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/Analysis/MemoryBuiltins.h"
28 #include "llvm/Analysis/TargetLibraryInfo.h"
29 #include "llvm/Analysis/ValueTracking.h"
30 #include "llvm/IR/CallSite.h"
31 #include "llvm/IR/DIBuilder.h"
32 #include "llvm/IR/DataLayout.h"
33 #include "llvm/IR/Dominators.h"
34 #include "llvm/IR/Function.h"
35 #include "llvm/IR/IRBuilder.h"
36 #include "llvm/IR/InlineAsm.h"
37 #include "llvm/IR/InstVisitor.h"
38 #include "llvm/IR/IntrinsicInst.h"
39 #include "llvm/IR/LLVMContext.h"
40 #include "llvm/IR/MDBuilder.h"
41 #include "llvm/IR/Module.h"
42 #include "llvm/IR/Type.h"
43 #include "llvm/MC/MCSectionMachO.h"
44 #include "llvm/Support/CommandLine.h"
45 #include "llvm/Support/DataTypes.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/Endian.h"
48 #include "llvm/Support/SwapByteOrder.h"
49 #include "llvm/Support/raw_ostream.h"
50 #include "llvm/Transforms/Scalar.h"
51 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
52 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
53 #include "llvm/Transforms/Utils/Cloning.h"
54 #include "llvm/Transforms/Utils/Local.h"
55 #include "llvm/Transforms/Utils/ModuleUtils.h"
56 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
59 #include <system_error>
63 #define DEBUG_TYPE "asan"
65 static const uint64_t kDefaultShadowScale = 3;
66 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
67 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
68 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
69 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
70 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
71 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
72 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
73 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
74 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
75 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
76 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
77 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
79 static const size_t kMinStackMallocSize = 1 << 6; // 64B
80 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
81 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
82 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
84 static const char *const kAsanModuleCtorName = "asan.module_ctor";
85 static const char *const kAsanModuleDtorName = "asan.module_dtor";
86 static const uint64_t kAsanCtorAndDtorPriority = 1;
87 static const char *const kAsanReportErrorTemplate = "__asan_report_";
88 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
89 static const char *const kAsanUnregisterGlobalsName =
90 "__asan_unregister_globals";
91 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
92 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
93 static const char *const kAsanInitName = "__asan_init_v5";
94 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
95 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
96 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
97 static const int kMaxAsanStackMallocSizeClass = 10;
98 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
99 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
100 static const char *const kAsanGenPrefix = "__asan_gen_";
101 static const char *const kSanCovGenPrefix = "__sancov_gen_";
102 static const char *const kAsanPoisonStackMemoryName =
103 "__asan_poison_stack_memory";
104 static const char *const kAsanUnpoisonStackMemoryName =
105 "__asan_unpoison_stack_memory";
107 static const char *const kAsanOptionDetectUAR =
108 "__asan_option_detect_stack_use_after_return";
110 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
111 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
113 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
114 static const size_t kNumberOfAccessSizes = 5;
116 static const unsigned kAllocaRzSize = 32;
118 // Command-line flags.
119 static cl::opt<bool> ClEnableKasan(
120 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
121 cl::Hidden, cl::init(false));
123 // This flag may need to be replaced with -f[no-]asan-reads.
124 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
125 cl::desc("instrument read instructions"),
126 cl::Hidden, cl::init(true));
127 static cl::opt<bool> ClInstrumentWrites(
128 "asan-instrument-writes", cl::desc("instrument write instructions"),
129 cl::Hidden, cl::init(true));
130 static cl::opt<bool> ClInstrumentAtomics(
131 "asan-instrument-atomics",
132 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
134 static cl::opt<bool> ClAlwaysSlowPath(
135 "asan-always-slow-path",
136 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
138 // This flag limits the number of instructions to be instrumented
139 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
140 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
142 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
143 "asan-max-ins-per-bb", cl::init(10000),
144 cl::desc("maximal number of instructions to instrument in any given BB"),
146 // This flag may need to be replaced with -f[no]asan-stack.
147 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
148 cl::Hidden, cl::init(true));
149 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
150 cl::desc("Check return-after-free"),
151 cl::Hidden, cl::init(true));
152 // This flag may need to be replaced with -f[no]asan-globals.
153 static cl::opt<bool> ClGlobals("asan-globals",
154 cl::desc("Handle global objects"), cl::Hidden,
156 static cl::opt<bool> ClInitializers("asan-initialization-order",
157 cl::desc("Handle C++ initializer order"),
158 cl::Hidden, cl::init(true));
159 static cl::opt<bool> ClInvalidPointerPairs(
160 "asan-detect-invalid-pointer-pair",
161 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
163 static cl::opt<unsigned> ClRealignStack(
164 "asan-realign-stack",
165 cl::desc("Realign stack to the value of this flag (power of two)"),
166 cl::Hidden, cl::init(32));
167 static cl::opt<int> ClInstrumentationWithCallsThreshold(
168 "asan-instrumentation-with-call-threshold",
170 "If the function being instrumented contains more than "
171 "this number of memory accesses, use callbacks instead of "
172 "inline checks (-1 means never use callbacks)."),
173 cl::Hidden, cl::init(7000));
174 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
175 "asan-memory-access-callback-prefix",
176 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
177 cl::init("__asan_"));
178 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
179 cl::desc("instrument dynamic allocas"),
180 cl::Hidden, cl::init(false));
181 static cl::opt<bool> ClSkipPromotableAllocas(
182 "asan-skip-promotable-allocas",
183 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
186 // These flags allow to change the shadow mapping.
187 // The shadow mapping looks like
188 // Shadow = (Mem >> scale) + (1 << offset_log)
189 static cl::opt<int> ClMappingScale("asan-mapping-scale",
190 cl::desc("scale of asan shadow mapping"),
191 cl::Hidden, cl::init(0));
193 // Optimization flags. Not user visible, used mostly for testing
194 // and benchmarking the tool.
195 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
196 cl::Hidden, cl::init(true));
197 static cl::opt<bool> ClOptSameTemp(
198 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
199 cl::Hidden, cl::init(true));
200 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
201 cl::desc("Don't instrument scalar globals"),
202 cl::Hidden, cl::init(true));
203 static cl::opt<bool> ClOptStack(
204 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
205 cl::Hidden, cl::init(false));
207 static cl::opt<bool> ClCheckLifetime(
208 "asan-check-lifetime",
209 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
212 static cl::opt<bool> ClDynamicAllocaStack(
213 "asan-stack-dynamic-alloca",
214 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
217 static cl::opt<uint32_t> ClForceExperiment(
218 "asan-force-experiment",
219 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
223 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
225 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
226 cl::Hidden, cl::init(0));
227 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
228 cl::desc("Debug func"));
229 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
230 cl::Hidden, cl::init(-1));
231 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
232 cl::Hidden, cl::init(-1));
234 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
235 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
236 STATISTIC(NumOptimizedAccessesToGlobalVar,
237 "Number of optimized accesses to global vars");
238 STATISTIC(NumOptimizedAccessesToStackVar,
239 "Number of optimized accesses to stack vars");
242 /// Frontend-provided metadata for source location.
243 struct LocationMetadata {
248 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
250 bool empty() const { return Filename.empty(); }
252 void parse(MDNode *MDN) {
253 assert(MDN->getNumOperands() == 3);
254 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
255 Filename = DIFilename->getString();
257 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
259 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
263 /// Frontend-provided metadata for global variables.
264 class GlobalsMetadata {
267 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
268 LocationMetadata SourceLoc;
274 GlobalsMetadata() : inited_(false) {}
276 void init(Module &M) {
279 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
280 if (!Globals) return;
281 for (auto MDN : Globals->operands()) {
282 // Metadata node contains the global and the fields of "Entry".
283 assert(MDN->getNumOperands() == 5);
284 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
285 // The optimizer may optimize away a global entirely.
287 // We can already have an entry for GV if it was merged with another
289 Entry &E = Entries[GV];
290 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
291 E.SourceLoc.parse(Loc);
292 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
293 E.Name = Name->getString();
294 ConstantInt *IsDynInit =
295 mdconst::extract<ConstantInt>(MDN->getOperand(3));
296 E.IsDynInit |= IsDynInit->isOne();
297 ConstantInt *IsBlacklisted =
298 mdconst::extract<ConstantInt>(MDN->getOperand(4));
299 E.IsBlacklisted |= IsBlacklisted->isOne();
303 /// Returns metadata entry for a given global.
304 Entry get(GlobalVariable *G) const {
305 auto Pos = Entries.find(G);
306 return (Pos != Entries.end()) ? Pos->second : Entry();
311 DenseMap<GlobalVariable *, Entry> Entries;
314 /// This struct defines the shadow mapping using the rule:
315 /// shadow = (mem >> Scale) ADD-or-OR Offset.
316 struct ShadowMapping {
322 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
324 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
325 bool IsIOS = TargetTriple.isiOS();
326 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
327 bool IsLinux = TargetTriple.isOSLinux();
328 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
329 TargetTriple.getArch() == llvm::Triple::ppc64le;
330 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
331 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
332 TargetTriple.getArch() == llvm::Triple::mipsel;
333 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
334 TargetTriple.getArch() == llvm::Triple::mips64el;
335 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
336 bool IsWindows = TargetTriple.isOSWindows();
338 ShadowMapping Mapping;
340 if (LongSize == 32) {
344 Mapping.Offset = kMIPS32_ShadowOffset32;
346 Mapping.Offset = kFreeBSD_ShadowOffset32;
348 Mapping.Offset = kIOSShadowOffset32;
350 Mapping.Offset = kWindowsShadowOffset32;
352 Mapping.Offset = kDefaultShadowOffset32;
353 } else { // LongSize == 64
355 Mapping.Offset = kPPC64_ShadowOffset64;
357 Mapping.Offset = kFreeBSD_ShadowOffset64;
358 else if (IsLinux && IsX86_64) {
360 Mapping.Offset = kLinuxKasan_ShadowOffset64;
362 Mapping.Offset = kSmallX86_64ShadowOffset;
364 Mapping.Offset = kMIPS64_ShadowOffset64;
366 Mapping.Offset = kAArch64_ShadowOffset64;
368 Mapping.Offset = kDefaultShadowOffset64;
371 Mapping.Scale = kDefaultShadowScale;
372 if (ClMappingScale) {
373 Mapping.Scale = ClMappingScale;
376 // OR-ing shadow offset if more efficient (at least on x86) if the offset
377 // is a power of two, but on ppc64 we have to use add since the shadow
378 // offset is not necessary 1/8-th of the address space.
379 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
384 static size_t RedzoneSizeForScale(int MappingScale) {
385 // Redzone used for stack and globals is at least 32 bytes.
386 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
387 return std::max(32U, 1U << MappingScale);
390 /// AddressSanitizer: instrument the code in module to find memory bugs.
391 struct AddressSanitizer : public FunctionPass {
392 explicit AddressSanitizer(bool CompileKernel = false)
393 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) {
394 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
396 const char *getPassName() const override {
397 return "AddressSanitizerFunctionPass";
399 void getAnalysisUsage(AnalysisUsage &AU) const override {
400 AU.addRequired<DominatorTreeWrapperPass>();
401 AU.addRequired<TargetLibraryInfoWrapperPass>();
403 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
404 Type *Ty = AI->getAllocatedType();
405 uint64_t SizeInBytes =
406 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
409 /// Check if we want (and can) handle this alloca.
410 bool isInterestingAlloca(AllocaInst &AI);
412 // Check if we have dynamic alloca.
413 bool isDynamicAlloca(AllocaInst &AI) const {
414 return AI.isArrayAllocation() || !AI.isStaticAlloca();
417 /// If it is an interesting memory access, return the PointerOperand
418 /// and set IsWrite/Alignment. Otherwise return nullptr.
419 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
420 uint64_t *TypeSize, unsigned *Alignment);
421 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
422 bool UseCalls, const DataLayout &DL);
423 void instrumentPointerComparisonOrSubtraction(Instruction *I);
424 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
425 Value *Addr, uint32_t TypeSize, bool IsWrite,
426 Value *SizeArgument, bool UseCalls, uint32_t Exp);
427 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
428 uint32_t TypeSize, bool IsWrite,
429 Value *SizeArgument, bool UseCalls,
431 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
432 Value *ShadowValue, uint32_t TypeSize);
433 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
434 bool IsWrite, size_t AccessSizeIndex,
435 Value *SizeArgument, uint32_t Exp);
436 void instrumentMemIntrinsic(MemIntrinsic *MI);
437 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
438 bool runOnFunction(Function &F) override;
439 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
440 bool doInitialization(Module &M) override;
441 static char ID; // Pass identification, replacement for typeid
443 DominatorTree &getDominatorTree() const { return *DT; }
446 void initializeCallbacks(Module &M);
448 bool LooksLikeCodeInBug11395(Instruction *I);
449 bool GlobalIsLinkerInitialized(GlobalVariable *G);
450 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
451 uint64_t TypeSize) const;
458 ShadowMapping Mapping;
460 Function *AsanCtorFunction = nullptr;
461 Function *AsanInitFunction = nullptr;
462 Function *AsanHandleNoReturnFunc;
463 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
464 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
465 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
466 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
467 // This array is indexed by AccessIsWrite and Experiment.
468 Function *AsanErrorCallbackSized[2][2];
469 Function *AsanMemoryAccessCallbackSized[2][2];
470 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
472 GlobalsMetadata GlobalsMD;
473 DenseMap<AllocaInst *, bool> ProcessedAllocas;
475 friend struct FunctionStackPoisoner;
478 class AddressSanitizerModule : public ModulePass {
480 explicit AddressSanitizerModule(bool CompileKernel = false)
481 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {}
482 bool runOnModule(Module &M) override;
483 static char ID; // Pass identification, replacement for typeid
484 const char *getPassName() const override { return "AddressSanitizerModule"; }
487 void initializeCallbacks(Module &M);
489 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
490 bool ShouldInstrumentGlobal(GlobalVariable *G);
491 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
492 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
493 size_t MinRedzoneSizeForGlobal() const {
494 return RedzoneSizeForScale(Mapping.Scale);
497 GlobalsMetadata GlobalsMD;
502 ShadowMapping Mapping;
503 Function *AsanPoisonGlobals;
504 Function *AsanUnpoisonGlobals;
505 Function *AsanRegisterGlobals;
506 Function *AsanUnregisterGlobals;
509 // Stack poisoning does not play well with exception handling.
510 // When an exception is thrown, we essentially bypass the code
511 // that unpoisones the stack. This is why the run-time library has
512 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
513 // stack in the interceptor. This however does not work inside the
514 // actual function which catches the exception. Most likely because the
515 // compiler hoists the load of the shadow value somewhere too high.
516 // This causes asan to report a non-existing bug on 453.povray.
517 // It sounds like an LLVM bug.
518 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
520 AddressSanitizer &ASan;
525 ShadowMapping Mapping;
527 SmallVector<AllocaInst *, 16> AllocaVec;
528 SmallVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
529 SmallVector<Instruction *, 8> RetVec;
530 unsigned StackAlignment;
532 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
533 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
534 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
535 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
537 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
538 struct AllocaPoisonCall {
539 IntrinsicInst *InsBefore;
544 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
546 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
547 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
548 AllocaInst *DynamicAllocaLayout = nullptr;
550 // Maps Value to an AllocaInst from which the Value is originated.
551 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
552 AllocaForValueMapTy AllocaForValue;
554 bool HasNonEmptyInlineAsm;
555 std::unique_ptr<CallInst> EmptyInlineAsm;
557 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
560 DIB(*F.getParent(), /*AllowUnresolved*/ false),
562 IntptrTy(ASan.IntptrTy),
563 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
564 Mapping(ASan.Mapping),
565 StackAlignment(1 << Mapping.Scale),
566 HasNonEmptyInlineAsm(false),
567 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
569 bool runOnFunction() {
570 if (!ClStack) return false;
571 // Collect alloca, ret, lifetime instructions etc.
572 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
574 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
576 initializeCallbacks(*F.getParent());
586 // Finds all Alloca instructions and puts
587 // poisoned red zones around all of them.
588 // Then unpoison everything back before the function returns.
591 void createDynamicAllocasInitStorage();
593 // ----------------------- Visitors.
594 /// \brief Collect all Ret instructions.
595 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
597 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
599 IRBuilder<> IRB(InstBefore);
600 IRB.CreateCall(AsanAllocasUnpoisonFunc,
601 {IRB.CreateLoad(DynamicAllocaLayout),
602 IRB.CreatePtrToInt(SavedStack, IntptrTy)});
605 // Unpoison dynamic allocas redzones.
606 void unpoisonDynamicAllocas() {
607 for (auto &Ret : RetVec)
608 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
610 for (auto &StackRestoreInst : StackRestoreVec)
611 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
612 StackRestoreInst->getOperand(0));
615 // Deploy and poison redzones around dynamic alloca call. To do this, we
616 // should replace this call with another one with changed parameters and
617 // replace all its uses with new address, so
618 // addr = alloca type, old_size, align
620 // new_size = (old_size + additional_size) * sizeof(type)
621 // tmp = alloca i8, new_size, max(align, 32)
622 // addr = tmp + 32 (first 32 bytes are for the left redzone).
623 // Additional_size is added to make new memory allocation contain not only
624 // requested memory, but also left, partial and right redzones.
625 void handleDynamicAllocaCall(AllocaInst *AI);
627 /// \brief Collect Alloca instructions we want (and can) handle.
628 void visitAllocaInst(AllocaInst &AI) {
629 if (!ASan.isInterestingAlloca(AI)) {
630 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.push_back(&AI);
634 StackAlignment = std::max(StackAlignment, AI.getAlignment());
635 if (ASan.isDynamicAlloca(AI))
636 DynamicAllocaVec.push_back(&AI);
638 AllocaVec.push_back(&AI);
641 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
643 void visitIntrinsicInst(IntrinsicInst &II) {
644 Intrinsic::ID ID = II.getIntrinsicID();
645 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
646 if (!ClCheckLifetime) return;
647 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
649 // Found lifetime intrinsic, add ASan instrumentation if necessary.
650 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
651 // If size argument is undefined, don't do anything.
652 if (Size->isMinusOne()) return;
653 // Check that size doesn't saturate uint64_t and can
654 // be stored in IntptrTy.
655 const uint64_t SizeValue = Size->getValue().getLimitedValue();
656 if (SizeValue == ~0ULL ||
657 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
659 // Find alloca instruction that corresponds to llvm.lifetime argument.
660 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
662 bool DoPoison = (ID == Intrinsic::lifetime_end);
663 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
664 AllocaPoisonCallVec.push_back(APC);
667 void visitCallInst(CallInst &CI) {
668 HasNonEmptyInlineAsm |=
669 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
672 // ---------------------- Helpers.
673 void initializeCallbacks(Module &M);
675 bool doesDominateAllExits(const Instruction *I) const {
676 for (auto Ret : RetVec) {
677 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
682 /// Finds alloca where the value comes from.
683 AllocaInst *findAllocaForValue(Value *V);
684 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
685 Value *ShadowBase, bool DoPoison);
686 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
688 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
690 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
692 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
693 Instruction *ThenTerm, Value *ValueIfFalse);
698 char AddressSanitizer::ID = 0;
699 INITIALIZE_PASS_BEGIN(
700 AddressSanitizer, "asan",
701 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
703 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
705 AddressSanitizer, "asan",
706 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
708 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
709 return new AddressSanitizer(CompileKernel);
712 char AddressSanitizerModule::ID = 0;
714 AddressSanitizerModule, "asan-module",
715 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
718 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
719 return new AddressSanitizerModule(CompileKernel);
722 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
723 size_t Res = countTrailingZeros(TypeSize / 8);
724 assert(Res < kNumberOfAccessSizes);
728 // \brief Create a constant for Str so that we can pass it to the run-time lib.
729 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
731 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
732 // We use private linkage for module-local strings. If they can be merged
733 // with another one, we set the unnamed_addr attribute.
735 new GlobalVariable(M, StrConst->getType(), true,
736 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
737 if (AllowMerging) GV->setUnnamedAddr(true);
738 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
742 /// \brief Create a global describing a source location.
743 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
744 LocationMetadata MD) {
745 Constant *LocData[] = {
746 createPrivateGlobalForString(M, MD.Filename, true),
747 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
748 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
750 auto LocStruct = ConstantStruct::getAnon(LocData);
751 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
752 GlobalValue::PrivateLinkage, LocStruct,
754 GV->setUnnamedAddr(true);
758 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
759 return G->getName().find(kAsanGenPrefix) == 0 ||
760 G->getName().find(kSanCovGenPrefix) == 0;
763 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
765 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
766 if (Mapping.Offset == 0) return Shadow;
767 // (Shadow >> scale) | offset
768 if (Mapping.OrShadowOffset)
769 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
771 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
774 // Instrument memset/memmove/memcpy
775 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
777 if (isa<MemTransferInst>(MI)) {
779 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
780 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
781 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
782 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
783 } else if (isa<MemSetInst>(MI)) {
786 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
787 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
788 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
790 MI->eraseFromParent();
793 /// Check if we want (and can) handle this alloca.
794 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
795 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
797 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
798 return PreviouslySeenAllocaInfo->getSecond();
801 (AI.getAllocatedType()->isSized() &&
802 // alloca() may be called with 0 size, ignore it.
803 getAllocaSizeInBytes(&AI) > 0 &&
804 // We are only interested in allocas not promotable to registers.
805 // Promotable allocas are common under -O0.
806 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI) ||
807 isDynamicAlloca(AI)));
809 ProcessedAllocas[&AI] = IsInteresting;
810 return IsInteresting;
813 /// If I is an interesting memory access, return the PointerOperand
814 /// and set IsWrite/Alignment. Otherwise return nullptr.
815 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
818 unsigned *Alignment) {
819 // Skip memory accesses inserted by another instrumentation.
820 if (I->getMetadata("nosanitize")) return nullptr;
822 Value *PtrOperand = nullptr;
823 const DataLayout &DL = I->getModule()->getDataLayout();
824 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
825 if (!ClInstrumentReads) return nullptr;
827 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
828 *Alignment = LI->getAlignment();
829 PtrOperand = LI->getPointerOperand();
830 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
831 if (!ClInstrumentWrites) return nullptr;
833 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
834 *Alignment = SI->getAlignment();
835 PtrOperand = SI->getPointerOperand();
836 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
837 if (!ClInstrumentAtomics) return nullptr;
839 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
841 PtrOperand = RMW->getPointerOperand();
842 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
843 if (!ClInstrumentAtomics) return nullptr;
845 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
847 PtrOperand = XCHG->getPointerOperand();
850 // Treat memory accesses to promotable allocas as non-interesting since they
851 // will not cause memory violations. This greatly speeds up the instrumented
852 // executable at -O0.
853 if (ClSkipPromotableAllocas)
854 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
855 return isInterestingAlloca(*AI) ? AI : nullptr;
860 static bool isPointerOperand(Value *V) {
861 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
864 // This is a rough heuristic; it may cause both false positives and
865 // false negatives. The proper implementation requires cooperation with
867 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
868 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
869 if (!Cmp->isRelational()) return false;
870 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
871 if (BO->getOpcode() != Instruction::Sub) return false;
875 if (!isPointerOperand(I->getOperand(0)) ||
876 !isPointerOperand(I->getOperand(1)))
881 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
882 // If a global variable does not have dynamic initialization we don't
883 // have to instrument it. However, if a global does not have initializer
884 // at all, we assume it has dynamic initializer (in other TU).
885 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
888 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
891 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
892 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
893 for (int i = 0; i < 2; i++) {
894 if (Param[i]->getType()->isPointerTy())
895 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
897 IRB.CreateCall(F, Param);
900 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
901 Instruction *I, bool UseCalls,
902 const DataLayout &DL) {
903 bool IsWrite = false;
904 unsigned Alignment = 0;
905 uint64_t TypeSize = 0;
906 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
909 // Optimization experiments.
910 // The experiments can be used to evaluate potential optimizations that remove
911 // instrumentation (assess false negatives). Instead of completely removing
912 // some instrumentation, you set Exp to a non-zero value (mask of optimization
913 // experiments that want to remove instrumentation of this instruction).
914 // If Exp is non-zero, this pass will emit special calls into runtime
915 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
916 // make runtime terminate the program in a special way (with a different
917 // exit status). Then you run the new compiler on a buggy corpus, collect
918 // the special terminations (ideally, you don't see them at all -- no false
919 // negatives) and make the decision on the optimization.
920 uint32_t Exp = ClForceExperiment;
922 if (ClOpt && ClOptGlobals) {
923 // If initialization order checking is disabled, a simple access to a
924 // dynamically initialized global is always valid.
925 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
926 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
927 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
928 NumOptimizedAccessesToGlobalVar++;
933 if (ClOpt && ClOptStack) {
934 // A direct inbounds access to a stack variable is always valid.
935 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
936 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
937 NumOptimizedAccessesToStackVar++;
943 NumInstrumentedWrites++;
945 NumInstrumentedReads++;
947 unsigned Granularity = 1 << Mapping.Scale;
948 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
949 // if the data is properly aligned.
950 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
952 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
953 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
955 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
959 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
960 Value *Addr, bool IsWrite,
961 size_t AccessSizeIndex,
964 IRBuilder<> IRB(InsertBefore);
965 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
966 CallInst *Call = nullptr;
969 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
970 {Addr, SizeArgument});
972 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
973 {Addr, SizeArgument, ExpVal});
977 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
979 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
983 // We don't do Call->setDoesNotReturn() because the BB already has
984 // UnreachableInst at the end.
985 // This EmptyAsm is required to avoid callback merge.
986 IRB.CreateCall(EmptyAsm, {});
990 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
993 size_t Granularity = 1 << Mapping.Scale;
994 // Addr & (Granularity - 1)
995 Value *LastAccessedByte =
996 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
997 // (Addr & (Granularity - 1)) + size - 1
998 if (TypeSize / 8 > 1)
999 LastAccessedByte = IRB.CreateAdd(
1000 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1001 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1003 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1004 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1005 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1008 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1009 Instruction *InsertBefore, Value *Addr,
1010 uint32_t TypeSize, bool IsWrite,
1011 Value *SizeArgument, bool UseCalls,
1013 IRBuilder<> IRB(InsertBefore);
1014 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1015 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1019 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1022 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1023 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1028 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1029 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1030 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1031 Value *CmpVal = Constant::getNullValue(ShadowTy);
1032 Value *ShadowValue =
1033 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1035 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1036 size_t Granularity = 1 << Mapping.Scale;
1037 TerminatorInst *CrashTerm = nullptr;
1039 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1040 // We use branch weights for the slow path check, to indicate that the slow
1041 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1042 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1043 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1044 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1045 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1046 IRB.SetInsertPoint(CheckTerm);
1047 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1048 BasicBlock *CrashBlock =
1049 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1050 CrashTerm = new UnreachableInst(*C, CrashBlock);
1051 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1052 ReplaceInstWithInst(CheckTerm, NewTerm);
1054 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1057 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1058 AccessSizeIndex, SizeArgument, Exp);
1059 Crash->setDebugLoc(OrigIns->getDebugLoc());
1062 // Instrument unusual size or unusual alignment.
1063 // We can not do it with a single check, so we do 1-byte check for the first
1064 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1065 // to report the actual access size.
1066 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1067 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1068 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1070 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1071 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1074 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1077 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1078 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1080 Value *LastByte = IRB.CreateIntToPtr(
1081 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1083 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1084 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1088 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1089 GlobalValue *ModuleName) {
1090 // Set up the arguments to our poison/unpoison functions.
1091 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1093 // Add a call to poison all external globals before the given function starts.
1094 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1095 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1097 // Add calls to unpoison all globals before each return instruction.
1098 for (auto &BB : GlobalInit.getBasicBlockList())
1099 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1100 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1103 void AddressSanitizerModule::createInitializerPoisonCalls(
1104 Module &M, GlobalValue *ModuleName) {
1105 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1107 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1108 for (Use &OP : CA->operands()) {
1109 if (isa<ConstantAggregateZero>(OP)) continue;
1110 ConstantStruct *CS = cast<ConstantStruct>(OP);
1112 // Must have a function or null ptr.
1113 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1114 if (F->getName() == kAsanModuleCtorName) continue;
1115 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1116 // Don't instrument CTORs that will run before asan.module_ctor.
1117 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1118 poisonOneInitializer(*F, ModuleName);
1123 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1124 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1125 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1127 if (GlobalsMD.get(G).IsBlacklisted) return false;
1128 if (!Ty->isSized()) return false;
1129 if (!G->hasInitializer()) return false;
1130 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1131 // Touch only those globals that will not be defined in other modules.
1132 // Don't handle ODR linkage types and COMDATs since other modules may be built
1134 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1135 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1136 G->getLinkage() != GlobalVariable::InternalLinkage)
1138 if (G->hasComdat()) return false;
1139 // Two problems with thread-locals:
1140 // - The address of the main thread's copy can't be computed at link-time.
1141 // - Need to poison all copies, not just the main thread's one.
1142 if (G->isThreadLocal()) return false;
1143 // For now, just ignore this Global if the alignment is large.
1144 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1146 if (G->hasSection()) {
1147 StringRef Section(G->getSection());
1149 // Globals from llvm.metadata aren't emitted, do not instrument them.
1150 if (Section == "llvm.metadata") return false;
1151 // Do not instrument globals from special LLVM sections.
1152 if (Section.find("__llvm") != StringRef::npos) return false;
1154 // Callbacks put into the CRT initializer/terminator sections
1155 // should not be instrumented.
1156 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1157 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1158 if (Section.startswith(".CRT")) {
1159 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1163 if (TargetTriple.isOSBinFormatMachO()) {
1164 StringRef ParsedSegment, ParsedSection;
1165 unsigned TAA = 0, StubSize = 0;
1167 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1168 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1169 if (!ErrorCode.empty()) {
1170 assert(false && "Invalid section specifier.");
1174 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1175 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1177 if (ParsedSegment == "__OBJC" ||
1178 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1179 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1182 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1183 // Constant CFString instances are compiled in the following way:
1184 // -- the string buffer is emitted into
1185 // __TEXT,__cstring,cstring_literals
1186 // -- the constant NSConstantString structure referencing that buffer
1187 // is placed into __DATA,__cfstring
1188 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1189 // Moreover, it causes the linker to crash on OS X 10.7
1190 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1191 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1194 // The linker merges the contents of cstring_literals and removes the
1196 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1197 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1206 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1207 IRBuilder<> IRB(*C);
1208 // Declare our poisoning and unpoisoning functions.
1209 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1210 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1211 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1212 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1213 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1214 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1215 // Declare functions that register/unregister globals.
1216 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1217 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1218 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1219 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1220 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1221 IntptrTy, IntptrTy, nullptr));
1222 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1225 // This function replaces all global variables with new variables that have
1226 // trailing redzones. It also creates a function that poisons
1227 // redzones and inserts this function into llvm.global_ctors.
1228 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1231 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1233 for (auto &G : M.globals()) {
1234 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1237 size_t n = GlobalsToChange.size();
1238 if (n == 0) return false;
1240 // A global is described by a structure
1243 // size_t size_with_redzone;
1244 // const char *name;
1245 // const char *module_name;
1246 // size_t has_dynamic_init;
1247 // void *source_location;
1248 // We initialize an array of such structures and pass it to a run-time call.
1249 StructType *GlobalStructTy =
1250 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1251 IntptrTy, IntptrTy, nullptr);
1252 SmallVector<Constant *, 16> Initializers(n);
1254 bool HasDynamicallyInitializedGlobals = false;
1256 // We shouldn't merge same module names, as this string serves as unique
1257 // module ID in runtime.
1258 GlobalVariable *ModuleName = createPrivateGlobalForString(
1259 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1261 auto &DL = M.getDataLayout();
1262 for (size_t i = 0; i < n; i++) {
1263 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1264 GlobalVariable *G = GlobalsToChange[i];
1266 auto MD = GlobalsMD.get(G);
1267 // Create string holding the global name (use global name from metadata
1268 // if it's available, otherwise just write the name of global variable).
1269 GlobalVariable *Name = createPrivateGlobalForString(
1270 M, MD.Name.empty() ? G->getName() : MD.Name,
1271 /*AllowMerging*/ true);
1273 PointerType *PtrTy = cast<PointerType>(G->getType());
1274 Type *Ty = PtrTy->getElementType();
1275 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1276 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1277 // MinRZ <= RZ <= kMaxGlobalRedzone
1278 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1279 uint64_t RZ = std::max(
1280 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1281 uint64_t RightRedzoneSize = RZ;
1282 // Round up to MinRZ
1283 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1284 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1285 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1287 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1288 Constant *NewInitializer =
1289 ConstantStruct::get(NewTy, G->getInitializer(),
1290 Constant::getNullValue(RightRedZoneTy), nullptr);
1292 // Create a new global variable with enough space for a redzone.
1293 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1294 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1295 Linkage = GlobalValue::InternalLinkage;
1296 GlobalVariable *NewGlobal =
1297 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1298 "", G, G->getThreadLocalMode());
1299 NewGlobal->copyAttributesFrom(G);
1300 NewGlobal->setAlignment(MinRZ);
1303 Indices2[0] = IRB.getInt32(0);
1304 Indices2[1] = IRB.getInt32(0);
1306 G->replaceAllUsesWith(
1307 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1308 NewGlobal->takeName(G);
1309 G->eraseFromParent();
1311 Constant *SourceLoc;
1312 if (!MD.SourceLoc.empty()) {
1313 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1314 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1316 SourceLoc = ConstantInt::get(IntptrTy, 0);
1319 Initializers[i] = ConstantStruct::get(
1320 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1321 ConstantInt::get(IntptrTy, SizeInBytes),
1322 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1323 ConstantExpr::getPointerCast(Name, IntptrTy),
1324 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1325 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1327 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1329 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1332 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1333 GlobalVariable *AllGlobals = new GlobalVariable(
1334 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1335 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1337 // Create calls for poisoning before initializers run and unpoisoning after.
1338 if (HasDynamicallyInitializedGlobals)
1339 createInitializerPoisonCalls(M, ModuleName);
1340 IRB.CreateCall(AsanRegisterGlobals,
1341 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1342 ConstantInt::get(IntptrTy, n)});
1344 // We also need to unregister globals at the end, e.g. when a shared library
1346 Function *AsanDtorFunction =
1347 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1348 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1349 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1350 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1351 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1352 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1353 ConstantInt::get(IntptrTy, n)});
1354 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1360 bool AddressSanitizerModule::runOnModule(Module &M) {
1361 C = &(M.getContext());
1362 int LongSize = M.getDataLayout().getPointerSizeInBits();
1363 IntptrTy = Type::getIntNTy(*C, LongSize);
1364 TargetTriple = Triple(M.getTargetTriple());
1365 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1366 initializeCallbacks(M);
1368 bool Changed = false;
1370 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1371 if (ClGlobals && !CompileKernel) {
1372 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1374 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1375 Changed |= InstrumentGlobals(IRB, M);
1381 void AddressSanitizer::initializeCallbacks(Module &M) {
1382 IRBuilder<> IRB(*C);
1383 // Create __asan_report* callbacks.
1384 // IsWrite, TypeSize and Exp are encoded in the function name.
1385 for (int Exp = 0; Exp < 2; Exp++) {
1386 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1387 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1388 const std::string ExpStr = Exp ? "exp_" : "";
1389 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1390 const std::string EndingStr = CompileKernel ? "_noabort" : "";
1391 const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1392 // TODO(glider): for KASan builds add _noabort to error reporting
1393 // functions and make them actually noabort (remove the UnreachableInst).
1394 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1395 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1396 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
1397 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1398 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1399 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1400 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1401 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1402 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1403 AccessSizeIndex++) {
1404 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1405 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1406 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1407 kAsanReportErrorTemplate + ExpStr + Suffix,
1408 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1409 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1410 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1411 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1412 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1417 const std::string MemIntrinCallbackPrefix =
1418 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1419 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1420 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1421 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1422 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1423 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1424 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1425 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1426 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1427 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1429 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1430 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1432 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1433 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1434 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1435 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1436 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1437 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1438 StringRef(""), StringRef(""),
1439 /*hasSideEffects=*/true);
1443 bool AddressSanitizer::doInitialization(Module &M) {
1444 // Initialize the private fields. No one has accessed them before.
1448 C = &(M.getContext());
1449 LongSize = M.getDataLayout().getPointerSizeInBits();
1450 IntptrTy = Type::getIntNTy(*C, LongSize);
1451 TargetTriple = Triple(M.getTargetTriple());
1453 if (!CompileKernel) {
1454 std::tie(AsanCtorFunction, AsanInitFunction) =
1455 createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName, kAsanInitName,
1456 /*InitArgTypes=*/{},
1458 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1460 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1464 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1465 // For each NSObject descendant having a +load method, this method is invoked
1466 // by the ObjC runtime before any of the static constructors is called.
1467 // Therefore we need to instrument such methods with a call to __asan_init
1468 // at the beginning in order to initialize our runtime before any access to
1469 // the shadow memory.
1470 // We cannot just ignore these methods, because they may call other
1471 // instrumented functions.
1472 if (F.getName().find(" load]") != std::string::npos) {
1473 IRBuilder<> IRB(F.begin()->begin());
1474 IRB.CreateCall(AsanInitFunction, {});
1480 bool AddressSanitizer::runOnFunction(Function &F) {
1481 if (&F == AsanCtorFunction) return false;
1482 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1483 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1484 initializeCallbacks(*F.getParent());
1486 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1488 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1489 maybeInsertAsanInitAtFunctionEntry(F);
1491 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1493 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1495 // We want to instrument every address only once per basic block (unless there
1496 // are calls between uses).
1497 SmallSet<Value *, 16> TempsToInstrument;
1498 SmallVector<Instruction *, 16> ToInstrument;
1499 SmallVector<Instruction *, 8> NoReturnCalls;
1500 SmallVector<BasicBlock *, 16> AllBlocks;
1501 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1507 // Fill the set of memory operations to instrument.
1508 for (auto &BB : F) {
1509 AllBlocks.push_back(&BB);
1510 TempsToInstrument.clear();
1511 int NumInsnsPerBB = 0;
1512 for (auto &Inst : BB) {
1513 if (LooksLikeCodeInBug11395(&Inst)) return false;
1514 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1516 if (ClOpt && ClOptSameTemp) {
1517 if (!TempsToInstrument.insert(Addr).second)
1518 continue; // We've seen this temp in the current BB.
1520 } else if (ClInvalidPointerPairs &&
1521 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1522 PointerComparisonsOrSubtracts.push_back(&Inst);
1524 } else if (isa<MemIntrinsic>(Inst)) {
1527 if (isa<AllocaInst>(Inst)) NumAllocas++;
1530 // A call inside BB.
1531 TempsToInstrument.clear();
1532 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1536 ToInstrument.push_back(&Inst);
1538 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1544 (ClInstrumentationWithCallsThreshold >= 0 &&
1545 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1546 const TargetLibraryInfo *TLI =
1547 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1548 const DataLayout &DL = F.getParent()->getDataLayout();
1549 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1550 /*RoundToAlign=*/true);
1553 int NumInstrumented = 0;
1554 for (auto Inst : ToInstrument) {
1555 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1556 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1557 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1558 instrumentMop(ObjSizeVis, Inst, UseCalls,
1559 F.getParent()->getDataLayout());
1561 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1566 FunctionStackPoisoner FSP(F, *this);
1567 bool ChangedStack = FSP.runOnFunction();
1569 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1570 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1571 for (auto CI : NoReturnCalls) {
1572 IRBuilder<> IRB(CI);
1573 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1576 for (auto Inst : PointerComparisonsOrSubtracts) {
1577 instrumentPointerComparisonOrSubtraction(Inst);
1581 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1583 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1588 // Workaround for bug 11395: we don't want to instrument stack in functions
1589 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1590 // FIXME: remove once the bug 11395 is fixed.
1591 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1592 if (LongSize != 32) return false;
1593 CallInst *CI = dyn_cast<CallInst>(I);
1594 if (!CI || !CI->isInlineAsm()) return false;
1595 if (CI->getNumArgOperands() <= 5) return false;
1596 // We have inline assembly with quite a few arguments.
1600 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1601 IRBuilder<> IRB(*C);
1602 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1603 std::string Suffix = itostr(i);
1604 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1605 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1606 IntptrTy, nullptr));
1607 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1608 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1609 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1611 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1612 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1613 IntptrTy, IntptrTy, nullptr));
1614 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1615 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1616 IntptrTy, IntptrTy, nullptr));
1617 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1618 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1619 AsanAllocasUnpoisonFunc =
1620 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1621 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1624 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1625 IRBuilder<> &IRB, Value *ShadowBase,
1627 size_t n = ShadowBytes.size();
1629 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1630 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1631 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1632 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1633 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1634 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1636 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1637 if (F.getParent()->getDataLayout().isLittleEndian())
1638 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1640 Val = (Val << 8) | ShadowBytes[i + j];
1643 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1644 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1645 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1646 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1651 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1652 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1653 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1654 assert(LocalStackSize <= kMaxStackMallocSize);
1655 uint64_t MaxSize = kMinStackMallocSize;
1656 for (int i = 0;; i++, MaxSize *= 2)
1657 if (LocalStackSize <= MaxSize) return i;
1658 llvm_unreachable("impossible LocalStackSize");
1661 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1662 // We can not use MemSet intrinsic because it may end up calling the actual
1663 // memset. Size is a multiple of 8.
1664 // Currently this generates 8-byte stores on x86_64; it may be better to
1665 // generate wider stores.
1666 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1667 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1668 assert(!(Size % 8));
1670 // kAsanStackAfterReturnMagic is 0xf5.
1671 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1673 for (int i = 0; i < Size; i += 8) {
1674 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1676 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1677 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1681 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1683 Instruction *ThenTerm,
1684 Value *ValueIfFalse) {
1685 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1686 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1687 PHI->addIncoming(ValueIfFalse, CondBlock);
1688 BasicBlock *ThenBlock = ThenTerm->getParent();
1689 PHI->addIncoming(ValueIfTrue, ThenBlock);
1693 Value *FunctionStackPoisoner::createAllocaForLayout(
1694 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1697 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1698 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1701 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1702 nullptr, "MyAlloca");
1703 assert(Alloca->isStaticAlloca());
1705 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1706 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1707 Alloca->setAlignment(FrameAlignment);
1708 return IRB.CreatePointerCast(Alloca, IntptrTy);
1711 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1712 BasicBlock &FirstBB = *F.begin();
1713 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1714 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1715 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1716 DynamicAllocaLayout->setAlignment(32);
1719 void FunctionStackPoisoner::poisonStack() {
1720 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1722 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1723 // Handle dynamic allocas.
1724 createDynamicAllocasInitStorage();
1725 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1727 unpoisonDynamicAllocas();
1730 if (AllocaVec.size() == 0) return;
1732 int StackMallocIdx = -1;
1733 DebugLoc EntryDebugLocation;
1734 if (auto SP = getDISubprogram(&F))
1735 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1737 Instruction *InsBefore = AllocaVec[0];
1738 IRBuilder<> IRB(InsBefore);
1739 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1741 // Make sure non-instrumented allocas stay in the first basic block.
1742 // Otherwise, debug info is broken, because only first-basic-block allocas are
1743 // treated as regular stack slots.
1744 for (auto *AI : NonInstrumentedStaticAllocaVec) AI->moveBefore(InsBefore);
1746 SmallVector<ASanStackVariableDescription, 16> SVD;
1747 SVD.reserve(AllocaVec.size());
1748 for (AllocaInst *AI : AllocaVec) {
1749 ASanStackVariableDescription D = {AI->getName().data(),
1750 ASan.getAllocaSizeInBytes(AI),
1751 AI->getAlignment(), AI, 0};
1754 // Minimal header size (left redzone) is 4 pointers,
1755 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1756 size_t MinHeaderSize = ASan.LongSize / 2;
1757 ASanStackFrameLayout L;
1758 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1759 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1760 uint64_t LocalStackSize = L.FrameSize;
1761 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1762 LocalStackSize <= kMaxStackMallocSize;
1763 // Don't do dynamic alloca or stack malloc in presence of inline asm:
1764 // too often it makes assumptions on which registers are available.
1765 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1766 DoStackMalloc &= !HasNonEmptyInlineAsm;
1768 Value *StaticAlloca =
1769 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1772 Value *LocalStackBase;
1774 if (DoStackMalloc) {
1775 // void *FakeStack = __asan_option_detect_stack_use_after_return
1776 // ? __asan_stack_malloc_N(LocalStackSize)
1778 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1779 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1780 kAsanOptionDetectUAR, IRB.getInt32Ty());
1781 Value *UARIsEnabled =
1782 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1783 Constant::getNullValue(IRB.getInt32Ty()));
1785 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1786 IRBuilder<> IRBIf(Term);
1787 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1788 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1789 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1790 Value *FakeStackValue =
1791 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1792 ConstantInt::get(IntptrTy, LocalStackSize));
1793 IRB.SetInsertPoint(InsBefore);
1794 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1795 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1796 ConstantInt::get(IntptrTy, 0));
1798 Value *NoFakeStack =
1799 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1800 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1801 IRBIf.SetInsertPoint(Term);
1802 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1803 Value *AllocaValue =
1804 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1805 IRB.SetInsertPoint(InsBefore);
1806 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1807 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1809 // void *FakeStack = nullptr;
1810 // void *LocalStackBase = alloca(LocalStackSize);
1811 FakeStack = ConstantInt::get(IntptrTy, 0);
1813 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1816 // Insert poison calls for lifetime intrinsics for alloca.
1817 bool HavePoisonedAllocas = false;
1818 for (const auto &APC : AllocaPoisonCallVec) {
1819 assert(APC.InsBefore);
1821 IRBuilder<> IRB(APC.InsBefore);
1822 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1823 HavePoisonedAllocas |= APC.DoPoison;
1826 // Replace Alloca instructions with base+offset.
1827 for (const auto &Desc : SVD) {
1828 AllocaInst *AI = Desc.AI;
1829 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1830 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1832 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1833 AI->replaceAllUsesWith(NewAllocaPtr);
1836 // The left-most redzone has enough space for at least 4 pointers.
1837 // Write the Magic value to redzone[0].
1838 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1839 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1841 // Write the frame description constant to redzone[1].
1842 Value *BasePlus1 = IRB.CreateIntToPtr(
1843 IRB.CreateAdd(LocalStackBase,
1844 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1846 GlobalVariable *StackDescriptionGlobal =
1847 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1848 /*AllowMerging*/ true);
1849 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1850 IRB.CreateStore(Description, BasePlus1);
1851 // Write the PC to redzone[2].
1852 Value *BasePlus2 = IRB.CreateIntToPtr(
1853 IRB.CreateAdd(LocalStackBase,
1854 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1856 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1858 // Poison the stack redzones at the entry.
1859 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1860 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1862 // (Un)poison the stack before all ret instructions.
1863 for (auto Ret : RetVec) {
1864 IRBuilder<> IRBRet(Ret);
1865 // Mark the current frame as retired.
1866 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1868 if (DoStackMalloc) {
1869 assert(StackMallocIdx >= 0);
1870 // if FakeStack != 0 // LocalStackBase == FakeStack
1871 // // In use-after-return mode, poison the whole stack frame.
1872 // if StackMallocIdx <= 4
1873 // // For small sizes inline the whole thing:
1874 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1875 // **SavedFlagPtr(FakeStack) = 0
1877 // __asan_stack_free_N(FakeStack, LocalStackSize)
1879 // <This is not a fake stack; unpoison the redzones>
1881 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1882 TerminatorInst *ThenTerm, *ElseTerm;
1883 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1885 IRBuilder<> IRBPoison(ThenTerm);
1886 if (StackMallocIdx <= 4) {
1887 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1888 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1889 ClassSize >> Mapping.Scale);
1890 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1892 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1893 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1894 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1895 IRBPoison.CreateStore(
1896 Constant::getNullValue(IRBPoison.getInt8Ty()),
1897 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1899 // For larger frames call __asan_stack_free_*.
1900 IRBPoison.CreateCall(
1901 AsanStackFreeFunc[StackMallocIdx],
1902 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1905 IRBuilder<> IRBElse(ElseTerm);
1906 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1907 } else if (HavePoisonedAllocas) {
1908 // If we poisoned some allocas in llvm.lifetime analysis,
1909 // unpoison whole stack frame now.
1910 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1912 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1916 // We are done. Remove the old unused alloca instructions.
1917 for (auto AI : AllocaVec) AI->eraseFromParent();
1920 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1921 IRBuilder<> &IRB, bool DoPoison) {
1922 // For now just insert the call to ASan runtime.
1923 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1924 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1926 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1927 {AddrArg, SizeArg});
1930 // Handling llvm.lifetime intrinsics for a given %alloca:
1931 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1932 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1933 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1934 // could be poisoned by previous llvm.lifetime.end instruction, as the
1935 // variable may go in and out of scope several times, e.g. in loops).
1936 // (3) if we poisoned at least one %alloca in a function,
1937 // unpoison the whole stack frame at function exit.
1939 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1940 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1941 // We're intested only in allocas we can handle.
1942 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
1943 // See if we've already calculated (or started to calculate) alloca for a
1945 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1946 if (I != AllocaForValue.end()) return I->second;
1947 // Store 0 while we're calculating alloca for value V to avoid
1948 // infinite recursion if the value references itself.
1949 AllocaForValue[V] = nullptr;
1950 AllocaInst *Res = nullptr;
1951 if (CastInst *CI = dyn_cast<CastInst>(V))
1952 Res = findAllocaForValue(CI->getOperand(0));
1953 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1954 for (Value *IncValue : PN->incoming_values()) {
1955 // Allow self-referencing phi-nodes.
1956 if (IncValue == PN) continue;
1957 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1958 // AI for incoming values should exist and should all be equal.
1959 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1964 if (Res) AllocaForValue[V] = Res;
1968 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
1969 IRBuilder<> IRB(AI);
1971 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
1972 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
1974 Value *Zero = Constant::getNullValue(IntptrTy);
1975 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
1976 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
1978 // Since we need to extend alloca with additional memory to locate
1979 // redzones, and OldSize is number of allocated blocks with
1980 // ElementSize size, get allocated memory size in bytes by
1981 // OldSize * ElementSize.
1982 const unsigned ElementSize =
1983 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
1985 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
1986 ConstantInt::get(IntptrTy, ElementSize));
1988 // PartialSize = OldSize % 32
1989 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
1991 // Misalign = kAllocaRzSize - PartialSize;
1992 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
1994 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
1995 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
1996 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
1998 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
1999 // Align is added to locate left redzone, PartialPadding for possible
2000 // partial redzone and kAllocaRzSize for right redzone respectively.
2001 Value *AdditionalChunkSize = IRB.CreateAdd(
2002 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2004 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2006 // Insert new alloca with new NewSize and Align params.
2007 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2008 NewAlloca->setAlignment(Align);
2010 // NewAddress = Address + Align
2011 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2012 ConstantInt::get(IntptrTy, Align));
2014 // Insert __asan_alloca_poison call for new created alloca.
2015 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2017 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2018 // for unpoisoning stuff.
2019 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2021 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2023 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2024 AI->replaceAllUsesWith(NewAddressPtr);
2026 // We are done. Erase old alloca from parent.
2027 AI->eraseFromParent();
2030 // isSafeAccess returns true if Addr is always inbounds with respect to its
2031 // base object. For example, it is a field access or an array access with
2032 // constant inbounds index.
2033 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2034 Value *Addr, uint64_t TypeSize) const {
2035 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2036 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2037 uint64_t Size = SizeOffset.first.getZExtValue();
2038 int64_t Offset = SizeOffset.second.getSExtValue();
2039 // Three checks are required to ensure safety:
2040 // . Offset >= 0 (since the offset is given from the base ptr)
2041 // . Size >= Offset (unsigned)
2042 // . Size - Offset >= NeededSize (unsigned)
2043 return Offset >= 0 && Size >= uint64_t(Offset) &&
2044 Size - uint64_t(Offset) >= TypeSize / 8;