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 bool ZeroBaseShadow) {
239 llvm::Triple TargetTriple(M.getTargetTriple());
240 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
241 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
242 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
243 TargetTriple.getArch() == llvm::Triple::ppc64le;
244 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
245 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
246 TargetTriple.getArch() == llvm::Triple::mipsel;
248 ShadowMapping Mapping;
250 // OR-ing shadow offset if more efficient (at least on x86),
251 // but on ppc64 we have to use add since the shadow offset is not neccesary
252 // 1/8-th of the address space.
253 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
255 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
257 (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
258 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
259 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
260 assert(LongSize == 64);
261 Mapping.Offset = kDefaultShort64bitShadowOffset;
263 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
264 // Zero offset log is the special case.
265 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
268 Mapping.Scale = kDefaultShadowScale;
269 if (ClMappingScale) {
270 Mapping.Scale = ClMappingScale;
276 static size_t RedzoneSizeForScale(int MappingScale) {
277 // Redzone used for stack and globals is at least 32 bytes.
278 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
279 return std::max(32U, 1U << MappingScale);
282 /// AddressSanitizer: instrument the code in module to find memory bugs.
283 struct AddressSanitizer : public FunctionPass {
284 AddressSanitizer(bool CheckInitOrder = true,
285 bool CheckUseAfterReturn = false,
286 bool CheckLifetime = false,
287 StringRef BlacklistFile = StringRef(),
288 bool ZeroBaseShadow = false)
290 CheckInitOrder(CheckInitOrder || ClInitializers),
291 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
292 CheckLifetime(CheckLifetime || ClCheckLifetime),
293 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
295 ZeroBaseShadow(ZeroBaseShadow) {}
296 virtual const char *getPassName() const {
297 return "AddressSanitizerFunctionPass";
299 void instrumentMop(Instruction *I);
300 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
301 Value *Addr, uint32_t TypeSize, bool IsWrite,
302 Value *SizeArgument);
303 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
304 Value *ShadowValue, uint32_t TypeSize);
305 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
306 bool IsWrite, size_t AccessSizeIndex,
307 Value *SizeArgument);
308 bool instrumentMemIntrinsic(MemIntrinsic *MI);
309 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
311 Instruction *InsertBefore, bool IsWrite);
312 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
313 bool runOnFunction(Function &F);
314 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
315 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
316 virtual bool doInitialization(Module &M);
317 static char ID; // Pass identification, replacement for typeid
320 void initializeCallbacks(Module &M);
322 bool ShouldInstrumentGlobal(GlobalVariable *G);
323 bool LooksLikeCodeInBug11395(Instruction *I);
324 void FindDynamicInitializers(Module &M);
325 bool GlobalIsLinkerInitialized(GlobalVariable *G);
326 bool InjectCoverage(Function &F);
329 bool CheckUseAfterReturn;
331 SmallString<64> BlacklistFile;
338 ShadowMapping Mapping;
339 Function *AsanCtorFunction;
340 Function *AsanInitFunction;
341 Function *AsanHandleNoReturnFunc;
342 Function *AsanCovFunction;
343 OwningPtr<SpecialCaseList> BL;
344 // This array is indexed by AccessIsWrite and log2(AccessSize).
345 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
346 // This array is indexed by AccessIsWrite.
347 Function *AsanErrorCallbackSized[2];
349 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
351 friend struct FunctionStackPoisoner;
354 class AddressSanitizerModule : public ModulePass {
356 AddressSanitizerModule(bool CheckInitOrder = true,
357 StringRef BlacklistFile = StringRef(),
358 bool ZeroBaseShadow = false)
360 CheckInitOrder(CheckInitOrder || ClInitializers),
361 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
363 ZeroBaseShadow(ZeroBaseShadow) {}
364 bool runOnModule(Module &M);
365 static char ID; // Pass identification, replacement for typeid
366 virtual const char *getPassName() const {
367 return "AddressSanitizerModule";
371 void initializeCallbacks(Module &M);
373 bool ShouldInstrumentGlobal(GlobalVariable *G);
374 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
375 size_t MinRedzoneSizeForGlobal() const {
376 return RedzoneSizeForScale(Mapping.Scale);
380 SmallString<64> BlacklistFile;
383 OwningPtr<SpecialCaseList> BL;
384 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
388 ShadowMapping Mapping;
389 Function *AsanPoisonGlobals;
390 Function *AsanUnpoisonGlobals;
391 Function *AsanRegisterGlobals;
392 Function *AsanUnregisterGlobals;
395 // Stack poisoning does not play well with exception handling.
396 // When an exception is thrown, we essentially bypass the code
397 // that unpoisones the stack. This is why the run-time library has
398 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
399 // stack in the interceptor. This however does not work inside the
400 // actual function which catches the exception. Most likely because the
401 // compiler hoists the load of the shadow value somewhere too high.
402 // This causes asan to report a non-existing bug on 453.povray.
403 // It sounds like an LLVM bug.
404 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
406 AddressSanitizer &ASan;
411 ShadowMapping Mapping;
413 SmallVector<AllocaInst*, 16> AllocaVec;
414 SmallVector<Instruction*, 8> RetVec;
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;
428 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
430 // Maps Value to an AllocaInst from which the Value is originated.
431 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
432 AllocaForValueMapTy AllocaForValue;
434 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
435 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
436 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
437 Mapping(ASan.Mapping),
438 StackAlignment(1 << Mapping.Scale) {}
440 bool runOnFunction() {
441 if (!ClStack) return false;
442 // Collect alloca, ret, lifetime instructions etc.
443 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
444 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
445 BasicBlock *BB = *DI;
448 if (AllocaVec.empty()) return false;
450 initializeCallbacks(*F.getParent());
460 // Finds all static Alloca instructions and puts
461 // poisoned red zones around all of them.
462 // Then unpoison everything back before the function returns.
465 // ----------------------- Visitors.
466 /// \brief Collect all Ret instructions.
467 void visitReturnInst(ReturnInst &RI) {
468 RetVec.push_back(&RI);
471 /// \brief Collect Alloca instructions we want (and can) handle.
472 void visitAllocaInst(AllocaInst &AI) {
473 if (!isInterestingAlloca(AI)) return;
475 StackAlignment = std::max(StackAlignment, AI.getAlignment());
476 AllocaVec.push_back(&AI);
479 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
481 void visitIntrinsicInst(IntrinsicInst &II) {
482 if (!ASan.CheckLifetime) return;
483 Intrinsic::ID ID = II.getIntrinsicID();
484 if (ID != Intrinsic::lifetime_start &&
485 ID != Intrinsic::lifetime_end)
487 // Found lifetime intrinsic, add ASan instrumentation if necessary.
488 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
489 // If size argument is undefined, don't do anything.
490 if (Size->isMinusOne()) return;
491 // Check that size doesn't saturate uint64_t and can
492 // be stored in IntptrTy.
493 const uint64_t SizeValue = Size->getValue().getLimitedValue();
494 if (SizeValue == ~0ULL ||
495 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
497 // Find alloca instruction that corresponds to llvm.lifetime argument.
498 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
500 bool DoPoison = (ID == Intrinsic::lifetime_end);
501 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
502 AllocaPoisonCallVec.push_back(APC);
505 // ---------------------- Helpers.
506 void initializeCallbacks(Module &M);
508 // Check if we want (and can) handle this alloca.
509 bool isInterestingAlloca(AllocaInst &AI) const {
510 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
511 AI.getAllocatedType()->isSized() &&
512 // alloca() may be called with 0 size, ignore it.
513 getAllocaSizeInBytes(&AI) > 0);
516 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
517 Type *Ty = AI->getAllocatedType();
518 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
521 /// Finds alloca where the value comes from.
522 AllocaInst *findAllocaForValue(Value *V);
523 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
524 Value *ShadowBase, bool DoPoison);
525 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
527 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
533 char AddressSanitizer::ID = 0;
534 INITIALIZE_PASS(AddressSanitizer, "asan",
535 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
537 FunctionPass *llvm::createAddressSanitizerFunctionPass(
538 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
539 StringRef BlacklistFile, bool ZeroBaseShadow) {
540 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
541 CheckLifetime, BlacklistFile, ZeroBaseShadow);
544 char AddressSanitizerModule::ID = 0;
545 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
546 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
547 "ModulePass", false, false)
548 ModulePass *llvm::createAddressSanitizerModulePass(
549 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
550 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
554 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
555 size_t Res = countTrailingZeros(TypeSize / 8);
556 assert(Res < kNumberOfAccessSizes);
560 // \brief Create a constant for Str so that we can pass it to the run-time lib.
561 static GlobalVariable *createPrivateGlobalForString(
562 Module &M, StringRef Str, bool AllowMerging) {
563 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
564 // For module-local strings that can be merged with another one we set the
565 // internal linkage and the unnamed_addr attribute.
566 // Non-mergeable strings are made linker_private to remove them from the
567 // symbol table. "private" linkage doesn't work for Darwin, where the
568 // "L"-prefixed globals end up in __TEXT,__const section
569 // (see http://llvm.org/bugs/show_bug.cgi?id=17976 for more info).
570 GlobalValue::LinkageTypes linkage =
571 AllowMerging ? GlobalValue::InternalLinkage
572 : GlobalValue::LinkerPrivateLinkage;
574 new GlobalVariable(M, StrConst->getType(), true,
575 linkage, StrConst, kAsanGenPrefix);
576 if (AllowMerging) GV->setUnnamedAddr(true);
577 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
581 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
582 return G->getName().find(kAsanGenPrefix) == 0;
585 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
587 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
588 if (Mapping.Offset == 0)
590 // (Shadow >> scale) | offset
591 if (Mapping.OrShadowOffset)
592 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
594 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
597 void AddressSanitizer::instrumentMemIntrinsicParam(
598 Instruction *OrigIns,
599 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
600 IRBuilder<> IRB(InsertBefore);
601 if (Size->getType() != IntptrTy)
602 Size = IRB.CreateIntCast(Size, IntptrTy, false);
603 // Check the first byte.
604 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
605 // Check the last byte.
606 IRB.SetInsertPoint(InsertBefore);
607 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
608 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
609 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
610 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
613 // Instrument memset/memmove/memcpy
614 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
615 Value *Dst = MI->getDest();
616 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
617 Value *Src = MemTran ? MemTran->getSource() : 0;
618 Value *Length = MI->getLength();
620 Constant *ConstLength = dyn_cast<Constant>(Length);
621 Instruction *InsertBefore = MI;
623 if (ConstLength->isNullValue()) return false;
625 // The size is not a constant so it could be zero -- check at run-time.
626 IRBuilder<> IRB(InsertBefore);
628 Value *Cmp = IRB.CreateICmpNE(Length,
629 Constant::getNullValue(Length->getType()));
630 InsertBefore = SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
633 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
635 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
639 // If I is an interesting memory access, return the PointerOperand
640 // and set IsWrite. Otherwise return NULL.
641 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
642 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
643 if (!ClInstrumentReads) return NULL;
645 return LI->getPointerOperand();
647 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
648 if (!ClInstrumentWrites) return NULL;
650 return SI->getPointerOperand();
652 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
653 if (!ClInstrumentAtomics) return NULL;
655 return RMW->getPointerOperand();
657 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
658 if (!ClInstrumentAtomics) return NULL;
660 return XCHG->getPointerOperand();
665 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
666 // If a global variable does not have dynamic initialization we don't
667 // have to instrument it. However, if a global does not have initializer
668 // at all, we assume it has dynamic initializer (in other TU).
669 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
672 void AddressSanitizer::instrumentMop(Instruction *I) {
673 bool IsWrite = false;
674 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
676 if (ClOpt && ClOptGlobals) {
677 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
678 // If initialization order checking is disabled, a simple access to a
679 // dynamically initialized global is always valid.
680 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
681 NumOptimizedAccessesToGlobalVar++;
685 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
686 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
687 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
688 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
689 NumOptimizedAccessesToGlobalArray++;
696 Type *OrigPtrTy = Addr->getType();
697 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
699 assert(OrigTy->isSized());
700 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
702 assert((TypeSize % 8) == 0);
705 NumInstrumentedWrites++;
707 NumInstrumentedReads++;
709 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
710 if (TypeSize == 8 || TypeSize == 16 ||
711 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
712 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
713 // Instrument unusual size (but still multiple of 8).
714 // We can not do it with a single check, so we do 1-byte check for the first
715 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
716 // to report the actual access size.
718 Value *LastByte = IRB.CreateIntToPtr(
719 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
720 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
722 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
723 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
724 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
727 // Validate the result of Module::getOrInsertFunction called for an interface
728 // function of AddressSanitizer. If the instrumented module defines a function
729 // with the same name, their prototypes must match, otherwise
730 // getOrInsertFunction returns a bitcast.
731 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
732 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
733 FuncOrBitcast->dump();
734 report_fatal_error("trying to redefine an AddressSanitizer "
735 "interface function");
738 Instruction *AddressSanitizer::generateCrashCode(
739 Instruction *InsertBefore, Value *Addr,
740 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
741 IRBuilder<> IRB(InsertBefore);
742 CallInst *Call = SizeArgument
743 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
744 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
746 // We don't do Call->setDoesNotReturn() because the BB already has
747 // UnreachableInst at the end.
748 // This EmptyAsm is required to avoid callback merge.
749 IRB.CreateCall(EmptyAsm);
753 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
756 size_t Granularity = 1 << Mapping.Scale;
757 // Addr & (Granularity - 1)
758 Value *LastAccessedByte = IRB.CreateAnd(
759 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
760 // (Addr & (Granularity - 1)) + size - 1
761 if (TypeSize / 8 > 1)
762 LastAccessedByte = IRB.CreateAdd(
763 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
764 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
765 LastAccessedByte = IRB.CreateIntCast(
766 LastAccessedByte, ShadowValue->getType(), false);
767 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
768 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
771 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
772 Instruction *InsertBefore,
773 Value *Addr, uint32_t TypeSize,
774 bool IsWrite, Value *SizeArgument) {
775 IRBuilder<> IRB(InsertBefore);
776 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
778 Type *ShadowTy = IntegerType::get(
779 *C, std::max(8U, TypeSize >> Mapping.Scale));
780 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
781 Value *ShadowPtr = memToShadow(AddrLong, IRB);
782 Value *CmpVal = Constant::getNullValue(ShadowTy);
783 Value *ShadowValue = IRB.CreateLoad(
784 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
786 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
787 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
788 size_t Granularity = 1 << Mapping.Scale;
789 TerminatorInst *CrashTerm = 0;
791 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
792 TerminatorInst *CheckTerm =
793 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
794 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
795 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
796 IRB.SetInsertPoint(CheckTerm);
797 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
798 BasicBlock *CrashBlock =
799 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
800 CrashTerm = new UnreachableInst(*C, CrashBlock);
801 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
802 ReplaceInstWithInst(CheckTerm, NewTerm);
804 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
807 Instruction *Crash = generateCrashCode(
808 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
809 Crash->setDebugLoc(OrigIns->getDebugLoc());
812 void AddressSanitizerModule::createInitializerPoisonCalls(
813 Module &M, GlobalValue *ModuleName) {
814 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
815 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
816 // If that function is not present, this TU contains no globals, or they have
817 // all been optimized away
821 // Set up the arguments to our poison/unpoison functions.
822 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
824 // Add a call to poison all external globals before the given function starts.
825 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
826 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
828 // Add calls to unpoison all globals before each return instruction.
829 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
831 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
832 CallInst::Create(AsanUnpoisonGlobals, "", RI);
837 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
838 Type *Ty = cast<PointerType>(G->getType())->getElementType();
839 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
841 if (BL->isIn(*G)) return false;
842 if (!Ty->isSized()) return false;
843 if (!G->hasInitializer()) return false;
844 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
845 // Touch only those globals that will not be defined in other modules.
846 // Don't handle ODR type linkages since other modules may be built w/o asan.
847 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
848 G->getLinkage() != GlobalVariable::PrivateLinkage &&
849 G->getLinkage() != GlobalVariable::InternalLinkage)
851 // Two problems with thread-locals:
852 // - The address of the main thread's copy can't be computed at link-time.
853 // - Need to poison all copies, not just the main thread's one.
854 if (G->isThreadLocal())
856 // For now, just ignore this Global if the alignment is large.
857 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
859 // Ignore all the globals with the names starting with "\01L_OBJC_".
860 // Many of those are put into the .cstring section. The linker compresses
861 // that section by removing the spare \0s after the string terminator, so
862 // our redzones get broken.
863 if ((G->getName().find("\01L_OBJC_") == 0) ||
864 (G->getName().find("\01l_OBJC_") == 0)) {
865 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
869 if (G->hasSection()) {
870 StringRef Section(G->getSection());
871 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
872 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
874 if ((Section.find("__OBJC,") == 0) ||
875 (Section.find("__DATA, __objc_") == 0)) {
876 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
879 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
880 // Constant CFString instances are compiled in the following way:
881 // -- the string buffer is emitted into
882 // __TEXT,__cstring,cstring_literals
883 // -- the constant NSConstantString structure referencing that buffer
884 // is placed into __DATA,__cfstring
885 // Therefore there's no point in placing redzones into __DATA,__cfstring.
886 // Moreover, it causes the linker to crash on OS X 10.7
887 if (Section.find("__DATA,__cfstring") == 0) {
888 DEBUG(dbgs() << "Ignoring CFString: " << *G);
896 void AddressSanitizerModule::initializeCallbacks(Module &M) {
898 // Declare our poisoning and unpoisoning functions.
899 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
900 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
901 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
902 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
903 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
904 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
905 // Declare functions that register/unregister globals.
906 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
907 kAsanRegisterGlobalsName, IRB.getVoidTy(),
908 IntptrTy, IntptrTy, NULL));
909 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
910 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
911 kAsanUnregisterGlobalsName,
912 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
913 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
916 // This function replaces all global variables with new variables that have
917 // trailing redzones. It also creates a function that poisons
918 // redzones and inserts this function into llvm.global_ctors.
919 bool AddressSanitizerModule::runOnModule(Module &M) {
920 if (!ClGlobals) return false;
921 TD = getAnalysisIfAvailable<DataLayout>();
924 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
925 if (BL->isIn(M)) return false;
926 C = &(M.getContext());
927 int LongSize = TD->getPointerSizeInBits();
928 IntptrTy = Type::getIntNTy(*C, LongSize);
929 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
930 initializeCallbacks(M);
931 DynamicallyInitializedGlobals.Init(M);
933 SmallVector<GlobalVariable *, 16> GlobalsToChange;
935 for (Module::GlobalListType::iterator G = M.global_begin(),
936 E = M.global_end(); G != E; ++G) {
937 if (ShouldInstrumentGlobal(G))
938 GlobalsToChange.push_back(G);
941 size_t n = GlobalsToChange.size();
942 if (n == 0) return false;
944 // A global is described by a structure
947 // size_t size_with_redzone;
949 // const char *module_name;
950 // size_t has_dynamic_init;
951 // We initialize an array of such structures and pass it to a run-time call.
952 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
954 IntptrTy, IntptrTy, NULL);
955 SmallVector<Constant *, 16> Initializers(n);
957 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
959 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
961 bool HasDynamicallyInitializedGlobals = false;
963 // We shouldn't merge same module names, as this string serves as unique
964 // module ID in runtime.
965 GlobalVariable *ModuleName = createPrivateGlobalForString(
966 M, M.getModuleIdentifier(), /*AllowMerging*/false);
968 for (size_t i = 0; i < n; i++) {
969 static const uint64_t kMaxGlobalRedzone = 1 << 18;
970 GlobalVariable *G = GlobalsToChange[i];
971 PointerType *PtrTy = cast<PointerType>(G->getType());
972 Type *Ty = PtrTy->getElementType();
973 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
974 uint64_t MinRZ = MinRedzoneSizeForGlobal();
975 // MinRZ <= RZ <= kMaxGlobalRedzone
976 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
977 uint64_t RZ = std::max(MinRZ,
978 std::min(kMaxGlobalRedzone,
979 (SizeInBytes / MinRZ / 4) * MinRZ));
980 uint64_t RightRedzoneSize = RZ;
982 if (SizeInBytes % MinRZ)
983 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
984 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
985 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
986 // Determine whether this global should be poisoned in initialization.
987 bool GlobalHasDynamicInitializer =
988 DynamicallyInitializedGlobals.Contains(G);
989 // Don't check initialization order if this global is blacklisted.
990 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
992 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
993 Constant *NewInitializer = ConstantStruct::get(
994 NewTy, G->getInitializer(),
995 Constant::getNullValue(RightRedZoneTy), NULL);
997 GlobalVariable *Name =
998 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1000 // Create a new global variable with enough space for a redzone.
1001 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1002 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1003 Linkage = GlobalValue::InternalLinkage;
1004 GlobalVariable *NewGlobal = new GlobalVariable(
1005 M, NewTy, G->isConstant(), Linkage,
1006 NewInitializer, "", G, G->getThreadLocalMode());
1007 NewGlobal->copyAttributesFrom(G);
1008 NewGlobal->setAlignment(MinRZ);
1011 Indices2[0] = IRB.getInt32(0);
1012 Indices2[1] = IRB.getInt32(0);
1014 G->replaceAllUsesWith(
1015 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1016 NewGlobal->takeName(G);
1017 G->eraseFromParent();
1019 Initializers[i] = ConstantStruct::get(
1021 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1022 ConstantInt::get(IntptrTy, SizeInBytes),
1023 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1024 ConstantExpr::getPointerCast(Name, IntptrTy),
1025 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1026 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1029 // Populate the first and last globals declared in this TU.
1030 if (CheckInitOrder && GlobalHasDynamicInitializer)
1031 HasDynamicallyInitializedGlobals = true;
1033 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1036 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1037 GlobalVariable *AllGlobals = new GlobalVariable(
1038 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1039 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1041 // Create calls for poisoning before initializers run and unpoisoning after.
1042 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1043 createInitializerPoisonCalls(M, ModuleName);
1044 IRB.CreateCall2(AsanRegisterGlobals,
1045 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1046 ConstantInt::get(IntptrTy, n));
1048 // We also need to unregister globals at the end, e.g. when a shared library
1050 Function *AsanDtorFunction = Function::Create(
1051 FunctionType::get(Type::getVoidTy(*C), false),
1052 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1053 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1054 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1055 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1056 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1057 ConstantInt::get(IntptrTy, n));
1058 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1064 void AddressSanitizer::initializeCallbacks(Module &M) {
1065 IRBuilder<> IRB(*C);
1066 // Create __asan_report* callbacks.
1067 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1068 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1069 AccessSizeIndex++) {
1070 // IsWrite and TypeSize are encoded in the function name.
1071 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1072 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1073 // If we are merging crash callbacks, they have two parameters.
1074 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1075 checkInterfaceFunction(M.getOrInsertFunction(
1076 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1079 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1080 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1081 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1082 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1084 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1085 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1086 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1087 kAsanCovName, IRB.getVoidTy(), IntptrTy, 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 // Poor man's coverage that works with ASan.
1160 // We create a Guard boolean variable with the same linkage
1161 // as the function and inject this code into the entry block:
1163 // __sanitizer_cov(&F);
1166 // The accesses to Guard are atomic. The rest of the logic is
1167 // in __sanitizer_cov (it's fine to call it more than once).
1169 // This coverage implementation provides very limited data:
1170 // it only tells if a given function was ever executed.
1171 // No counters, no per-basic-block or per-edge data.
1172 // But for many use cases this is what we need and the added slowdown
1173 // is negligible. This simple implementation will probably be obsoleted
1174 // by the upcoming Clang-based coverage implementation.
1175 // By having it here and now we hope to
1176 // a) get the functionality to users earlier and
1177 // b) collect usage statistics to help improve Clang coverage design.
1178 bool AddressSanitizer::InjectCoverage(Function &F) {
1179 if (!ClCoverage) return false;
1181 // Skip static allocas at the top of the entry block so they don't become
1182 // dynamic when we split the block. If we used our optimized stack layout,
1183 // then there will only be one alloca and it will come first.
1184 BasicBlock &Entry = F.getEntryBlock();
1185 BasicBlock::iterator IP = Entry.getFirstInsertionPt(), BE = Entry.end();
1186 for (; IP != BE; ++IP) {
1187 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1188 if (!AI || !AI->isStaticAlloca())
1192 IRBuilder<> IRB(IP);
1193 Type *Int8Ty = IRB.getInt8Ty();
1194 GlobalVariable *Guard = new GlobalVariable(
1195 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1196 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1197 LoadInst *Load = IRB.CreateLoad(Guard);
1198 Load->setAtomic(Monotonic);
1199 Load->setAlignment(1);
1200 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1201 Instruction *Ins = SplitBlockAndInsertIfThen(Cmp, IP, false);
1202 IRB.SetInsertPoint(Ins);
1203 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1204 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1205 IRB.CreateCall(AsanCovFunction, IRB.CreatePointerCast(&F, IntptrTy));
1206 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1207 Store->setAtomic(Monotonic);
1208 Store->setAlignment(1);
1212 bool AddressSanitizer::runOnFunction(Function &F) {
1213 if (BL->isIn(F)) return false;
1214 if (&F == AsanCtorFunction) return false;
1215 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1216 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1217 initializeCallbacks(*F.getParent());
1219 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1220 maybeInsertAsanInitAtFunctionEntry(F);
1222 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1225 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1228 // We want to instrument every address only once per basic block (unless there
1229 // are calls between uses).
1230 SmallSet<Value*, 16> TempsToInstrument;
1231 SmallVector<Instruction*, 16> ToInstrument;
1232 SmallVector<Instruction*, 8> NoReturnCalls;
1236 // Fill the set of memory operations to instrument.
1237 for (Function::iterator FI = F.begin(), FE = F.end();
1239 TempsToInstrument.clear();
1240 int NumInsnsPerBB = 0;
1241 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1243 if (LooksLikeCodeInBug11395(BI)) return false;
1244 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1245 if (ClOpt && ClOptSameTemp) {
1246 if (!TempsToInstrument.insert(Addr))
1247 continue; // We've seen this temp in the current BB.
1249 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1252 if (isa<AllocaInst>(BI))
1256 // A call inside BB.
1257 TempsToInstrument.clear();
1258 if (CS.doesNotReturn())
1259 NoReturnCalls.push_back(CS.getInstruction());
1263 ToInstrument.push_back(BI);
1265 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1270 Function *UninstrumentedDuplicate = 0;
1271 bool LikelyToInstrument =
1272 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1273 if (ClKeepUninstrumented && LikelyToInstrument) {
1274 ValueToValueMapTy VMap;
1275 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1276 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1277 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1278 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1282 int NumInstrumented = 0;
1283 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1284 Instruction *Inst = ToInstrument[i];
1285 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1286 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1287 if (isInterestingMemoryAccess(Inst, &IsWrite))
1288 instrumentMop(Inst);
1290 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1295 FunctionStackPoisoner FSP(F, *this);
1296 bool ChangedStack = FSP.runOnFunction();
1298 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1299 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1300 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1301 Instruction *CI = NoReturnCalls[i];
1302 IRBuilder<> IRB(CI);
1303 IRB.CreateCall(AsanHandleNoReturnFunc);
1306 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1308 if (InjectCoverage(F))
1311 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1313 if (ClKeepUninstrumented) {
1315 // No instrumentation is done, no need for the duplicate.
1316 if (UninstrumentedDuplicate)
1317 UninstrumentedDuplicate->eraseFromParent();
1319 // The function was instrumented. We must have the duplicate.
1320 assert(UninstrumentedDuplicate);
1321 UninstrumentedDuplicate->setSection("NOASAN");
1322 assert(!F.hasSection());
1323 F.setSection("ASAN");
1330 // Workaround for bug 11395: we don't want to instrument stack in functions
1331 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1332 // FIXME: remove once the bug 11395 is fixed.
1333 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1334 if (LongSize != 32) return false;
1335 CallInst *CI = dyn_cast<CallInst>(I);
1336 if (!CI || !CI->isInlineAsm()) return false;
1337 if (CI->getNumArgOperands() <= 5) return false;
1338 // We have inline assembly with quite a few arguments.
1342 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1343 IRBuilder<> IRB(*C);
1344 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1345 std::string Suffix = itostr(i);
1346 AsanStackMallocFunc[i] = checkInterfaceFunction(
1347 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1348 IntptrTy, IntptrTy, NULL));
1349 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1350 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1351 IntptrTy, IntptrTy, NULL));
1353 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1354 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1355 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1356 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1360 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1361 IRBuilder<> &IRB, Value *ShadowBase,
1363 size_t n = ShadowBytes.size();
1365 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1366 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1367 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1368 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1369 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1370 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1372 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1373 if (ASan.TD->isLittleEndian())
1374 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1376 Val = (Val << 8) | ShadowBytes[i + j];
1379 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1380 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1381 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1382 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1387 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1388 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1389 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1390 assert(LocalStackSize <= kMaxStackMallocSize);
1391 uint64_t MaxSize = kMinStackMallocSize;
1392 for (int i = 0; ; i++, MaxSize *= 2)
1393 if (LocalStackSize <= MaxSize)
1395 llvm_unreachable("impossible LocalStackSize");
1398 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1399 // We can not use MemSet intrinsic because it may end up calling the actual
1400 // memset. Size is a multiple of 8.
1401 // Currently this generates 8-byte stores on x86_64; it may be better to
1402 // generate wider stores.
1403 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1404 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1405 assert(!(Size % 8));
1406 assert(kAsanStackAfterReturnMagic == 0xf5);
1407 for (int i = 0; i < Size; i += 8) {
1408 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1409 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1410 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1414 void FunctionStackPoisoner::poisonStack() {
1415 int StackMallocIdx = -1;
1417 assert(AllocaVec.size() > 0);
1418 Instruction *InsBefore = AllocaVec[0];
1419 IRBuilder<> IRB(InsBefore);
1421 SmallVector<ASanStackVariableDescription, 16> SVD;
1422 SVD.reserve(AllocaVec.size());
1423 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1424 AllocaInst *AI = AllocaVec[i];
1425 ASanStackVariableDescription D = { AI->getName().data(),
1426 getAllocaSizeInBytes(AI),
1427 AI->getAlignment(), AI, 0};
1430 // Minimal header size (left redzone) is 4 pointers,
1431 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1432 size_t MinHeaderSize = ASan.LongSize / 2;
1433 ASanStackFrameLayout L;
1434 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1435 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1436 uint64_t LocalStackSize = L.FrameSize;
1437 bool DoStackMalloc =
1438 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1440 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1441 AllocaInst *MyAlloca =
1442 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1443 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1444 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1445 MyAlloca->setAlignment(FrameAlignment);
1446 assert(MyAlloca->isStaticAlloca());
1447 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1448 Value *LocalStackBase = OrigStackBase;
1450 if (DoStackMalloc) {
1451 // LocalStackBase = OrigStackBase
1452 // if (__asan_option_detect_stack_use_after_return)
1453 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1454 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1455 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1456 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1457 kAsanOptionDetectUAR, IRB.getInt32Ty());
1458 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1459 Constant::getNullValue(IRB.getInt32Ty()));
1460 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1461 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1462 IRBuilder<> IRBIf(Term);
1463 LocalStackBase = IRBIf.CreateCall2(
1464 AsanStackMallocFunc[StackMallocIdx],
1465 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1466 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1467 IRB.SetInsertPoint(InsBefore);
1468 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1469 Phi->addIncoming(OrigStackBase, CmpBlock);
1470 Phi->addIncoming(LocalStackBase, SetBlock);
1471 LocalStackBase = Phi;
1474 // Insert poison calls for lifetime intrinsics for alloca.
1475 bool HavePoisonedAllocas = false;
1476 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1477 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1478 assert(APC.InsBefore);
1480 IRBuilder<> IRB(APC.InsBefore);
1481 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1482 HavePoisonedAllocas |= APC.DoPoison;
1485 // Replace Alloca instructions with base+offset.
1486 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1487 AllocaInst *AI = SVD[i].AI;
1488 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1489 IRB.CreateAdd(LocalStackBase,
1490 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1492 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1493 AI->replaceAllUsesWith(NewAllocaPtr);
1496 // The left-most redzone has enough space for at least 4 pointers.
1497 // Write the Magic value to redzone[0].
1498 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1499 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1501 // Write the frame description constant to redzone[1].
1502 Value *BasePlus1 = IRB.CreateIntToPtr(
1503 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1505 GlobalVariable *StackDescriptionGlobal =
1506 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1507 /*AllowMerging*/true);
1508 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1510 IRB.CreateStore(Description, BasePlus1);
1511 // Write the PC to redzone[2].
1512 Value *BasePlus2 = IRB.CreateIntToPtr(
1513 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1514 2 * ASan.LongSize/8)),
1516 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1518 // Poison the stack redzones at the entry.
1519 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1520 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1522 // (Un)poison the stack before all ret instructions.
1523 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1524 Instruction *Ret = RetVec[i];
1525 IRBuilder<> IRBRet(Ret);
1526 // Mark the current frame as retired.
1527 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1529 if (DoStackMalloc) {
1530 assert(StackMallocIdx >= 0);
1531 // if LocalStackBase != OrigStackBase:
1532 // // In use-after-return mode, poison the whole stack frame.
1533 // if StackMallocIdx <= 4
1534 // // For small sizes inline the whole thing:
1535 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1536 // **SavedFlagPtr(LocalStackBase) = 0
1538 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1540 // <This is not a fake stack; unpoison the redzones>
1541 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1542 TerminatorInst *ThenTerm, *ElseTerm;
1543 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1545 IRBuilder<> IRBPoison(ThenTerm);
1546 if (StackMallocIdx <= 4) {
1547 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1548 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1549 ClassSize >> Mapping.Scale);
1550 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1552 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1553 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1554 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1555 IRBPoison.CreateStore(
1556 Constant::getNullValue(IRBPoison.getInt8Ty()),
1557 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1559 // For larger frames call __asan_stack_free_*.
1560 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1561 ConstantInt::get(IntptrTy, LocalStackSize),
1565 IRBuilder<> IRBElse(ElseTerm);
1566 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1567 } else if (HavePoisonedAllocas) {
1568 // If we poisoned some allocas in llvm.lifetime analysis,
1569 // unpoison whole stack frame now.
1570 assert(LocalStackBase == OrigStackBase);
1571 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1573 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1577 // We are done. Remove the old unused alloca instructions.
1578 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1579 AllocaVec[i]->eraseFromParent();
1582 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1583 IRBuilder<> &IRB, bool DoPoison) {
1584 // For now just insert the call to ASan runtime.
1585 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1586 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1587 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1588 : AsanUnpoisonStackMemoryFunc,
1592 // Handling llvm.lifetime intrinsics for a given %alloca:
1593 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1594 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1595 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1596 // could be poisoned by previous llvm.lifetime.end instruction, as the
1597 // variable may go in and out of scope several times, e.g. in loops).
1598 // (3) if we poisoned at least one %alloca in a function,
1599 // unpoison the whole stack frame at function exit.
1601 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1602 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1603 // We're intested only in allocas we can handle.
1604 return isInterestingAlloca(*AI) ? AI : 0;
1605 // See if we've already calculated (or started to calculate) alloca for a
1607 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1608 if (I != AllocaForValue.end())
1610 // Store 0 while we're calculating alloca for value V to avoid
1611 // infinite recursion if the value references itself.
1612 AllocaForValue[V] = 0;
1613 AllocaInst *Res = 0;
1614 if (CastInst *CI = dyn_cast<CastInst>(V))
1615 Res = findAllocaForValue(CI->getOperand(0));
1616 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1617 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1618 Value *IncValue = PN->getIncomingValue(i);
1619 // Allow self-referencing phi-nodes.
1620 if (IncValue == PN) continue;
1621 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1622 // AI for incoming values should exist and should all be equal.
1623 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1629 AllocaForValue[V] = Res;