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/SetVector.h"
22 #include "llvm/ADT/SmallSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/Analysis/MemoryBuiltins.h"
29 #include "llvm/Analysis/TargetLibraryInfo.h"
30 #include "llvm/Analysis/ValueTracking.h"
31 #include "llvm/IR/CallSite.h"
32 #include "llvm/IR/DIBuilder.h"
33 #include "llvm/IR/DataLayout.h"
34 #include "llvm/IR/Dominators.h"
35 #include "llvm/IR/Function.h"
36 #include "llvm/IR/IRBuilder.h"
37 #include "llvm/IR/InlineAsm.h"
38 #include "llvm/IR/InstVisitor.h"
39 #include "llvm/IR/IntrinsicInst.h"
40 #include "llvm/IR/LLVMContext.h"
41 #include "llvm/IR/MDBuilder.h"
42 #include "llvm/IR/Module.h"
43 #include "llvm/IR/Type.h"
44 #include "llvm/MC/MCSectionMachO.h"
45 #include "llvm/Support/CommandLine.h"
46 #include "llvm/Support/DataTypes.h"
47 #include "llvm/Support/Debug.h"
48 #include "llvm/Support/Endian.h"
49 #include "llvm/Support/SwapByteOrder.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include "llvm/Transforms/Scalar.h"
52 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
53 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
54 #include "llvm/Transforms/Utils/Cloning.h"
55 #include "llvm/Transforms/Utils/Local.h"
56 #include "llvm/Transforms/Utils/ModuleUtils.h"
57 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
60 #include <system_error>
64 #define DEBUG_TYPE "asan"
66 // VMA size definition for architecture that support multiple sizes.
67 // AArch64 has 3 VMA sizes: 39, 42 and 48.
68 #ifndef SANITIZER_AARCH64_VMA
69 # define SANITIZER_AARCH64_VMA 39
71 # if SANITIZER_AARCH64_VMA != 39 && SANITIZER_AARCH64_VMA != 42
72 # error "invalid SANITIZER_AARCH64_VMA size"
76 static const uint64_t kDefaultShadowScale = 3;
77 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
78 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
79 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
80 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
81 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
82 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
83 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
84 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
85 #if SANITIZER_AARCH64_VMA == 39
86 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
87 #elif SANITIZER_AARCH64_VMA == 42
88 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 39;
90 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
91 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
92 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
94 static const size_t kMinStackMallocSize = 1 << 6; // 64B
95 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
96 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
97 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
99 static const char *const kAsanModuleCtorName = "asan.module_ctor";
100 static const char *const kAsanModuleDtorName = "asan.module_dtor";
101 static const uint64_t kAsanCtorAndDtorPriority = 1;
102 static const char *const kAsanReportErrorTemplate = "__asan_report_";
103 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
104 static const char *const kAsanUnregisterGlobalsName =
105 "__asan_unregister_globals";
106 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
107 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
108 static const char *const kAsanInitName = "__asan_init";
109 static const char *const kAsanVersionCheckName =
110 "__asan_version_mismatch_check_v6";
111 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
112 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
113 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
114 static const int kMaxAsanStackMallocSizeClass = 10;
115 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
116 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
117 static const char *const kAsanGenPrefix = "__asan_gen_";
118 static const char *const kSanCovGenPrefix = "__sancov_gen_";
119 static const char *const kAsanPoisonStackMemoryName =
120 "__asan_poison_stack_memory";
121 static const char *const kAsanUnpoisonStackMemoryName =
122 "__asan_unpoison_stack_memory";
124 static const char *const kAsanOptionDetectUAR =
125 "__asan_option_detect_stack_use_after_return";
127 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
128 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
130 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
131 static const size_t kNumberOfAccessSizes = 5;
133 static const unsigned kAllocaRzSize = 32;
135 // Command-line flags.
136 static cl::opt<bool> ClEnableKasan(
137 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
138 cl::Hidden, cl::init(false));
140 // This flag may need to be replaced with -f[no-]asan-reads.
141 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
142 cl::desc("instrument read instructions"),
143 cl::Hidden, cl::init(true));
144 static cl::opt<bool> ClInstrumentWrites(
145 "asan-instrument-writes", cl::desc("instrument write instructions"),
146 cl::Hidden, cl::init(true));
147 static cl::opt<bool> ClInstrumentAtomics(
148 "asan-instrument-atomics",
149 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
151 static cl::opt<bool> ClAlwaysSlowPath(
152 "asan-always-slow-path",
153 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
155 // This flag limits the number of instructions to be instrumented
156 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
157 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
159 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
160 "asan-max-ins-per-bb", cl::init(10000),
161 cl::desc("maximal number of instructions to instrument in any given BB"),
163 // This flag may need to be replaced with -f[no]asan-stack.
164 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
165 cl::Hidden, cl::init(true));
166 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
167 cl::desc("Check return-after-free"),
168 cl::Hidden, cl::init(true));
169 // This flag may need to be replaced with -f[no]asan-globals.
170 static cl::opt<bool> ClGlobals("asan-globals",
171 cl::desc("Handle global objects"), cl::Hidden,
173 static cl::opt<bool> ClInitializers("asan-initialization-order",
174 cl::desc("Handle C++ initializer order"),
175 cl::Hidden, cl::init(true));
176 static cl::opt<bool> ClInvalidPointerPairs(
177 "asan-detect-invalid-pointer-pair",
178 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
180 static cl::opt<unsigned> ClRealignStack(
181 "asan-realign-stack",
182 cl::desc("Realign stack to the value of this flag (power of two)"),
183 cl::Hidden, cl::init(32));
184 static cl::opt<int> ClInstrumentationWithCallsThreshold(
185 "asan-instrumentation-with-call-threshold",
187 "If the function being instrumented contains more than "
188 "this number of memory accesses, use callbacks instead of "
189 "inline checks (-1 means never use callbacks)."),
190 cl::Hidden, cl::init(7000));
191 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
192 "asan-memory-access-callback-prefix",
193 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
194 cl::init("__asan_"));
195 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
196 cl::desc("instrument dynamic allocas"),
197 cl::Hidden, cl::init(true));
198 static cl::opt<bool> ClSkipPromotableAllocas(
199 "asan-skip-promotable-allocas",
200 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
203 // These flags allow to change the shadow mapping.
204 // The shadow mapping looks like
205 // Shadow = (Mem >> scale) + (1 << offset_log)
206 static cl::opt<int> ClMappingScale("asan-mapping-scale",
207 cl::desc("scale of asan shadow mapping"),
208 cl::Hidden, cl::init(0));
210 // Optimization flags. Not user visible, used mostly for testing
211 // and benchmarking the tool.
212 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
213 cl::Hidden, cl::init(true));
214 static cl::opt<bool> ClOptSameTemp(
215 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
216 cl::Hidden, cl::init(true));
217 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
218 cl::desc("Don't instrument scalar globals"),
219 cl::Hidden, cl::init(true));
220 static cl::opt<bool> ClOptStack(
221 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
222 cl::Hidden, cl::init(false));
224 static cl::opt<bool> ClCheckLifetime(
225 "asan-check-lifetime",
226 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
229 static cl::opt<bool> ClDynamicAllocaStack(
230 "asan-stack-dynamic-alloca",
231 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
234 static cl::opt<uint32_t> ClForceExperiment(
235 "asan-force-experiment",
236 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
240 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
242 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
243 cl::Hidden, cl::init(0));
244 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
245 cl::desc("Debug func"));
246 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
247 cl::Hidden, cl::init(-1));
248 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
249 cl::Hidden, cl::init(-1));
251 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
252 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
253 STATISTIC(NumOptimizedAccessesToGlobalVar,
254 "Number of optimized accesses to global vars");
255 STATISTIC(NumOptimizedAccessesToStackVar,
256 "Number of optimized accesses to stack vars");
259 /// Frontend-provided metadata for source location.
260 struct LocationMetadata {
265 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
267 bool empty() const { return Filename.empty(); }
269 void parse(MDNode *MDN) {
270 assert(MDN->getNumOperands() == 3);
271 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
272 Filename = DIFilename->getString();
274 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
276 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
280 /// Frontend-provided metadata for global variables.
281 class GlobalsMetadata {
284 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
285 LocationMetadata SourceLoc;
291 GlobalsMetadata() : inited_(false) {}
293 void init(Module &M) {
296 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
297 if (!Globals) return;
298 for (auto MDN : Globals->operands()) {
299 // Metadata node contains the global and the fields of "Entry".
300 assert(MDN->getNumOperands() == 5);
301 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
302 // The optimizer may optimize away a global entirely.
304 // We can already have an entry for GV if it was merged with another
306 Entry &E = Entries[GV];
307 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
308 E.SourceLoc.parse(Loc);
309 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
310 E.Name = Name->getString();
311 ConstantInt *IsDynInit =
312 mdconst::extract<ConstantInt>(MDN->getOperand(3));
313 E.IsDynInit |= IsDynInit->isOne();
314 ConstantInt *IsBlacklisted =
315 mdconst::extract<ConstantInt>(MDN->getOperand(4));
316 E.IsBlacklisted |= IsBlacklisted->isOne();
320 /// Returns metadata entry for a given global.
321 Entry get(GlobalVariable *G) const {
322 auto Pos = Entries.find(G);
323 return (Pos != Entries.end()) ? Pos->second : Entry();
328 DenseMap<GlobalVariable *, Entry> Entries;
331 /// This struct defines the shadow mapping using the rule:
332 /// shadow = (mem >> Scale) ADD-or-OR Offset.
333 struct ShadowMapping {
339 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
341 bool IsAndroid = TargetTriple.isAndroid();
342 bool IsIOS = TargetTriple.isiOS();
343 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
344 bool IsLinux = TargetTriple.isOSLinux();
345 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
346 TargetTriple.getArch() == llvm::Triple::ppc64le;
347 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
348 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
349 TargetTriple.getArch() == llvm::Triple::mipsel;
350 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
351 TargetTriple.getArch() == llvm::Triple::mips64el;
352 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
353 bool IsWindows = TargetTriple.isOSWindows();
355 ShadowMapping Mapping;
357 if (LongSize == 32) {
358 // Android is always PIE, which means that the beginning of the address
359 // space is always available.
363 Mapping.Offset = kMIPS32_ShadowOffset32;
365 Mapping.Offset = kFreeBSD_ShadowOffset32;
367 Mapping.Offset = kIOSShadowOffset32;
369 Mapping.Offset = kWindowsShadowOffset32;
371 Mapping.Offset = kDefaultShadowOffset32;
372 } else { // LongSize == 64
374 Mapping.Offset = kPPC64_ShadowOffset64;
376 Mapping.Offset = kFreeBSD_ShadowOffset64;
377 else if (IsLinux && IsX86_64) {
379 Mapping.Offset = kLinuxKasan_ShadowOffset64;
381 Mapping.Offset = kSmallX86_64ShadowOffset;
383 Mapping.Offset = kMIPS64_ShadowOffset64;
385 Mapping.Offset = kAArch64_ShadowOffset64;
387 Mapping.Offset = kDefaultShadowOffset64;
390 Mapping.Scale = kDefaultShadowScale;
391 if (ClMappingScale) {
392 Mapping.Scale = ClMappingScale;
395 // OR-ing shadow offset if more efficient (at least on x86) if the offset
396 // is a power of two, but on ppc64 we have to use add since the shadow
397 // offset is not necessary 1/8-th of the address space.
398 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
403 static size_t RedzoneSizeForScale(int MappingScale) {
404 // Redzone used for stack and globals is at least 32 bytes.
405 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
406 return std::max(32U, 1U << MappingScale);
409 /// AddressSanitizer: instrument the code in module to find memory bugs.
410 struct AddressSanitizer : public FunctionPass {
411 explicit AddressSanitizer(bool CompileKernel = false)
412 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) {
413 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
415 const char *getPassName() const override {
416 return "AddressSanitizerFunctionPass";
418 void getAnalysisUsage(AnalysisUsage &AU) const override {
419 AU.addRequired<DominatorTreeWrapperPass>();
420 AU.addRequired<TargetLibraryInfoWrapperPass>();
422 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
423 Type *Ty = AI->getAllocatedType();
424 uint64_t SizeInBytes =
425 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
428 /// Check if we want (and can) handle this alloca.
429 bool isInterestingAlloca(AllocaInst &AI);
431 // Check if we have dynamic alloca.
432 bool isDynamicAlloca(AllocaInst &AI) const {
433 return AI.isArrayAllocation() || !AI.isStaticAlloca();
436 /// If it is an interesting memory access, return the PointerOperand
437 /// and set IsWrite/Alignment. Otherwise return nullptr.
438 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
439 uint64_t *TypeSize, unsigned *Alignment);
440 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
441 bool UseCalls, const DataLayout &DL);
442 void instrumentPointerComparisonOrSubtraction(Instruction *I);
443 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
444 Value *Addr, uint32_t TypeSize, bool IsWrite,
445 Value *SizeArgument, bool UseCalls, uint32_t Exp);
446 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
447 uint32_t TypeSize, bool IsWrite,
448 Value *SizeArgument, bool UseCalls,
450 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
451 Value *ShadowValue, uint32_t TypeSize);
452 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
453 bool IsWrite, size_t AccessSizeIndex,
454 Value *SizeArgument, uint32_t Exp);
455 void instrumentMemIntrinsic(MemIntrinsic *MI);
456 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
457 bool runOnFunction(Function &F) override;
458 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
459 void markEscapedLocalAllocas(Function &F);
460 bool doInitialization(Module &M) override;
461 static char ID; // Pass identification, replacement for typeid
463 DominatorTree &getDominatorTree() const { return *DT; }
466 void initializeCallbacks(Module &M);
468 bool LooksLikeCodeInBug11395(Instruction *I);
469 bool GlobalIsLinkerInitialized(GlobalVariable *G);
470 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
471 uint64_t TypeSize) const;
473 /// Helper to cleanup per-function state.
474 struct FunctionStateRAII {
475 AddressSanitizer *Pass;
476 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
477 assert(Pass->ProcessedAllocas.empty() &&
478 "last pass forgot to clear cache");
480 ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); }
488 ShadowMapping Mapping;
490 Function *AsanCtorFunction = nullptr;
491 Function *AsanInitFunction = nullptr;
492 Function *AsanHandleNoReturnFunc;
493 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
494 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
495 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
496 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
497 // This array is indexed by AccessIsWrite and Experiment.
498 Function *AsanErrorCallbackSized[2][2];
499 Function *AsanMemoryAccessCallbackSized[2][2];
500 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
502 GlobalsMetadata GlobalsMD;
503 DenseMap<AllocaInst *, bool> ProcessedAllocas;
505 friend struct FunctionStackPoisoner;
508 class AddressSanitizerModule : public ModulePass {
510 explicit AddressSanitizerModule(bool CompileKernel = false)
511 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {}
512 bool runOnModule(Module &M) override;
513 static char ID; // Pass identification, replacement for typeid
514 const char *getPassName() const override { return "AddressSanitizerModule"; }
517 void initializeCallbacks(Module &M);
519 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
520 bool ShouldInstrumentGlobal(GlobalVariable *G);
521 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
522 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
523 size_t MinRedzoneSizeForGlobal() const {
524 return RedzoneSizeForScale(Mapping.Scale);
527 GlobalsMetadata GlobalsMD;
532 ShadowMapping Mapping;
533 Function *AsanPoisonGlobals;
534 Function *AsanUnpoisonGlobals;
535 Function *AsanRegisterGlobals;
536 Function *AsanUnregisterGlobals;
539 // Stack poisoning does not play well with exception handling.
540 // When an exception is thrown, we essentially bypass the code
541 // that unpoisones the stack. This is why the run-time library has
542 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
543 // stack in the interceptor. This however does not work inside the
544 // actual function which catches the exception. Most likely because the
545 // compiler hoists the load of the shadow value somewhere too high.
546 // This causes asan to report a non-existing bug on 453.povray.
547 // It sounds like an LLVM bug.
548 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
550 AddressSanitizer &ASan;
555 ShadowMapping Mapping;
557 SmallVector<AllocaInst *, 16> AllocaVec;
558 SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
559 SmallVector<Instruction *, 8> RetVec;
560 unsigned StackAlignment;
562 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
563 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
564 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
565 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
567 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
568 struct AllocaPoisonCall {
569 IntrinsicInst *InsBefore;
574 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
576 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
577 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
578 AllocaInst *DynamicAllocaLayout = nullptr;
579 IntrinsicInst *LocalEscapeCall = nullptr;
581 // Maps Value to an AllocaInst from which the Value is originated.
582 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
583 AllocaForValueMapTy AllocaForValue;
585 bool HasNonEmptyInlineAsm = false;
586 bool HasReturnsTwiceCall = false;
587 std::unique_ptr<CallInst> EmptyInlineAsm;
589 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
592 DIB(*F.getParent(), /*AllowUnresolved*/ false),
594 IntptrTy(ASan.IntptrTy),
595 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
596 Mapping(ASan.Mapping),
597 StackAlignment(1 << Mapping.Scale),
598 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
600 bool runOnFunction() {
601 if (!ClStack) return false;
602 // Collect alloca, ret, lifetime instructions etc.
603 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
605 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
607 initializeCallbacks(*F.getParent());
617 // Finds all Alloca instructions and puts
618 // poisoned red zones around all of them.
619 // Then unpoison everything back before the function returns.
622 void createDynamicAllocasInitStorage();
624 // ----------------------- Visitors.
625 /// \brief Collect all Ret instructions.
626 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
628 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
630 IRBuilder<> IRB(InstBefore);
631 IRB.CreateCall(AsanAllocasUnpoisonFunc,
632 {IRB.CreateLoad(DynamicAllocaLayout),
633 IRB.CreatePtrToInt(SavedStack, IntptrTy)});
636 // Unpoison dynamic allocas redzones.
637 void unpoisonDynamicAllocas() {
638 for (auto &Ret : RetVec)
639 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
641 for (auto &StackRestoreInst : StackRestoreVec)
642 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
643 StackRestoreInst->getOperand(0));
646 // Deploy and poison redzones around dynamic alloca call. To do this, we
647 // should replace this call with another one with changed parameters and
648 // replace all its uses with new address, so
649 // addr = alloca type, old_size, align
651 // new_size = (old_size + additional_size) * sizeof(type)
652 // tmp = alloca i8, new_size, max(align, 32)
653 // addr = tmp + 32 (first 32 bytes are for the left redzone).
654 // Additional_size is added to make new memory allocation contain not only
655 // requested memory, but also left, partial and right redzones.
656 void handleDynamicAllocaCall(AllocaInst *AI);
658 /// \brief Collect Alloca instructions we want (and can) handle.
659 void visitAllocaInst(AllocaInst &AI) {
660 if (!ASan.isInterestingAlloca(AI)) {
661 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI);
665 StackAlignment = std::max(StackAlignment, AI.getAlignment());
666 if (ASan.isDynamicAlloca(AI))
667 DynamicAllocaVec.push_back(&AI);
669 AllocaVec.push_back(&AI);
672 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
674 void visitIntrinsicInst(IntrinsicInst &II) {
675 Intrinsic::ID ID = II.getIntrinsicID();
676 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
677 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
678 if (!ClCheckLifetime) return;
679 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
681 // Found lifetime intrinsic, add ASan instrumentation if necessary.
682 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
683 // If size argument is undefined, don't do anything.
684 if (Size->isMinusOne()) return;
685 // Check that size doesn't saturate uint64_t and can
686 // be stored in IntptrTy.
687 const uint64_t SizeValue = Size->getValue().getLimitedValue();
688 if (SizeValue == ~0ULL ||
689 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
691 // Find alloca instruction that corresponds to llvm.lifetime argument.
692 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
694 bool DoPoison = (ID == Intrinsic::lifetime_end);
695 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
696 AllocaPoisonCallVec.push_back(APC);
699 void visitCallSite(CallSite CS) {
700 Instruction *I = CS.getInstruction();
701 if (CallInst *CI = dyn_cast<CallInst>(I)) {
702 HasNonEmptyInlineAsm |=
703 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
704 HasReturnsTwiceCall |= CI->canReturnTwice();
708 // ---------------------- Helpers.
709 void initializeCallbacks(Module &M);
711 bool doesDominateAllExits(const Instruction *I) const {
712 for (auto Ret : RetVec) {
713 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
718 /// Finds alloca where the value comes from.
719 AllocaInst *findAllocaForValue(Value *V);
720 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
721 Value *ShadowBase, bool DoPoison);
722 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
724 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
726 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
728 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
729 Instruction *ThenTerm, Value *ValueIfFalse);
732 } // anonymous namespace
734 char AddressSanitizer::ID = 0;
735 INITIALIZE_PASS_BEGIN(
736 AddressSanitizer, "asan",
737 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
739 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
740 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
742 AddressSanitizer, "asan",
743 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
745 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
746 return new AddressSanitizer(CompileKernel);
749 char AddressSanitizerModule::ID = 0;
751 AddressSanitizerModule, "asan-module",
752 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
755 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
756 return new AddressSanitizerModule(CompileKernel);
759 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
760 size_t Res = countTrailingZeros(TypeSize / 8);
761 assert(Res < kNumberOfAccessSizes);
765 // \brief Create a constant for Str so that we can pass it to the run-time lib.
766 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
768 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
769 // We use private linkage for module-local strings. If they can be merged
770 // with another one, we set the unnamed_addr attribute.
772 new GlobalVariable(M, StrConst->getType(), true,
773 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
774 if (AllowMerging) GV->setUnnamedAddr(true);
775 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
779 /// \brief Create a global describing a source location.
780 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
781 LocationMetadata MD) {
782 Constant *LocData[] = {
783 createPrivateGlobalForString(M, MD.Filename, true),
784 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
785 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
787 auto LocStruct = ConstantStruct::getAnon(LocData);
788 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
789 GlobalValue::PrivateLinkage, LocStruct,
791 GV->setUnnamedAddr(true);
795 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
796 return G->getName().find(kAsanGenPrefix) == 0 ||
797 G->getName().find(kSanCovGenPrefix) == 0;
800 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
802 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
803 if (Mapping.Offset == 0) return Shadow;
804 // (Shadow >> scale) | offset
805 if (Mapping.OrShadowOffset)
806 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
808 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
811 // Instrument memset/memmove/memcpy
812 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
814 if (isa<MemTransferInst>(MI)) {
816 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
817 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
818 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
819 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
820 } else if (isa<MemSetInst>(MI)) {
823 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
824 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
825 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
827 MI->eraseFromParent();
830 /// Check if we want (and can) handle this alloca.
831 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
832 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
834 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
835 return PreviouslySeenAllocaInfo->getSecond();
838 (AI.getAllocatedType()->isSized() &&
839 // alloca() may be called with 0 size, ignore it.
840 getAllocaSizeInBytes(&AI) > 0 &&
841 // We are only interested in allocas not promotable to registers.
842 // Promotable allocas are common under -O0.
843 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)));
845 ProcessedAllocas[&AI] = IsInteresting;
846 return IsInteresting;
849 /// If I is an interesting memory access, return the PointerOperand
850 /// and set IsWrite/Alignment. Otherwise return nullptr.
851 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
854 unsigned *Alignment) {
855 // Skip memory accesses inserted by another instrumentation.
856 if (I->getMetadata("nosanitize")) return nullptr;
858 Value *PtrOperand = nullptr;
859 const DataLayout &DL = I->getModule()->getDataLayout();
860 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
861 if (!ClInstrumentReads) return nullptr;
863 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
864 *Alignment = LI->getAlignment();
865 PtrOperand = LI->getPointerOperand();
866 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
867 if (!ClInstrumentWrites) return nullptr;
869 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
870 *Alignment = SI->getAlignment();
871 PtrOperand = SI->getPointerOperand();
872 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
873 if (!ClInstrumentAtomics) return nullptr;
875 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
877 PtrOperand = RMW->getPointerOperand();
878 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
879 if (!ClInstrumentAtomics) return nullptr;
881 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
883 PtrOperand = XCHG->getPointerOperand();
886 // Treat memory accesses to promotable allocas as non-interesting since they
887 // will not cause memory violations. This greatly speeds up the instrumented
888 // executable at -O0.
889 if (ClSkipPromotableAllocas)
890 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
891 return isInterestingAlloca(*AI) ? AI : nullptr;
896 static bool isPointerOperand(Value *V) {
897 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
900 // This is a rough heuristic; it may cause both false positives and
901 // false negatives. The proper implementation requires cooperation with
903 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
904 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
905 if (!Cmp->isRelational()) return false;
906 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
907 if (BO->getOpcode() != Instruction::Sub) return false;
911 return isPointerOperand(I->getOperand(0)) &&
912 isPointerOperand(I->getOperand(1));
915 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
916 // If a global variable does not have dynamic initialization we don't
917 // have to instrument it. However, if a global does not have initializer
918 // at all, we assume it has dynamic initializer (in other TU).
919 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
922 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
925 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
926 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
927 for (int i = 0; i < 2; i++) {
928 if (Param[i]->getType()->isPointerTy())
929 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
931 IRB.CreateCall(F, Param);
934 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
935 Instruction *I, bool UseCalls,
936 const DataLayout &DL) {
937 bool IsWrite = false;
938 unsigned Alignment = 0;
939 uint64_t TypeSize = 0;
940 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
943 // Optimization experiments.
944 // The experiments can be used to evaluate potential optimizations that remove
945 // instrumentation (assess false negatives). Instead of completely removing
946 // some instrumentation, you set Exp to a non-zero value (mask of optimization
947 // experiments that want to remove instrumentation of this instruction).
948 // If Exp is non-zero, this pass will emit special calls into runtime
949 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
950 // make runtime terminate the program in a special way (with a different
951 // exit status). Then you run the new compiler on a buggy corpus, collect
952 // the special terminations (ideally, you don't see them at all -- no false
953 // negatives) and make the decision on the optimization.
954 uint32_t Exp = ClForceExperiment;
956 if (ClOpt && ClOptGlobals) {
957 // If initialization order checking is disabled, a simple access to a
958 // dynamically initialized global is always valid.
959 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
960 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
961 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
962 NumOptimizedAccessesToGlobalVar++;
967 if (ClOpt && ClOptStack) {
968 // A direct inbounds access to a stack variable is always valid.
969 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
970 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
971 NumOptimizedAccessesToStackVar++;
977 NumInstrumentedWrites++;
979 NumInstrumentedReads++;
981 unsigned Granularity = 1 << Mapping.Scale;
982 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
983 // if the data is properly aligned.
984 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
986 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
987 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
989 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
993 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
994 Value *Addr, bool IsWrite,
995 size_t AccessSizeIndex,
998 IRBuilder<> IRB(InsertBefore);
999 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1000 CallInst *Call = nullptr;
1003 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1004 {Addr, SizeArgument});
1006 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1007 {Addr, SizeArgument, ExpVal});
1011 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1013 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1017 // We don't do Call->setDoesNotReturn() because the BB already has
1018 // UnreachableInst at the end.
1019 // This EmptyAsm is required to avoid callback merge.
1020 IRB.CreateCall(EmptyAsm, {});
1024 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1026 uint32_t TypeSize) {
1027 size_t Granularity = 1 << Mapping.Scale;
1028 // Addr & (Granularity - 1)
1029 Value *LastAccessedByte =
1030 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1031 // (Addr & (Granularity - 1)) + size - 1
1032 if (TypeSize / 8 > 1)
1033 LastAccessedByte = IRB.CreateAdd(
1034 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1035 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1037 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1038 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1039 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1042 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1043 Instruction *InsertBefore, Value *Addr,
1044 uint32_t TypeSize, bool IsWrite,
1045 Value *SizeArgument, bool UseCalls,
1047 IRBuilder<> IRB(InsertBefore);
1048 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1049 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1053 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1056 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1057 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1062 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1063 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1064 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1065 Value *CmpVal = Constant::getNullValue(ShadowTy);
1066 Value *ShadowValue =
1067 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1069 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1070 size_t Granularity = 1 << Mapping.Scale;
1071 TerminatorInst *CrashTerm = nullptr;
1073 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1074 // We use branch weights for the slow path check, to indicate that the slow
1075 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1076 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1077 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1078 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1079 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1080 IRB.SetInsertPoint(CheckTerm);
1081 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1082 BasicBlock *CrashBlock =
1083 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1084 CrashTerm = new UnreachableInst(*C, CrashBlock);
1085 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1086 ReplaceInstWithInst(CheckTerm, NewTerm);
1088 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1091 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1092 AccessSizeIndex, SizeArgument, Exp);
1093 Crash->setDebugLoc(OrigIns->getDebugLoc());
1096 // Instrument unusual size or unusual alignment.
1097 // We can not do it with a single check, so we do 1-byte check for the first
1098 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1099 // to report the actual access size.
1100 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1101 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1102 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1104 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1105 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1108 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1111 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1112 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1114 Value *LastByte = IRB.CreateIntToPtr(
1115 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1117 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1118 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1122 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1123 GlobalValue *ModuleName) {
1124 // Set up the arguments to our poison/unpoison functions.
1125 IRBuilder<> IRB(&GlobalInit.front(),
1126 GlobalInit.front().getFirstInsertionPt());
1128 // Add a call to poison all external globals before the given function starts.
1129 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1130 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1132 // Add calls to unpoison all globals before each return instruction.
1133 for (auto &BB : GlobalInit.getBasicBlockList())
1134 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1135 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1138 void AddressSanitizerModule::createInitializerPoisonCalls(
1139 Module &M, GlobalValue *ModuleName) {
1140 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1142 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1143 for (Use &OP : CA->operands()) {
1144 if (isa<ConstantAggregateZero>(OP)) continue;
1145 ConstantStruct *CS = cast<ConstantStruct>(OP);
1147 // Must have a function or null ptr.
1148 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1149 if (F->getName() == kAsanModuleCtorName) continue;
1150 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1151 // Don't instrument CTORs that will run before asan.module_ctor.
1152 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1153 poisonOneInitializer(*F, ModuleName);
1158 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1159 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1160 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1162 if (GlobalsMD.get(G).IsBlacklisted) return false;
1163 if (!Ty->isSized()) return false;
1164 if (!G->hasInitializer()) return false;
1165 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1166 // Touch only those globals that will not be defined in other modules.
1167 // Don't handle ODR linkage types and COMDATs since other modules may be built
1169 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1170 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1171 G->getLinkage() != GlobalVariable::InternalLinkage)
1173 if (G->hasComdat()) return false;
1174 // Two problems with thread-locals:
1175 // - The address of the main thread's copy can't be computed at link-time.
1176 // - Need to poison all copies, not just the main thread's one.
1177 if (G->isThreadLocal()) return false;
1178 // For now, just ignore this Global if the alignment is large.
1179 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1181 if (G->hasSection()) {
1182 StringRef Section(G->getSection());
1184 // Globals from llvm.metadata aren't emitted, do not instrument them.
1185 if (Section == "llvm.metadata") return false;
1186 // Do not instrument globals from special LLVM sections.
1187 if (Section.find("__llvm") != StringRef::npos) return false;
1189 // Do not instrument function pointers to initialization and termination
1190 // routines: dynamic linker will not properly handle redzones.
1191 if (Section.startswith(".preinit_array") ||
1192 Section.startswith(".init_array") ||
1193 Section.startswith(".fini_array")) {
1197 // Callbacks put into the CRT initializer/terminator sections
1198 // should not be instrumented.
1199 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1200 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1201 if (Section.startswith(".CRT")) {
1202 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1206 if (TargetTriple.isOSBinFormatMachO()) {
1207 StringRef ParsedSegment, ParsedSection;
1208 unsigned TAA = 0, StubSize = 0;
1210 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1211 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1212 if (!ErrorCode.empty()) {
1213 assert(false && "Invalid section specifier.");
1217 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1218 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1220 if (ParsedSegment == "__OBJC" ||
1221 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1222 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1225 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1226 // Constant CFString instances are compiled in the following way:
1227 // -- the string buffer is emitted into
1228 // __TEXT,__cstring,cstring_literals
1229 // -- the constant NSConstantString structure referencing that buffer
1230 // is placed into __DATA,__cfstring
1231 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1232 // Moreover, it causes the linker to crash on OS X 10.7
1233 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1234 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1237 // The linker merges the contents of cstring_literals and removes the
1239 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1240 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1249 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1250 IRBuilder<> IRB(*C);
1251 // Declare our poisoning and unpoisoning functions.
1252 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1253 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1254 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1255 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1256 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1257 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1258 // Declare functions that register/unregister globals.
1259 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1260 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1261 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1262 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1263 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1264 IntptrTy, IntptrTy, nullptr));
1265 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1268 // This function replaces all global variables with new variables that have
1269 // trailing redzones. It also creates a function that poisons
1270 // redzones and inserts this function into llvm.global_ctors.
1271 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1274 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1276 for (auto &G : M.globals()) {
1277 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1280 size_t n = GlobalsToChange.size();
1281 if (n == 0) return false;
1283 // A global is described by a structure
1286 // size_t size_with_redzone;
1287 // const char *name;
1288 // const char *module_name;
1289 // size_t has_dynamic_init;
1290 // void *source_location;
1291 // We initialize an array of such structures and pass it to a run-time call.
1292 StructType *GlobalStructTy =
1293 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1294 IntptrTy, IntptrTy, nullptr);
1295 SmallVector<Constant *, 16> Initializers(n);
1297 bool HasDynamicallyInitializedGlobals = false;
1299 // We shouldn't merge same module names, as this string serves as unique
1300 // module ID in runtime.
1301 GlobalVariable *ModuleName = createPrivateGlobalForString(
1302 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1304 auto &DL = M.getDataLayout();
1305 for (size_t i = 0; i < n; i++) {
1306 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1307 GlobalVariable *G = GlobalsToChange[i];
1309 auto MD = GlobalsMD.get(G);
1310 // Create string holding the global name (use global name from metadata
1311 // if it's available, otherwise just write the name of global variable).
1312 GlobalVariable *Name = createPrivateGlobalForString(
1313 M, MD.Name.empty() ? G->getName() : MD.Name,
1314 /*AllowMerging*/ true);
1316 PointerType *PtrTy = cast<PointerType>(G->getType());
1317 Type *Ty = PtrTy->getElementType();
1318 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1319 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1320 // MinRZ <= RZ <= kMaxGlobalRedzone
1321 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1322 uint64_t RZ = std::max(
1323 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1324 uint64_t RightRedzoneSize = RZ;
1325 // Round up to MinRZ
1326 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1327 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1328 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1330 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1331 Constant *NewInitializer =
1332 ConstantStruct::get(NewTy, G->getInitializer(),
1333 Constant::getNullValue(RightRedZoneTy), nullptr);
1335 // Create a new global variable with enough space for a redzone.
1336 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1337 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1338 Linkage = GlobalValue::InternalLinkage;
1339 GlobalVariable *NewGlobal =
1340 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1341 "", G, G->getThreadLocalMode());
1342 NewGlobal->copyAttributesFrom(G);
1343 NewGlobal->setAlignment(MinRZ);
1346 Indices2[0] = IRB.getInt32(0);
1347 Indices2[1] = IRB.getInt32(0);
1349 G->replaceAllUsesWith(
1350 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1351 NewGlobal->takeName(G);
1352 G->eraseFromParent();
1354 Constant *SourceLoc;
1355 if (!MD.SourceLoc.empty()) {
1356 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1357 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1359 SourceLoc = ConstantInt::get(IntptrTy, 0);
1362 Initializers[i] = ConstantStruct::get(
1363 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1364 ConstantInt::get(IntptrTy, SizeInBytes),
1365 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1366 ConstantExpr::getPointerCast(Name, IntptrTy),
1367 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1368 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1370 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1372 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1375 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1376 GlobalVariable *AllGlobals = new GlobalVariable(
1377 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1378 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1380 // Create calls for poisoning before initializers run and unpoisoning after.
1381 if (HasDynamicallyInitializedGlobals)
1382 createInitializerPoisonCalls(M, ModuleName);
1383 IRB.CreateCall(AsanRegisterGlobals,
1384 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1385 ConstantInt::get(IntptrTy, n)});
1387 // We also need to unregister globals at the end, e.g. when a shared library
1389 Function *AsanDtorFunction =
1390 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1391 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1392 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1393 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1394 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1395 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1396 ConstantInt::get(IntptrTy, n)});
1397 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1403 bool AddressSanitizerModule::runOnModule(Module &M) {
1404 C = &(M.getContext());
1405 int LongSize = M.getDataLayout().getPointerSizeInBits();
1406 IntptrTy = Type::getIntNTy(*C, LongSize);
1407 TargetTriple = Triple(M.getTargetTriple());
1408 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1409 initializeCallbacks(M);
1411 bool Changed = false;
1413 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1414 if (ClGlobals && !CompileKernel) {
1415 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1417 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1418 Changed |= InstrumentGlobals(IRB, M);
1424 void AddressSanitizer::initializeCallbacks(Module &M) {
1425 IRBuilder<> IRB(*C);
1426 // Create __asan_report* callbacks.
1427 // IsWrite, TypeSize and Exp are encoded in the function name.
1428 for (int Exp = 0; Exp < 2; Exp++) {
1429 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1430 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1431 const std::string ExpStr = Exp ? "exp_" : "";
1432 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1433 const std::string EndingStr = CompileKernel ? "_noabort" : "";
1434 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1435 // TODO(glider): for KASan builds add _noabort to error reporting
1436 // functions and make them actually noabort (remove the UnreachableInst).
1437 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1438 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1439 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
1440 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1441 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1442 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1443 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1444 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1445 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1446 AccessSizeIndex++) {
1447 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1448 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1449 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1450 kAsanReportErrorTemplate + ExpStr + Suffix,
1451 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1452 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1453 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1454 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1455 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1460 const std::string MemIntrinCallbackPrefix =
1461 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1462 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1463 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1464 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1465 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1466 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1467 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1468 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1469 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1470 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1472 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1473 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1475 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1476 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1477 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1478 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1479 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1480 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1481 StringRef(""), StringRef(""),
1482 /*hasSideEffects=*/true);
1486 bool AddressSanitizer::doInitialization(Module &M) {
1487 // Initialize the private fields. No one has accessed them before.
1491 C = &(M.getContext());
1492 LongSize = M.getDataLayout().getPointerSizeInBits();
1493 IntptrTy = Type::getIntNTy(*C, LongSize);
1494 TargetTriple = Triple(M.getTargetTriple());
1496 if (!CompileKernel) {
1497 std::tie(AsanCtorFunction, AsanInitFunction) =
1498 createSanitizerCtorAndInitFunctions(
1499 M, kAsanModuleCtorName, kAsanInitName,
1500 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1501 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1503 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1507 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1508 // For each NSObject descendant having a +load method, this method is invoked
1509 // by the ObjC runtime before any of the static constructors is called.
1510 // Therefore we need to instrument such methods with a call to __asan_init
1511 // at the beginning in order to initialize our runtime before any access to
1512 // the shadow memory.
1513 // We cannot just ignore these methods, because they may call other
1514 // instrumented functions.
1515 if (F.getName().find(" load]") != std::string::npos) {
1516 IRBuilder<> IRB(&F.front(), F.front().begin());
1517 IRB.CreateCall(AsanInitFunction, {});
1523 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1524 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1525 // to it as uninteresting. This assumes we haven't started processing allocas
1526 // yet. This check is done up front because iterating the use list in
1527 // isInterestingAlloca would be algorithmically slower.
1528 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1530 // Try to get the declaration of llvm.localescape. If it's not in the module,
1531 // we can exit early.
1532 if (!F.getParent()->getFunction("llvm.localescape")) return;
1534 // Look for a call to llvm.localescape call in the entry block. It can't be in
1536 for (Instruction &I : F.getEntryBlock()) {
1537 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
1538 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
1539 // We found a call. Mark all the allocas passed in as uninteresting.
1540 for (Value *Arg : II->arg_operands()) {
1541 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
1542 assert(AI && AI->isStaticAlloca() &&
1543 "non-static alloca arg to localescape");
1544 ProcessedAllocas[AI] = false;
1551 bool AddressSanitizer::runOnFunction(Function &F) {
1552 if (&F == AsanCtorFunction) return false;
1553 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1554 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1555 initializeCallbacks(*F.getParent());
1557 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1559 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1560 maybeInsertAsanInitAtFunctionEntry(F);
1562 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1564 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1566 FunctionStateRAII CleanupObj(this);
1568 // We can't instrument allocas used with llvm.localescape. Only static allocas
1569 // can be passed to that intrinsic.
1570 markEscapedLocalAllocas(F);
1572 // We want to instrument every address only once per basic block (unless there
1573 // are calls between uses).
1574 SmallSet<Value *, 16> TempsToInstrument;
1575 SmallVector<Instruction *, 16> ToInstrument;
1576 SmallVector<Instruction *, 8> NoReturnCalls;
1577 SmallVector<BasicBlock *, 16> AllBlocks;
1578 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1584 // Fill the set of memory operations to instrument.
1585 for (auto &BB : F) {
1586 AllBlocks.push_back(&BB);
1587 TempsToInstrument.clear();
1588 int NumInsnsPerBB = 0;
1589 for (auto &Inst : BB) {
1590 if (LooksLikeCodeInBug11395(&Inst)) return false;
1591 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1593 if (ClOpt && ClOptSameTemp) {
1594 if (!TempsToInstrument.insert(Addr).second)
1595 continue; // We've seen this temp in the current BB.
1597 } else if (ClInvalidPointerPairs &&
1598 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1599 PointerComparisonsOrSubtracts.push_back(&Inst);
1601 } else if (isa<MemIntrinsic>(Inst)) {
1604 if (isa<AllocaInst>(Inst)) NumAllocas++;
1607 // A call inside BB.
1608 TempsToInstrument.clear();
1609 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1613 ToInstrument.push_back(&Inst);
1615 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1621 (ClInstrumentationWithCallsThreshold >= 0 &&
1622 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1623 const TargetLibraryInfo *TLI =
1624 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1625 const DataLayout &DL = F.getParent()->getDataLayout();
1626 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1627 /*RoundToAlign=*/true);
1630 int NumInstrumented = 0;
1631 for (auto Inst : ToInstrument) {
1632 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1633 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1634 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1635 instrumentMop(ObjSizeVis, Inst, UseCalls,
1636 F.getParent()->getDataLayout());
1638 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1643 FunctionStackPoisoner FSP(F, *this);
1644 bool ChangedStack = FSP.runOnFunction();
1646 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1647 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1648 for (auto CI : NoReturnCalls) {
1649 IRBuilder<> IRB(CI);
1650 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1653 for (auto Inst : PointerComparisonsOrSubtracts) {
1654 instrumentPointerComparisonOrSubtraction(Inst);
1658 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1660 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1665 // Workaround for bug 11395: we don't want to instrument stack in functions
1666 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1667 // FIXME: remove once the bug 11395 is fixed.
1668 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1669 if (LongSize != 32) return false;
1670 CallInst *CI = dyn_cast<CallInst>(I);
1671 if (!CI || !CI->isInlineAsm()) return false;
1672 if (CI->getNumArgOperands() <= 5) return false;
1673 // We have inline assembly with quite a few arguments.
1677 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1678 IRBuilder<> IRB(*C);
1679 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1680 std::string Suffix = itostr(i);
1681 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1682 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1683 IntptrTy, nullptr));
1684 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1685 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1686 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1688 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1689 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1690 IntptrTy, IntptrTy, nullptr));
1691 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1692 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1693 IntptrTy, IntptrTy, nullptr));
1694 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1695 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1696 AsanAllocasUnpoisonFunc =
1697 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1698 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1701 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1702 IRBuilder<> &IRB, Value *ShadowBase,
1704 size_t n = ShadowBytes.size();
1706 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1707 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1708 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1709 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1710 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1711 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1713 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1714 if (F.getParent()->getDataLayout().isLittleEndian())
1715 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1717 Val = (Val << 8) | ShadowBytes[i + j];
1720 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1721 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1722 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1723 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1728 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1729 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1730 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1731 assert(LocalStackSize <= kMaxStackMallocSize);
1732 uint64_t MaxSize = kMinStackMallocSize;
1733 for (int i = 0;; i++, MaxSize *= 2)
1734 if (LocalStackSize <= MaxSize) return i;
1735 llvm_unreachable("impossible LocalStackSize");
1738 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1739 // We can not use MemSet intrinsic because it may end up calling the actual
1740 // memset. Size is a multiple of 8.
1741 // Currently this generates 8-byte stores on x86_64; it may be better to
1742 // generate wider stores.
1743 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1744 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1745 assert(!(Size % 8));
1747 // kAsanStackAfterReturnMagic is 0xf5.
1748 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1750 for (int i = 0; i < Size; i += 8) {
1751 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1753 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1754 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1758 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1760 Instruction *ThenTerm,
1761 Value *ValueIfFalse) {
1762 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1763 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1764 PHI->addIncoming(ValueIfFalse, CondBlock);
1765 BasicBlock *ThenBlock = ThenTerm->getParent();
1766 PHI->addIncoming(ValueIfTrue, ThenBlock);
1770 Value *FunctionStackPoisoner::createAllocaForLayout(
1771 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1774 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1775 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1778 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1779 nullptr, "MyAlloca");
1780 assert(Alloca->isStaticAlloca());
1782 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1783 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1784 Alloca->setAlignment(FrameAlignment);
1785 return IRB.CreatePointerCast(Alloca, IntptrTy);
1788 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1789 BasicBlock &FirstBB = *F.begin();
1790 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1791 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1792 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1793 DynamicAllocaLayout->setAlignment(32);
1796 void FunctionStackPoisoner::poisonStack() {
1797 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1799 // Insert poison calls for lifetime intrinsics for alloca.
1800 bool HavePoisonedAllocas = false;
1801 for (const auto &APC : AllocaPoisonCallVec) {
1802 assert(APC.InsBefore);
1804 IRBuilder<> IRB(APC.InsBefore);
1805 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1806 HavePoisonedAllocas |= APC.DoPoison;
1809 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1810 // Handle dynamic allocas.
1811 createDynamicAllocasInitStorage();
1812 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1814 unpoisonDynamicAllocas();
1817 if (AllocaVec.empty()) return;
1819 int StackMallocIdx = -1;
1820 DebugLoc EntryDebugLocation;
1821 if (auto SP = getDISubprogram(&F))
1822 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1824 Instruction *InsBefore = AllocaVec[0];
1825 IRBuilder<> IRB(InsBefore);
1826 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1828 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
1829 // debug info is broken, because only entry-block allocas are treated as
1830 // regular stack slots.
1831 auto InsBeforeB = InsBefore->getParent();
1832 assert(InsBeforeB == &F.getEntryBlock());
1833 for (BasicBlock::iterator I(InsBefore); I != InsBeforeB->end(); ++I)
1834 if (auto *AI = dyn_cast<AllocaInst>(I))
1835 if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
1836 AI->moveBefore(InsBefore);
1838 // If we have a call to llvm.localescape, keep it in the entry block.
1839 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
1841 SmallVector<ASanStackVariableDescription, 16> SVD;
1842 SVD.reserve(AllocaVec.size());
1843 for (AllocaInst *AI : AllocaVec) {
1844 ASanStackVariableDescription D = {AI->getName().data(),
1845 ASan.getAllocaSizeInBytes(AI),
1846 AI->getAlignment(), AI, 0};
1849 // Minimal header size (left redzone) is 4 pointers,
1850 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1851 size_t MinHeaderSize = ASan.LongSize / 2;
1852 ASanStackFrameLayout L;
1853 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1854 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1855 uint64_t LocalStackSize = L.FrameSize;
1856 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1857 LocalStackSize <= kMaxStackMallocSize;
1858 bool DoDynamicAlloca = ClDynamicAllocaStack;
1859 // Don't do dynamic alloca or stack malloc if:
1860 // 1) There is inline asm: too often it makes assumptions on which registers
1862 // 2) There is a returns_twice call (typically setjmp), which is
1863 // optimization-hostile, and doesn't play well with introduced indirect
1864 // register-relative calculation of local variable addresses.
1865 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1866 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1868 Value *StaticAlloca =
1869 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1872 Value *LocalStackBase;
1874 if (DoStackMalloc) {
1875 // void *FakeStack = __asan_option_detect_stack_use_after_return
1876 // ? __asan_stack_malloc_N(LocalStackSize)
1878 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1879 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1880 kAsanOptionDetectUAR, IRB.getInt32Ty());
1881 Value *UARIsEnabled =
1882 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1883 Constant::getNullValue(IRB.getInt32Ty()));
1885 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1886 IRBuilder<> IRBIf(Term);
1887 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1888 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1889 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1890 Value *FakeStackValue =
1891 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1892 ConstantInt::get(IntptrTy, LocalStackSize));
1893 IRB.SetInsertPoint(InsBefore);
1894 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1895 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1896 ConstantInt::get(IntptrTy, 0));
1898 Value *NoFakeStack =
1899 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1900 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1901 IRBIf.SetInsertPoint(Term);
1902 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1903 Value *AllocaValue =
1904 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1905 IRB.SetInsertPoint(InsBefore);
1906 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1907 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1909 // void *FakeStack = nullptr;
1910 // void *LocalStackBase = alloca(LocalStackSize);
1911 FakeStack = ConstantInt::get(IntptrTy, 0);
1913 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1916 // Replace Alloca instructions with base+offset.
1917 for (const auto &Desc : SVD) {
1918 AllocaInst *AI = Desc.AI;
1919 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1920 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1922 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1923 AI->replaceAllUsesWith(NewAllocaPtr);
1926 // The left-most redzone has enough space for at least 4 pointers.
1927 // Write the Magic value to redzone[0].
1928 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1929 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1931 // Write the frame description constant to redzone[1].
1932 Value *BasePlus1 = IRB.CreateIntToPtr(
1933 IRB.CreateAdd(LocalStackBase,
1934 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1936 GlobalVariable *StackDescriptionGlobal =
1937 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1938 /*AllowMerging*/ true);
1939 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1940 IRB.CreateStore(Description, BasePlus1);
1941 // Write the PC to redzone[2].
1942 Value *BasePlus2 = IRB.CreateIntToPtr(
1943 IRB.CreateAdd(LocalStackBase,
1944 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1946 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1948 // Poison the stack redzones at the entry.
1949 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1950 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1952 // (Un)poison the stack before all ret instructions.
1953 for (auto Ret : RetVec) {
1954 IRBuilder<> IRBRet(Ret);
1955 // Mark the current frame as retired.
1956 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1958 if (DoStackMalloc) {
1959 assert(StackMallocIdx >= 0);
1960 // if FakeStack != 0 // LocalStackBase == FakeStack
1961 // // In use-after-return mode, poison the whole stack frame.
1962 // if StackMallocIdx <= 4
1963 // // For small sizes inline the whole thing:
1964 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1965 // **SavedFlagPtr(FakeStack) = 0
1967 // __asan_stack_free_N(FakeStack, LocalStackSize)
1969 // <This is not a fake stack; unpoison the redzones>
1971 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1972 TerminatorInst *ThenTerm, *ElseTerm;
1973 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1975 IRBuilder<> IRBPoison(ThenTerm);
1976 if (StackMallocIdx <= 4) {
1977 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1978 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1979 ClassSize >> Mapping.Scale);
1980 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1982 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1983 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1984 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1985 IRBPoison.CreateStore(
1986 Constant::getNullValue(IRBPoison.getInt8Ty()),
1987 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1989 // For larger frames call __asan_stack_free_*.
1990 IRBPoison.CreateCall(
1991 AsanStackFreeFunc[StackMallocIdx],
1992 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1995 IRBuilder<> IRBElse(ElseTerm);
1996 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1997 } else if (HavePoisonedAllocas) {
1998 // If we poisoned some allocas in llvm.lifetime analysis,
1999 // unpoison whole stack frame now.
2000 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
2002 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
2006 // We are done. Remove the old unused alloca instructions.
2007 for (auto AI : AllocaVec) AI->eraseFromParent();
2010 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2011 IRBuilder<> &IRB, bool DoPoison) {
2012 // For now just insert the call to ASan runtime.
2013 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2014 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2016 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2017 {AddrArg, SizeArg});
2020 // Handling llvm.lifetime intrinsics for a given %alloca:
2021 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2022 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2023 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2024 // could be poisoned by previous llvm.lifetime.end instruction, as the
2025 // variable may go in and out of scope several times, e.g. in loops).
2026 // (3) if we poisoned at least one %alloca in a function,
2027 // unpoison the whole stack frame at function exit.
2029 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2030 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2031 // We're intested only in allocas we can handle.
2032 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2033 // See if we've already calculated (or started to calculate) alloca for a
2035 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2036 if (I != AllocaForValue.end()) return I->second;
2037 // Store 0 while we're calculating alloca for value V to avoid
2038 // infinite recursion if the value references itself.
2039 AllocaForValue[V] = nullptr;
2040 AllocaInst *Res = nullptr;
2041 if (CastInst *CI = dyn_cast<CastInst>(V))
2042 Res = findAllocaForValue(CI->getOperand(0));
2043 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2044 for (Value *IncValue : PN->incoming_values()) {
2045 // Allow self-referencing phi-nodes.
2046 if (IncValue == PN) continue;
2047 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2048 // AI for incoming values should exist and should all be equal.
2049 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2054 if (Res) AllocaForValue[V] = Res;
2058 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2059 IRBuilder<> IRB(AI);
2061 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2062 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2064 Value *Zero = Constant::getNullValue(IntptrTy);
2065 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2066 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2068 // Since we need to extend alloca with additional memory to locate
2069 // redzones, and OldSize is number of allocated blocks with
2070 // ElementSize size, get allocated memory size in bytes by
2071 // OldSize * ElementSize.
2072 const unsigned ElementSize =
2073 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2075 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2076 ConstantInt::get(IntptrTy, ElementSize));
2078 // PartialSize = OldSize % 32
2079 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2081 // Misalign = kAllocaRzSize - PartialSize;
2082 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2084 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2085 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2086 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2088 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2089 // Align is added to locate left redzone, PartialPadding for possible
2090 // partial redzone and kAllocaRzSize for right redzone respectively.
2091 Value *AdditionalChunkSize = IRB.CreateAdd(
2092 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2094 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2096 // Insert new alloca with new NewSize and Align params.
2097 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2098 NewAlloca->setAlignment(Align);
2100 // NewAddress = Address + Align
2101 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2102 ConstantInt::get(IntptrTy, Align));
2104 // Insert __asan_alloca_poison call for new created alloca.
2105 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2107 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2108 // for unpoisoning stuff.
2109 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2111 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2113 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2114 AI->replaceAllUsesWith(NewAddressPtr);
2116 // We are done. Erase old alloca from parent.
2117 AI->eraseFromParent();
2120 // isSafeAccess returns true if Addr is always inbounds with respect to its
2121 // base object. For example, it is a field access or an array access with
2122 // constant inbounds index.
2123 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2124 Value *Addr, uint64_t TypeSize) const {
2125 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2126 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2127 uint64_t Size = SizeOffset.first.getZExtValue();
2128 int64_t Offset = SizeOffset.second.getSExtValue();
2129 // Three checks are required to ensure safety:
2130 // . Offset >= 0 (since the offset is given from the base ptr)
2131 // . Size >= Offset (unsigned)
2132 // . Size - Offset >= NeededSize (unsigned)
2133 return Offset >= 0 && Size >= uint64_t(Offset) &&
2134 Size - uint64_t(Offset) >= TypeSize / 8;