itostr(i);
1338 AsanStackMallocFunc[i] = checkInterfaceFunction(
1339 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1340 IntptrTy, IntptrTy, NULL));
1341 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1342 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1343 IntptrTy, IntptrTy, NULL));
1345 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1346 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1347 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1348 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1352 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1353 IRBuilder<> &IRB, Value *ShadowBase,
1355 size_t n = ShadowBytes.size();
1357 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1358 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1359 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1360 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1361 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1362 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1364 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1365 if (ASan.TD->isLittleEndian())
1366 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1368 Val = (Val << 8) | ShadowBytes[i + j];
1371 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1372 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1373 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1374 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1379 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1380 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1381 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1382 assert(LocalStackSize <= kMaxStackMallocSize);
1383 uint64_t MaxSize = kMinStackMallocSize;
1384 for (int i = 0; ; i++, MaxSize *= 2)
1385 if (LocalStackSize <= MaxSize)
1387 llvm_unreachable("impossible LocalStackSize");
1390 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1391 // We can not use MemSet intrinsic because it may end up calling the actual
1392 // memset. Size is a multiple of 8.
1393 // Currently this generates 8-byte stores on x86_64; it may be better to
1394 // generate wider stores.
1395 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1396 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1397 assert(!(Size % 8));
1398 assert(kAsanStackAfterReturnMagic == 0xf5);
1399 for (int i = 0; i < Size; i += 8) {
1400 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1401 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1402 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1406 void FunctionStackPoisoner::poisonStack() {
1407 int StackMallocIdx = -1;
1409 assert(AllocaVec.size() > 0);
1410 Instruction *InsBefore = AllocaVec[0];
1411 IRBuilder<> IRB(InsBefore);
1413 SmallVector<ASanStackVariableDescription, 16> SVD;
1414 SVD.reserve(AllocaVec.size());
1415 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1416 AllocaInst *AI = AllocaVec[i];
1417 ASanStackVariableDescription D = { AI->getName().data(),
1418 getAllocaSizeInBytes(AI),
1419 AI->getAlignment(), AI, 0};
1422 // Minimal header size (left redzone) is 4 pointers,
1423 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1424 size_t MinHeaderSize = ASan.LongSize / 2;
1425 ASanStackFrameLayout L;
1426 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1427 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1428 uint64_t LocalStackSize = L.FrameSize;
1429 bool DoStackMalloc =
1430 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1432 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1433 AllocaInst *MyAlloca =
1434 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1435 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1436 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1437 MyAlloca->setAlignment(FrameAlignment);
1438 assert(MyAlloca->isStaticAlloca());
1439 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1440 Value *LocalStackBase = OrigStackBase;
1442 if (DoStackMalloc) {
1443 // LocalStackBase = OrigStackBase
1444 // if (__asan_option_detect_stack_use_after_return)
1445 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1446 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1447 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1448 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1449 kAsanOptionDetectUAR, IRB.getInt32Ty());
1450 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1451 Constant::getNullValue(IRB.getInt32Ty()));
1452 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1453 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1454 IRBuilder<> IRBIf(Term);
1455 LocalStackBase = IRBIf.CreateCall2(
1456 AsanStackMallocFunc[StackMallocIdx],
1457 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1458 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1459 IRB.SetInsertPoint(InsBefore);
1460 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1461 Phi->addIncoming(OrigStackBase, CmpBlock);
1462 Phi->addIncoming(LocalStackBase, SetBlock);
1463 LocalStackBase = Phi;
1466 // Insert poison calls for lifetime intrinsics for alloca.
1467 bool HavePoisonedAllocas = false;
1468 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1469 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1470 assert(APC.InsBefore);
1472 IRBuilder<> IRB(APC.InsBefore);
1473 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1474 HavePoisonedAllocas |= APC.DoPoison;
1477 // Replace Alloca instructions with base+offset.
1478 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1479 AllocaInst *AI = SVD[i].AI;
1480 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1481 IRB.CreateAdd(LocalStackBase,
1482 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1484 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1485 AI->replaceAllUsesWith(NewAllocaPtr);
1488 // The left-most redzone has enough space for at least 4 pointers.
1489 // Write the Magic value to redzone[0].
1490 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1491 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1493 // Write the frame description constant to redzone[1].
1494 Value *BasePlus1 = IRB.CreateIntToPtr(
1495 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1497 GlobalVariable *StackDescriptionGlobal =
1498 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1499 /*AllowMerging*/true);
1500 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1502 IRB.CreateStore(Description, BasePlus1);
1503 // Write the PC to redzone[2].
1504 Value *BasePlus2 = IRB.CreateIntToPtr(
1505 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1506 2 * ASan.LongSize/8)),
1508 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1510 // Poison the stack redzones at the entry.
1511 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1512 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1514 // (Un)poison the stack before all ret instructions.
1515 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1516 Instruction *Ret = RetVec[i];
1517 IRBuilder<> IRBRet(Ret);
1518 // Mark the current frame as retired.
1519 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1521 if (DoStackMalloc) {
1522 assert(StackMallocIdx >= 0);
1523 // if LocalStackBase != OrigStackBase:
1524 // // In use-after-return mode, poison the whole stack frame.
1525 // if StackMallocIdx <= 4
1526 // // For small sizes inline the whole thing:
1527 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1528 // **SavedFlagPtr(LocalStackBase) = 0
1530 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1532 // <This is not a fake stack; unpoison the redzones>
1533 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1534 TerminatorInst *ThenTerm, *ElseTerm;
1535 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1537 IRBuilder<> IRBPoison(ThenTerm);
1538 if (StackMallocIdx <= 4) {
1539 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1540 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1541 ClassSize >> Mapping.Scale);
1542 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1544 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1545 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1546 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1547 IRBPoison.CreateStore(
1548 Constant::getNullValue(IRBPoison.getInt8Ty()),
1549 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1551 // For larger frames call __asan_stack_free_*.
1552 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1553 ConstantInt::get(IntptrTy, LocalStackSize),
1557 IRBuilder<> IRBElse(ElseTerm);
1558 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1559 } else if (HavePoisonedAllocas) {
1560 // If we poisoned some allocas in llvm.lifetime analysis,
1561 // unpoison whole stack frame now.
1562 assert(LocalStackBase == OrigStackBase);
1563 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1565 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1569 // We are done. Remove the old unused alloca instructions.
1570 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1571 AllocaVec[i]->eraseFromParent();
1574 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1575 IRBuilder<> &IRB, bool DoPoison) {
1576 // For now just insert the call to ASan runtime.
1577 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1578 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1579 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1580 : AsanUnpoisonStackMemoryFunc,
1584 // Handling llvm.lifetime intrinsics for a given %alloca:
1585 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1586 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1587 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1588 // could be poisoned by previous llvm.lifetime.end instruction, as the
1589 // variable may go in and out of scope several times, e.g. in loops).
1590 // (3) if we poisoned at least one %alloca in a function,
1591 // unpoison the whole stack frame at function exit.
1593 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1594 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1595 // We're intested only in allocas we can handle.
1596 return isInterestingAlloca(*AI) ? AI : 0;
1597 // See if we've already calculated (or started to calculate) alloca for a
1599 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1600 if (I != AllocaForValue.end())
1602 // Store 0 while we're calculating alloca for value V to avoid
1603 // infinite recursion if the value references itself.
1604 AllocaForValue[V] = 0;
1605 AllocaInst *Res = 0;
1606 if (CastInst *CI = dyn_cast<CastInst>(V))
1607 Res = findAllocaForValue(CI->getOperand(0));
1608 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1609 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1610 Value *IncValue = PN->getIncomingValue(i);
1611 // Allow self-referencing phi-nodes.
1612 if (IncValue == PN) continue;
1613 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1614 // AI for incoming values should exist and should all be equal.
1615 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1621 AllocaForValue[V] = Res;