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/MDBuilder.h"
37 #include "llvm/IR/Module.h"
38 #include "llvm/IR/Type.h"
39 #include "llvm/InstVisitor.h"
40 #include "llvm/Support/CallSite.h"
41 #include "llvm/Support/CommandLine.h"
42 #include "llvm/Support/DataTypes.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/Endian.h"
45 #include "llvm/Support/system_error.h"
46 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
47 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
48 #include "llvm/Transforms/Utils/Cloning.h"
49 #include "llvm/Transforms/Utils/Local.h"
50 #include "llvm/Transforms/Utils/ModuleUtils.h"
51 #include "llvm/Transforms/Utils/SpecialCaseList.h"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
60 static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
61 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
62 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
64 static const size_t kMinStackMallocSize = 1 << 6; // 64B
65 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
66 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
67 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
69 static const char *const kAsanModuleCtorName = "asan.module_ctor";
70 static const char *const kAsanModuleDtorName = "asan.module_dtor";
71 static const int kAsanCtorAndCtorPriority = 1;
72 static const char *const kAsanReportErrorTemplate = "__asan_report_";
73 static const char *const kAsanReportLoadN = "__asan_report_load_n";
74 static const char *const kAsanReportStoreN = "__asan_report_store_n";
75 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
76 static const char *const kAsanUnregisterGlobalsName =
77 "__asan_unregister_globals";
78 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
79 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
80 static const char *const kAsanInitName = "__asan_init_v3";
81 static const char *const kAsanCovName = "__sanitizer_cov";
82 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
83 static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
84 static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
85 static const int kMaxAsanStackMallocSizeClass = 10;
86 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
87 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
88 static const char *const kAsanGenPrefix = "__asan_gen_";
89 static const char *const kAsanPoisonStackMemoryName =
90 "__asan_poison_stack_memory";
91 static const char *const kAsanUnpoisonStackMemoryName =
92 "__asan_unpoison_stack_memory";
94 static const char *const kAsanOptionDetectUAR =
95 "__asan_option_detect_stack_use_after_return";
98 static const int kAsanStackAfterReturnMagic = 0xf5;
101 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
102 static const size_t kNumberOfAccessSizes = 5;
104 // Command-line flags.
106 // This flag may need to be replaced with -f[no-]asan-reads.
107 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
108 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
109 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
110 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
111 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
112 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
113 cl::Hidden, cl::init(true));
114 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
115 cl::desc("use instrumentation with slow path for all accesses"),
116 cl::Hidden, cl::init(false));
117 // This flag limits the number of instructions to be instrumented
118 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
119 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
121 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
123 cl::desc("maximal number of instructions to instrument in any given BB"),
125 // This flag may need to be replaced with -f[no]asan-stack.
126 static cl::opt<bool> ClStack("asan-stack",
127 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
128 // This flag may need to be replaced with -f[no]asan-use-after-return.
129 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
130 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
131 // This flag may need to be replaced with -f[no]asan-globals.
132 static cl::opt<bool> ClGlobals("asan-globals",
133 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
134 static cl::opt<int> ClCoverage("asan-coverage",
135 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
136 cl::Hidden, cl::init(false));
137 static cl::opt<bool> ClInitializers("asan-initialization-order",
138 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
139 static cl::opt<bool> ClMemIntrin("asan-memintrin",
140 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
141 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
142 cl::desc("Realign stack to the value of this flag (power of two)"),
143 cl::Hidden, cl::init(32));
144 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
145 cl::desc("File containing the list of objects to ignore "
146 "during instrumentation"), cl::Hidden);
148 // This is an experimental feature that will allow to choose between
149 // instrumented and non-instrumented code at link-time.
150 // If this option is on, just before instrumenting a function we create its
151 // clone; if the function is not changed by asan the clone is deleted.
152 // If we end up with a clone, we put the instrumented function into a section
153 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
155 // This is still a prototype, we need to figure out a way to keep two copies of
156 // a function so that the linker can easily choose one of them.
157 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
158 cl::desc("Keep uninstrumented copies of functions"),
159 cl::Hidden, cl::init(false));
161 // These flags allow to change the shadow mapping.
162 // The shadow mapping looks like
163 // Shadow = (Mem >> scale) + (1 << offset_log)
164 static cl::opt<int> ClMappingScale("asan-mapping-scale",
165 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
166 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
167 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
168 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
169 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
170 cl::Hidden, cl::init(true));
172 // Optimization flags. Not user visible, used mostly for testing
173 // and benchmarking the tool.
174 static cl::opt<bool> ClOpt("asan-opt",
175 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
176 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
177 cl::desc("Instrument the same temp just once"), cl::Hidden,
179 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
180 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
182 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
183 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
184 cl::Hidden, cl::init(false));
187 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
189 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
190 cl::Hidden, cl::init(0));
191 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
192 cl::Hidden, cl::desc("Debug func"));
193 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
194 cl::Hidden, cl::init(-1));
195 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
196 cl::Hidden, cl::init(-1));
198 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
199 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
200 STATISTIC(NumOptimizedAccessesToGlobalArray,
201 "Number of optimized accesses to global arrays");
202 STATISTIC(NumOptimizedAccessesToGlobalVar,
203 "Number of optimized accesses to global vars");
206 /// A set of dynamically initialized globals extracted from metadata.
207 class SetOfDynamicallyInitializedGlobals {
209 void Init(Module& M) {
210 // Clang generates metadata identifying all dynamically initialized globals.
211 NamedMDNode *DynamicGlobals =
212 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
215 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
216 MDNode *MDN = DynamicGlobals->getOperand(i);
217 assert(MDN->getNumOperands() == 1);
218 Value *VG = MDN->getOperand(0);
219 // The optimizer may optimize away a global entirely, in which case we
220 // cannot instrument access to it.
223 DynInitGlobals.insert(cast<GlobalVariable>(VG));
226 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
228 SmallSet<GlobalValue*, 32> DynInitGlobals;
231 /// This struct defines the shadow mapping using the rule:
232 /// shadow = (mem >> Scale) ADD-or-OR Offset.
233 struct ShadowMapping {
239 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
240 llvm::Triple TargetTriple(M.getTargetTriple());
241 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
242 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
243 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
244 TargetTriple.getArch() == llvm::Triple::ppc64le;
245 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
246 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
247 TargetTriple.getArch() == llvm::Triple::mipsel;
249 ShadowMapping Mapping;
251 // OR-ing shadow offset if more efficient (at least on x86),
252 // but on ppc64 we have to use add since the shadow offset is not neccesary
253 // 1/8-th of the address space.
254 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
256 Mapping.Offset = IsAndroid ? 0 :
258 (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
259 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
260 if (!IsAndroid && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
261 assert(LongSize == 64);
262 Mapping.Offset = kDefaultShort64bitShadowOffset;
264 if (!IsAndroid && ClMappingOffsetLog >= 0) {
265 // Zero offset log is the special case.
266 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
269 Mapping.Scale = kDefaultShadowScale;
270 if (ClMappingScale) {
271 Mapping.Scale = ClMappingScale;
277 static size_t RedzoneSizeForScale(int MappingScale) {
278 // Redzone used for stack and globals is at least 32 bytes.
279 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
280 return std::max(32U, 1U << MappingScale);
283 /// AddressSanitizer: instrument the code in module to find memory bugs.
284 struct AddressSanitizer : public FunctionPass {
285 AddressSanitizer(bool CheckInitOrder = true,
286 bool CheckUseAfterReturn = false,
287 bool CheckLifetime = false,
288 StringRef BlacklistFile = StringRef())
290 CheckInitOrder(CheckInitOrder || ClInitializers),
291 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
292 CheckLifetime(CheckLifetime || ClCheckLifetime),
293 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
295 virtual const char *getPassName() const {
296 return "AddressSanitizerFunctionPass";
298 void instrumentMop(Instruction *I);
299 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
300 Value *Addr, uint32_t TypeSize, bool IsWrite,
301 Value *SizeArgument);
302 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
303 Value *ShadowValue, uint32_t TypeSize);
304 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
305 bool IsWrite, size_t AccessSizeIndex,
306 Value *SizeArgument);
307 bool instrumentMemIntrinsic(MemIntrinsic *MI);
308 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
310 Instruction *InsertBefore, bool IsWrite);
311 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
312 bool runOnFunction(Function &F);
313 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
314 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
315 virtual bool doInitialization(Module &M);
316 static char ID; // Pass identification, replacement for typeid
319 void initializeCallbacks(Module &M);
321 bool ShouldInstrumentGlobal(GlobalVariable *G);
322 bool LooksLikeCodeInBug11395(Instruction *I);
323 void FindDynamicInitializers(Module &M);
324 bool GlobalIsLinkerInitialized(GlobalVariable *G);
325 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
326 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
329 bool CheckUseAfterReturn;
331 SmallString<64> BlacklistFile;
337 ShadowMapping Mapping;
338 Function *AsanCtorFunction;
339 Function *AsanInitFunction;
340 Function *AsanHandleNoReturnFunc;
341 Function *AsanCovFunction;
342 OwningPtr<SpecialCaseList> BL;
343 // This array is indexed by AccessIsWrite and log2(AccessSize).
344 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
345 // This array is indexed by AccessIsWrite.
346 Function *AsanErrorCallbackSized[2];
348 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
350 friend struct FunctionStackPoisoner;
353 class AddressSanitizerModule : public ModulePass {
355 AddressSanitizerModule(bool CheckInitOrder = true,
356 StringRef BlacklistFile = StringRef())
358 CheckInitOrder(CheckInitOrder || ClInitializers),
359 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
361 bool runOnModule(Module &M);
362 static char ID; // Pass identification, replacement for typeid
363 virtual const char *getPassName() const {
364 return "AddressSanitizerModule";
368 void initializeCallbacks(Module &M);
370 bool ShouldInstrumentGlobal(GlobalVariable *G);
371 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
372 size_t MinRedzoneSizeForGlobal() const {
373 return RedzoneSizeForScale(Mapping.Scale);
377 SmallString<64> BlacklistFile;
379 OwningPtr<SpecialCaseList> BL;
380 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
384 ShadowMapping Mapping;
385 Function *AsanPoisonGlobals;
386 Function *AsanUnpoisonGlobals;
387 Function *AsanRegisterGlobals;
388 Function *AsanUnregisterGlobals;
391 // Stack poisoning does not play well with exception handling.
392 // When an exception is thrown, we essentially bypass the code
393 // that unpoisones the stack. This is why the run-time library has
394 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
395 // stack in the interceptor. This however does not work inside the
396 // actual function which catches the exception. Most likely because the
397 // compiler hoists the load of the shadow value somewhere too high.
398 // This causes asan to report a non-existing bug on 453.povray.
399 // It sounds like an LLVM bug.
400 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
402 AddressSanitizer &ASan;
407 ShadowMapping Mapping;
409 SmallVector<AllocaInst*, 16> AllocaVec;
410 SmallVector<Instruction*, 8> RetVec;
411 unsigned StackAlignment;
413 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
414 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
415 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
417 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
418 struct AllocaPoisonCall {
419 IntrinsicInst *InsBefore;
424 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
426 // Maps Value to an AllocaInst from which the Value is originated.
427 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
428 AllocaForValueMapTy AllocaForValue;
430 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
431 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
432 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
433 Mapping(ASan.Mapping),
434 StackAlignment(1 << Mapping.Scale) {}
436 bool runOnFunction() {
437 if (!ClStack) return false;
438 // Collect alloca, ret, lifetime instructions etc.
439 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
440 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
441 BasicBlock *BB = *DI;
444 if (AllocaVec.empty()) return false;
446 initializeCallbacks(*F.getParent());
456 // Finds all static Alloca instructions and puts
457 // poisoned red zones around all of them.
458 // Then unpoison everything back before the function returns.
461 // ----------------------- Visitors.
462 /// \brief Collect all Ret instructions.
463 void visitReturnInst(ReturnInst &RI) {
464 RetVec.push_back(&RI);
467 /// \brief Collect Alloca instructions we want (and can) handle.
468 void visitAllocaInst(AllocaInst &AI) {
469 if (!isInterestingAlloca(AI)) return;
471 StackAlignment = std::max(StackAlignment, AI.getAlignment());
472 AllocaVec.push_back(&AI);
475 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
477 void visitIntrinsicInst(IntrinsicInst &II) {
478 if (!ASan.CheckLifetime) return;
479 Intrinsic::ID ID = II.getIntrinsicID();
480 if (ID != Intrinsic::lifetime_start &&
481 ID != Intrinsic::lifetime_end)
483 // Found lifetime intrinsic, add ASan instrumentation if necessary.
484 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
485 // If size argument is undefined, don't do anything.
486 if (Size->isMinusOne()) return;
487 // Check that size doesn't saturate uint64_t and can
488 // be stored in IntptrTy.
489 const uint64_t SizeValue = Size->getValue().getLimitedValue();
490 if (SizeValue == ~0ULL ||
491 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
493 // Find alloca instruction that corresponds to llvm.lifetime argument.
494 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
496 bool DoPoison = (ID == Intrinsic::lifetime_end);
497 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
498 AllocaPoisonCallVec.push_back(APC);
501 // ---------------------- Helpers.
502 void initializeCallbacks(Module &M);
504 // Check if we want (and can) handle this alloca.
505 bool isInterestingAlloca(AllocaInst &AI) const {
506 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
507 AI.getAllocatedType()->isSized() &&
508 // alloca() may be called with 0 size, ignore it.
509 getAllocaSizeInBytes(&AI) > 0);
512 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
513 Type *Ty = AI->getAllocatedType();
514 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
517 /// Finds alloca where the value comes from.
518 AllocaInst *findAllocaForValue(Value *V);
519 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
520 Value *ShadowBase, bool DoPoison);
521 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
523 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
529 char AddressSanitizer::ID = 0;
530 INITIALIZE_PASS(AddressSanitizer, "asan",
531 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
533 FunctionPass *llvm::createAddressSanitizerFunctionPass(
534 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
535 StringRef BlacklistFile) {
536 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
537 CheckLifetime, BlacklistFile);
540 char AddressSanitizerModule::ID = 0;
541 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
542 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
543 "ModulePass", false, false)
544 ModulePass *llvm::createAddressSanitizerModulePass(
545 bool CheckInitOrder, StringRef BlacklistFile) {
546 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
549 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
550 size_t Res = countTrailingZeros(TypeSize / 8);
551 assert(Res < kNumberOfAccessSizes);
555 // \brief Create a constant for Str so that we can pass it to the run-time lib.
556 static GlobalVariable *createPrivateGlobalForString(
557 Module &M, StringRef Str, bool AllowMerging) {
558 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
559 // For module-local strings that can be merged with another one we set the
560 // private linkage and the unnamed_addr attribute.
561 // Non-mergeable strings are made linker_private to remove them from the
562 // symbol table. "private" linkage doesn't work for Darwin, where the
563 // "L"-prefixed globals end up in __TEXT,__const section
564 // (see http://llvm.org/bugs/show_bug.cgi?id=17976 for more info).
565 GlobalValue::LinkageTypes linkage =
566 AllowMerging ? GlobalValue::PrivateLinkage
567 : GlobalValue::LinkerPrivateLinkage;
569 new GlobalVariable(M, StrConst->getType(), true,
570 linkage, StrConst, kAsanGenPrefix);
571 if (AllowMerging) GV->setUnnamedAddr(true);
572 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
576 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
577 return G->getName().find(kAsanGenPrefix) == 0;
580 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
582 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
583 if (Mapping.Offset == 0)
585 // (Shadow >> scale) | offset
586 if (Mapping.OrShadowOffset)
587 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
589 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
592 void AddressSanitizer::instrumentMemIntrinsicParam(
593 Instruction *OrigIns,
594 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
595 IRBuilder<> IRB(InsertBefore);
596 if (Size->getType() != IntptrTy)
597 Size = IRB.CreateIntCast(Size, IntptrTy, false);
598 // Check the first byte.
599 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
600 // Check the last byte.
601 IRB.SetInsertPoint(InsertBefore);
602 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
603 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
604 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
605 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
608 // Instrument memset/memmove/memcpy
609 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
610 Value *Dst = MI->getDest();
611 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
612 Value *Src = MemTran ? MemTran->getSource() : 0;
613 Value *Length = MI->getLength();
615 Constant *ConstLength = dyn_cast<Constant>(Length);
616 Instruction *InsertBefore = MI;
618 if (ConstLength->isNullValue()) return false;
620 // The size is not a constant so it could be zero -- check at run-time.
621 IRBuilder<> IRB(InsertBefore);
623 Value *Cmp = IRB.CreateICmpNE(Length,
624 Constant::getNullValue(Length->getType()));
625 InsertBefore = SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
628 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
630 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
634 // If I is an interesting memory access, return the PointerOperand
635 // and set IsWrite. Otherwise return NULL.
636 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
637 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
638 if (!ClInstrumentReads) return NULL;
640 return LI->getPointerOperand();
642 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
643 if (!ClInstrumentWrites) return NULL;
645 return SI->getPointerOperand();
647 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
648 if (!ClInstrumentAtomics) return NULL;
650 return RMW->getPointerOperand();
652 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
653 if (!ClInstrumentAtomics) return NULL;
655 return XCHG->getPointerOperand();
660 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
661 // If a global variable does not have dynamic initialization we don't
662 // have to instrument it. However, if a global does not have initializer
663 // at all, we assume it has dynamic initializer (in other TU).
664 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
667 void AddressSanitizer::instrumentMop(Instruction *I) {
668 bool IsWrite = false;
669 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
671 if (ClOpt && ClOptGlobals) {
672 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
673 // If initialization order checking is disabled, a simple access to a
674 // dynamically initialized global is always valid.
675 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
676 NumOptimizedAccessesToGlobalVar++;
680 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
681 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
682 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
683 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
684 NumOptimizedAccessesToGlobalArray++;
691 Type *OrigPtrTy = Addr->getType();
692 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
694 assert(OrigTy->isSized());
695 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
697 assert((TypeSize % 8) == 0);
700 NumInstrumentedWrites++;
702 NumInstrumentedReads++;
704 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
705 if (TypeSize == 8 || TypeSize == 16 ||
706 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
707 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
708 // Instrument unusual size (but still multiple of 8).
709 // We can not do it with a single check, so we do 1-byte check for the first
710 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
711 // to report the actual access size.
713 Value *LastByte = IRB.CreateIntToPtr(
714 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
715 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
717 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
718 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
719 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
722 // Validate the result of Module::getOrInsertFunction called for an interface
723 // function of AddressSanitizer. If the instrumented module defines a function
724 // with the same name, their prototypes must match, otherwise
725 // getOrInsertFunction returns a bitcast.
726 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
727 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
728 FuncOrBitcast->dump();
729 report_fatal_error("trying to redefine an AddressSanitizer "
730 "interface function");
733 Instruction *AddressSanitizer::generateCrashCode(
734 Instruction *InsertBefore, Value *Addr,
735 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
736 IRBuilder<> IRB(InsertBefore);
737 CallInst *Call = SizeArgument
738 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
739 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
741 // We don't do Call->setDoesNotReturn() because the BB already has
742 // UnreachableInst at the end.
743 // This EmptyAsm is required to avoid callback merge.
744 IRB.CreateCall(EmptyAsm);
748 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
751 size_t Granularity = 1 << Mapping.Scale;
752 // Addr & (Granularity - 1)
753 Value *LastAccessedByte = IRB.CreateAnd(
754 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
755 // (Addr & (Granularity - 1)) + size - 1
756 if (TypeSize / 8 > 1)
757 LastAccessedByte = IRB.CreateAdd(
758 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
759 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
760 LastAccessedByte = IRB.CreateIntCast(
761 LastAccessedByte, ShadowValue->getType(), false);
762 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
763 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
766 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
767 Instruction *InsertBefore,
768 Value *Addr, uint32_t TypeSize,
769 bool IsWrite, Value *SizeArgument) {
770 IRBuilder<> IRB(InsertBefore);
771 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
773 Type *ShadowTy = IntegerType::get(
774 *C, std::max(8U, TypeSize >> Mapping.Scale));
775 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
776 Value *ShadowPtr = memToShadow(AddrLong, IRB);
777 Value *CmpVal = Constant::getNullValue(ShadowTy);
778 Value *ShadowValue = IRB.CreateLoad(
779 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
781 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
782 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
783 size_t Granularity = 1 << Mapping.Scale;
784 TerminatorInst *CrashTerm = 0;
786 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
787 TerminatorInst *CheckTerm =
788 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
789 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
790 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
791 IRB.SetInsertPoint(CheckTerm);
792 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
793 BasicBlock *CrashBlock =
794 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
795 CrashTerm = new UnreachableInst(*C, CrashBlock);
796 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
797 ReplaceInstWithInst(CheckTerm, NewTerm);
799 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
802 Instruction *Crash = generateCrashCode(
803 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
804 Crash->setDebugLoc(OrigIns->getDebugLoc());
807 void AddressSanitizerModule::createInitializerPoisonCalls(
808 Module &M, GlobalValue *ModuleName) {
809 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
810 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
811 // If that function is not present, this TU contains no globals, or they have
812 // all been optimized away
816 // Set up the arguments to our poison/unpoison functions.
817 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
819 // Add a call to poison all external globals before the given function starts.
820 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
821 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
823 // Add calls to unpoison all globals before each return instruction.
824 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
826 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
827 CallInst::Create(AsanUnpoisonGlobals, "", RI);
832 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
833 Type *Ty = cast<PointerType>(G->getType())->getElementType();
834 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
836 if (BL->isIn(*G)) return false;
837 if (!Ty->isSized()) return false;
838 if (!G->hasInitializer()) return false;
839 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
840 // Touch only those globals that will not be defined in other modules.
841 // Don't handle ODR type linkages since other modules may be built w/o asan.
842 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
843 G->getLinkage() != GlobalVariable::PrivateLinkage &&
844 G->getLinkage() != GlobalVariable::InternalLinkage)
846 // Two problems with thread-locals:
847 // - The address of the main thread's copy can't be computed at link-time.
848 // - Need to poison all copies, not just the main thread's one.
849 if (G->isThreadLocal())
851 // For now, just ignore this Global if the alignment is large.
852 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
854 // Ignore all the globals with the names starting with "\01L_OBJC_".
855 // Many of those are put into the .cstring section. The linker compresses
856 // that section by removing the spare \0s after the string terminator, so
857 // our redzones get broken.
858 if ((G->getName().find("\01L_OBJC_") == 0) ||
859 (G->getName().find("\01l_OBJC_") == 0)) {
860 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
864 if (G->hasSection()) {
865 StringRef Section(G->getSection());
866 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
867 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
869 if ((Section.find("__OBJC,") == 0) ||
870 (Section.find("__DATA, __objc_") == 0)) {
871 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
874 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
875 // Constant CFString instances are compiled in the following way:
876 // -- the string buffer is emitted into
877 // __TEXT,__cstring,cstring_literals
878 // -- the constant NSConstantString structure referencing that buffer
879 // is placed into __DATA,__cfstring
880 // Therefore there's no point in placing redzones into __DATA,__cfstring.
881 // Moreover, it causes the linker to crash on OS X 10.7
882 if (Section.find("__DATA,__cfstring") == 0) {
883 DEBUG(dbgs() << "Ignoring CFString: " << *G);
891 void AddressSanitizerModule::initializeCallbacks(Module &M) {
893 // Declare our poisoning and unpoisoning functions.
894 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
895 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
896 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
897 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
898 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
899 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
900 // Declare functions that register/unregister globals.
901 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
902 kAsanRegisterGlobalsName, IRB.getVoidTy(),
903 IntptrTy, IntptrTy, NULL));
904 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
905 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
906 kAsanUnregisterGlobalsName,
907 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
908 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
911 // This function replaces all global variables with new variables that have
912 // trailing redzones. It also creates a function that poisons
913 // redzones and inserts this function into llvm.global_ctors.
914 bool AddressSanitizerModule::runOnModule(Module &M) {
915 if (!ClGlobals) return false;
916 TD = getAnalysisIfAvailable<DataLayout>();
919 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
920 if (BL->isIn(M)) return false;
921 C = &(M.getContext());
922 int LongSize = TD->getPointerSizeInBits();
923 IntptrTy = Type::getIntNTy(*C, LongSize);
924 Mapping = getShadowMapping(M, LongSize);
925 initializeCallbacks(M);
926 DynamicallyInitializedGlobals.Init(M);
928 SmallVector<GlobalVariable *, 16> GlobalsToChange;
930 for (Module::GlobalListType::iterator G = M.global_begin(),
931 E = M.global_end(); G != E; ++G) {
932 if (ShouldInstrumentGlobal(G))
933 GlobalsToChange.push_back(G);
936 size_t n = GlobalsToChange.size();
937 if (n == 0) return false;
939 // A global is described by a structure
942 // size_t size_with_redzone;
944 // const char *module_name;
945 // size_t has_dynamic_init;
946 // We initialize an array of such structures and pass it to a run-time call.
947 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
949 IntptrTy, IntptrTy, NULL);
950 SmallVector<Constant *, 16> Initializers(n);
952 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
954 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
956 bool HasDynamicallyInitializedGlobals = false;
958 // We shouldn't merge same module names, as this string serves as unique
959 // module ID in runtime.
960 GlobalVariable *ModuleName = createPrivateGlobalForString(
961 M, M.getModuleIdentifier(), /*AllowMerging*/false);
963 for (size_t i = 0; i < n; i++) {
964 static const uint64_t kMaxGlobalRedzone = 1 << 18;
965 GlobalVariable *G = GlobalsToChange[i];
966 PointerType *PtrTy = cast<PointerType>(G->getType());
967 Type *Ty = PtrTy->getElementType();
968 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
969 uint64_t MinRZ = MinRedzoneSizeForGlobal();
970 // MinRZ <= RZ <= kMaxGlobalRedzone
971 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
972 uint64_t RZ = std::max(MinRZ,
973 std::min(kMaxGlobalRedzone,
974 (SizeInBytes / MinRZ / 4) * MinRZ));
975 uint64_t RightRedzoneSize = RZ;
977 if (SizeInBytes % MinRZ)
978 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
979 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
980 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
981 // Determine whether this global should be poisoned in initialization.
982 bool GlobalHasDynamicInitializer =
983 DynamicallyInitializedGlobals.Contains(G);
984 // Don't check initialization order if this global is blacklisted.
985 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
987 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
988 Constant *NewInitializer = ConstantStruct::get(
989 NewTy, G->getInitializer(),
990 Constant::getNullValue(RightRedZoneTy), NULL);
992 GlobalVariable *Name =
993 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
995 // Create a new global variable with enough space for a redzone.
996 GlobalValue::LinkageTypes Linkage = G->getLinkage();
997 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
998 Linkage = GlobalValue::InternalLinkage;
999 GlobalVariable *NewGlobal = new GlobalVariable(
1000 M, NewTy, G->isConstant(), Linkage,
1001 NewInitializer, "", G, G->getThreadLocalMode());
1002 NewGlobal->copyAttributesFrom(G);
1003 NewGlobal->setAlignment(MinRZ);
1006 Indices2[0] = IRB.getInt32(0);
1007 Indices2[1] = IRB.getInt32(0);
1009 G->replaceAllUsesWith(
1010 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1011 NewGlobal->takeName(G);
1012 G->eraseFromParent();
1014 Initializers[i] = ConstantStruct::get(
1016 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1017 ConstantInt::get(IntptrTy, SizeInBytes),
1018 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1019 ConstantExpr::getPointerCast(Name, IntptrTy),
1020 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1021 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1024 // Populate the first and last globals declared in this TU.
1025 if (CheckInitOrder && GlobalHasDynamicInitializer)
1026 HasDynamicallyInitializedGlobals = true;
1028 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1031 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1032 GlobalVariable *AllGlobals = new GlobalVariable(
1033 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1034 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1036 // Create calls for poisoning before initializers run and unpoisoning after.
1037 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1038 createInitializerPoisonCalls(M, ModuleName);
1039 IRB.CreateCall2(AsanRegisterGlobals,
1040 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1041 ConstantInt::get(IntptrTy, n));
1043 // We also need to unregister globals at the end, e.g. when a shared library
1045 Function *AsanDtorFunction = Function::Create(
1046 FunctionType::get(Type::getVoidTy(*C), false),
1047 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1048 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1049 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1050 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1051 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1052 ConstantInt::get(IntptrTy, n));
1053 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1059 void AddressSanitizer::initializeCallbacks(Module &M) {
1060 IRBuilder<> IRB(*C);
1061 // Create __asan_report* callbacks.
1062 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1063 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1064 AccessSizeIndex++) {
1065 // IsWrite and TypeSize are encoded in the function name.
1066 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1067 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1068 // If we are merging crash callbacks, they have two parameters.
1069 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1070 checkInterfaceFunction(M.getOrInsertFunction(
1071 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1074 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1075 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1076 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1077 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1079 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1080 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1081 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1082 kAsanCovName, IRB.getVoidTy(), NULL));
1083 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1084 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1085 StringRef(""), StringRef(""),
1086 /*hasSideEffects=*/true);
1089 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1090 // Tell the values of mapping offset and scale to the run-time.
1091 GlobalValue *asan_mapping_offset =
1092 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1093 ConstantInt::get(IntptrTy, Mapping.Offset),
1094 kAsanMappingOffsetName);
1095 // Read the global, otherwise it may be optimized away.
1096 IRB.CreateLoad(asan_mapping_offset, true);
1098 GlobalValue *asan_mapping_scale =
1099 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1100 ConstantInt::get(IntptrTy, Mapping.Scale),
1101 kAsanMappingScaleName);
1102 // Read the global, otherwise it may be optimized away.
1103 IRB.CreateLoad(asan_mapping_scale, true);
1107 bool AddressSanitizer::doInitialization(Module &M) {
1108 // Initialize the private fields. No one has accessed them before.
1109 TD = getAnalysisIfAvailable<DataLayout>();
1113 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1114 DynamicallyInitializedGlobals.Init(M);
1116 C = &(M.getContext());
1117 LongSize = TD->getPointerSizeInBits();
1118 IntptrTy = Type::getIntNTy(*C, LongSize);
1120 AsanCtorFunction = Function::Create(
1121 FunctionType::get(Type::getVoidTy(*C), false),
1122 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1123 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1124 // call __asan_init in the module ctor.
1125 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1126 AsanInitFunction = checkInterfaceFunction(
1127 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1128 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1129 IRB.CreateCall(AsanInitFunction);
1131 Mapping = getShadowMapping(M, LongSize);
1132 emitShadowMapping(M, IRB);
1134 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1138 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1139 // For each NSObject descendant having a +load method, this method is invoked
1140 // by the ObjC runtime before any of the static constructors is called.
1141 // Therefore we need to instrument such methods with a call to __asan_init
1142 // at the beginning in order to initialize our runtime before any access to
1143 // the shadow memory.
1144 // We cannot just ignore these methods, because they may call other
1145 // instrumented functions.
1146 if (F.getName().find(" load]") != std::string::npos) {
1147 IRBuilder<> IRB(F.begin()->begin());
1148 IRB.CreateCall(AsanInitFunction);
1154 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1155 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1156 // Skip static allocas at the top of the entry block so they don't become
1157 // dynamic when we split the block. If we used our optimized stack layout,
1158 // then there will only be one alloca and it will come first.
1159 for (; IP != BE; ++IP) {
1160 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1161 if (!AI || !AI->isStaticAlloca())
1165 IRBuilder<> IRB(IP);
1166 Type *Int8Ty = IRB.getInt8Ty();
1167 GlobalVariable *Guard = new GlobalVariable(
1168 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1169 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1170 LoadInst *Load = IRB.CreateLoad(Guard);
1171 Load->setAtomic(Monotonic);
1172 Load->setAlignment(1);
1173 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1174 Instruction *Ins = SplitBlockAndInsertIfThen(
1175 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1176 IRB.SetInsertPoint(Ins);
1177 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1178 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1179 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1180 Call->setDebugLoc(IP->getDebugLoc());
1181 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1182 Store->setAtomic(Monotonic);
1183 Store->setAlignment(1);
1186 // Poor man's coverage that works with ASan.
1187 // We create a Guard boolean variable with the same linkage
1188 // as the function and inject this code into the entry block (-asan-coverage=1)
1189 // or all blocks (-asan-coverage=2):
1191 // __sanitizer_cov(&F);
1194 // The accesses to Guard are atomic. The rest of the logic is
1195 // in __sanitizer_cov (it's fine to call it more than once).
1197 // This coverage implementation provides very limited data:
1198 // it only tells if a given function (block) was ever executed.
1199 // No counters, no per-edge data.
1200 // But for many use cases this is what we need and the added slowdown
1201 // is negligible. This simple implementation will probably be obsoleted
1202 // by the upcoming Clang-based coverage implementation.
1203 // By having it here and now we hope to
1204 // a) get the functionality to users earlier and
1205 // b) collect usage statistics to help improve Clang coverage design.
1206 bool AddressSanitizer::InjectCoverage(Function &F,
1207 const ArrayRef<BasicBlock *> AllBlocks) {
1208 if (!ClCoverage) return false;
1210 if (ClCoverage == 1) {
1211 InjectCoverageAtBlock(F, F.getEntryBlock());
1213 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1214 InjectCoverageAtBlock(F, *AllBlocks[i]);
1219 bool AddressSanitizer::runOnFunction(Function &F) {
1220 if (BL->isIn(F)) return false;
1221 if (&F == AsanCtorFunction) return false;
1222 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1223 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1224 initializeCallbacks(*F.getParent());
1226 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1227 maybeInsertAsanInitAtFunctionEntry(F);
1229 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1232 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1235 // We want to instrument every address only once per basic block (unless there
1236 // are calls between uses).
1237 SmallSet<Value*, 16> TempsToInstrument;
1238 SmallVector<Instruction*, 16> ToInstrument;
1239 SmallVector<Instruction*, 8> NoReturnCalls;
1240 SmallVector<BasicBlock*, 16> AllBlocks;
1244 // Fill the set of memory operations to instrument.
1245 for (Function::iterator FI = F.begin(), FE = F.end();
1247 AllBlocks.push_back(FI);
1248 TempsToInstrument.clear();
1249 int NumInsnsPerBB = 0;
1250 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1252 if (LooksLikeCodeInBug11395(BI)) return false;
1253 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1254 if (ClOpt && ClOptSameTemp) {
1255 if (!TempsToInstrument.insert(Addr))
1256 continue; // We've seen this temp in the current BB.
1258 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1261 if (isa<AllocaInst>(BI))
1265 // A call inside BB.
1266 TempsToInstrument.clear();
1267 if (CS.doesNotReturn())
1268 NoReturnCalls.push_back(CS.getInstruction());
1272 ToInstrument.push_back(BI);
1274 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1279 Function *UninstrumentedDuplicate = 0;
1280 bool LikelyToInstrument =
1281 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1282 if (ClKeepUninstrumented && LikelyToInstrument) {
1283 ValueToValueMapTy VMap;
1284 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1285 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1286 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1287 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1291 int NumInstrumented = 0;
1292 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1293 Instruction *Inst = ToInstrument[i];
1294 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1295 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1296 if (isInterestingMemoryAccess(Inst, &IsWrite))
1297 instrumentMop(Inst);
1299 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1304 FunctionStackPoisoner FSP(F, *this);
1305 bool ChangedStack = FSP.runOnFunction();
1307 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1308 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1309 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1310 Instruction *CI = NoReturnCalls[i];
1311 IRBuilder<> IRB(CI);
1312 IRB.CreateCall(AsanHandleNoReturnFunc);
1315 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1317 if (InjectCoverage(F, AllBlocks))
1320 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1322 if (ClKeepUninstrumented) {
1324 // No instrumentation is done, no need for the duplicate.
1325 if (UninstrumentedDuplicate)
1326 UninstrumentedDuplicate->eraseFromParent();
1328 // The function was instrumented. We must have the duplicate.
1329 assert(UninstrumentedDuplicate);
1330 UninstrumentedDuplicate->setSection("NOASAN");
1331 assert(!F.hasSection());
1332 F.setSection("ASAN");
1339 // Workaround for bug 11395: we don't want to instrument stack in functions
1340 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1341 // FIXME: remove once the bug 11395 is fixed.
1342 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1343 if (LongSize != 32) return false;
1344 CallInst *CI = dyn_cast<CallInst>(I);
1345 if (!CI || !CI->isInlineAsm()) return false;
1346 if (CI->getNumArgOperands() <= 5) return false;
1347 // We have inline assembly with quite a few arguments.
1351 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1352 IRBuilder<> IRB(*C);
1353 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1354 std::string Suffix = itostr(i);
1355 AsanStackMallocFunc[i] = checkInterfaceFunction(
1356 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1357 IntptrTy, IntptrTy, NULL));
1358 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1359 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1360 IntptrTy, IntptrTy, NULL));
1362 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1363 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1364 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1365 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1369 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1370 IRBuilder<> &IRB, Value *ShadowBase,
1372 size_t n = ShadowBytes.size();
1374 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1375 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1376 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1377 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1378 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1379 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1381 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1382 if (ASan.TD->isLittleEndian())
1383 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1385 Val = (Val << 8) | ShadowBytes[i + j];
1388 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1389 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1390 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1391 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1396 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1397 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1398 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1399 assert(LocalStackSize <= kMaxStackMallocSize);
1400 uint64_t MaxSize = kMinStackMallocSize;
1401 for (int i = 0; ; i++, MaxSize *= 2)
1402 if (LocalStackSize <= MaxSize)
1404 llvm_unreachable("impossible LocalStackSize");
1407 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1408 // We can not use MemSet intrinsic because it may end up calling the actual
1409 // memset. Size is a multiple of 8.
1410 // Currently this generates 8-byte stores on x86_64; it may be better to
1411 // generate wider stores.
1412 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1413 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1414 assert(!(Size % 8));
1415 assert(kAsanStackAfterReturnMagic == 0xf5);
1416 for (int i = 0; i < Size; i += 8) {
1417 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1418 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1419 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1423 void FunctionStackPoisoner::poisonStack() {
1424 int StackMallocIdx = -1;
1426 assert(AllocaVec.size() > 0);
1427 Instruction *InsBefore = AllocaVec[0];
1428 IRBuilder<> IRB(InsBefore);
1430 SmallVector<ASanStackVariableDescription, 16> SVD;
1431 SVD.reserve(AllocaVec.size());
1432 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1433 AllocaInst *AI = AllocaVec[i];
1434 ASanStackVariableDescription D = { AI->getName().data(),
1435 getAllocaSizeInBytes(AI),
1436 AI->getAlignment(), AI, 0};
1439 // Minimal header size (left redzone) is 4 pointers,
1440 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1441 size_t MinHeaderSize = ASan.LongSize / 2;
1442 ASanStackFrameLayout L;
1443 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1444 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1445 uint64_t LocalStackSize = L.FrameSize;
1446 bool DoStackMalloc =
1447 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1449 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1450 AllocaInst *MyAlloca =
1451 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1452 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1453 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1454 MyAlloca->setAlignment(FrameAlignment);
1455 assert(MyAlloca->isStaticAlloca());
1456 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1457 Value *LocalStackBase = OrigStackBase;
1459 if (DoStackMalloc) {
1460 // LocalStackBase = OrigStackBase
1461 // if (__asan_option_detect_stack_use_after_return)
1462 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1463 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1464 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1465 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1466 kAsanOptionDetectUAR, IRB.getInt32Ty());
1467 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1468 Constant::getNullValue(IRB.getInt32Ty()));
1469 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1470 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1471 IRBuilder<> IRBIf(Term);
1472 LocalStackBase = IRBIf.CreateCall2(
1473 AsanStackMallocFunc[StackMallocIdx],
1474 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1475 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1476 IRB.SetInsertPoint(InsBefore);
1477 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1478 Phi->addIncoming(OrigStackBase, CmpBlock);
1479 Phi->addIncoming(LocalStackBase, SetBlock);
1480 LocalStackBase = Phi;
1483 // Insert poison calls for lifetime intrinsics for alloca.
1484 bool HavePoisonedAllocas = false;
1485 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1486 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1487 assert(APC.InsBefore);
1489 IRBuilder<> IRB(APC.InsBefore);
1490 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1491 HavePoisonedAllocas |= APC.DoPoison;
1494 // Replace Alloca instructions with base+offset.
1495 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1496 AllocaInst *AI = SVD[i].AI;
1497 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1498 IRB.CreateAdd(LocalStackBase,
1499 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1501 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1502 AI->replaceAllUsesWith(NewAllocaPtr);
1505 // The left-most redzone has enough space for at least 4 pointers.
1506 // Write the Magic value to redzone[0].
1507 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1508 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1510 // Write the frame description constant to redzone[1].
1511 Value *BasePlus1 = IRB.CreateIntToPtr(
1512 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1514 GlobalVariable *StackDescriptionGlobal =
1515 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1516 /*AllowMerging*/true);
1517 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1519 IRB.CreateStore(Description, BasePlus1);
1520 // Write the PC to redzone[2].
1521 Value *BasePlus2 = IRB.CreateIntToPtr(
1522 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1523 2 * ASan.LongSize/8)),
1525 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1527 // Poison the stack redzones at the entry.
1528 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1529 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1531 // (Un)poison the stack before all ret instructions.
1532 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1533 Instruction *Ret = RetVec[i];
1534 IRBuilder<> IRBRet(Ret);
1535 // Mark the current frame as retired.
1536 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1538 if (DoStackMalloc) {
1539 assert(StackMallocIdx >= 0);
1540 // if LocalStackBase != OrigStackBase:
1541 // // In use-after-return mode, poison the whole stack frame.
1542 // if StackMallocIdx <= 4
1543 // // For small sizes inline the whole thing:
1544 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1545 // **SavedFlagPtr(LocalStackBase) = 0
1547 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1549 // <This is not a fake stack; unpoison the redzones>
1550 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1551 TerminatorInst *ThenTerm, *ElseTerm;
1552 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1554 IRBuilder<> IRBPoison(ThenTerm);
1555 if (StackMallocIdx <= 4) {
1556 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1557 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1558 ClassSize >> Mapping.Scale);
1559 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1561 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1562 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1563 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1564 IRBPoison.CreateStore(
1565 Constant::getNullValue(IRBPoison.getInt8Ty()),
1566 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1568 // For larger frames call __asan_stack_free_*.
1569 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1570 ConstantInt::get(IntptrTy, LocalStackSize),
1574 IRBuilder<> IRBElse(ElseTerm);
1575 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1576 } else if (HavePoisonedAllocas) {
1577 // If we poisoned some allocas in llvm.lifetime analysis,
1578 // unpoison whole stack frame now.
1579 assert(LocalStackBase == OrigStackBase);
1580 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1582 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1586 // We are done. Remove the old unused alloca instructions.
1587 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1588 AllocaVec[i]->eraseFromParent();
1591 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1592 IRBuilder<> &IRB, bool DoPoison) {
1593 // For now just insert the call to ASan runtime.
1594 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1595 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1596 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1597 : AsanUnpoisonStackMemoryFunc,
1601 // Handling llvm.lifetime intrinsics for a given %alloca:
1602 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1603 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1604 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1605 // could be poisoned by previous llvm.lifetime.end instruction, as the
1606 // variable may go in and out of scope several times, e.g. in loops).
1607 // (3) if we poisoned at least one %alloca in a function,
1608 // unpoison the whole stack frame at function exit.
1610 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1611 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1612 // We're intested only in allocas we can handle.
1613 return isInterestingAlloca(*AI) ? AI : 0;
1614 // See if we've already calculated (or started to calculate) alloca for a
1616 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1617 if (I != AllocaForValue.end())
1619 // Store 0 while we're calculating alloca for value V to avoid
1620 // infinite recursion if the value references itself.
1621 AllocaForValue[V] = 0;
1622 AllocaInst *Res = 0;
1623 if (CastInst *CI = dyn_cast<CastInst>(V))
1624 Res = findAllocaForValue(CI->getOperand(0));
1625 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1626 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1627 Value *IncValue = PN->getIncomingValue(i);
1628 // Allow self-referencing phi-nodes.
1629 if (IncValue == PN) continue;
1630 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1631 // AI for incoming values should exist and should all be equal.
1632 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1638 AllocaForValue[V] = Res;