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(7000));
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/Alignment. Otherwise return NULL.
627 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
628 unsigned *Alignment) {
629 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
630 if (!ClInstrumentReads) return nullptr;
632 *Alignment = LI->getAlignment();
633 return LI->getPointerOperand();
635 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
636 if (!ClInstrumentWrites) return nullptr;
638 *Alignment = SI->getAlignment();
639 return SI->getPointerOperand();
641 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
642 if (!ClInstrumentAtomics) return nullptr;
645 return RMW->getPointerOperand();
647 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
648 if (!ClInstrumentAtomics) return nullptr;
651 return XCHG->getPointerOperand();
656 static bool isPointerOperand(Value *V) {
657 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
660 // This is a rough heuristic; it may cause both false positives and
661 // false negatives. The proper implementation requires cooperation with
663 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
664 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
665 if (!Cmp->isRelational())
667 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
668 if (BO->getOpcode() != Instruction::Sub)
673 if (!isPointerOperand(I->getOperand(0)) ||
674 !isPointerOperand(I->getOperand(1)))
679 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
680 // If a global variable does not have dynamic initialization we don't
681 // have to instrument it. However, if a global does not have initializer
682 // at all, we assume it has dynamic initializer (in other TU).
683 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
687 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
689 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
690 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
691 for (int i = 0; i < 2; i++) {
692 if (Param[i]->getType()->isPointerTy())
693 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
695 IRB.CreateCall2(F, Param[0], Param[1]);
698 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
699 bool IsWrite = false;
700 unsigned Alignment = 0;
701 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
703 if (ClOpt && ClOptGlobals) {
704 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
705 // If initialization order checking is disabled, a simple access to a
706 // dynamically initialized global is always valid.
707 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
708 NumOptimizedAccessesToGlobalVar++;
712 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
713 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
714 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
715 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
716 NumOptimizedAccessesToGlobalArray++;
723 Type *OrigPtrTy = Addr->getType();
724 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
726 assert(OrigTy->isSized());
727 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
729 assert((TypeSize % 8) == 0);
732 NumInstrumentedWrites++;
734 NumInstrumentedReads++;
736 unsigned Granularity = 1 << Mapping.Scale;
737 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
738 // if the data is properly aligned.
739 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
741 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
742 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
743 // Instrument unusual size or unusual alignment.
744 // We can not do it with a single check, so we do 1-byte check for the first
745 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
746 // to report the actual access size.
748 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
749 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
751 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
753 Value *LastByte = IRB.CreateIntToPtr(
754 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
756 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
757 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
761 // Validate the result of Module::getOrInsertFunction called for an interface
762 // function of AddressSanitizer. If the instrumented module defines a function
763 // with the same name, their prototypes must match, otherwise
764 // getOrInsertFunction returns a bitcast.
765 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
766 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
767 FuncOrBitcast->dump();
768 report_fatal_error("trying to redefine an AddressSanitizer "
769 "interface function");
772 Instruction *AddressSanitizer::generateCrashCode(
773 Instruction *InsertBefore, Value *Addr,
774 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
775 IRBuilder<> IRB(InsertBefore);
776 CallInst *Call = SizeArgument
777 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
778 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
780 // We don't do Call->setDoesNotReturn() because the BB already has
781 // UnreachableInst at the end.
782 // This EmptyAsm is required to avoid callback merge.
783 IRB.CreateCall(EmptyAsm);
787 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
790 size_t Granularity = 1 << Mapping.Scale;
791 // Addr & (Granularity - 1)
792 Value *LastAccessedByte = IRB.CreateAnd(
793 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
794 // (Addr & (Granularity - 1)) + size - 1
795 if (TypeSize / 8 > 1)
796 LastAccessedByte = IRB.CreateAdd(
797 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
798 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
799 LastAccessedByte = IRB.CreateIntCast(
800 LastAccessedByte, ShadowValue->getType(), false);
801 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
802 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
805 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
806 Instruction *InsertBefore, Value *Addr,
807 uint32_t TypeSize, bool IsWrite,
808 Value *SizeArgument, bool UseCalls) {
809 IRBuilder<> IRB(InsertBefore);
810 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
811 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
814 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
819 Type *ShadowTy = IntegerType::get(
820 *C, std::max(8U, TypeSize >> Mapping.Scale));
821 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
822 Value *ShadowPtr = memToShadow(AddrLong, IRB);
823 Value *CmpVal = Constant::getNullValue(ShadowTy);
824 Value *ShadowValue = IRB.CreateLoad(
825 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
827 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
828 size_t Granularity = 1 << Mapping.Scale;
829 TerminatorInst *CrashTerm = nullptr;
831 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
832 TerminatorInst *CheckTerm =
833 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
834 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
835 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
836 IRB.SetInsertPoint(CheckTerm);
837 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
838 BasicBlock *CrashBlock =
839 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
840 CrashTerm = new UnreachableInst(*C, CrashBlock);
841 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
842 ReplaceInstWithInst(CheckTerm, NewTerm);
844 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
847 Instruction *Crash = generateCrashCode(
848 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
849 Crash->setDebugLoc(OrigIns->getDebugLoc());
852 void AddressSanitizerModule::createInitializerPoisonCalls(
853 Module &M, GlobalValue *ModuleName) {
854 // We do all of our poisoning and unpoisoning within a global constructor.
855 // These are called _GLOBAL__(sub_)?I_.*.
856 // TODO: Consider looking through the functions in
857 // M.getGlobalVariable("llvm.global_ctors") instead of using this stringly
859 Function *GlobalInit = nullptr;
860 for (auto &F : M.getFunctionList()) {
861 StringRef FName = F.getName();
863 const char kGlobalPrefix[] = "_GLOBAL__";
864 if (!FName.startswith(kGlobalPrefix))
866 FName = FName.substr(strlen(kGlobalPrefix));
868 const char kOptionalSub[] = "sub_";
869 if (FName.startswith(kOptionalSub))
870 FName = FName.substr(strlen(kOptionalSub));
872 if (FName.startswith("I_")) {
877 // If that function is not present, this TU contains no globals, or they have
878 // all been optimized away
882 // Set up the arguments to our poison/unpoison functions.
883 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
885 // Add a call to poison all external globals before the given function starts.
886 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
887 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
889 // Add calls to unpoison all globals before each return instruction.
890 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
892 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
893 CallInst::Create(AsanUnpoisonGlobals, "", RI);
898 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
899 Type *Ty = cast<PointerType>(G->getType())->getElementType();
900 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
902 if (BL->isIn(*G)) return false;
903 if (!Ty->isSized()) return false;
904 if (!G->hasInitializer()) return false;
905 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
906 // Touch only those globals that will not be defined in other modules.
907 // Don't handle ODR type linkages since other modules may be built w/o asan.
908 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
909 G->getLinkage() != GlobalVariable::PrivateLinkage &&
910 G->getLinkage() != GlobalVariable::InternalLinkage)
912 // Two problems with thread-locals:
913 // - The address of the main thread's copy can't be computed at link-time.
914 // - Need to poison all copies, not just the main thread's one.
915 if (G->isThreadLocal())
917 // For now, just ignore this Global if the alignment is large.
918 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
920 // Ignore all the globals with the names starting with "\01L_OBJC_".
921 // Many of those are put into the .cstring section. The linker compresses
922 // that section by removing the spare \0s after the string terminator, so
923 // our redzones get broken.
924 if ((G->getName().find("\01L_OBJC_") == 0) ||
925 (G->getName().find("\01l_OBJC_") == 0)) {
926 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
930 if (G->hasSection()) {
931 StringRef Section(G->getSection());
932 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
933 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
935 if (Section.startswith("__OBJC,") ||
936 Section.startswith("__DATA, __objc_")) {
937 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
940 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
941 // Constant CFString instances are compiled in the following way:
942 // -- the string buffer is emitted into
943 // __TEXT,__cstring,cstring_literals
944 // -- the constant NSConstantString structure referencing that buffer
945 // is placed into __DATA,__cfstring
946 // Therefore there's no point in placing redzones into __DATA,__cfstring.
947 // Moreover, it causes the linker to crash on OS X 10.7
948 if (Section.startswith("__DATA,__cfstring")) {
949 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
952 // The linker merges the contents of cstring_literals and removes the
954 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
955 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
959 // Callbacks put into the CRT initializer/terminator sections
960 // should not be instrumented.
961 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
962 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
963 if (Section.startswith(".CRT")) {
964 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
968 // Globals from llvm.metadata aren't emitted, do not instrument them.
969 if (Section == "llvm.metadata") return false;
975 void AddressSanitizerModule::initializeCallbacks(Module &M) {
977 // Declare our poisoning and unpoisoning functions.
978 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
979 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
980 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
981 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
982 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
983 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
984 // Declare functions that register/unregister globals.
985 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
986 kAsanRegisterGlobalsName, IRB.getVoidTy(),
987 IntptrTy, IntptrTy, NULL));
988 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
989 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
990 kAsanUnregisterGlobalsName,
991 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
992 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
995 // This function replaces all global variables with new variables that have
996 // trailing redzones. It also creates a function that poisons
997 // redzones and inserts this function into llvm.global_ctors.
998 bool AddressSanitizerModule::runOnModule(Module &M) {
999 if (!ClGlobals) return false;
1001 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1004 DL = &DLP->getDataLayout();
1006 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1007 if (BL->isIn(M)) return false;
1008 C = &(M.getContext());
1009 int LongSize = DL->getPointerSizeInBits();
1010 IntptrTy = Type::getIntNTy(*C, LongSize);
1011 Mapping = getShadowMapping(M, LongSize);
1012 initializeCallbacks(M);
1013 DynamicallyInitializedGlobals.Init(M);
1015 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1017 for (Module::GlobalListType::iterator G = M.global_begin(),
1018 E = M.global_end(); G != E; ++G) {
1019 if (ShouldInstrumentGlobal(G))
1020 GlobalsToChange.push_back(G);
1023 size_t n = GlobalsToChange.size();
1024 if (n == 0) return false;
1026 // A global is described by a structure
1029 // size_t size_with_redzone;
1030 // const char *name;
1031 // const char *module_name;
1032 // size_t has_dynamic_init;
1033 // We initialize an array of such structures and pass it to a run-time call.
1034 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
1036 IntptrTy, IntptrTy, NULL);
1037 SmallVector<Constant *, 16> Initializers(n);
1039 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1041 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1043 bool HasDynamicallyInitializedGlobals = false;
1045 // We shouldn't merge same module names, as this string serves as unique
1046 // module ID in runtime.
1047 GlobalVariable *ModuleName = createPrivateGlobalForString(
1048 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1050 for (size_t i = 0; i < n; i++) {
1051 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1052 GlobalVariable *G = GlobalsToChange[i];
1053 PointerType *PtrTy = cast<PointerType>(G->getType());
1054 Type *Ty = PtrTy->getElementType();
1055 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1056 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1057 // MinRZ <= RZ <= kMaxGlobalRedzone
1058 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1059 uint64_t RZ = std::max(MinRZ,
1060 std::min(kMaxGlobalRedzone,
1061 (SizeInBytes / MinRZ / 4) * MinRZ));
1062 uint64_t RightRedzoneSize = RZ;
1063 // Round up to MinRZ
1064 if (SizeInBytes % MinRZ)
1065 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1066 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1067 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1068 // Determine whether this global should be poisoned in initialization.
1069 bool GlobalHasDynamicInitializer =
1070 DynamicallyInitializedGlobals.Contains(G);
1071 // Don't check initialization order if this global is blacklisted.
1072 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
1074 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1075 Constant *NewInitializer = ConstantStruct::get(
1076 NewTy, G->getInitializer(),
1077 Constant::getNullValue(RightRedZoneTy), NULL);
1079 GlobalVariable *Name =
1080 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1082 // Create a new global variable with enough space for a redzone.
1083 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1084 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1085 Linkage = GlobalValue::InternalLinkage;
1086 GlobalVariable *NewGlobal = new GlobalVariable(
1087 M, NewTy, G->isConstant(), Linkage,
1088 NewInitializer, "", G, G->getThreadLocalMode());
1089 NewGlobal->copyAttributesFrom(G);
1090 NewGlobal->setAlignment(MinRZ);
1093 Indices2[0] = IRB.getInt32(0);
1094 Indices2[1] = IRB.getInt32(0);
1096 G->replaceAllUsesWith(
1097 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1098 NewGlobal->takeName(G);
1099 G->eraseFromParent();
1101 Initializers[i] = ConstantStruct::get(
1103 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1104 ConstantInt::get(IntptrTy, SizeInBytes),
1105 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1106 ConstantExpr::getPointerCast(Name, IntptrTy),
1107 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1108 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1111 // Populate the first and last globals declared in this TU.
1112 if (CheckInitOrder && GlobalHasDynamicInitializer)
1113 HasDynamicallyInitializedGlobals = true;
1115 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1118 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1119 GlobalVariable *AllGlobals = new GlobalVariable(
1120 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1121 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1123 // Create calls for poisoning before initializers run and unpoisoning after.
1124 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1125 createInitializerPoisonCalls(M, ModuleName);
1126 IRB.CreateCall2(AsanRegisterGlobals,
1127 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1128 ConstantInt::get(IntptrTy, n));
1130 // We also need to unregister globals at the end, e.g. when a shared library
1132 Function *AsanDtorFunction = Function::Create(
1133 FunctionType::get(Type::getVoidTy(*C), false),
1134 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1135 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1136 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1137 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1138 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1139 ConstantInt::get(IntptrTy, n));
1140 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1146 void AddressSanitizer::initializeCallbacks(Module &M) {
1147 IRBuilder<> IRB(*C);
1148 // Create __asan_report* callbacks.
1149 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1150 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1151 AccessSizeIndex++) {
1152 // IsWrite and TypeSize are encoded in the function name.
1153 std::string Suffix =
1154 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1155 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1156 checkInterfaceFunction(
1157 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1158 IRB.getVoidTy(), IntptrTy, NULL));
1159 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1160 checkInterfaceFunction(
1161 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1162 IRB.getVoidTy(), IntptrTy, NULL));
1165 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1166 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1167 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1168 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1170 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1171 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1172 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1173 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1174 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1175 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1177 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1178 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1179 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1180 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1181 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1182 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1183 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1184 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1185 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1187 AsanHandleNoReturnFunc = checkInterfaceFunction(
1188 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1189 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1190 kAsanCovName, IRB.getVoidTy(), NULL));
1191 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1192 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1193 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1194 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1195 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1196 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1197 StringRef(""), StringRef(""),
1198 /*hasSideEffects=*/true);
1202 bool AddressSanitizer::doInitialization(Module &M) {
1203 // Initialize the private fields. No one has accessed them before.
1204 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1206 report_fatal_error("data layout missing");
1207 DL = &DLP->getDataLayout();
1209 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1210 DynamicallyInitializedGlobals.Init(M);
1212 C = &(M.getContext());
1213 LongSize = DL->getPointerSizeInBits();
1214 IntptrTy = Type::getIntNTy(*C, LongSize);
1216 AsanCtorFunction = Function::Create(
1217 FunctionType::get(Type::getVoidTy(*C), false),
1218 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1219 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1220 // call __asan_init in the module ctor.
1221 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1222 AsanInitFunction = checkInterfaceFunction(
1223 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1224 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1225 IRB.CreateCall(AsanInitFunction);
1227 Mapping = getShadowMapping(M, LongSize);
1229 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1233 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1234 // For each NSObject descendant having a +load method, this method is invoked
1235 // by the ObjC runtime before any of the static constructors is called.
1236 // Therefore we need to instrument such methods with a call to __asan_init
1237 // at the beginning in order to initialize our runtime before any access to
1238 // the shadow memory.
1239 // We cannot just ignore these methods, because they may call other
1240 // instrumented functions.
1241 if (F.getName().find(" load]") != std::string::npos) {
1242 IRBuilder<> IRB(F.begin()->begin());
1243 IRB.CreateCall(AsanInitFunction);
1249 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1250 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1251 // Skip static allocas at the top of the entry block so they don't become
1252 // dynamic when we split the block. If we used our optimized stack layout,
1253 // then there will only be one alloca and it will come first.
1254 for (; IP != BE; ++IP) {
1255 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1256 if (!AI || !AI->isStaticAlloca())
1260 IRBuilder<> IRB(IP);
1261 Type *Int8Ty = IRB.getInt8Ty();
1262 GlobalVariable *Guard = new GlobalVariable(
1263 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1264 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1265 LoadInst *Load = IRB.CreateLoad(Guard);
1266 Load->setAtomic(Monotonic);
1267 Load->setAlignment(1);
1268 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1269 Instruction *Ins = SplitBlockAndInsertIfThen(
1270 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1271 IRB.SetInsertPoint(Ins);
1272 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1273 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1274 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1275 Call->setDebugLoc(IP->getDebugLoc());
1276 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1277 Store->setAtomic(Monotonic);
1278 Store->setAlignment(1);
1281 // Poor man's coverage that works with ASan.
1282 // We create a Guard boolean variable with the same linkage
1283 // as the function and inject this code into the entry block (-asan-coverage=1)
1284 // or all blocks (-asan-coverage=2):
1286 // __sanitizer_cov(&F);
1289 // The accesses to Guard are atomic. The rest of the logic is
1290 // in __sanitizer_cov (it's fine to call it more than once).
1292 // This coverage implementation provides very limited data:
1293 // it only tells if a given function (block) was ever executed.
1294 // No counters, no per-edge data.
1295 // But for many use cases this is what we need and the added slowdown
1296 // is negligible. This simple implementation will probably be obsoleted
1297 // by the upcoming Clang-based coverage implementation.
1298 // By having it here and now we hope to
1299 // a) get the functionality to users earlier and
1300 // b) collect usage statistics to help improve Clang coverage design.
1301 bool AddressSanitizer::InjectCoverage(Function &F,
1302 const ArrayRef<BasicBlock *> AllBlocks) {
1303 if (!ClCoverage) return false;
1305 if (ClCoverage == 1 ||
1306 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1307 InjectCoverageAtBlock(F, F.getEntryBlock());
1309 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1310 InjectCoverageAtBlock(F, *AllBlocks[i]);
1315 bool AddressSanitizer::runOnFunction(Function &F) {
1316 if (BL->isIn(F)) return false;
1317 if (&F == AsanCtorFunction) return false;
1318 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1319 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1320 initializeCallbacks(*F.getParent());
1322 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1323 maybeInsertAsanInitAtFunctionEntry(F);
1325 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1328 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1331 // We want to instrument every address only once per basic block (unless there
1332 // are calls between uses).
1333 SmallSet<Value*, 16> TempsToInstrument;
1334 SmallVector<Instruction*, 16> ToInstrument;
1335 SmallVector<Instruction*, 8> NoReturnCalls;
1336 SmallVector<BasicBlock*, 16> AllBlocks;
1337 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1342 // Fill the set of memory operations to instrument.
1343 for (Function::iterator FI = F.begin(), FE = F.end();
1345 AllBlocks.push_back(FI);
1346 TempsToInstrument.clear();
1347 int NumInsnsPerBB = 0;
1348 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1350 if (LooksLikeCodeInBug11395(BI)) return false;
1351 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite, &Alignment)) {
1352 if (ClOpt && ClOptSameTemp) {
1353 if (!TempsToInstrument.insert(Addr))
1354 continue; // We've seen this temp in the current BB.
1356 } else if (ClInvalidPointerPairs &&
1357 isInterestingPointerComparisonOrSubtraction(BI)) {
1358 PointerComparisonsOrSubtracts.push_back(BI);
1360 } else if (isa<MemIntrinsic>(BI)) {
1363 if (isa<AllocaInst>(BI))
1367 // A call inside BB.
1368 TempsToInstrument.clear();
1369 if (CS.doesNotReturn())
1370 NoReturnCalls.push_back(CS.getInstruction());
1374 ToInstrument.push_back(BI);
1376 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1381 Function *UninstrumentedDuplicate = nullptr;
1382 bool LikelyToInstrument =
1383 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1384 if (ClKeepUninstrumented && LikelyToInstrument) {
1385 ValueToValueMapTy VMap;
1386 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1387 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1388 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1389 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1392 bool UseCalls = false;
1393 if (ClInstrumentationWithCallsThreshold >= 0 &&
1394 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1398 int NumInstrumented = 0;
1399 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1400 Instruction *Inst = ToInstrument[i];
1401 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1402 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1403 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1404 instrumentMop(Inst, UseCalls);
1406 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1411 FunctionStackPoisoner FSP(F, *this);
1412 bool ChangedStack = FSP.runOnFunction();
1414 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1415 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1416 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1417 Instruction *CI = NoReturnCalls[i];
1418 IRBuilder<> IRB(CI);
1419 IRB.CreateCall(AsanHandleNoReturnFunc);
1422 for (size_t i = 0, n = PointerComparisonsOrSubtracts.size(); i != n; i++) {
1423 instrumentPointerComparisonOrSubtraction(PointerComparisonsOrSubtracts[i]);
1427 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1429 if (InjectCoverage(F, AllBlocks))
1432 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1434 if (ClKeepUninstrumented) {
1436 // No instrumentation is done, no need for the duplicate.
1437 if (UninstrumentedDuplicate)
1438 UninstrumentedDuplicate->eraseFromParent();
1440 // The function was instrumented. We must have the duplicate.
1441 assert(UninstrumentedDuplicate);
1442 UninstrumentedDuplicate->setSection("NOASAN");
1443 assert(!F.hasSection());
1444 F.setSection("ASAN");
1451 // Workaround for bug 11395: we don't want to instrument stack in functions
1452 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1453 // FIXME: remove once the bug 11395 is fixed.
1454 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1455 if (LongSize != 32) return false;
1456 CallInst *CI = dyn_cast<CallInst>(I);
1457 if (!CI || !CI->isInlineAsm()) return false;
1458 if (CI->getNumArgOperands() <= 5) return false;
1459 // We have inline assembly with quite a few arguments.
1463 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1464 IRBuilder<> IRB(*C);
1465 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1466 std::string Suffix = itostr(i);
1467 AsanStackMallocFunc[i] = checkInterfaceFunction(
1468 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1469 IntptrTy, IntptrTy, NULL));
1470 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1471 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1472 IntptrTy, IntptrTy, NULL));
1474 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1475 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1476 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1477 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1481 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1482 IRBuilder<> &IRB, Value *ShadowBase,
1484 size_t n = ShadowBytes.size();
1486 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1487 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1488 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1489 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1490 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1491 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1493 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1494 if (ASan.DL->isLittleEndian())
1495 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1497 Val = (Val << 8) | ShadowBytes[i + j];
1500 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1501 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1502 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1503 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1508 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1509 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1510 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1511 assert(LocalStackSize <= kMaxStackMallocSize);
1512 uint64_t MaxSize = kMinStackMallocSize;
1513 for (int i = 0; ; i++, MaxSize *= 2)
1514 if (LocalStackSize <= MaxSize)
1516 llvm_unreachable("impossible LocalStackSize");
1519 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1520 // We can not use MemSet intrinsic because it may end up calling the actual
1521 // memset. Size is a multiple of 8.
1522 // Currently this generates 8-byte stores on x86_64; it may be better to
1523 // generate wider stores.
1524 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1525 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1526 assert(!(Size % 8));
1527 assert(kAsanStackAfterReturnMagic == 0xf5);
1528 for (int i = 0; i < Size; i += 8) {
1529 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1530 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1531 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1535 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1536 BasicBlock::iterator I = F.getEntryBlock().begin(),
1537 E = F.getEntryBlock().end();
1539 if (!isa<AllocaInst>(I))
1541 return I->getDebugLoc();
1544 void FunctionStackPoisoner::poisonStack() {
1545 int StackMallocIdx = -1;
1546 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1548 assert(AllocaVec.size() > 0);
1549 Instruction *InsBefore = AllocaVec[0];
1550 IRBuilder<> IRB(InsBefore);
1551 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1553 SmallVector<ASanStackVariableDescription, 16> SVD;
1554 SVD.reserve(AllocaVec.size());
1555 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1556 AllocaInst *AI = AllocaVec[i];
1557 ASanStackVariableDescription D = { AI->getName().data(),
1558 getAllocaSizeInBytes(AI),
1559 AI->getAlignment(), AI, 0};
1562 // Minimal header size (left redzone) is 4 pointers,
1563 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1564 size_t MinHeaderSize = ASan.LongSize / 2;
1565 ASanStackFrameLayout L;
1566 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1567 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1568 uint64_t LocalStackSize = L.FrameSize;
1569 bool DoStackMalloc =
1570 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1572 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1573 AllocaInst *MyAlloca =
1574 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1575 MyAlloca->setDebugLoc(EntryDebugLocation);
1576 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1577 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1578 MyAlloca->setAlignment(FrameAlignment);
1579 assert(MyAlloca->isStaticAlloca());
1580 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1581 Value *LocalStackBase = OrigStackBase;
1583 if (DoStackMalloc) {
1584 // LocalStackBase = OrigStackBase
1585 // if (__asan_option_detect_stack_use_after_return)
1586 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1587 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1588 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1589 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1590 kAsanOptionDetectUAR, IRB.getInt32Ty());
1591 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1592 Constant::getNullValue(IRB.getInt32Ty()));
1593 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1594 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1595 IRBuilder<> IRBIf(Term);
1596 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1597 LocalStackBase = IRBIf.CreateCall2(
1598 AsanStackMallocFunc[StackMallocIdx],
1599 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1600 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1601 IRB.SetInsertPoint(InsBefore);
1602 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1603 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1604 Phi->addIncoming(OrigStackBase, CmpBlock);
1605 Phi->addIncoming(LocalStackBase, SetBlock);
1606 LocalStackBase = Phi;
1609 // Insert poison calls for lifetime intrinsics for alloca.
1610 bool HavePoisonedAllocas = false;
1611 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1612 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1613 assert(APC.InsBefore);
1615 IRBuilder<> IRB(APC.InsBefore);
1616 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1617 HavePoisonedAllocas |= APC.DoPoison;
1620 // Replace Alloca instructions with base+offset.
1621 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1622 AllocaInst *AI = SVD[i].AI;
1623 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1624 IRB.CreateAdd(LocalStackBase,
1625 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1627 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1628 AI->replaceAllUsesWith(NewAllocaPtr);
1631 // The left-most redzone has enough space for at least 4 pointers.
1632 // Write the Magic value to redzone[0].
1633 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1634 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1636 // Write the frame description constant to redzone[1].
1637 Value *BasePlus1 = IRB.CreateIntToPtr(
1638 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1640 GlobalVariable *StackDescriptionGlobal =
1641 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1642 /*AllowMerging*/true);
1643 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1645 IRB.CreateStore(Description, BasePlus1);
1646 // Write the PC to redzone[2].
1647 Value *BasePlus2 = IRB.CreateIntToPtr(
1648 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1649 2 * ASan.LongSize/8)),
1651 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1653 // Poison the stack redzones at the entry.
1654 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1655 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1657 // (Un)poison the stack before all ret instructions.
1658 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1659 Instruction *Ret = RetVec[i];
1660 IRBuilder<> IRBRet(Ret);
1661 // Mark the current frame as retired.
1662 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1664 if (DoStackMalloc) {
1665 assert(StackMallocIdx >= 0);
1666 // if LocalStackBase != OrigStackBase:
1667 // // In use-after-return mode, poison the whole stack frame.
1668 // if StackMallocIdx <= 4
1669 // // For small sizes inline the whole thing:
1670 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1671 // **SavedFlagPtr(LocalStackBase) = 0
1673 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1675 // <This is not a fake stack; unpoison the redzones>
1676 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1677 TerminatorInst *ThenTerm, *ElseTerm;
1678 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1680 IRBuilder<> IRBPoison(ThenTerm);
1681 if (StackMallocIdx <= 4) {
1682 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1683 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1684 ClassSize >> Mapping.Scale);
1685 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1687 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1688 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1689 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1690 IRBPoison.CreateStore(
1691 Constant::getNullValue(IRBPoison.getInt8Ty()),
1692 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1694 // For larger frames call __asan_stack_free_*.
1695 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1696 ConstantInt::get(IntptrTy, LocalStackSize),
1700 IRBuilder<> IRBElse(ElseTerm);
1701 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1702 } else if (HavePoisonedAllocas) {
1703 // If we poisoned some allocas in llvm.lifetime analysis,
1704 // unpoison whole stack frame now.
1705 assert(LocalStackBase == OrigStackBase);
1706 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1708 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1712 // We are done. Remove the old unused alloca instructions.
1713 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1714 AllocaVec[i]->eraseFromParent();
1717 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1718 IRBuilder<> &IRB, bool DoPoison) {
1719 // For now just insert the call to ASan runtime.
1720 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1721 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1722 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1723 : AsanUnpoisonStackMemoryFunc,
1727 // Handling llvm.lifetime intrinsics for a given %alloca:
1728 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1729 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1730 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1731 // could be poisoned by previous llvm.lifetime.end instruction, as the
1732 // variable may go in and out of scope several times, e.g. in loops).
1733 // (3) if we poisoned at least one %alloca in a function,
1734 // unpoison the whole stack frame at function exit.
1736 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1737 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1738 // We're intested only in allocas we can handle.
1739 return isInterestingAlloca(*AI) ? AI : nullptr;
1740 // See if we've already calculated (or started to calculate) alloca for a
1742 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1743 if (I != AllocaForValue.end())
1745 // Store 0 while we're calculating alloca for value V to avoid
1746 // infinite recursion if the value references itself.
1747 AllocaForValue[V] = nullptr;
1748 AllocaInst *Res = nullptr;
1749 if (CastInst *CI = dyn_cast<CastInst>(V))
1750 Res = findAllocaForValue(CI->getOperand(0));
1751 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1752 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1753 Value *IncValue = PN->getIncomingValue(i);
1754 // Allow self-referencing phi-nodes.
1755 if (IncValue == PN) continue;
1756 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1757 // AI for incoming values should exist and should all be equal.
1758 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1764 AllocaForValue[V] = Res;