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/DenseSet.h"
20 #include "llvm/ADT/DepthFirstIterator.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/IR/CallSite.h"
28 #include "llvm/IR/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/InstVisitor.h"
34 #include "llvm/IR/IntrinsicInst.h"
35 #include "llvm/IR/LLVMContext.h"
36 #include "llvm/IR/MDBuilder.h"
37 #include "llvm/IR/Module.h"
38 #include "llvm/IR/Type.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/DataTypes.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/Endian.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"
51 #include <system_error>
55 #define DEBUG_TYPE "asan"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
60 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
61 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
62 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
63 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
64 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
65 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
67 static const size_t kMinStackMallocSize = 1 << 6; // 64B
68 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
69 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
70 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
72 static const char *const kAsanModuleCtorName = "asan.module_ctor";
73 static const char *const kAsanModuleDtorName = "asan.module_dtor";
74 static const int kAsanCtorAndDtorPriority = 1;
75 static const char *const kAsanReportErrorTemplate = "__asan_report_";
76 static const char *const kAsanReportLoadN = "__asan_report_load_n";
77 static const char *const kAsanReportStoreN = "__asan_report_store_n";
78 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
79 static const char *const kAsanUnregisterGlobalsName =
80 "__asan_unregister_globals";
81 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
82 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
83 static const char *const kAsanInitName = "__asan_init_v4";
84 static const char *const kAsanCovModuleInitName = "__sanitizer_cov_module_init";
85 static const char *const kAsanCovName = "__sanitizer_cov";
86 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
87 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
88 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
89 static const int kMaxAsanStackMallocSizeClass = 10;
90 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
91 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
92 static const char *const kAsanGenPrefix = "__asan_gen_";
93 static const char *const kAsanPoisonStackMemoryName =
94 "__asan_poison_stack_memory";
95 static const char *const kAsanUnpoisonStackMemoryName =
96 "__asan_unpoison_stack_memory";
98 static const char *const kAsanOptionDetectUAR =
99 "__asan_option_detect_stack_use_after_return";
102 static const int kAsanStackAfterReturnMagic = 0xf5;
105 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
106 static const size_t kNumberOfAccessSizes = 5;
108 // Command-line flags.
110 // This flag may need to be replaced with -f[no-]asan-reads.
111 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
112 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
114 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
115 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
116 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
117 cl::Hidden, cl::init(true));
118 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
119 cl::desc("use instrumentation with slow path for all accesses"),
120 cl::Hidden, cl::init(false));
121 // This flag limits the number of instructions to be instrumented
122 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
123 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
125 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
127 cl::desc("maximal number of instructions to instrument in any given BB"),
129 // This flag may need to be replaced with -f[no]asan-stack.
130 static cl::opt<bool> ClStack("asan-stack",
131 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
132 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
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(true));
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 /// Frontend-provided metadata for global variables.
220 class GlobalsMetadata {
222 void init(Module& M) {
225 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
228 for (auto MDN : Globals->operands()) {
229 // Format of the metadata node for the global:
233 // i1 is_dynamically_initialized,
236 assert(MDN->getNumOperands() == 4);
237 Value *V = MDN->getOperand(0);
238 // The optimizer may optimize away a global entirely.
241 GlobalVariable *GV = cast<GlobalVariable>(V);
242 if (Value *Loc = MDN->getOperand(1)) {
243 GlobalVariable *GVLoc = cast<GlobalVariable>(Loc);
244 // We may already know the source location for GV, if it was merged
245 // with another global.
246 if (SourceLocation.insert(std::make_pair(GV, GVLoc)).second)
247 addSourceLocationGlobal(GVLoc);
249 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(2));
250 if (IsDynInit->isOne())
251 DynInitGlobals.insert(GV);
252 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(3));
253 if (IsBlacklisted->isOne())
254 BlacklistedGlobals.insert(GV);
258 GlobalVariable *getSourceLocation(GlobalVariable *G) const {
259 auto Pos = SourceLocation.find(G);
260 return (Pos != SourceLocation.end()) ? Pos->second : nullptr;
263 /// Check if the global is dynamically initialized.
264 bool isDynInit(GlobalVariable *G) const {
265 return DynInitGlobals.count(G);
268 /// Check if the global was blacklisted.
269 bool isBlacklisted(GlobalVariable *G) const {
270 return BlacklistedGlobals.count(G);
273 /// Check if the global was generated to describe source location of another
274 /// global (we don't want to instrument them).
275 bool isSourceLocationGlobal(GlobalVariable *G) const {
276 return LocationGlobals.count(G);
280 bool inited_ = false;
281 DenseMap<GlobalVariable*, GlobalVariable*> SourceLocation;
282 DenseSet<GlobalVariable*> DynInitGlobals;
283 DenseSet<GlobalVariable*> BlacklistedGlobals;
284 DenseSet<GlobalVariable*> LocationGlobals;
286 void addSourceLocationGlobal(GlobalVariable *SourceLocGV) {
287 // Source location global is a struct with layout:
291 // i32 column_number,
293 LocationGlobals.insert(SourceLocGV);
294 ConstantStruct *Contents =
295 cast<ConstantStruct>(SourceLocGV->getInitializer());
296 GlobalVariable *FilenameGV = cast<GlobalVariable>(Contents->getOperand(0));
297 LocationGlobals.insert(FilenameGV);
301 /// This struct defines the shadow mapping using the rule:
302 /// shadow = (mem >> Scale) ADD-or-OR Offset.
303 struct ShadowMapping {
309 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
310 llvm::Triple TargetTriple(M.getTargetTriple());
311 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
312 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
313 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
314 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
315 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
316 TargetTriple.getArch() == llvm::Triple::ppc64le;
317 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
318 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
319 TargetTriple.getArch() == llvm::Triple::mipsel;
321 ShadowMapping Mapping;
323 if (LongSize == 32) {
327 Mapping.Offset = kMIPS32_ShadowOffset32;
329 Mapping.Offset = kFreeBSD_ShadowOffset32;
331 Mapping.Offset = kIOSShadowOffset32;
333 Mapping.Offset = kDefaultShadowOffset32;
334 } else { // LongSize == 64
336 Mapping.Offset = kPPC64_ShadowOffset64;
338 Mapping.Offset = kFreeBSD_ShadowOffset64;
339 else if (IsLinux && IsX86_64)
340 Mapping.Offset = kSmallX86_64ShadowOffset;
342 Mapping.Offset = kDefaultShadowOffset64;
345 Mapping.Scale = kDefaultShadowScale;
346 if (ClMappingScale) {
347 Mapping.Scale = ClMappingScale;
350 // OR-ing shadow offset if more efficient (at least on x86) if the offset
351 // is a power of two, but on ppc64 we have to use add since the shadow
352 // offset is not necessary 1/8-th of the address space.
353 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
358 static size_t RedzoneSizeForScale(int MappingScale) {
359 // Redzone used for stack and globals is at least 32 bytes.
360 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
361 return std::max(32U, 1U << MappingScale);
364 /// AddressSanitizer: instrument the code in module to find memory bugs.
365 struct AddressSanitizer : public FunctionPass {
366 AddressSanitizer() : FunctionPass(ID) {}
367 const char *getPassName() const override {
368 return "AddressSanitizerFunctionPass";
370 void instrumentMop(Instruction *I, bool UseCalls);
371 void instrumentPointerComparisonOrSubtraction(Instruction *I);
372 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
373 Value *Addr, uint32_t TypeSize, bool IsWrite,
374 Value *SizeArgument, bool UseCalls);
375 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
376 Value *ShadowValue, uint32_t TypeSize);
377 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
378 bool IsWrite, size_t AccessSizeIndex,
379 Value *SizeArgument);
380 void instrumentMemIntrinsic(MemIntrinsic *MI);
381 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
382 bool runOnFunction(Function &F) override;
383 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
384 bool doInitialization(Module &M) override;
385 static char ID; // Pass identification, replacement for typeid
388 void initializeCallbacks(Module &M);
390 bool LooksLikeCodeInBug11395(Instruction *I);
391 bool GlobalIsLinkerInitialized(GlobalVariable *G);
392 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
393 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
396 const DataLayout *DL;
399 ShadowMapping Mapping;
400 Function *AsanCtorFunction;
401 Function *AsanInitFunction;
402 Function *AsanHandleNoReturnFunc;
403 Function *AsanCovFunction;
404 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
405 // This array is indexed by AccessIsWrite and log2(AccessSize).
406 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
407 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
408 // This array is indexed by AccessIsWrite.
409 Function *AsanErrorCallbackSized[2],
410 *AsanMemoryAccessCallbackSized[2];
411 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
413 GlobalsMetadata GlobalsMD;
415 friend struct FunctionStackPoisoner;
418 class AddressSanitizerModule : public ModulePass {
420 AddressSanitizerModule(StringRef BlacklistFile = StringRef())
421 : ModulePass(ID), BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
423 bool runOnModule(Module &M) override;
424 static char ID; // Pass identification, replacement for typeid
425 const char *getPassName() const override {
426 return "AddressSanitizerModule";
430 void initializeCallbacks(Module &M);
432 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
433 bool ShouldInstrumentGlobal(GlobalVariable *G);
434 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
435 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
436 size_t MinRedzoneSizeForGlobal() const {
437 return RedzoneSizeForScale(Mapping.Scale);
440 SmallString<64> BlacklistFile;
442 std::unique_ptr<SpecialCaseList> BL;
443 GlobalsMetadata GlobalsMD;
446 const DataLayout *DL;
447 ShadowMapping Mapping;
448 Function *AsanPoisonGlobals;
449 Function *AsanUnpoisonGlobals;
450 Function *AsanRegisterGlobals;
451 Function *AsanUnregisterGlobals;
452 Function *AsanCovModuleInit;
455 // Stack poisoning does not play well with exception handling.
456 // When an exception is thrown, we essentially bypass the code
457 // that unpoisones the stack. This is why the run-time library has
458 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
459 // stack in the interceptor. This however does not work inside the
460 // actual function which catches the exception. Most likely because the
461 // compiler hoists the load of the shadow value somewhere too high.
462 // This causes asan to report a non-existing bug on 453.povray.
463 // It sounds like an LLVM bug.
464 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
466 AddressSanitizer &ASan;
471 ShadowMapping Mapping;
473 SmallVector<AllocaInst*, 16> AllocaVec;
474 SmallVector<Instruction*, 8> RetVec;
475 unsigned StackAlignment;
477 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
478 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
479 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
481 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
482 struct AllocaPoisonCall {
483 IntrinsicInst *InsBefore;
488 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
490 // Maps Value to an AllocaInst from which the Value is originated.
491 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
492 AllocaForValueMapTy AllocaForValue;
494 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
495 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
496 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
497 Mapping(ASan.Mapping),
498 StackAlignment(1 << Mapping.Scale) {}
500 bool runOnFunction() {
501 if (!ClStack) return false;
502 // Collect alloca, ret, lifetime instructions etc.
503 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
506 if (AllocaVec.empty()) return false;
508 initializeCallbacks(*F.getParent());
518 // Finds all static Alloca instructions and puts
519 // poisoned red zones around all of them.
520 // Then unpoison everything back before the function returns.
523 // ----------------------- Visitors.
524 /// \brief Collect all Ret instructions.
525 void visitReturnInst(ReturnInst &RI) {
526 RetVec.push_back(&RI);
529 /// \brief Collect Alloca instructions we want (and can) handle.
530 void visitAllocaInst(AllocaInst &AI) {
531 if (!isInterestingAlloca(AI)) return;
533 StackAlignment = std::max(StackAlignment, AI.getAlignment());
534 AllocaVec.push_back(&AI);
537 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
539 void visitIntrinsicInst(IntrinsicInst &II) {
540 if (!ClCheckLifetime) return;
541 Intrinsic::ID ID = II.getIntrinsicID();
542 if (ID != Intrinsic::lifetime_start &&
543 ID != Intrinsic::lifetime_end)
545 // Found lifetime intrinsic, add ASan instrumentation if necessary.
546 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
547 // If size argument is undefined, don't do anything.
548 if (Size->isMinusOne()) return;
549 // Check that size doesn't saturate uint64_t and can
550 // be stored in IntptrTy.
551 const uint64_t SizeValue = Size->getValue().getLimitedValue();
552 if (SizeValue == ~0ULL ||
553 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
555 // Find alloca instruction that corresponds to llvm.lifetime argument.
556 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
558 bool DoPoison = (ID == Intrinsic::lifetime_end);
559 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
560 AllocaPoisonCallVec.push_back(APC);
563 // ---------------------- Helpers.
564 void initializeCallbacks(Module &M);
566 // Check if we want (and can) handle this alloca.
567 bool isInterestingAlloca(AllocaInst &AI) const {
568 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
569 AI.getAllocatedType()->isSized() &&
570 // alloca() may be called with 0 size, ignore it.
571 getAllocaSizeInBytes(&AI) > 0);
574 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
575 Type *Ty = AI->getAllocatedType();
576 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
579 /// Finds alloca where the value comes from.
580 AllocaInst *findAllocaForValue(Value *V);
581 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
582 Value *ShadowBase, bool DoPoison);
583 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
585 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
591 char AddressSanitizer::ID = 0;
592 INITIALIZE_PASS(AddressSanitizer, "asan",
593 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
595 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
596 return new AddressSanitizer();
599 char AddressSanitizerModule::ID = 0;
600 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
601 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
602 "ModulePass", false, false)
603 ModulePass *llvm::createAddressSanitizerModulePass(StringRef BlacklistFile) {
604 return new AddressSanitizerModule(BlacklistFile);
607 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
608 size_t Res = countTrailingZeros(TypeSize / 8);
609 assert(Res < kNumberOfAccessSizes);
613 // \brief Create a constant for Str so that we can pass it to the run-time lib.
614 static GlobalVariable *createPrivateGlobalForString(
615 Module &M, StringRef Str, bool AllowMerging) {
616 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
617 // We use private linkage for module-local strings. If they can be merged
618 // with another one, we set the unnamed_addr attribute.
620 new GlobalVariable(M, StrConst->getType(), true,
621 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
623 GV->setUnnamedAddr(true);
624 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
628 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
629 return G->getName().find(kAsanGenPrefix) == 0;
632 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
634 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
635 if (Mapping.Offset == 0)
637 // (Shadow >> scale) | offset
638 if (Mapping.OrShadowOffset)
639 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
641 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
644 // Instrument memset/memmove/memcpy
645 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
647 if (isa<MemTransferInst>(MI)) {
649 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
650 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
651 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
652 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
653 } else if (isa<MemSetInst>(MI)) {
656 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
657 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
658 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
660 MI->eraseFromParent();
663 // If I is an interesting memory access, return the PointerOperand
664 // and set IsWrite/Alignment. Otherwise return NULL.
665 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
666 unsigned *Alignment) {
667 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
668 if (!ClInstrumentReads) return nullptr;
670 *Alignment = LI->getAlignment();
671 return LI->getPointerOperand();
673 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
674 if (!ClInstrumentWrites) return nullptr;
676 *Alignment = SI->getAlignment();
677 return SI->getPointerOperand();
679 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
680 if (!ClInstrumentAtomics) return nullptr;
683 return RMW->getPointerOperand();
685 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
686 if (!ClInstrumentAtomics) return nullptr;
689 return XCHG->getPointerOperand();
694 static bool isPointerOperand(Value *V) {
695 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
698 // This is a rough heuristic; it may cause both false positives and
699 // false negatives. The proper implementation requires cooperation with
701 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
702 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
703 if (!Cmp->isRelational())
705 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
706 if (BO->getOpcode() != Instruction::Sub)
711 if (!isPointerOperand(I->getOperand(0)) ||
712 !isPointerOperand(I->getOperand(1)))
717 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
718 // If a global variable does not have dynamic initialization we don't
719 // have to instrument it. However, if a global does not have initializer
720 // at all, we assume it has dynamic initializer (in other TU).
721 return G->hasInitializer() && !GlobalsMD.isDynInit(G);
725 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
727 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
728 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
729 for (int i = 0; i < 2; i++) {
730 if (Param[i]->getType()->isPointerTy())
731 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
733 IRB.CreateCall2(F, Param[0], Param[1]);
736 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
737 bool IsWrite = false;
738 unsigned Alignment = 0;
739 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
741 if (ClOpt && ClOptGlobals) {
742 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
743 // If initialization order checking is disabled, a simple access to a
744 // dynamically initialized global is always valid.
745 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
746 NumOptimizedAccessesToGlobalVar++;
750 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
751 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
752 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
753 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
754 NumOptimizedAccessesToGlobalArray++;
761 Type *OrigPtrTy = Addr->getType();
762 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
764 assert(OrigTy->isSized());
765 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
767 assert((TypeSize % 8) == 0);
770 NumInstrumentedWrites++;
772 NumInstrumentedReads++;
774 unsigned Granularity = 1 << Mapping.Scale;
775 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
776 // if the data is properly aligned.
777 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
779 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
780 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
781 // Instrument unusual size or unusual alignment.
782 // We can not do it with a single check, so we do 1-byte check for the first
783 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
784 // to report the actual access size.
786 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
787 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
789 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
791 Value *LastByte = IRB.CreateIntToPtr(
792 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
794 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
795 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
799 // Validate the result of Module::getOrInsertFunction called for an interface
800 // function of AddressSanitizer. If the instrumented module defines a function
801 // with the same name, their prototypes must match, otherwise
802 // getOrInsertFunction returns a bitcast.
803 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
804 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
805 FuncOrBitcast->dump();
806 report_fatal_error("trying to redefine an AddressSanitizer "
807 "interface function");
810 Instruction *AddressSanitizer::generateCrashCode(
811 Instruction *InsertBefore, Value *Addr,
812 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
813 IRBuilder<> IRB(InsertBefore);
814 CallInst *Call = SizeArgument
815 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
816 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
818 // We don't do Call->setDoesNotReturn() because the BB already has
819 // UnreachableInst at the end.
820 // This EmptyAsm is required to avoid callback merge.
821 IRB.CreateCall(EmptyAsm);
825 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
828 size_t Granularity = 1 << Mapping.Scale;
829 // Addr & (Granularity - 1)
830 Value *LastAccessedByte = IRB.CreateAnd(
831 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
832 // (Addr & (Granularity - 1)) + size - 1
833 if (TypeSize / 8 > 1)
834 LastAccessedByte = IRB.CreateAdd(
835 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
836 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
837 LastAccessedByte = IRB.CreateIntCast(
838 LastAccessedByte, ShadowValue->getType(), false);
839 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
840 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
843 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
844 Instruction *InsertBefore, Value *Addr,
845 uint32_t TypeSize, bool IsWrite,
846 Value *SizeArgument, bool UseCalls) {
847 IRBuilder<> IRB(InsertBefore);
848 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
849 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
852 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
857 Type *ShadowTy = IntegerType::get(
858 *C, std::max(8U, TypeSize >> Mapping.Scale));
859 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
860 Value *ShadowPtr = memToShadow(AddrLong, IRB);
861 Value *CmpVal = Constant::getNullValue(ShadowTy);
862 Value *ShadowValue = IRB.CreateLoad(
863 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
865 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
866 size_t Granularity = 1 << Mapping.Scale;
867 TerminatorInst *CrashTerm = nullptr;
869 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
870 TerminatorInst *CheckTerm =
871 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
872 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
873 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
874 IRB.SetInsertPoint(CheckTerm);
875 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
876 BasicBlock *CrashBlock =
877 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
878 CrashTerm = new UnreachableInst(*C, CrashBlock);
879 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
880 ReplaceInstWithInst(CheckTerm, NewTerm);
882 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
885 Instruction *Crash = generateCrashCode(
886 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
887 Crash->setDebugLoc(OrigIns->getDebugLoc());
890 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
891 GlobalValue *ModuleName) {
892 // Set up the arguments to our poison/unpoison functions.
893 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
895 // Add a call to poison all external globals before the given function starts.
896 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
897 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
899 // Add calls to unpoison all globals before each return instruction.
900 for (auto &BB : GlobalInit.getBasicBlockList())
901 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
902 CallInst::Create(AsanUnpoisonGlobals, "", RI);
905 void AddressSanitizerModule::createInitializerPoisonCalls(
906 Module &M, GlobalValue *ModuleName) {
907 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
909 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
910 for (Use &OP : CA->operands()) {
911 if (isa<ConstantAggregateZero>(OP))
913 ConstantStruct *CS = cast<ConstantStruct>(OP);
915 // Must have a function or null ptr.
916 // (CS->getOperand(0) is the init priority.)
917 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
918 if (F->getName() != kAsanModuleCtorName)
919 poisonOneInitializer(*F, ModuleName);
924 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
925 Type *Ty = cast<PointerType>(G->getType())->getElementType();
926 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
928 // FIXME: Don't use the blacklist here, all the data should be collected
929 // by the frontend and passed in globals metadata.
930 if (BL->isIn(*G)) return false;
931 if (GlobalsMD.isBlacklisted(G)) return false;
932 if (GlobalsMD.isSourceLocationGlobal(G)) return false;
933 if (!Ty->isSized()) return false;
934 if (!G->hasInitializer()) return false;
935 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
936 // Touch only those globals that will not be defined in other modules.
937 // Don't handle ODR type linkages since other modules may be built w/o asan.
938 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
939 G->getLinkage() != GlobalVariable::PrivateLinkage &&
940 G->getLinkage() != GlobalVariable::InternalLinkage)
942 // Two problems with thread-locals:
943 // - The address of the main thread's copy can't be computed at link-time.
944 // - Need to poison all copies, not just the main thread's one.
945 if (G->isThreadLocal())
947 // For now, just ignore this Global if the alignment is large.
948 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
950 // Ignore all the globals with the names starting with "\01L_OBJC_".
951 // Many of those are put into the .cstring section. The linker compresses
952 // that section by removing the spare \0s after the string terminator, so
953 // our redzones get broken.
954 if ((G->getName().find("\01L_OBJC_") == 0) ||
955 (G->getName().find("\01l_OBJC_") == 0)) {
956 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
960 if (G->hasSection()) {
961 StringRef Section(G->getSection());
962 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
963 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
965 if (Section.startswith("__OBJC,") ||
966 Section.startswith("__DATA, __objc_")) {
967 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
970 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
971 // Constant CFString instances are compiled in the following way:
972 // -- the string buffer is emitted into
973 // __TEXT,__cstring,cstring_literals
974 // -- the constant NSConstantString structure referencing that buffer
975 // is placed into __DATA,__cfstring
976 // Therefore there's no point in placing redzones into __DATA,__cfstring.
977 // Moreover, it causes the linker to crash on OS X 10.7
978 if (Section.startswith("__DATA,__cfstring")) {
979 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
982 // The linker merges the contents of cstring_literals and removes the
984 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
985 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
989 // Callbacks put into the CRT initializer/terminator sections
990 // should not be instrumented.
991 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
992 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
993 if (Section.startswith(".CRT")) {
994 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
998 // Globals from llvm.metadata aren't emitted, do not instrument them.
999 if (Section == "llvm.metadata") return false;
1005 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1006 IRBuilder<> IRB(*C);
1007 // Declare our poisoning and unpoisoning functions.
1008 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1009 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
1010 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1011 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1012 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
1013 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1014 // Declare functions that register/unregister globals.
1015 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1016 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1017 IntptrTy, IntptrTy, NULL));
1018 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1019 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1020 kAsanUnregisterGlobalsName,
1021 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1022 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1023 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
1024 kAsanCovModuleInitName,
1025 IRB.getVoidTy(), IntptrTy, NULL));
1026 AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
1029 // This function replaces all global variables with new variables that have
1030 // trailing redzones. It also creates a function that poisons
1031 // redzones and inserts this function into llvm.global_ctors.
1032 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1035 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1037 for (auto &G : M.globals()) {
1038 if (ShouldInstrumentGlobal(&G))
1039 GlobalsToChange.push_back(&G);
1042 size_t n = GlobalsToChange.size();
1043 if (n == 0) return false;
1045 // A global is described by a structure
1048 // size_t size_with_redzone;
1049 // const char *name;
1050 // const char *module_name;
1051 // size_t has_dynamic_init;
1052 // void *source_location;
1053 // We initialize an array of such structures and pass it to a run-time call.
1054 StructType *GlobalStructTy =
1055 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1056 IntptrTy, IntptrTy, NULL);
1057 SmallVector<Constant *, 16> Initializers(n);
1059 bool HasDynamicallyInitializedGlobals = false;
1061 // We shouldn't merge same module names, as this string serves as unique
1062 // module ID in runtime.
1063 GlobalVariable *ModuleName = createPrivateGlobalForString(
1064 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1066 for (size_t i = 0; i < n; i++) {
1067 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1068 GlobalVariable *G = GlobalsToChange[i];
1069 PointerType *PtrTy = cast<PointerType>(G->getType());
1070 Type *Ty = PtrTy->getElementType();
1071 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1072 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1073 // MinRZ <= RZ <= kMaxGlobalRedzone
1074 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1075 uint64_t RZ = std::max(MinRZ,
1076 std::min(kMaxGlobalRedzone,
1077 (SizeInBytes / MinRZ / 4) * MinRZ));
1078 uint64_t RightRedzoneSize = RZ;
1079 // Round up to MinRZ
1080 if (SizeInBytes % MinRZ)
1081 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1082 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1083 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1085 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1086 Constant *NewInitializer = ConstantStruct::get(
1087 NewTy, G->getInitializer(),
1088 Constant::getNullValue(RightRedZoneTy), NULL);
1090 GlobalVariable *Name =
1091 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1093 // Create a new global variable with enough space for a redzone.
1094 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1095 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1096 Linkage = GlobalValue::InternalLinkage;
1097 GlobalVariable *NewGlobal = new GlobalVariable(
1098 M, NewTy, G->isConstant(), Linkage,
1099 NewInitializer, "", G, G->getThreadLocalMode());
1100 NewGlobal->copyAttributesFrom(G);
1101 NewGlobal->setAlignment(MinRZ);
1104 Indices2[0] = IRB.getInt32(0);
1105 Indices2[1] = IRB.getInt32(0);
1107 G->replaceAllUsesWith(
1108 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1109 NewGlobal->takeName(G);
1110 G->eraseFromParent();
1112 bool GlobalHasDynamicInitializer = GlobalsMD.isDynInit(G);
1113 GlobalVariable *SourceLoc = GlobalsMD.getSourceLocation(G);
1115 Initializers[i] = ConstantStruct::get(
1116 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1117 ConstantInt::get(IntptrTy, SizeInBytes),
1118 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1119 ConstantExpr::getPointerCast(Name, IntptrTy),
1120 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1121 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1122 SourceLoc ? ConstantExpr::getPointerCast(SourceLoc, IntptrTy)
1123 : ConstantInt::get(IntptrTy, 0),
1126 if (ClInitializers && GlobalHasDynamicInitializer)
1127 HasDynamicallyInitializedGlobals = true;
1129 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1132 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1133 GlobalVariable *AllGlobals = new GlobalVariable(
1134 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1135 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1137 // Create calls for poisoning before initializers run and unpoisoning after.
1138 if (HasDynamicallyInitializedGlobals)
1139 createInitializerPoisonCalls(M, ModuleName);
1140 IRB.CreateCall2(AsanRegisterGlobals,
1141 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1142 ConstantInt::get(IntptrTy, n));
1144 // We also need to unregister globals at the end, e.g. when a shared library
1146 Function *AsanDtorFunction = Function::Create(
1147 FunctionType::get(Type::getVoidTy(*C), false),
1148 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1149 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1150 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1151 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1152 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1153 ConstantInt::get(IntptrTy, n));
1154 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1160 bool AddressSanitizerModule::runOnModule(Module &M) {
1161 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1164 DL = &DLP->getDataLayout();
1165 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1166 C = &(M.getContext());
1167 int LongSize = DL->getPointerSizeInBits();
1168 IntptrTy = Type::getIntNTy(*C, LongSize);
1169 Mapping = getShadowMapping(M, LongSize);
1170 initializeCallbacks(M);
1172 bool Changed = false;
1174 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1176 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1178 if (ClCoverage > 0) {
1179 Function *CovFunc = M.getFunction(kAsanCovName);
1180 int nCov = CovFunc ? CovFunc->getNumUses() : 0;
1181 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
1185 if (ClGlobals && !BL->isIn(M)) Changed |= InstrumentGlobals(IRB, M);
1190 void AddressSanitizer::initializeCallbacks(Module &M) {
1191 IRBuilder<> IRB(*C);
1192 // Create __asan_report* callbacks.
1193 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1194 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1195 AccessSizeIndex++) {
1196 // IsWrite and TypeSize are encoded in the function name.
1197 std::string Suffix =
1198 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1199 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1200 checkInterfaceFunction(
1201 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1202 IRB.getVoidTy(), IntptrTy, NULL));
1203 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1204 checkInterfaceFunction(
1205 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1206 IRB.getVoidTy(), IntptrTy, NULL));
1209 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1210 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1211 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1212 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1214 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1215 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1216 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1217 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1218 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1219 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1221 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1222 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1223 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1224 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1225 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1226 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1227 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1228 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1229 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1231 AsanHandleNoReturnFunc = checkInterfaceFunction(
1232 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1233 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1234 kAsanCovName, IRB.getVoidTy(), NULL));
1235 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1236 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1237 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1238 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1239 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1240 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1241 StringRef(""), StringRef(""),
1242 /*hasSideEffects=*/true);
1246 bool AddressSanitizer::doInitialization(Module &M) {
1247 // Initialize the private fields. No one has accessed them before.
1248 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1250 report_fatal_error("data layout missing");
1251 DL = &DLP->getDataLayout();
1255 C = &(M.getContext());
1256 LongSize = DL->getPointerSizeInBits();
1257 IntptrTy = Type::getIntNTy(*C, LongSize);
1259 AsanCtorFunction = Function::Create(
1260 FunctionType::get(Type::getVoidTy(*C), false),
1261 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1262 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1263 // call __asan_init in the module ctor.
1264 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1265 AsanInitFunction = checkInterfaceFunction(
1266 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1267 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1268 IRB.CreateCall(AsanInitFunction);
1270 Mapping = getShadowMapping(M, LongSize);
1272 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1276 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1277 // For each NSObject descendant having a +load method, this method is invoked
1278 // by the ObjC runtime before any of the static constructors is called.
1279 // Therefore we need to instrument such methods with a call to __asan_init
1280 // at the beginning in order to initialize our runtime before any access to
1281 // the shadow memory.
1282 // We cannot just ignore these methods, because they may call other
1283 // instrumented functions.
1284 if (F.getName().find(" load]") != std::string::npos) {
1285 IRBuilder<> IRB(F.begin()->begin());
1286 IRB.CreateCall(AsanInitFunction);
1292 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1293 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1294 // Skip static allocas at the top of the entry block so they don't become
1295 // dynamic when we split the block. If we used our optimized stack layout,
1296 // then there will only be one alloca and it will come first.
1297 for (; IP != BE; ++IP) {
1298 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1299 if (!AI || !AI->isStaticAlloca())
1303 DebugLoc EntryLoc = IP->getDebugLoc().getFnDebugLoc(*C);
1304 IRBuilder<> IRB(IP);
1305 IRB.SetCurrentDebugLocation(EntryLoc);
1306 Type *Int8Ty = IRB.getInt8Ty();
1307 GlobalVariable *Guard = new GlobalVariable(
1308 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1309 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1310 LoadInst *Load = IRB.CreateLoad(Guard);
1311 Load->setAtomic(Monotonic);
1312 Load->setAlignment(1);
1313 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1314 Instruction *Ins = SplitBlockAndInsertIfThen(
1315 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1316 IRB.SetInsertPoint(Ins);
1317 IRB.SetCurrentDebugLocation(EntryLoc);
1318 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1319 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1320 IRB.CreateCall(AsanCovFunction);
1321 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1322 Store->setAtomic(Monotonic);
1323 Store->setAlignment(1);
1326 // Poor man's coverage that works with ASan.
1327 // We create a Guard boolean variable with the same linkage
1328 // as the function and inject this code into the entry block (-asan-coverage=1)
1329 // or all blocks (-asan-coverage=2):
1331 // __sanitizer_cov(&F);
1334 // The accesses to Guard are atomic. The rest of the logic is
1335 // in __sanitizer_cov (it's fine to call it more than once).
1337 // This coverage implementation provides very limited data:
1338 // it only tells if a given function (block) was ever executed.
1339 // No counters, no per-edge data.
1340 // But for many use cases this is what we need and the added slowdown
1341 // is negligible. This simple implementation will probably be obsoleted
1342 // by the upcoming Clang-based coverage implementation.
1343 // By having it here and now we hope to
1344 // a) get the functionality to users earlier and
1345 // b) collect usage statistics to help improve Clang coverage design.
1346 bool AddressSanitizer::InjectCoverage(Function &F,
1347 const ArrayRef<BasicBlock *> AllBlocks) {
1348 if (!ClCoverage) return false;
1350 if (ClCoverage == 1 ||
1351 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1352 InjectCoverageAtBlock(F, F.getEntryBlock());
1354 for (auto BB : AllBlocks)
1355 InjectCoverageAtBlock(F, *BB);
1360 bool AddressSanitizer::runOnFunction(Function &F) {
1361 if (&F == AsanCtorFunction) return false;
1362 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1363 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1364 initializeCallbacks(*F.getParent());
1366 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1367 maybeInsertAsanInitAtFunctionEntry(F);
1369 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1372 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1375 // We want to instrument every address only once per basic block (unless there
1376 // are calls between uses).
1377 SmallSet<Value*, 16> TempsToInstrument;
1378 SmallVector<Instruction*, 16> ToInstrument;
1379 SmallVector<Instruction*, 8> NoReturnCalls;
1380 SmallVector<BasicBlock*, 16> AllBlocks;
1381 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1386 // Fill the set of memory operations to instrument.
1387 for (auto &BB : F) {
1388 AllBlocks.push_back(&BB);
1389 TempsToInstrument.clear();
1390 int NumInsnsPerBB = 0;
1391 for (auto &Inst : BB) {
1392 if (LooksLikeCodeInBug11395(&Inst)) return false;
1394 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1395 if (ClOpt && ClOptSameTemp) {
1396 if (!TempsToInstrument.insert(Addr))
1397 continue; // We've seen this temp in the current BB.
1399 } else if (ClInvalidPointerPairs &&
1400 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1401 PointerComparisonsOrSubtracts.push_back(&Inst);
1403 } else if (isa<MemIntrinsic>(Inst)) {
1406 if (isa<AllocaInst>(Inst))
1410 // A call inside BB.
1411 TempsToInstrument.clear();
1412 if (CS.doesNotReturn())
1413 NoReturnCalls.push_back(CS.getInstruction());
1417 ToInstrument.push_back(&Inst);
1419 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1424 Function *UninstrumentedDuplicate = nullptr;
1425 bool LikelyToInstrument =
1426 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1427 if (ClKeepUninstrumented && LikelyToInstrument) {
1428 ValueToValueMapTy VMap;
1429 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1430 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1431 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1432 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1435 bool UseCalls = false;
1436 if (ClInstrumentationWithCallsThreshold >= 0 &&
1437 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1441 int NumInstrumented = 0;
1442 for (auto Inst : ToInstrument) {
1443 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1444 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1445 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1446 instrumentMop(Inst, UseCalls);
1448 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1453 FunctionStackPoisoner FSP(F, *this);
1454 bool ChangedStack = FSP.runOnFunction();
1456 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1457 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1458 for (auto CI : NoReturnCalls) {
1459 IRBuilder<> IRB(CI);
1460 IRB.CreateCall(AsanHandleNoReturnFunc);
1463 for (auto Inst : PointerComparisonsOrSubtracts) {
1464 instrumentPointerComparisonOrSubtraction(Inst);
1468 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1470 if (InjectCoverage(F, AllBlocks))
1473 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1475 if (ClKeepUninstrumented) {
1477 // No instrumentation is done, no need for the duplicate.
1478 if (UninstrumentedDuplicate)
1479 UninstrumentedDuplicate->eraseFromParent();
1481 // The function was instrumented. We must have the duplicate.
1482 assert(UninstrumentedDuplicate);
1483 UninstrumentedDuplicate->setSection("NOASAN");
1484 assert(!F.hasSection());
1485 F.setSection("ASAN");
1492 // Workaround for bug 11395: we don't want to instrument stack in functions
1493 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1494 // FIXME: remove once the bug 11395 is fixed.
1495 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1496 if (LongSize != 32) return false;
1497 CallInst *CI = dyn_cast<CallInst>(I);
1498 if (!CI || !CI->isInlineAsm()) return false;
1499 if (CI->getNumArgOperands() <= 5) return false;
1500 // We have inline assembly with quite a few arguments.
1504 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1505 IRBuilder<> IRB(*C);
1506 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1507 std::string Suffix = itostr(i);
1508 AsanStackMallocFunc[i] = checkInterfaceFunction(
1509 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1510 IntptrTy, IntptrTy, NULL));
1511 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1512 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1513 IntptrTy, IntptrTy, NULL));
1515 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1516 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1517 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1518 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1522 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1523 IRBuilder<> &IRB, Value *ShadowBase,
1525 size_t n = ShadowBytes.size();
1527 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1528 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1529 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1530 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1531 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1532 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1534 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1535 if (ASan.DL->isLittleEndian())
1536 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1538 Val = (Val << 8) | ShadowBytes[i + j];
1541 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1542 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1543 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1544 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1549 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1550 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1551 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1552 assert(LocalStackSize <= kMaxStackMallocSize);
1553 uint64_t MaxSize = kMinStackMallocSize;
1554 for (int i = 0; ; i++, MaxSize *= 2)
1555 if (LocalStackSize <= MaxSize)
1557 llvm_unreachable("impossible LocalStackSize");
1560 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1561 // We can not use MemSet intrinsic because it may end up calling the actual
1562 // memset. Size is a multiple of 8.
1563 // Currently this generates 8-byte stores on x86_64; it may be better to
1564 // generate wider stores.
1565 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1566 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1567 assert(!(Size % 8));
1568 assert(kAsanStackAfterReturnMagic == 0xf5);
1569 for (int i = 0; i < Size; i += 8) {
1570 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1571 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1572 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1576 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1577 for (const auto &Inst : F.getEntryBlock())
1578 if (!isa<AllocaInst>(Inst))
1579 return Inst.getDebugLoc();
1583 void FunctionStackPoisoner::poisonStack() {
1584 int StackMallocIdx = -1;
1585 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1587 assert(AllocaVec.size() > 0);
1588 Instruction *InsBefore = AllocaVec[0];
1589 IRBuilder<> IRB(InsBefore);
1590 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1592 SmallVector<ASanStackVariableDescription, 16> SVD;
1593 SVD.reserve(AllocaVec.size());
1594 for (AllocaInst *AI : AllocaVec) {
1595 ASanStackVariableDescription D = { AI->getName().data(),
1596 getAllocaSizeInBytes(AI),
1597 AI->getAlignment(), AI, 0};
1600 // Minimal header size (left redzone) is 4 pointers,
1601 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1602 size_t MinHeaderSize = ASan.LongSize / 2;
1603 ASanStackFrameLayout L;
1604 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1605 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1606 uint64_t LocalStackSize = L.FrameSize;
1607 bool DoStackMalloc =
1608 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1610 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1611 AllocaInst *MyAlloca =
1612 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1613 MyAlloca->setDebugLoc(EntryDebugLocation);
1614 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1615 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1616 MyAlloca->setAlignment(FrameAlignment);
1617 assert(MyAlloca->isStaticAlloca());
1618 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1619 Value *LocalStackBase = OrigStackBase;
1621 if (DoStackMalloc) {
1622 // LocalStackBase = OrigStackBase
1623 // if (__asan_option_detect_stack_use_after_return)
1624 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1625 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1626 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1627 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1628 kAsanOptionDetectUAR, IRB.getInt32Ty());
1629 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1630 Constant::getNullValue(IRB.getInt32Ty()));
1631 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1632 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1633 IRBuilder<> IRBIf(Term);
1634 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1635 LocalStackBase = IRBIf.CreateCall2(
1636 AsanStackMallocFunc[StackMallocIdx],
1637 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1638 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1639 IRB.SetInsertPoint(InsBefore);
1640 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1641 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1642 Phi->addIncoming(OrigStackBase, CmpBlock);
1643 Phi->addIncoming(LocalStackBase, SetBlock);
1644 LocalStackBase = Phi;
1647 // Insert poison calls for lifetime intrinsics for alloca.
1648 bool HavePoisonedAllocas = false;
1649 for (const auto &APC : AllocaPoisonCallVec) {
1650 assert(APC.InsBefore);
1652 IRBuilder<> IRB(APC.InsBefore);
1653 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1654 HavePoisonedAllocas |= APC.DoPoison;
1657 // Replace Alloca instructions with base+offset.
1658 for (const auto &Desc : SVD) {
1659 AllocaInst *AI = Desc.AI;
1660 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1661 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1663 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1664 AI->replaceAllUsesWith(NewAllocaPtr);
1667 // The left-most redzone has enough space for at least 4 pointers.
1668 // Write the Magic value to redzone[0].
1669 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1670 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1672 // Write the frame description constant to redzone[1].
1673 Value *BasePlus1 = IRB.CreateIntToPtr(
1674 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1676 GlobalVariable *StackDescriptionGlobal =
1677 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1678 /*AllowMerging*/true);
1679 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1681 IRB.CreateStore(Description, BasePlus1);
1682 // Write the PC to redzone[2].
1683 Value *BasePlus2 = IRB.CreateIntToPtr(
1684 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1685 2 * ASan.LongSize/8)),
1687 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1689 // Poison the stack redzones at the entry.
1690 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1691 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1693 // (Un)poison the stack before all ret instructions.
1694 for (auto Ret : RetVec) {
1695 IRBuilder<> IRBRet(Ret);
1696 // Mark the current frame as retired.
1697 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1699 if (DoStackMalloc) {
1700 assert(StackMallocIdx >= 0);
1701 // if LocalStackBase != OrigStackBase:
1702 // // In use-after-return mode, poison the whole stack frame.
1703 // if StackMallocIdx <= 4
1704 // // For small sizes inline the whole thing:
1705 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1706 // **SavedFlagPtr(LocalStackBase) = 0
1708 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1710 // <This is not a fake stack; unpoison the redzones>
1711 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1712 TerminatorInst *ThenTerm, *ElseTerm;
1713 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1715 IRBuilder<> IRBPoison(ThenTerm);
1716 if (StackMallocIdx <= 4) {
1717 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1718 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1719 ClassSize >> Mapping.Scale);
1720 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1722 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1723 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1724 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1725 IRBPoison.CreateStore(
1726 Constant::getNullValue(IRBPoison.getInt8Ty()),
1727 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1729 // For larger frames call __asan_stack_free_*.
1730 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1731 ConstantInt::get(IntptrTy, LocalStackSize),
1735 IRBuilder<> IRBElse(ElseTerm);
1736 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1737 } else if (HavePoisonedAllocas) {
1738 // If we poisoned some allocas in llvm.lifetime analysis,
1739 // unpoison whole stack frame now.
1740 assert(LocalStackBase == OrigStackBase);
1741 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1743 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1747 // We are done. Remove the old unused alloca instructions.
1748 for (auto AI : AllocaVec)
1749 AI->eraseFromParent();
1752 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1753 IRBuilder<> &IRB, bool DoPoison) {
1754 // For now just insert the call to ASan runtime.
1755 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1756 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1757 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1758 : AsanUnpoisonStackMemoryFunc,
1762 // Handling llvm.lifetime intrinsics for a given %alloca:
1763 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1764 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1765 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1766 // could be poisoned by previous llvm.lifetime.end instruction, as the
1767 // variable may go in and out of scope several times, e.g. in loops).
1768 // (3) if we poisoned at least one %alloca in a function,
1769 // unpoison the whole stack frame at function exit.
1771 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1772 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1773 // We're intested only in allocas we can handle.
1774 return isInterestingAlloca(*AI) ? AI : nullptr;
1775 // See if we've already calculated (or started to calculate) alloca for a
1777 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1778 if (I != AllocaForValue.end())
1780 // Store 0 while we're calculating alloca for value V to avoid
1781 // infinite recursion if the value references itself.
1782 AllocaForValue[V] = nullptr;
1783 AllocaInst *Res = nullptr;
1784 if (CastInst *CI = dyn_cast<CastInst>(V))
1785 Res = findAllocaForValue(CI->getOperand(0));
1786 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1787 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1788 Value *IncValue = PN->getIncomingValue(i);
1789 // Allow self-referencing phi-nodes.
1790 if (IncValue == PN) continue;
1791 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1792 // AI for incoming values should exist and should all be equal.
1793 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1799 AllocaForValue[V] = Res;