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 #include "llvm/Transforms/Instrumentation.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DepthFirstIterator.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/ADT/StringExtras.h"
25 #include "llvm/ADT/Triple.h"
26 #include "llvm/IR/CallSite.h"
27 #include "llvm/IR/DIBuilder.h"
28 #include "llvm/IR/DataLayout.h"
29 #include "llvm/IR/Function.h"
30 #include "llvm/IR/IRBuilder.h"
31 #include "llvm/IR/InlineAsm.h"
32 #include "llvm/IR/InstVisitor.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/MDBuilder.h"
36 #include "llvm/IR/Module.h"
37 #include "llvm/IR/Type.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/DataTypes.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/Endian.h"
42 #include "llvm/Support/system_error.h"
43 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/Cloning.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
48 #include "llvm/Transforms/Utils/SpecialCaseList.h"
54 #define DEBUG_TYPE "asan"
56 static const uint64_t kDefaultShadowScale = 3;
57 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
58 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
60 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
61 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
62 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
63 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
64 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
66 static const size_t kMinStackMallocSize = 1 << 6; // 64B
67 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
68 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
69 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
71 static const char *const kAsanModuleCtorName = "asan.module_ctor";
72 static const char *const kAsanModuleDtorName = "asan.module_dtor";
73 static const int kAsanCtorAndCtorPriority = 1;
74 static const char *const kAsanReportErrorTemplate = "__asan_report_";
75 static const char *const kAsanReportLoadN = "__asan_report_load_n";
76 static const char *const kAsanReportStoreN = "__asan_report_store_n";
77 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
78 static const char *const kAsanUnregisterGlobalsName =
79 "__asan_unregister_globals";
80 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
81 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
82 static const char *const kAsanInitName = "__asan_init_v3";
83 static const char *const kAsanCovName = "__sanitizer_cov";
84 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
85 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
86 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
87 static const int kMaxAsanStackMallocSizeClass = 10;
88 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
89 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
90 static const char *const kAsanGenPrefix = "__asan_gen_";
91 static const char *const kAsanPoisonStackMemoryName =
92 "__asan_poison_stack_memory";
93 static const char *const kAsanUnpoisonStackMemoryName =
94 "__asan_unpoison_stack_memory";
96 static const char *const kAsanOptionDetectUAR =
97 "__asan_option_detect_stack_use_after_return";
100 static const int kAsanStackAfterReturnMagic = 0xf5;
103 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
104 static const size_t kNumberOfAccessSizes = 5;
106 // Command-line flags.
108 // This flag may need to be replaced with -f[no-]asan-reads.
109 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
110 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
111 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
112 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
114 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
115 cl::Hidden, cl::init(true));
116 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
117 cl::desc("use instrumentation with slow path for all accesses"),
118 cl::Hidden, cl::init(false));
119 // This flag limits the number of instructions to be instrumented
120 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
121 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
123 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
125 cl::desc("maximal number of instructions to instrument in any given BB"),
127 // This flag may need to be replaced with -f[no]asan-stack.
128 static cl::opt<bool> ClStack("asan-stack",
129 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
130 // This flag may need to be replaced with -f[no]asan-use-after-return.
131 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
132 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
133 // This flag may need to be replaced with -f[no]asan-globals.
134 static cl::opt<bool> ClGlobals("asan-globals",
135 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
136 static cl::opt<int> ClCoverage("asan-coverage",
137 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
138 cl::Hidden, cl::init(false));
139 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
140 cl::desc("Add coverage instrumentation only to the entry block if there "
141 "are more than this number of blocks."),
142 cl::Hidden, cl::init(1500));
143 static cl::opt<bool> ClInitializers("asan-initialization-order",
144 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
145 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
146 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
147 cl::Hidden, cl::init(false));
148 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
149 cl::desc("Realign stack to the value of this flag (power of two)"),
150 cl::Hidden, cl::init(32));
151 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
152 cl::desc("File containing the list of objects to ignore "
153 "during instrumentation"), cl::Hidden);
154 static cl::opt<int> ClInstrumentationWithCallsThreshold(
155 "asan-instrumentation-with-call-threshold",
156 cl::desc("If the function being instrumented contains more than "
157 "this number of memory accesses, use callbacks instead of "
158 "inline checks (-1 means never use callbacks)."),
159 cl::Hidden, cl::init(10000));
160 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
161 "asan-memory-access-callback-prefix",
162 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
163 cl::init("__asan_"));
165 // This is an experimental feature that will allow to choose between
166 // instrumented and non-instrumented code at link-time.
167 // If this option is on, just before instrumenting a function we create its
168 // clone; if the function is not changed by asan the clone is deleted.
169 // If we end up with a clone, we put the instrumented function into a section
170 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
172 // This is still a prototype, we need to figure out a way to keep two copies of
173 // a function so that the linker can easily choose one of them.
174 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
175 cl::desc("Keep uninstrumented copies of functions"),
176 cl::Hidden, cl::init(false));
178 // These flags allow to change the shadow mapping.
179 // The shadow mapping looks like
180 // Shadow = (Mem >> scale) + (1 << offset_log)
181 static cl::opt<int> ClMappingScale("asan-mapping-scale",
182 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
184 // Optimization flags. Not user visible, used mostly for testing
185 // and benchmarking the tool.
186 static cl::opt<bool> ClOpt("asan-opt",
187 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
188 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
189 cl::desc("Instrument the same temp just once"), cl::Hidden,
191 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
192 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
194 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
195 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
196 cl::Hidden, cl::init(false));
199 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
201 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
202 cl::Hidden, cl::init(0));
203 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
204 cl::Hidden, cl::desc("Debug func"));
205 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
206 cl::Hidden, cl::init(-1));
207 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
208 cl::Hidden, cl::init(-1));
210 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
211 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
212 STATISTIC(NumOptimizedAccessesToGlobalArray,
213 "Number of optimized accesses to global arrays");
214 STATISTIC(NumOptimizedAccessesToGlobalVar,
215 "Number of optimized accesses to global vars");
218 /// A set of dynamically initialized globals extracted from metadata.
219 class SetOfDynamicallyInitializedGlobals {
221 void Init(Module& M) {
222 // Clang generates metadata identifying all dynamically initialized globals.
223 NamedMDNode *DynamicGlobals =
224 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
227 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
228 MDNode *MDN = DynamicGlobals->getOperand(i);
229 assert(MDN->getNumOperands() == 1);
230 Value *VG = MDN->getOperand(0);
231 // The optimizer may optimize away a global entirely, in which case we
232 // cannot instrument access to it.
235 DynInitGlobals.insert(cast<GlobalVariable>(VG));
238 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
240 SmallSet<GlobalValue*, 32> DynInitGlobals;
243 /// This struct defines the shadow mapping using the rule:
244 /// shadow = (mem >> Scale) ADD-or-OR Offset.
245 struct ShadowMapping {
251 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
252 llvm::Triple TargetTriple(M.getTargetTriple());
253 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
254 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
255 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
256 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
257 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
258 TargetTriple.getArch() == llvm::Triple::ppc64le;
259 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
260 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
261 TargetTriple.getArch() == llvm::Triple::mipsel;
263 ShadowMapping Mapping;
265 if (LongSize == 32) {
269 Mapping.Offset = kMIPS32_ShadowOffset32;
271 Mapping.Offset = kFreeBSD_ShadowOffset32;
273 Mapping.Offset = kIOSShadowOffset32;
275 Mapping.Offset = kDefaultShadowOffset32;
276 } else { // LongSize == 64
278 Mapping.Offset = kPPC64_ShadowOffset64;
280 Mapping.Offset = kFreeBSD_ShadowOffset64;
281 else if (IsLinux && IsX86_64)
282 Mapping.Offset = kSmallX86_64ShadowOffset;
284 Mapping.Offset = kDefaultShadowOffset64;
287 Mapping.Scale = kDefaultShadowScale;
288 if (ClMappingScale) {
289 Mapping.Scale = ClMappingScale;
292 // OR-ing shadow offset if more efficient (at least on x86) if the offset
293 // is a power of two, but on ppc64 we have to use add since the shadow
294 // offset is not necessary 1/8-th of the address space.
295 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
300 static size_t RedzoneSizeForScale(int MappingScale) {
301 // Redzone used for stack and globals is at least 32 bytes.
302 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
303 return std::max(32U, 1U << MappingScale);
306 /// AddressSanitizer: instrument the code in module to find memory bugs.
307 struct AddressSanitizer : public FunctionPass {
308 AddressSanitizer(bool CheckInitOrder = true,
309 bool CheckUseAfterReturn = false,
310 bool CheckLifetime = false,
311 StringRef BlacklistFile = StringRef())
313 CheckInitOrder(CheckInitOrder || ClInitializers),
314 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
315 CheckLifetime(CheckLifetime || ClCheckLifetime),
316 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
318 const char *getPassName() const override {
319 return "AddressSanitizerFunctionPass";
321 void instrumentMop(Instruction *I, bool UseCalls);
322 void instrumentPointerComparisonOrSubtraction(Instruction *I);
323 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
324 Value *Addr, uint32_t TypeSize, bool IsWrite,
325 Value *SizeArgument, bool UseCalls);
326 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
327 Value *ShadowValue, uint32_t TypeSize);
328 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
329 bool IsWrite, size_t AccessSizeIndex,
330 Value *SizeArgument);
331 void instrumentMemIntrinsic(MemIntrinsic *MI);
332 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
333 bool runOnFunction(Function &F) override;
334 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
335 bool doInitialization(Module &M) override;
336 static char ID; // Pass identification, replacement for typeid
339 void initializeCallbacks(Module &M);
341 bool LooksLikeCodeInBug11395(Instruction *I);
342 bool GlobalIsLinkerInitialized(GlobalVariable *G);
343 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
344 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
347 bool CheckUseAfterReturn;
349 SmallString<64> BlacklistFile;
352 const DataLayout *DL;
355 ShadowMapping Mapping;
356 Function *AsanCtorFunction;
357 Function *AsanInitFunction;
358 Function *AsanHandleNoReturnFunc;
359 Function *AsanCovFunction;
360 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
361 std::unique_ptr<SpecialCaseList> BL;
362 // This array is indexed by AccessIsWrite and log2(AccessSize).
363 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
364 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
365 // This array is indexed by AccessIsWrite.
366 Function *AsanErrorCallbackSized[2],
367 *AsanMemoryAccessCallbackSized[2];
368 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
370 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
372 friend struct FunctionStackPoisoner;
375 class AddressSanitizerModule : public ModulePass {
377 AddressSanitizerModule(bool CheckInitOrder = true,
378 StringRef BlacklistFile = StringRef())
380 CheckInitOrder(CheckInitOrder || ClInitializers),
381 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
383 bool runOnModule(Module &M) override;
384 static char ID; // Pass identification, replacement for typeid
385 const char *getPassName() const override {
386 return "AddressSanitizerModule";
390 void initializeCallbacks(Module &M);
392 bool ShouldInstrumentGlobal(GlobalVariable *G);
393 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
394 size_t MinRedzoneSizeForGlobal() const {
395 return RedzoneSizeForScale(Mapping.Scale);
399 SmallString<64> BlacklistFile;
401 std::unique_ptr<SpecialCaseList> BL;
402 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
405 const DataLayout *DL;
406 ShadowMapping Mapping;
407 Function *AsanPoisonGlobals;
408 Function *AsanUnpoisonGlobals;
409 Function *AsanRegisterGlobals;
410 Function *AsanUnregisterGlobals;
413 // Stack poisoning does not play well with exception handling.
414 // When an exception is thrown, we essentially bypass the code
415 // that unpoisones the stack. This is why the run-time library has
416 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
417 // stack in the interceptor. This however does not work inside the
418 // actual function which catches the exception. Most likely because the
419 // compiler hoists the load of the shadow value somewhere too high.
420 // This causes asan to report a non-existing bug on 453.povray.
421 // It sounds like an LLVM bug.
422 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
424 AddressSanitizer &ASan;
429 ShadowMapping Mapping;
431 SmallVector<AllocaInst*, 16> AllocaVec;
432 SmallVector<Instruction*, 8> RetVec;
433 unsigned StackAlignment;
435 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
436 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
437 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
439 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
440 struct AllocaPoisonCall {
441 IntrinsicInst *InsBefore;
446 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
448 // Maps Value to an AllocaInst from which the Value is originated.
449 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
450 AllocaForValueMapTy AllocaForValue;
452 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
453 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
454 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
455 Mapping(ASan.Mapping),
456 StackAlignment(1 << Mapping.Scale) {}
458 bool runOnFunction() {
459 if (!ClStack) return false;
460 // Collect alloca, ret, lifetime instructions etc.
461 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
464 if (AllocaVec.empty()) return false;
466 initializeCallbacks(*F.getParent());
476 // Finds all static Alloca instructions and puts
477 // poisoned red zones around all of them.
478 // Then unpoison everything back before the function returns.
481 // ----------------------- Visitors.
482 /// \brief Collect all Ret instructions.
483 void visitReturnInst(ReturnInst &RI) {
484 RetVec.push_back(&RI);
487 /// \brief Collect Alloca instructions we want (and can) handle.
488 void visitAllocaInst(AllocaInst &AI) {
489 if (!isInterestingAlloca(AI)) return;
491 StackAlignment = std::max(StackAlignment, AI.getAlignment());
492 AllocaVec.push_back(&AI);
495 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
497 void visitIntrinsicInst(IntrinsicInst &II) {
498 if (!ASan.CheckLifetime) return;
499 Intrinsic::ID ID = II.getIntrinsicID();
500 if (ID != Intrinsic::lifetime_start &&
501 ID != Intrinsic::lifetime_end)
503 // Found lifetime intrinsic, add ASan instrumentation if necessary.
504 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
505 // If size argument is undefined, don't do anything.
506 if (Size->isMinusOne()) return;
507 // Check that size doesn't saturate uint64_t and can
508 // be stored in IntptrTy.
509 const uint64_t SizeValue = Size->getValue().getLimitedValue();
510 if (SizeValue == ~0ULL ||
511 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
513 // Find alloca instruction that corresponds to llvm.lifetime argument.
514 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
516 bool DoPoison = (ID == Intrinsic::lifetime_end);
517 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
518 AllocaPoisonCallVec.push_back(APC);
521 // ---------------------- Helpers.
522 void initializeCallbacks(Module &M);
524 // Check if we want (and can) handle this alloca.
525 bool isInterestingAlloca(AllocaInst &AI) const {
526 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
527 AI.getAllocatedType()->isSized() &&
528 // alloca() may be called with 0 size, ignore it.
529 getAllocaSizeInBytes(&AI) > 0);
532 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
533 Type *Ty = AI->getAllocatedType();
534 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
537 /// Finds alloca where the value comes from.
538 AllocaInst *findAllocaForValue(Value *V);
539 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
540 Value *ShadowBase, bool DoPoison);
541 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
543 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
549 char AddressSanitizer::ID = 0;
550 INITIALIZE_PASS(AddressSanitizer, "asan",
551 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
553 FunctionPass *llvm::createAddressSanitizerFunctionPass(
554 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
555 StringRef BlacklistFile) {
556 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
557 CheckLifetime, BlacklistFile);
560 char AddressSanitizerModule::ID = 0;
561 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
562 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
563 "ModulePass", false, false)
564 ModulePass *llvm::createAddressSanitizerModulePass(
565 bool CheckInitOrder, StringRef BlacklistFile) {
566 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
569 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
570 size_t Res = countTrailingZeros(TypeSize / 8);
571 assert(Res < kNumberOfAccessSizes);
575 // \brief Create a constant for Str so that we can pass it to the run-time lib.
576 static GlobalVariable *createPrivateGlobalForString(
577 Module &M, StringRef Str, bool AllowMerging) {
578 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
579 // We use private linkage for module-local strings. If they can be merged
580 // with another one, we set the unnamed_addr attribute.
582 new GlobalVariable(M, StrConst->getType(), true,
583 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
585 GV->setUnnamedAddr(true);
586 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
590 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
591 return G->getName().find(kAsanGenPrefix) == 0;
594 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
596 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
597 if (Mapping.Offset == 0)
599 // (Shadow >> scale) | offset
600 if (Mapping.OrShadowOffset)
601 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
603 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
606 // Instrument memset/memmove/memcpy
607 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
609 if (isa<MemTransferInst>(MI)) {
611 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
612 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
613 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
614 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
615 } else if (isa<MemSetInst>(MI)) {
618 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
619 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
620 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
622 MI->eraseFromParent();
625 // If I is an interesting memory access, return the PointerOperand
626 // and set IsWrite. Otherwise return NULL.
627 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
628 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
629 if (!ClInstrumentReads) return nullptr;
631 return LI->getPointerOperand();
633 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
634 if (!ClInstrumentWrites) return nullptr;
636 return SI->getPointerOperand();
638 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
639 if (!ClInstrumentAtomics) return nullptr;
641 return RMW->getPointerOperand();
643 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
644 if (!ClInstrumentAtomics) return nullptr;
646 return XCHG->getPointerOperand();
651 static bool isPointerOperand(Value *V) {
652 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
655 // This is a rough heuristic; it may cause both false positives and
656 // false negatives. The proper implementation requires cooperation with
658 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
659 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
660 if (!Cmp->isRelational())
662 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
663 if (BO->getOpcode() != Instruction::Sub)
668 if (!isPointerOperand(I->getOperand(0)) ||
669 !isPointerOperand(I->getOperand(1)))
674 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
675 // If a global variable does not have dynamic initialization we don't
676 // have to instrument it. However, if a global does not have initializer
677 // at all, we assume it has dynamic initializer (in other TU).
678 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
682 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
684 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
685 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
686 for (int i = 0; i < 2; i++) {
687 if (Param[i]->getType()->isPointerTy())
688 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
690 IRB.CreateCall2(F, Param[0], Param[1]);
693 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
694 bool IsWrite = false;
695 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
697 if (ClOpt && ClOptGlobals) {
698 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
699 // If initialization order checking is disabled, a simple access to a
700 // dynamically initialized global is always valid.
701 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
702 NumOptimizedAccessesToGlobalVar++;
706 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
707 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
708 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
709 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
710 NumOptimizedAccessesToGlobalArray++;
717 Type *OrigPtrTy = Addr->getType();
718 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
720 assert(OrigTy->isSized());
721 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
723 assert((TypeSize % 8) == 0);
726 NumInstrumentedWrites++;
728 NumInstrumentedReads++;
730 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
731 if (TypeSize == 8 || TypeSize == 16 ||
732 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
733 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
734 // Instrument unusual size (but still multiple of 8).
735 // We can not do it with a single check, so we do 1-byte check for the first
736 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
737 // to report the actual access size.
739 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
740 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
742 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
744 Value *LastByte = IRB.CreateIntToPtr(
745 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
747 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
748 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
752 // Validate the result of Module::getOrInsertFunction called for an interface
753 // function of AddressSanitizer. If the instrumented module defines a function
754 // with the same name, their prototypes must match, otherwise
755 // getOrInsertFunction returns a bitcast.
756 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
757 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
758 FuncOrBitcast->dump();
759 report_fatal_error("trying to redefine an AddressSanitizer "
760 "interface function");
763 Instruction *AddressSanitizer::generateCrashCode(
764 Instruction *InsertBefore, Value *Addr,
765 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
766 IRBuilder<> IRB(InsertBefore);
767 CallInst *Call = SizeArgument
768 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
769 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
771 // We don't do Call->setDoesNotReturn() because the BB already has
772 // UnreachableInst at the end.
773 // This EmptyAsm is required to avoid callback merge.
774 IRB.CreateCall(EmptyAsm);
778 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
781 size_t Granularity = 1 << Mapping.Scale;
782 // Addr & (Granularity - 1)
783 Value *LastAccessedByte = IRB.CreateAnd(
784 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
785 // (Addr & (Granularity - 1)) + size - 1
786 if (TypeSize / 8 > 1)
787 LastAccessedByte = IRB.CreateAdd(
788 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
789 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
790 LastAccessedByte = IRB.CreateIntCast(
791 LastAccessedByte, ShadowValue->getType(), false);
792 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
793 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
796 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
797 Instruction *InsertBefore, Value *Addr,
798 uint32_t TypeSize, bool IsWrite,
799 Value *SizeArgument, bool UseCalls) {
800 IRBuilder<> IRB(InsertBefore);
801 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
802 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
805 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
810 Type *ShadowTy = IntegerType::get(
811 *C, std::max(8U, TypeSize >> Mapping.Scale));
812 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
813 Value *ShadowPtr = memToShadow(AddrLong, IRB);
814 Value *CmpVal = Constant::getNullValue(ShadowTy);
815 Value *ShadowValue = IRB.CreateLoad(
816 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
818 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
819 size_t Granularity = 1 << Mapping.Scale;
820 TerminatorInst *CrashTerm = nullptr;
822 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
823 TerminatorInst *CheckTerm =
824 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
825 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
826 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
827 IRB.SetInsertPoint(CheckTerm);
828 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
829 BasicBlock *CrashBlock =
830 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
831 CrashTerm = new UnreachableInst(*C, CrashBlock);
832 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
833 ReplaceInstWithInst(CheckTerm, NewTerm);
835 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
838 Instruction *Crash = generateCrashCode(
839 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
840 Crash->setDebugLoc(OrigIns->getDebugLoc());
843 void AddressSanitizerModule::createInitializerPoisonCalls(
844 Module &M, GlobalValue *ModuleName) {
845 // We do all of our poisoning and unpoisoning within a global constructor.
846 // These are called _GLOBAL__(sub_)?I_.*.
847 // TODO: Consider looking through the functions in
848 // M.getGlobalVariable("llvm.global_ctors") instead of using this stringly
850 Function *GlobalInit = nullptr;
851 for (auto &F : M.getFunctionList()) {
852 StringRef FName = F.getName();
854 const char kGlobalPrefix[] = "_GLOBAL__";
855 if (!FName.startswith(kGlobalPrefix))
857 FName = FName.substr(strlen(kGlobalPrefix));
859 const char kOptionalSub[] = "sub_";
860 if (FName.startswith(kOptionalSub))
861 FName = FName.substr(strlen(kOptionalSub));
863 if (FName.startswith("I_")) {
868 // If that function is not present, this TU contains no globals, or they have
869 // all been optimized away
873 // Set up the arguments to our poison/unpoison functions.
874 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
876 // Add a call to poison all external globals before the given function starts.
877 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
878 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
880 // Add calls to unpoison all globals before each return instruction.
881 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
883 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
884 CallInst::Create(AsanUnpoisonGlobals, "", RI);
889 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
890 Type *Ty = cast<PointerType>(G->getType())->getElementType();
891 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
893 if (BL->isIn(*G)) return false;
894 if (!Ty->isSized()) return false;
895 if (!G->hasInitializer()) return false;
896 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
897 // Touch only those globals that will not be defined in other modules.
898 // Don't handle ODR type linkages since other modules may be built w/o asan.
899 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
900 G->getLinkage() != GlobalVariable::PrivateLinkage &&
901 G->getLinkage() != GlobalVariable::InternalLinkage)
903 // Two problems with thread-locals:
904 // - The address of the main thread's copy can't be computed at link-time.
905 // - Need to poison all copies, not just the main thread's one.
906 if (G->isThreadLocal())
908 // For now, just ignore this Global if the alignment is large.
909 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
911 // Ignore all the globals with the names starting with "\01L_OBJC_".
912 // Many of those are put into the .cstring section. The linker compresses
913 // that section by removing the spare \0s after the string terminator, so
914 // our redzones get broken.
915 if ((G->getName().find("\01L_OBJC_") == 0) ||
916 (G->getName().find("\01l_OBJC_") == 0)) {
917 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
921 if (G->hasSection()) {
922 StringRef Section(G->getSection());
923 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
924 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
926 if (Section.startswith("__OBJC,") ||
927 Section.startswith("__DATA, __objc_")) {
928 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
931 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
932 // Constant CFString instances are compiled in the following way:
933 // -- the string buffer is emitted into
934 // __TEXT,__cstring,cstring_literals
935 // -- the constant NSConstantString structure referencing that buffer
936 // is placed into __DATA,__cfstring
937 // Therefore there's no point in placing redzones into __DATA,__cfstring.
938 // Moreover, it causes the linker to crash on OS X 10.7
939 if (Section.startswith("__DATA,__cfstring")) {
940 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
943 // The linker merges the contents of cstring_literals and removes the
945 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
946 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
950 // Callbacks put into the CRT initializer/terminator sections
951 // should not be instrumented.
952 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
953 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
954 if (Section.startswith(".CRT")) {
955 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
959 // Globals from llvm.metadata aren't emitted, do not instrument them.
960 if (Section == "llvm.metadata") return false;
966 void AddressSanitizerModule::initializeCallbacks(Module &M) {
968 // Declare our poisoning and unpoisoning functions.
969 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
970 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
971 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
972 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
973 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
974 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
975 // Declare functions that register/unregister globals.
976 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
977 kAsanRegisterGlobalsName, IRB.getVoidTy(),
978 IntptrTy, IntptrTy, NULL));
979 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
980 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
981 kAsanUnregisterGlobalsName,
982 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
983 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
986 // This function replaces all global variables with new variables that have
987 // trailing redzones. It also creates a function that poisons
988 // redzones and inserts this function into llvm.global_ctors.
989 bool AddressSanitizerModule::runOnModule(Module &M) {
990 if (!ClGlobals) return false;
992 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
995 DL = &DLP->getDataLayout();
997 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
998 if (BL->isIn(M)) return false;
999 C = &(M.getContext());
1000 int LongSize = DL->getPointerSizeInBits();
1001 IntptrTy = Type::getIntNTy(*C, LongSize);
1002 Mapping = getShadowMapping(M, LongSize);
1003 initializeCallbacks(M);
1004 DynamicallyInitializedGlobals.Init(M);
1006 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1008 for (Module::GlobalListType::iterator G = M.global_begin(),
1009 E = M.global_end(); G != E; ++G) {
1010 if (ShouldInstrumentGlobal(G))
1011 GlobalsToChange.push_back(G);
1014 size_t n = GlobalsToChange.size();
1015 if (n == 0) return false;
1017 // A global is described by a structure
1020 // size_t size_with_redzone;
1021 // const char *name;
1022 // const char *module_name;
1023 // size_t has_dynamic_init;
1024 // We initialize an array of such structures and pass it to a run-time call.
1025 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
1027 IntptrTy, IntptrTy, NULL);
1028 SmallVector<Constant *, 16> Initializers(n);
1030 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1032 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1034 bool HasDynamicallyInitializedGlobals = false;
1036 // We shouldn't merge same module names, as this string serves as unique
1037 // module ID in runtime.
1038 GlobalVariable *ModuleName = createPrivateGlobalForString(
1039 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1041 for (size_t i = 0; i < n; i++) {
1042 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1043 GlobalVariable *G = GlobalsToChange[i];
1044 PointerType *PtrTy = cast<PointerType>(G->getType());
1045 Type *Ty = PtrTy->getElementType();
1046 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1047 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1048 // MinRZ <= RZ <= kMaxGlobalRedzone
1049 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1050 uint64_t RZ = std::max(MinRZ,
1051 std::min(kMaxGlobalRedzone,
1052 (SizeInBytes / MinRZ / 4) * MinRZ));
1053 uint64_t RightRedzoneSize = RZ;
1054 // Round up to MinRZ
1055 if (SizeInBytes % MinRZ)
1056 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1057 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1058 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1059 // Determine whether this global should be poisoned in initialization.
1060 bool GlobalHasDynamicInitializer =
1061 DynamicallyInitializedGlobals.Contains(G);
1062 // Don't check initialization order if this global is blacklisted.
1063 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
1065 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1066 Constant *NewInitializer = ConstantStruct::get(
1067 NewTy, G->getInitializer(),
1068 Constant::getNullValue(RightRedZoneTy), NULL);
1070 GlobalVariable *Name =
1071 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1073 // Create a new global variable with enough space for a redzone.
1074 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1075 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1076 Linkage = GlobalValue::InternalLinkage;
1077 GlobalVariable *NewGlobal = new GlobalVariable(
1078 M, NewTy, G->isConstant(), Linkage,
1079 NewInitializer, "", G, G->getThreadLocalMode());
1080 NewGlobal->copyAttributesFrom(G);
1081 NewGlobal->setAlignment(MinRZ);
1084 Indices2[0] = IRB.getInt32(0);
1085 Indices2[1] = IRB.getInt32(0);
1087 G->replaceAllUsesWith(
1088 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1089 NewGlobal->takeName(G);
1090 G->eraseFromParent();
1092 Initializers[i] = ConstantStruct::get(
1094 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1095 ConstantInt::get(IntptrTy, SizeInBytes),
1096 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1097 ConstantExpr::getPointerCast(Name, IntptrTy),
1098 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1099 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1102 // Populate the first and last globals declared in this TU.
1103 if (CheckInitOrder && GlobalHasDynamicInitializer)
1104 HasDynamicallyInitializedGlobals = true;
1106 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1109 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1110 GlobalVariable *AllGlobals = new GlobalVariable(
1111 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1112 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1114 // Create calls for poisoning before initializers run and unpoisoning after.
1115 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1116 createInitializerPoisonCalls(M, ModuleName);
1117 IRB.CreateCall2(AsanRegisterGlobals,
1118 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1119 ConstantInt::get(IntptrTy, n));
1121 // We also need to unregister globals at the end, e.g. when a shared library
1123 Function *AsanDtorFunction = Function::Create(
1124 FunctionType::get(Type::getVoidTy(*C), false),
1125 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1126 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1127 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1128 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1129 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1130 ConstantInt::get(IntptrTy, n));
1131 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1137 void AddressSanitizer::initializeCallbacks(Module &M) {
1138 IRBuilder<> IRB(*C);
1139 // Create __asan_report* callbacks.
1140 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1141 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1142 AccessSizeIndex++) {
1143 // IsWrite and TypeSize are encoded in the function name.
1144 std::string Suffix =
1145 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1146 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1147 checkInterfaceFunction(
1148 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1149 IRB.getVoidTy(), IntptrTy, NULL));
1150 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1151 checkInterfaceFunction(
1152 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1153 IRB.getVoidTy(), IntptrTy, NULL));
1156 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1157 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1158 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1159 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1161 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1162 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1163 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1164 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1165 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1166 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1168 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1169 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1170 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1171 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1172 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1173 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1174 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1175 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1176 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1178 AsanHandleNoReturnFunc = checkInterfaceFunction(
1179 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1180 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1181 kAsanCovName, IRB.getVoidTy(), NULL));
1182 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1183 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1184 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1185 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1186 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1187 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1188 StringRef(""), StringRef(""),
1189 /*hasSideEffects=*/true);
1193 bool AddressSanitizer::doInitialization(Module &M) {
1194 // Initialize the private fields. No one has accessed them before.
1195 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1197 report_fatal_error("data layout missing");
1198 DL = &DLP->getDataLayout();
1200 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1201 DynamicallyInitializedGlobals.Init(M);
1203 C = &(M.getContext());
1204 LongSize = DL->getPointerSizeInBits();
1205 IntptrTy = Type::getIntNTy(*C, LongSize);
1207 AsanCtorFunction = Function::Create(
1208 FunctionType::get(Type::getVoidTy(*C), false),
1209 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1210 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1211 // call __asan_init in the module ctor.
1212 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1213 AsanInitFunction = checkInterfaceFunction(
1214 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1215 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1216 IRB.CreateCall(AsanInitFunction);
1218 Mapping = getShadowMapping(M, LongSize);
1220 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1224 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1225 // For each NSObject descendant having a +load method, this method is invoked
1226 // by the ObjC runtime before any of the static constructors is called.
1227 // Therefore we need to instrument such methods with a call to __asan_init
1228 // at the beginning in order to initialize our runtime before any access to
1229 // the shadow memory.
1230 // We cannot just ignore these methods, because they may call other
1231 // instrumented functions.
1232 if (F.getName().find(" load]") != std::string::npos) {
1233 IRBuilder<> IRB(F.begin()->begin());
1234 IRB.CreateCall(AsanInitFunction);
1240 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1241 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1242 // Skip static allocas at the top of the entry block so they don't become
1243 // dynamic when we split the block. If we used our optimized stack layout,
1244 // then there will only be one alloca and it will come first.
1245 for (; IP != BE; ++IP) {
1246 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1247 if (!AI || !AI->isStaticAlloca())
1251 IRBuilder<> IRB(IP);
1252 Type *Int8Ty = IRB.getInt8Ty();
1253 GlobalVariable *Guard = new GlobalVariable(
1254 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1255 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1256 LoadInst *Load = IRB.CreateLoad(Guard);
1257 Load->setAtomic(Monotonic);
1258 Load->setAlignment(1);
1259 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1260 Instruction *Ins = SplitBlockAndInsertIfThen(
1261 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1262 IRB.SetInsertPoint(Ins);
1263 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1264 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1265 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1266 Call->setDebugLoc(IP->getDebugLoc());
1267 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1268 Store->setAtomic(Monotonic);
1269 Store->setAlignment(1);
1272 // Poor man's coverage that works with ASan.
1273 // We create a Guard boolean variable with the same linkage
1274 // as the function and inject this code into the entry block (-asan-coverage=1)
1275 // or all blocks (-asan-coverage=2):
1277 // __sanitizer_cov(&F);
1280 // The accesses to Guard are atomic. The rest of the logic is
1281 // in __sanitizer_cov (it's fine to call it more than once).
1283 // This coverage implementation provides very limited data:
1284 // it only tells if a given function (block) was ever executed.
1285 // No counters, no per-edge data.
1286 // But for many use cases this is what we need and the added slowdown
1287 // is negligible. This simple implementation will probably be obsoleted
1288 // by the upcoming Clang-based coverage implementation.
1289 // By having it here and now we hope to
1290 // a) get the functionality to users earlier and
1291 // b) collect usage statistics to help improve Clang coverage design.
1292 bool AddressSanitizer::InjectCoverage(Function &F,
1293 const ArrayRef<BasicBlock *> AllBlocks) {
1294 if (!ClCoverage) return false;
1296 if (ClCoverage == 1 ||
1297 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1298 InjectCoverageAtBlock(F, F.getEntryBlock());
1300 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1301 InjectCoverageAtBlock(F, *AllBlocks[i]);
1306 bool AddressSanitizer::runOnFunction(Function &F) {
1307 if (BL->isIn(F)) return false;
1308 if (&F == AsanCtorFunction) return false;
1309 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1310 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1311 initializeCallbacks(*F.getParent());
1313 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1314 maybeInsertAsanInitAtFunctionEntry(F);
1316 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1319 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1322 // We want to instrument every address only once per basic block (unless there
1323 // are calls between uses).
1324 SmallSet<Value*, 16> TempsToInstrument;
1325 SmallVector<Instruction*, 16> ToInstrument;
1326 SmallVector<Instruction*, 8> NoReturnCalls;
1327 SmallVector<BasicBlock*, 16> AllBlocks;
1328 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1332 // Fill the set of memory operations to instrument.
1333 for (Function::iterator FI = F.begin(), FE = F.end();
1335 AllBlocks.push_back(FI);
1336 TempsToInstrument.clear();
1337 int NumInsnsPerBB = 0;
1338 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1340 if (LooksLikeCodeInBug11395(BI)) return false;
1341 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1342 if (ClOpt && ClOptSameTemp) {
1343 if (!TempsToInstrument.insert(Addr))
1344 continue; // We've seen this temp in the current BB.
1346 } else if (ClInvalidPointerPairs &&
1347 isInterestingPointerComparisonOrSubtraction(BI)) {
1348 PointerComparisonsOrSubtracts.push_back(BI);
1350 } else if (isa<MemIntrinsic>(BI)) {
1353 if (isa<AllocaInst>(BI))
1357 // A call inside BB.
1358 TempsToInstrument.clear();
1359 if (CS.doesNotReturn())
1360 NoReturnCalls.push_back(CS.getInstruction());
1364 ToInstrument.push_back(BI);
1366 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1371 Function *UninstrumentedDuplicate = nullptr;
1372 bool LikelyToInstrument =
1373 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1374 if (ClKeepUninstrumented && LikelyToInstrument) {
1375 ValueToValueMapTy VMap;
1376 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1377 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1378 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1379 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1382 bool UseCalls = false;
1383 if (ClInstrumentationWithCallsThreshold >= 0 &&
1384 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1388 int NumInstrumented = 0;
1389 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1390 Instruction *Inst = ToInstrument[i];
1391 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1392 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1393 if (isInterestingMemoryAccess(Inst, &IsWrite))
1394 instrumentMop(Inst, UseCalls);
1396 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1401 FunctionStackPoisoner FSP(F, *this);
1402 bool ChangedStack = FSP.runOnFunction();
1404 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1405 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1406 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1407 Instruction *CI = NoReturnCalls[i];
1408 IRBuilder<> IRB(CI);
1409 IRB.CreateCall(AsanHandleNoReturnFunc);
1412 for (size_t i = 0, n = PointerComparisonsOrSubtracts.size(); i != n; i++) {
1413 instrumentPointerComparisonOrSubtraction(PointerComparisonsOrSubtracts[i]);
1417 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1419 if (InjectCoverage(F, AllBlocks))
1422 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1424 if (ClKeepUninstrumented) {
1426 // No instrumentation is done, no need for the duplicate.
1427 if (UninstrumentedDuplicate)
1428 UninstrumentedDuplicate->eraseFromParent();
1430 // The function was instrumented. We must have the duplicate.
1431 assert(UninstrumentedDuplicate);
1432 UninstrumentedDuplicate->setSection("NOASAN");
1433 assert(!F.hasSection());
1434 F.setSection("ASAN");
1441 // Workaround for bug 11395: we don't want to instrument stack in functions
1442 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1443 // FIXME: remove once the bug 11395 is fixed.
1444 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1445 if (LongSize != 32) return false;
1446 CallInst *CI = dyn_cast<CallInst>(I);
1447 if (!CI || !CI->isInlineAsm()) return false;
1448 if (CI->getNumArgOperands() <= 5) return false;
1449 // We have inline assembly with quite a few arguments.
1453 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1454 IRBuilder<> IRB(*C);
1455 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1456 std::string Suffix = itostr(i);
1457 AsanStackMallocFunc[i] = checkInterfaceFunction(
1458 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1459 IntptrTy, IntptrTy, NULL));
1460 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1461 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1462 IntptrTy, IntptrTy, NULL));
1464 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1465 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1466 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1467 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1471 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1472 IRBuilder<> &IRB, Value *ShadowBase,
1474 size_t n = ShadowBytes.size();
1476 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1477 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1478 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1479 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1480 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1481 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1483 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1484 if (ASan.DL->isLittleEndian())
1485 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1487 Val = (Val << 8) | ShadowBytes[i + j];
1490 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1491 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1492 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1493 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1498 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1499 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1500 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1501 assert(LocalStackSize <= kMaxStackMallocSize);
1502 uint64_t MaxSize = kMinStackMallocSize;
1503 for (int i = 0; ; i++, MaxSize *= 2)
1504 if (LocalStackSize <= MaxSize)
1506 llvm_unreachable("impossible LocalStackSize");
1509 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1510 // We can not use MemSet intrinsic because it may end up calling the actual
1511 // memset. Size is a multiple of 8.
1512 // Currently this generates 8-byte stores on x86_64; it may be better to
1513 // generate wider stores.
1514 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1515 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1516 assert(!(Size % 8));
1517 assert(kAsanStackAfterReturnMagic == 0xf5);
1518 for (int i = 0; i < Size; i += 8) {
1519 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1520 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1521 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1525 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1526 BasicBlock::iterator I = F.getEntryBlock().begin(),
1527 E = F.getEntryBlock().end();
1529 if (!isa<AllocaInst>(I))
1531 return I->getDebugLoc();
1534 void FunctionStackPoisoner::poisonStack() {
1535 int StackMallocIdx = -1;
1536 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1538 assert(AllocaVec.size() > 0);
1539 Instruction *InsBefore = AllocaVec[0];
1540 IRBuilder<> IRB(InsBefore);
1541 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1543 SmallVector<ASanStackVariableDescription, 16> SVD;
1544 SVD.reserve(AllocaVec.size());
1545 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1546 AllocaInst *AI = AllocaVec[i];
1547 ASanStackVariableDescription D = { AI->getName().data(),
1548 getAllocaSizeInBytes(AI),
1549 AI->getAlignment(), AI, 0};
1552 // Minimal header size (left redzone) is 4 pointers,
1553 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1554 size_t MinHeaderSize = ASan.LongSize / 2;
1555 ASanStackFrameLayout L;
1556 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1557 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1558 uint64_t LocalStackSize = L.FrameSize;
1559 bool DoStackMalloc =
1560 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1562 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1563 AllocaInst *MyAlloca =
1564 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1565 MyAlloca->setDebugLoc(EntryDebugLocation);
1566 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1567 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1568 MyAlloca->setAlignment(FrameAlignment);
1569 assert(MyAlloca->isStaticAlloca());
1570 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1571 Value *LocalStackBase = OrigStackBase;
1573 if (DoStackMalloc) {
1574 // LocalStackBase = OrigStackBase
1575 // if (__asan_option_detect_stack_use_after_return)
1576 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1577 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1578 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1579 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1580 kAsanOptionDetectUAR, IRB.getInt32Ty());
1581 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1582 Constant::getNullValue(IRB.getInt32Ty()));
1583 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1584 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1585 IRBuilder<> IRBIf(Term);
1586 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1587 LocalStackBase = IRBIf.CreateCall2(
1588 AsanStackMallocFunc[StackMallocIdx],
1589 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1590 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1591 IRB.SetInsertPoint(InsBefore);
1592 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1593 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1594 Phi->addIncoming(OrigStackBase, CmpBlock);
1595 Phi->addIncoming(LocalStackBase, SetBlock);
1596 LocalStackBase = Phi;
1599 // Insert poison calls for lifetime intrinsics for alloca.
1600 bool HavePoisonedAllocas = false;
1601 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1602 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1603 assert(APC.InsBefore);
1605 IRBuilder<> IRB(APC.InsBefore);
1606 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1607 HavePoisonedAllocas |= APC.DoPoison;
1610 // Replace Alloca instructions with base+offset.
1611 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1612 AllocaInst *AI = SVD[i].AI;
1613 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1614 IRB.CreateAdd(LocalStackBase,
1615 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1617 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1618 AI->replaceAllUsesWith(NewAllocaPtr);
1621 // The left-most redzone has enough space for at least 4 pointers.
1622 // Write the Magic value to redzone[0].
1623 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1624 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1626 // Write the frame description constant to redzone[1].
1627 Value *BasePlus1 = IRB.CreateIntToPtr(
1628 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1630 GlobalVariable *StackDescriptionGlobal =
1631 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1632 /*AllowMerging*/true);
1633 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1635 IRB.CreateStore(Description, BasePlus1);
1636 // Write the PC to redzone[2].
1637 Value *BasePlus2 = IRB.CreateIntToPtr(
1638 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1639 2 * ASan.LongSize/8)),
1641 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1643 // Poison the stack redzones at the entry.
1644 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1645 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1647 // (Un)poison the stack before all ret instructions.
1648 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1649 Instruction *Ret = RetVec[i];
1650 IRBuilder<> IRBRet(Ret);
1651 // Mark the current frame as retired.
1652 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1654 if (DoStackMalloc) {
1655 assert(StackMallocIdx >= 0);
1656 // if LocalStackBase != OrigStackBase:
1657 // // In use-after-return mode, poison the whole stack frame.
1658 // if StackMallocIdx <= 4
1659 // // For small sizes inline the whole thing:
1660 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1661 // **SavedFlagPtr(LocalStackBase) = 0
1663 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1665 // <This is not a fake stack; unpoison the redzones>
1666 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1667 TerminatorInst *ThenTerm, *ElseTerm;
1668 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1670 IRBuilder<> IRBPoison(ThenTerm);
1671 if (StackMallocIdx <= 4) {
1672 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1673 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1674 ClassSize >> Mapping.Scale);
1675 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1677 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1678 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1679 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1680 IRBPoison.CreateStore(
1681 Constant::getNullValue(IRBPoison.getInt8Ty()),
1682 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1684 // For larger frames call __asan_stack_free_*.
1685 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1686 ConstantInt::get(IntptrTy, LocalStackSize),
1690 IRBuilder<> IRBElse(ElseTerm);
1691 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1692 } else if (HavePoisonedAllocas) {
1693 // If we poisoned some allocas in llvm.lifetime analysis,
1694 // unpoison whole stack frame now.
1695 assert(LocalStackBase == OrigStackBase);
1696 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1698 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1702 // We are done. Remove the old unused alloca instructions.
1703 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1704 AllocaVec[i]->eraseFromParent();
1707 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1708 IRBuilder<> &IRB, bool DoPoison) {
1709 // For now just insert the call to ASan runtime.
1710 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1711 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1712 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1713 : AsanUnpoisonStackMemoryFunc,
1717 // Handling llvm.lifetime intrinsics for a given %alloca:
1718 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1719 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1720 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1721 // could be poisoned by previous llvm.lifetime.end instruction, as the
1722 // variable may go in and out of scope several times, e.g. in loops).
1723 // (3) if we poisoned at least one %alloca in a function,
1724 // unpoison the whole stack frame at function exit.
1726 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1727 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1728 // We're intested only in allocas we can handle.
1729 return isInterestingAlloca(*AI) ? AI : nullptr;
1730 // See if we've already calculated (or started to calculate) alloca for a
1732 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1733 if (I != AllocaForValue.end())
1735 // Store 0 while we're calculating alloca for value V to avoid
1736 // infinite recursion if the value references itself.
1737 AllocaForValue[V] = nullptr;
1738 AllocaInst *Res = nullptr;
1739 if (CastInst *CI = dyn_cast<CastInst>(V))
1740 Res = findAllocaForValue(CI->getOperand(0));
1741 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1742 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1743 Value *IncValue = PN->getIncomingValue(i);
1744 // Allow self-referencing phi-nodes.
1745 if (IncValue == PN) continue;
1746 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1747 // AI for incoming values should exist and should all be equal.
1748 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1754 AllocaForValue[V] = Res;