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 kAsanCtorAndDtorPriority = 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 kAsanCovModuleInitName = "__sanitizer_cov_module_init";
84 static const char *const kAsanCovName = "__sanitizer_cov";
85 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
86 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
87 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
88 static const int kMaxAsanStackMallocSizeClass = 10;
89 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
90 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
91 static const char *const kAsanGenPrefix = "__asan_gen_";
92 static const char *const kAsanPoisonStackMemoryName =
93 "__asan_poison_stack_memory";
94 static const char *const kAsanUnpoisonStackMemoryName =
95 "__asan_unpoison_stack_memory";
97 static const char *const kAsanOptionDetectUAR =
98 "__asan_option_detect_stack_use_after_return";
101 static const int kAsanStackAfterReturnMagic = 0xf5;
104 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105 static const size_t kNumberOfAccessSizes = 5;
107 // Command-line flags.
109 // This flag may need to be replaced with -f[no-]asan-reads.
110 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
111 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
112 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
113 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
114 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
115 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
116 cl::Hidden, cl::init(true));
117 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
118 cl::desc("use instrumentation with slow path for all accesses"),
119 cl::Hidden, cl::init(false));
120 // This flag limits the number of instructions to be instrumented
121 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
122 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
124 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
126 cl::desc("maximal number of instructions to instrument in any given BB"),
128 // This flag may need to be replaced with -f[no]asan-stack.
129 static cl::opt<bool> ClStack("asan-stack",
130 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
131 // This flag may need to be replaced with -f[no]asan-use-after-return.
132 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
134 // This flag may need to be replaced with -f[no]asan-globals.
135 static cl::opt<bool> ClGlobals("asan-globals",
136 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
137 static cl::opt<int> ClCoverage("asan-coverage",
138 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
139 cl::Hidden, cl::init(false));
140 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
141 cl::desc("Add coverage instrumentation only to the entry block if there "
142 "are more than this number of blocks."),
143 cl::Hidden, cl::init(1500));
144 static cl::opt<bool> ClInitializers("asan-initialization-order",
145 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
146 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
147 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
148 cl::Hidden, cl::init(false));
149 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
150 cl::desc("Realign stack to the value of this flag (power of two)"),
151 cl::Hidden, cl::init(32));
152 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
153 cl::desc("File containing the list of objects to ignore "
154 "during instrumentation"), cl::Hidden);
155 static cl::opt<int> ClInstrumentationWithCallsThreshold(
156 "asan-instrumentation-with-call-threshold",
157 cl::desc("If the function being instrumented contains more than "
158 "this number of memory accesses, use callbacks instead of "
159 "inline checks (-1 means never use callbacks)."),
160 cl::Hidden, cl::init(7000));
161 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
162 "asan-memory-access-callback-prefix",
163 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
164 cl::init("__asan_"));
166 // This is an experimental feature that will allow to choose between
167 // instrumented and non-instrumented code at link-time.
168 // If this option is on, just before instrumenting a function we create its
169 // clone; if the function is not changed by asan the clone is deleted.
170 // If we end up with a clone, we put the instrumented function into a section
171 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
173 // This is still a prototype, we need to figure out a way to keep two copies of
174 // a function so that the linker can easily choose one of them.
175 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
176 cl::desc("Keep uninstrumented copies of functions"),
177 cl::Hidden, cl::init(false));
179 // These flags allow to change the shadow mapping.
180 // The shadow mapping looks like
181 // Shadow = (Mem >> scale) + (1 << offset_log)
182 static cl::opt<int> ClMappingScale("asan-mapping-scale",
183 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
185 // Optimization flags. Not user visible, used mostly for testing
186 // and benchmarking the tool.
187 static cl::opt<bool> ClOpt("asan-opt",
188 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
189 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
190 cl::desc("Instrument the same temp just once"), cl::Hidden,
192 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
193 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
195 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
196 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
197 cl::Hidden, cl::init(false));
200 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
202 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
203 cl::Hidden, cl::init(0));
204 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
205 cl::Hidden, cl::desc("Debug func"));
206 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
207 cl::Hidden, cl::init(-1));
208 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
209 cl::Hidden, cl::init(-1));
211 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
212 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
213 STATISTIC(NumOptimizedAccessesToGlobalArray,
214 "Number of optimized accesses to global arrays");
215 STATISTIC(NumOptimizedAccessesToGlobalVar,
216 "Number of optimized accesses to global vars");
219 /// A set of dynamically initialized globals extracted from metadata.
220 class SetOfDynamicallyInitializedGlobals {
222 void Init(Module& M) {
223 // Clang generates metadata identifying all dynamically initialized globals.
224 NamedMDNode *DynamicGlobals =
225 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
228 for (const auto MDN : DynamicGlobals->operands()) {
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 poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
394 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
395 size_t MinRedzoneSizeForGlobal() const {
396 return RedzoneSizeForScale(Mapping.Scale);
400 SmallString<64> BlacklistFile;
402 std::unique_ptr<SpecialCaseList> BL;
403 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
406 const DataLayout *DL;
407 ShadowMapping Mapping;
408 Function *AsanPoisonGlobals;
409 Function *AsanUnpoisonGlobals;
410 Function *AsanRegisterGlobals;
411 Function *AsanUnregisterGlobals;
412 Function *AsanCovModuleInit;
415 // Stack poisoning does not play well with exception handling.
416 // When an exception is thrown, we essentially bypass the code
417 // that unpoisones the stack. This is why the run-time library has
418 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
419 // stack in the interceptor. This however does not work inside the
420 // actual function which catches the exception. Most likely because the
421 // compiler hoists the load of the shadow value somewhere too high.
422 // This causes asan to report a non-existing bug on 453.povray.
423 // It sounds like an LLVM bug.
424 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
426 AddressSanitizer &ASan;
431 ShadowMapping Mapping;
433 SmallVector<AllocaInst*, 16> AllocaVec;
434 SmallVector<Instruction*, 8> RetVec;
435 unsigned StackAlignment;
437 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
438 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
439 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
441 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
442 struct AllocaPoisonCall {
443 IntrinsicInst *InsBefore;
448 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
450 // Maps Value to an AllocaInst from which the Value is originated.
451 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
452 AllocaForValueMapTy AllocaForValue;
454 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
455 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
456 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
457 Mapping(ASan.Mapping),
458 StackAlignment(1 << Mapping.Scale) {}
460 bool runOnFunction() {
461 if (!ClStack) return false;
462 // Collect alloca, ret, lifetime instructions etc.
463 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
466 if (AllocaVec.empty()) return false;
468 initializeCallbacks(*F.getParent());
478 // Finds all static Alloca instructions and puts
479 // poisoned red zones around all of them.
480 // Then unpoison everything back before the function returns.
483 // ----------------------- Visitors.
484 /// \brief Collect all Ret instructions.
485 void visitReturnInst(ReturnInst &RI) {
486 RetVec.push_back(&RI);
489 /// \brief Collect Alloca instructions we want (and can) handle.
490 void visitAllocaInst(AllocaInst &AI) {
491 if (!isInterestingAlloca(AI)) return;
493 StackAlignment = std::max(StackAlignment, AI.getAlignment());
494 AllocaVec.push_back(&AI);
497 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
499 void visitIntrinsicInst(IntrinsicInst &II) {
500 if (!ASan.CheckLifetime) return;
501 Intrinsic::ID ID = II.getIntrinsicID();
502 if (ID != Intrinsic::lifetime_start &&
503 ID != Intrinsic::lifetime_end)
505 // Found lifetime intrinsic, add ASan instrumentation if necessary.
506 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
507 // If size argument is undefined, don't do anything.
508 if (Size->isMinusOne()) return;
509 // Check that size doesn't saturate uint64_t and can
510 // be stored in IntptrTy.
511 const uint64_t SizeValue = Size->getValue().getLimitedValue();
512 if (SizeValue == ~0ULL ||
513 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
515 // Find alloca instruction that corresponds to llvm.lifetime argument.
516 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
518 bool DoPoison = (ID == Intrinsic::lifetime_end);
519 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
520 AllocaPoisonCallVec.push_back(APC);
523 // ---------------------- Helpers.
524 void initializeCallbacks(Module &M);
526 // Check if we want (and can) handle this alloca.
527 bool isInterestingAlloca(AllocaInst &AI) const {
528 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
529 AI.getAllocatedType()->isSized() &&
530 // alloca() may be called with 0 size, ignore it.
531 getAllocaSizeInBytes(&AI) > 0);
534 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
535 Type *Ty = AI->getAllocatedType();
536 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
539 /// Finds alloca where the value comes from.
540 AllocaInst *findAllocaForValue(Value *V);
541 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
542 Value *ShadowBase, bool DoPoison);
543 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
545 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
551 char AddressSanitizer::ID = 0;
552 INITIALIZE_PASS(AddressSanitizer, "asan",
553 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
555 FunctionPass *llvm::createAddressSanitizerFunctionPass(
556 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
557 StringRef BlacklistFile) {
558 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
559 CheckLifetime, BlacklistFile);
562 char AddressSanitizerModule::ID = 0;
563 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
564 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
565 "ModulePass", false, false)
566 ModulePass *llvm::createAddressSanitizerModulePass(
567 bool CheckInitOrder, StringRef BlacklistFile) {
568 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
571 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
572 size_t Res = countTrailingZeros(TypeSize / 8);
573 assert(Res < kNumberOfAccessSizes);
577 // \brief Create a constant for Str so that we can pass it to the run-time lib.
578 static GlobalVariable *createPrivateGlobalForString(
579 Module &M, StringRef Str, bool AllowMerging) {
580 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
581 // We use private linkage for module-local strings. If they can be merged
582 // with another one, we set the unnamed_addr attribute.
584 new GlobalVariable(M, StrConst->getType(), true,
585 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
587 GV->setUnnamedAddr(true);
588 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
592 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
593 return G->getName().find(kAsanGenPrefix) == 0;
596 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
598 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
599 if (Mapping.Offset == 0)
601 // (Shadow >> scale) | offset
602 if (Mapping.OrShadowOffset)
603 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
605 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
608 // Instrument memset/memmove/memcpy
609 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
611 if (isa<MemTransferInst>(MI)) {
613 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
614 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
615 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
616 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
617 } else if (isa<MemSetInst>(MI)) {
620 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
621 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
622 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
624 MI->eraseFromParent();
627 // If I is an interesting memory access, return the PointerOperand
628 // and set IsWrite/Alignment. Otherwise return NULL.
629 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
630 unsigned *Alignment) {
631 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
632 if (!ClInstrumentReads) return nullptr;
634 *Alignment = LI->getAlignment();
635 return LI->getPointerOperand();
637 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
638 if (!ClInstrumentWrites) return nullptr;
640 *Alignment = SI->getAlignment();
641 return SI->getPointerOperand();
643 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
644 if (!ClInstrumentAtomics) return nullptr;
647 return RMW->getPointerOperand();
649 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
650 if (!ClInstrumentAtomics) return nullptr;
653 return XCHG->getPointerOperand();
658 static bool isPointerOperand(Value *V) {
659 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
662 // This is a rough heuristic; it may cause both false positives and
663 // false negatives. The proper implementation requires cooperation with
665 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
666 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
667 if (!Cmp->isRelational())
669 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
670 if (BO->getOpcode() != Instruction::Sub)
675 if (!isPointerOperand(I->getOperand(0)) ||
676 !isPointerOperand(I->getOperand(1)))
681 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
682 // If a global variable does not have dynamic initialization we don't
683 // have to instrument it. However, if a global does not have initializer
684 // at all, we assume it has dynamic initializer (in other TU).
685 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
689 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
691 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
692 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
693 for (int i = 0; i < 2; i++) {
694 if (Param[i]->getType()->isPointerTy())
695 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
697 IRB.CreateCall2(F, Param[0], Param[1]);
700 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
701 bool IsWrite = false;
702 unsigned Alignment = 0;
703 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
705 if (ClOpt && ClOptGlobals) {
706 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
707 // If initialization order checking is disabled, a simple access to a
708 // dynamically initialized global is always valid.
709 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
710 NumOptimizedAccessesToGlobalVar++;
714 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
715 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
716 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
717 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
718 NumOptimizedAccessesToGlobalArray++;
725 Type *OrigPtrTy = Addr->getType();
726 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
728 assert(OrigTy->isSized());
729 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
731 assert((TypeSize % 8) == 0);
734 NumInstrumentedWrites++;
736 NumInstrumentedReads++;
738 unsigned Granularity = 1 << Mapping.Scale;
739 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
740 // if the data is properly aligned.
741 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
743 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
744 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
745 // Instrument unusual size or unusual alignment.
746 // We can not do it with a single check, so we do 1-byte check for the first
747 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
748 // to report the actual access size.
750 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
751 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
753 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
755 Value *LastByte = IRB.CreateIntToPtr(
756 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
758 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
759 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
763 // Validate the result of Module::getOrInsertFunction called for an interface
764 // function of AddressSanitizer. If the instrumented module defines a function
765 // with the same name, their prototypes must match, otherwise
766 // getOrInsertFunction returns a bitcast.
767 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
768 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
769 FuncOrBitcast->dump();
770 report_fatal_error("trying to redefine an AddressSanitizer "
771 "interface function");
774 Instruction *AddressSanitizer::generateCrashCode(
775 Instruction *InsertBefore, Value *Addr,
776 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
777 IRBuilder<> IRB(InsertBefore);
778 CallInst *Call = SizeArgument
779 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
780 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
782 // We don't do Call->setDoesNotReturn() because the BB already has
783 // UnreachableInst at the end.
784 // This EmptyAsm is required to avoid callback merge.
785 IRB.CreateCall(EmptyAsm);
789 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
792 size_t Granularity = 1 << Mapping.Scale;
793 // Addr & (Granularity - 1)
794 Value *LastAccessedByte = IRB.CreateAnd(
795 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
796 // (Addr & (Granularity - 1)) + size - 1
797 if (TypeSize / 8 > 1)
798 LastAccessedByte = IRB.CreateAdd(
799 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
800 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
801 LastAccessedByte = IRB.CreateIntCast(
802 LastAccessedByte, ShadowValue->getType(), false);
803 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
804 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
807 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
808 Instruction *InsertBefore, Value *Addr,
809 uint32_t TypeSize, bool IsWrite,
810 Value *SizeArgument, bool UseCalls) {
811 IRBuilder<> IRB(InsertBefore);
812 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
813 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
816 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
821 Type *ShadowTy = IntegerType::get(
822 *C, std::max(8U, TypeSize >> Mapping.Scale));
823 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
824 Value *ShadowPtr = memToShadow(AddrLong, IRB);
825 Value *CmpVal = Constant::getNullValue(ShadowTy);
826 Value *ShadowValue = IRB.CreateLoad(
827 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
829 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
830 size_t Granularity = 1 << Mapping.Scale;
831 TerminatorInst *CrashTerm = nullptr;
833 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
834 TerminatorInst *CheckTerm =
835 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
836 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
837 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
838 IRB.SetInsertPoint(CheckTerm);
839 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
840 BasicBlock *CrashBlock =
841 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
842 CrashTerm = new UnreachableInst(*C, CrashBlock);
843 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
844 ReplaceInstWithInst(CheckTerm, NewTerm);
846 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
849 Instruction *Crash = generateCrashCode(
850 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
851 Crash->setDebugLoc(OrigIns->getDebugLoc());
854 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
855 GlobalValue *ModuleName) {
856 // Set up the arguments to our poison/unpoison functions.
857 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
859 // Add a call to poison all external globals before the given function starts.
860 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
861 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
863 // Add calls to unpoison all globals before each return instruction.
864 for (auto &BB : GlobalInit.getBasicBlockList())
865 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
866 CallInst::Create(AsanUnpoisonGlobals, "", RI);
869 void AddressSanitizerModule::createInitializerPoisonCalls(
870 Module &M, GlobalValue *ModuleName) {
871 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
873 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
874 for (Use &OP : CA->operands()) {
875 if (isa<ConstantAggregateZero>(OP))
877 ConstantStruct *CS = cast<ConstantStruct>(OP);
879 // Must have a function or null ptr.
880 // (CS->getOperand(0) is the init priority.)
881 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
882 if (F->getName() != kAsanModuleCtorName)
883 poisonOneInitializer(*F, ModuleName);
888 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
889 Type *Ty = cast<PointerType>(G->getType())->getElementType();
890 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
892 if (BL->isIn(*G)) return false;
893 if (!Ty->isSized()) return false;
894 if (!G->hasInitializer()) return false;
895 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
896 // Touch only those globals that will not be defined in other modules.
897 // Don't handle ODR type linkages since other modules may be built w/o asan.
898 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
899 G->getLinkage() != GlobalVariable::PrivateLinkage &&
900 G->getLinkage() != GlobalVariable::InternalLinkage)
902 // Two problems with thread-locals:
903 // - The address of the main thread's copy can't be computed at link-time.
904 // - Need to poison all copies, not just the main thread's one.
905 if (G->isThreadLocal())
907 // For now, just ignore this Global if the alignment is large.
908 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
910 // Ignore all the globals with the names starting with "\01L_OBJC_".
911 // Many of those are put into the .cstring section. The linker compresses
912 // that section by removing the spare \0s after the string terminator, so
913 // our redzones get broken.
914 if ((G->getName().find("\01L_OBJC_") == 0) ||
915 (G->getName().find("\01l_OBJC_") == 0)) {
916 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
920 if (G->hasSection()) {
921 StringRef Section(G->getSection());
922 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
923 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
925 if (Section.startswith("__OBJC,") ||
926 Section.startswith("__DATA, __objc_")) {
927 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
930 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
931 // Constant CFString instances are compiled in the following way:
932 // -- the string buffer is emitted into
933 // __TEXT,__cstring,cstring_literals
934 // -- the constant NSConstantString structure referencing that buffer
935 // is placed into __DATA,__cfstring
936 // Therefore there's no point in placing redzones into __DATA,__cfstring.
937 // Moreover, it causes the linker to crash on OS X 10.7
938 if (Section.startswith("__DATA,__cfstring")) {
939 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
942 // The linker merges the contents of cstring_literals and removes the
944 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
945 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
949 // Callbacks put into the CRT initializer/terminator sections
950 // should not be instrumented.
951 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
952 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
953 if (Section.startswith(".CRT")) {
954 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
958 // Globals from llvm.metadata aren't emitted, do not instrument them.
959 if (Section == "llvm.metadata") return false;
965 void AddressSanitizerModule::initializeCallbacks(Module &M) {
967 // Declare our poisoning and unpoisoning functions.
968 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
969 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
970 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
971 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
972 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
973 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
974 // Declare functions that register/unregister globals.
975 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
976 kAsanRegisterGlobalsName, IRB.getVoidTy(),
977 IntptrTy, IntptrTy, NULL));
978 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
979 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
980 kAsanUnregisterGlobalsName,
981 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
982 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
983 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
984 kAsanCovModuleInitName,
985 IRB.getVoidTy(), IntptrTy, NULL));
986 AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
989 // This function replaces all global variables with new variables that have
990 // trailing redzones. It also creates a function that poisons
991 // redzones and inserts this function into llvm.global_ctors.
992 bool AddressSanitizerModule::runOnModule(Module &M) {
993 if (!ClGlobals) return false;
995 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
998 DL = &DLP->getDataLayout();
1000 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1001 if (BL->isIn(M)) return false;
1002 C = &(M.getContext());
1003 int LongSize = DL->getPointerSizeInBits();
1004 IntptrTy = Type::getIntNTy(*C, LongSize);
1005 Mapping = getShadowMapping(M, LongSize);
1006 initializeCallbacks(M);
1007 DynamicallyInitializedGlobals.Init(M);
1009 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1011 for (auto &G : M.globals()) {
1012 if (ShouldInstrumentGlobal(&G))
1013 GlobalsToChange.push_back(&G);
1016 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1018 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1020 if (ClCoverage > 0) {
1021 Function *CovFunc = M.getFunction(kAsanCovName);
1022 int nCov = CovFunc ? CovFunc->getNumUses() : 0;
1023 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
1026 size_t n = GlobalsToChange.size();
1027 if (n == 0) return false;
1029 // A global is described by a structure
1032 // size_t size_with_redzone;
1033 // const char *name;
1034 // const char *module_name;
1035 // size_t has_dynamic_init;
1036 // We initialize an array of such structures and pass it to a run-time call.
1037 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
1039 IntptrTy, IntptrTy, NULL);
1040 SmallVector<Constant *, 16> Initializers(n);
1042 bool HasDynamicallyInitializedGlobals = false;
1044 // We shouldn't merge same module names, as this string serves as unique
1045 // module ID in runtime.
1046 GlobalVariable *ModuleName = createPrivateGlobalForString(
1047 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1049 for (size_t i = 0; i < n; i++) {
1050 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1051 GlobalVariable *G = GlobalsToChange[i];
1052 PointerType *PtrTy = cast<PointerType>(G->getType());
1053 Type *Ty = PtrTy->getElementType();
1054 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1055 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1056 // MinRZ <= RZ <= kMaxGlobalRedzone
1057 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1058 uint64_t RZ = std::max(MinRZ,
1059 std::min(kMaxGlobalRedzone,
1060 (SizeInBytes / MinRZ / 4) * MinRZ));
1061 uint64_t RightRedzoneSize = RZ;
1062 // Round up to MinRZ
1063 if (SizeInBytes % MinRZ)
1064 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1065 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1066 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1067 // Determine whether this global should be poisoned in initialization.
1068 bool GlobalHasDynamicInitializer =
1069 DynamicallyInitializedGlobals.Contains(G);
1071 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1072 Constant *NewInitializer = ConstantStruct::get(
1073 NewTy, G->getInitializer(),
1074 Constant::getNullValue(RightRedZoneTy), NULL);
1076 GlobalVariable *Name =
1077 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1079 // Create a new global variable with enough space for a redzone.
1080 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1081 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1082 Linkage = GlobalValue::InternalLinkage;
1083 GlobalVariable *NewGlobal = new GlobalVariable(
1084 M, NewTy, G->isConstant(), Linkage,
1085 NewInitializer, "", G, G->getThreadLocalMode());
1086 NewGlobal->copyAttributesFrom(G);
1087 NewGlobal->setAlignment(MinRZ);
1090 Indices2[0] = IRB.getInt32(0);
1091 Indices2[1] = IRB.getInt32(0);
1093 G->replaceAllUsesWith(
1094 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1095 NewGlobal->takeName(G);
1096 G->eraseFromParent();
1098 Initializers[i] = ConstantStruct::get(
1100 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1101 ConstantInt::get(IntptrTy, SizeInBytes),
1102 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1103 ConstantExpr::getPointerCast(Name, IntptrTy),
1104 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1105 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1108 // Populate the first and last globals declared in this TU.
1109 if (CheckInitOrder && GlobalHasDynamicInitializer)
1110 HasDynamicallyInitializedGlobals = true;
1112 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1115 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1116 GlobalVariable *AllGlobals = new GlobalVariable(
1117 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1118 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1120 // Create calls for poisoning before initializers run and unpoisoning after.
1121 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1122 createInitializerPoisonCalls(M, ModuleName);
1123 IRB.CreateCall2(AsanRegisterGlobals,
1124 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1125 ConstantInt::get(IntptrTy, n));
1127 // We also need to unregister globals at the end, e.g. when a shared library
1129 Function *AsanDtorFunction = Function::Create(
1130 FunctionType::get(Type::getVoidTy(*C), false),
1131 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1132 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1133 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1134 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1135 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1136 ConstantInt::get(IntptrTy, n));
1137 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1143 void AddressSanitizer::initializeCallbacks(Module &M) {
1144 IRBuilder<> IRB(*C);
1145 // Create __asan_report* callbacks.
1146 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1147 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1148 AccessSizeIndex++) {
1149 // IsWrite and TypeSize are encoded in the function name.
1150 std::string Suffix =
1151 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1152 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1153 checkInterfaceFunction(
1154 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1155 IRB.getVoidTy(), IntptrTy, NULL));
1156 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1157 checkInterfaceFunction(
1158 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1159 IRB.getVoidTy(), IntptrTy, NULL));
1162 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1163 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1164 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1165 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1167 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1168 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1169 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1170 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1171 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1172 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1174 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1175 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1176 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1177 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1178 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1179 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1180 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1181 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1182 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1184 AsanHandleNoReturnFunc = checkInterfaceFunction(
1185 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1186 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1187 kAsanCovName, IRB.getVoidTy(), NULL));
1188 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1189 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1190 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1191 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1192 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1193 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1194 StringRef(""), StringRef(""),
1195 /*hasSideEffects=*/true);
1199 bool AddressSanitizer::doInitialization(Module &M) {
1200 // Initialize the private fields. No one has accessed them before.
1201 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1203 report_fatal_error("data layout missing");
1204 DL = &DLP->getDataLayout();
1206 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1207 DynamicallyInitializedGlobals.Init(M);
1209 C = &(M.getContext());
1210 LongSize = DL->getPointerSizeInBits();
1211 IntptrTy = Type::getIntNTy(*C, LongSize);
1213 AsanCtorFunction = Function::Create(
1214 FunctionType::get(Type::getVoidTy(*C), false),
1215 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1216 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1217 // call __asan_init in the module ctor.
1218 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1219 AsanInitFunction = checkInterfaceFunction(
1220 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1221 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1222 IRB.CreateCall(AsanInitFunction);
1224 Mapping = getShadowMapping(M, LongSize);
1226 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1230 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1231 // For each NSObject descendant having a +load method, this method is invoked
1232 // by the ObjC runtime before any of the static constructors is called.
1233 // Therefore we need to instrument such methods with a call to __asan_init
1234 // at the beginning in order to initialize our runtime before any access to
1235 // the shadow memory.
1236 // We cannot just ignore these methods, because they may call other
1237 // instrumented functions.
1238 if (F.getName().find(" load]") != std::string::npos) {
1239 IRBuilder<> IRB(F.begin()->begin());
1240 IRB.CreateCall(AsanInitFunction);
1246 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1247 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1248 // Skip static allocas at the top of the entry block so they don't become
1249 // dynamic when we split the block. If we used our optimized stack layout,
1250 // then there will only be one alloca and it will come first.
1251 for (; IP != BE; ++IP) {
1252 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1253 if (!AI || !AI->isStaticAlloca())
1257 IRBuilder<> IRB(IP);
1258 Type *Int8Ty = IRB.getInt8Ty();
1259 GlobalVariable *Guard = new GlobalVariable(
1260 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1261 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1262 LoadInst *Load = IRB.CreateLoad(Guard);
1263 Load->setAtomic(Monotonic);
1264 Load->setAlignment(1);
1265 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1266 Instruction *Ins = SplitBlockAndInsertIfThen(
1267 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1268 IRB.SetInsertPoint(Ins);
1269 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1270 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1271 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1272 Call->setDebugLoc(IP->getDebugLoc());
1273 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1274 Store->setAtomic(Monotonic);
1275 Store->setAlignment(1);
1278 // Poor man's coverage that works with ASan.
1279 // We create a Guard boolean variable with the same linkage
1280 // as the function and inject this code into the entry block (-asan-coverage=1)
1281 // or all blocks (-asan-coverage=2):
1283 // __sanitizer_cov(&F);
1286 // The accesses to Guard are atomic. The rest of the logic is
1287 // in __sanitizer_cov (it's fine to call it more than once).
1289 // This coverage implementation provides very limited data:
1290 // it only tells if a given function (block) was ever executed.
1291 // No counters, no per-edge data.
1292 // But for many use cases this is what we need and the added slowdown
1293 // is negligible. This simple implementation will probably be obsoleted
1294 // by the upcoming Clang-based coverage implementation.
1295 // By having it here and now we hope to
1296 // a) get the functionality to users earlier and
1297 // b) collect usage statistics to help improve Clang coverage design.
1298 bool AddressSanitizer::InjectCoverage(Function &F,
1299 const ArrayRef<BasicBlock *> AllBlocks) {
1300 if (!ClCoverage) return false;
1302 if (ClCoverage == 1 ||
1303 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1304 InjectCoverageAtBlock(F, F.getEntryBlock());
1306 for (auto BB : AllBlocks)
1307 InjectCoverageAtBlock(F, *BB);
1312 bool AddressSanitizer::runOnFunction(Function &F) {
1313 if (BL->isIn(F)) return false;
1314 if (&F == AsanCtorFunction) return false;
1315 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1316 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1317 initializeCallbacks(*F.getParent());
1319 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1320 maybeInsertAsanInitAtFunctionEntry(F);
1322 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1325 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1328 // We want to instrument every address only once per basic block (unless there
1329 // are calls between uses).
1330 SmallSet<Value*, 16> TempsToInstrument;
1331 SmallVector<Instruction*, 16> ToInstrument;
1332 SmallVector<Instruction*, 8> NoReturnCalls;
1333 SmallVector<BasicBlock*, 16> AllBlocks;
1334 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1339 // Fill the set of memory operations to instrument.
1340 for (auto &BB : F) {
1341 AllBlocks.push_back(&BB);
1342 TempsToInstrument.clear();
1343 int NumInsnsPerBB = 0;
1344 for (auto &Inst : BB) {
1345 if (LooksLikeCodeInBug11395(&Inst)) return false;
1347 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1348 if (ClOpt && ClOptSameTemp) {
1349 if (!TempsToInstrument.insert(Addr))
1350 continue; // We've seen this temp in the current BB.
1352 } else if (ClInvalidPointerPairs &&
1353 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1354 PointerComparisonsOrSubtracts.push_back(&Inst);
1356 } else if (isa<MemIntrinsic>(Inst)) {
1359 if (isa<AllocaInst>(Inst))
1363 // A call inside BB.
1364 TempsToInstrument.clear();
1365 if (CS.doesNotReturn())
1366 NoReturnCalls.push_back(CS.getInstruction());
1370 ToInstrument.push_back(&Inst);
1372 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1377 Function *UninstrumentedDuplicate = nullptr;
1378 bool LikelyToInstrument =
1379 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1380 if (ClKeepUninstrumented && LikelyToInstrument) {
1381 ValueToValueMapTy VMap;
1382 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1383 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1384 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1385 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1388 bool UseCalls = false;
1389 if (ClInstrumentationWithCallsThreshold >= 0 &&
1390 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1394 int NumInstrumented = 0;
1395 for (auto Inst : ToInstrument) {
1396 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1397 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1398 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1399 instrumentMop(Inst, UseCalls);
1401 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1406 FunctionStackPoisoner FSP(F, *this);
1407 bool ChangedStack = FSP.runOnFunction();
1409 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1410 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1411 for (auto CI : NoReturnCalls) {
1412 IRBuilder<> IRB(CI);
1413 IRB.CreateCall(AsanHandleNoReturnFunc);
1416 for (auto Inst : PointerComparisonsOrSubtracts) {
1417 instrumentPointerComparisonOrSubtraction(Inst);
1421 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1423 if (InjectCoverage(F, AllBlocks))
1426 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1428 if (ClKeepUninstrumented) {
1430 // No instrumentation is done, no need for the duplicate.
1431 if (UninstrumentedDuplicate)
1432 UninstrumentedDuplicate->eraseFromParent();
1434 // The function was instrumented. We must have the duplicate.
1435 assert(UninstrumentedDuplicate);
1436 UninstrumentedDuplicate->setSection("NOASAN");
1437 assert(!F.hasSection());
1438 F.setSection("ASAN");
1445 // Workaround for bug 11395: we don't want to instrument stack in functions
1446 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1447 // FIXME: remove once the bug 11395 is fixed.
1448 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1449 if (LongSize != 32) return false;
1450 CallInst *CI = dyn_cast<CallInst>(I);
1451 if (!CI || !CI->isInlineAsm()) return false;
1452 if (CI->getNumArgOperands() <= 5) return false;
1453 // We have inline assembly with quite a few arguments.
1457 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1458 IRBuilder<> IRB(*C);
1459 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1460 std::string Suffix = itostr(i);
1461 AsanStackMallocFunc[i] = checkInterfaceFunction(
1462 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1463 IntptrTy, IntptrTy, NULL));
1464 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1465 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1466 IntptrTy, IntptrTy, NULL));
1468 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1469 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1470 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1471 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1475 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1476 IRBuilder<> &IRB, Value *ShadowBase,
1478 size_t n = ShadowBytes.size();
1480 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1481 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1482 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1483 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1484 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1485 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1487 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1488 if (ASan.DL->isLittleEndian())
1489 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1491 Val = (Val << 8) | ShadowBytes[i + j];
1494 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1495 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1496 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1497 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1502 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1503 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1504 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1505 assert(LocalStackSize <= kMaxStackMallocSize);
1506 uint64_t MaxSize = kMinStackMallocSize;
1507 for (int i = 0; ; i++, MaxSize *= 2)
1508 if (LocalStackSize <= MaxSize)
1510 llvm_unreachable("impossible LocalStackSize");
1513 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1514 // We can not use MemSet intrinsic because it may end up calling the actual
1515 // memset. Size is a multiple of 8.
1516 // Currently this generates 8-byte stores on x86_64; it may be better to
1517 // generate wider stores.
1518 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1519 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1520 assert(!(Size % 8));
1521 assert(kAsanStackAfterReturnMagic == 0xf5);
1522 for (int i = 0; i < Size; i += 8) {
1523 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1524 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1525 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1529 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1530 for (const auto &Inst : F.getEntryBlock())
1531 if (!isa<AllocaInst>(Inst))
1532 return Inst.getDebugLoc();
1536 void FunctionStackPoisoner::poisonStack() {
1537 int StackMallocIdx = -1;
1538 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1540 assert(AllocaVec.size() > 0);
1541 Instruction *InsBefore = AllocaVec[0];
1542 IRBuilder<> IRB(InsBefore);
1543 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1545 SmallVector<ASanStackVariableDescription, 16> SVD;
1546 SVD.reserve(AllocaVec.size());
1547 for (AllocaInst *AI : AllocaVec) {
1548 ASanStackVariableDescription D = { AI->getName().data(),
1549 getAllocaSizeInBytes(AI),
1550 AI->getAlignment(), AI, 0};
1553 // Minimal header size (left redzone) is 4 pointers,
1554 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1555 size_t MinHeaderSize = ASan.LongSize / 2;
1556 ASanStackFrameLayout L;
1557 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1558 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1559 uint64_t LocalStackSize = L.FrameSize;
1560 bool DoStackMalloc =
1561 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1563 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1564 AllocaInst *MyAlloca =
1565 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1566 MyAlloca->setDebugLoc(EntryDebugLocation);
1567 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1568 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1569 MyAlloca->setAlignment(FrameAlignment);
1570 assert(MyAlloca->isStaticAlloca());
1571 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1572 Value *LocalStackBase = OrigStackBase;
1574 if (DoStackMalloc) {
1575 // LocalStackBase = OrigStackBase
1576 // if (__asan_option_detect_stack_use_after_return)
1577 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1578 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1579 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1580 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1581 kAsanOptionDetectUAR, IRB.getInt32Ty());
1582 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1583 Constant::getNullValue(IRB.getInt32Ty()));
1584 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1585 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1586 IRBuilder<> IRBIf(Term);
1587 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1588 LocalStackBase = IRBIf.CreateCall2(
1589 AsanStackMallocFunc[StackMallocIdx],
1590 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1591 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1592 IRB.SetInsertPoint(InsBefore);
1593 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1594 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1595 Phi->addIncoming(OrigStackBase, CmpBlock);
1596 Phi->addIncoming(LocalStackBase, SetBlock);
1597 LocalStackBase = Phi;
1600 // Insert poison calls for lifetime intrinsics for alloca.
1601 bool HavePoisonedAllocas = false;
1602 for (const auto &APC : AllocaPoisonCallVec) {
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 (const auto &Desc : SVD) {
1612 AllocaInst *AI = Desc.AI;
1613 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1614 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1616 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1617 AI->replaceAllUsesWith(NewAllocaPtr);
1620 // The left-most redzone has enough space for at least 4 pointers.
1621 // Write the Magic value to redzone[0].
1622 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1623 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1625 // Write the frame description constant to redzone[1].
1626 Value *BasePlus1 = IRB.CreateIntToPtr(
1627 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1629 GlobalVariable *StackDescriptionGlobal =
1630 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1631 /*AllowMerging*/true);
1632 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1634 IRB.CreateStore(Description, BasePlus1);
1635 // Write the PC to redzone[2].
1636 Value *BasePlus2 = IRB.CreateIntToPtr(
1637 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1638 2 * ASan.LongSize/8)),
1640 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1642 // Poison the stack redzones at the entry.
1643 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1644 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1646 // (Un)poison the stack before all ret instructions.
1647 for (auto Ret : RetVec) {
1648 IRBuilder<> IRBRet(Ret);
1649 // Mark the current frame as retired.
1650 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1652 if (DoStackMalloc) {
1653 assert(StackMallocIdx >= 0);
1654 // if LocalStackBase != OrigStackBase:
1655 // // In use-after-return mode, poison the whole stack frame.
1656 // if StackMallocIdx <= 4
1657 // // For small sizes inline the whole thing:
1658 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1659 // **SavedFlagPtr(LocalStackBase) = 0
1661 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1663 // <This is not a fake stack; unpoison the redzones>
1664 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1665 TerminatorInst *ThenTerm, *ElseTerm;
1666 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1668 IRBuilder<> IRBPoison(ThenTerm);
1669 if (StackMallocIdx <= 4) {
1670 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1671 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1672 ClassSize >> Mapping.Scale);
1673 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1675 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1676 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1677 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1678 IRBPoison.CreateStore(
1679 Constant::getNullValue(IRBPoison.getInt8Ty()),
1680 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1682 // For larger frames call __asan_stack_free_*.
1683 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1684 ConstantInt::get(IntptrTy, LocalStackSize),
1688 IRBuilder<> IRBElse(ElseTerm);
1689 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1690 } else if (HavePoisonedAllocas) {
1691 // If we poisoned some allocas in llvm.lifetime analysis,
1692 // unpoison whole stack frame now.
1693 assert(LocalStackBase == OrigStackBase);
1694 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1696 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1700 // We are done. Remove the old unused alloca instructions.
1701 for (auto AI : AllocaVec)
1702 AI->eraseFromParent();
1705 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1706 IRBuilder<> &IRB, bool DoPoison) {
1707 // For now just insert the call to ASan runtime.
1708 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1709 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1710 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1711 : AsanUnpoisonStackMemoryFunc,
1715 // Handling llvm.lifetime intrinsics for a given %alloca:
1716 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1717 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1718 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1719 // could be poisoned by previous llvm.lifetime.end instruction, as the
1720 // variable may go in and out of scope several times, e.g. in loops).
1721 // (3) if we poisoned at least one %alloca in a function,
1722 // unpoison the whole stack frame at function exit.
1724 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1725 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1726 // We're intested only in allocas we can handle.
1727 return isInterestingAlloca(*AI) ? AI : nullptr;
1728 // See if we've already calculated (or started to calculate) alloca for a
1730 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1731 if (I != AllocaForValue.end())
1733 // Store 0 while we're calculating alloca for value V to avoid
1734 // infinite recursion if the value references itself.
1735 AllocaForValue[V] = nullptr;
1736 AllocaInst *Res = nullptr;
1737 if (CastInst *CI = dyn_cast<CastInst>(V))
1738 Res = findAllocaForValue(CI->getOperand(0));
1739 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1740 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1741 Value *IncValue = PN->getIncomingValue(i);
1742 // Allow self-referencing phi-nodes.
1743 if (IncValue == PN) continue;
1744 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1745 // AI for incoming values should exist and should all be equal.
1746 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1752 AllocaForValue[V] = Res;