1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Instrumentation.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/ADT/DepthFirstIterator.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/IR/CallSite.h"
28 #include "llvm/IR/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/InstVisitor.h"
34 #include "llvm/IR/IntrinsicInst.h"
35 #include "llvm/IR/LLVMContext.h"
36 #include "llvm/IR/MDBuilder.h"
37 #include "llvm/IR/Module.h"
38 #include "llvm/IR/Type.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/DataTypes.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/Endian.h"
43 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/Cloning.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
50 #include <system_error>
54 #define DEBUG_TYPE "asan"
56 static const uint64_t kDefaultShadowScale = 3;
57 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
58 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
60 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
61 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
62 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
63 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
64 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
66 static const size_t kMinStackMallocSize = 1 << 6; // 64B
67 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
68 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
69 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
71 static const char *const kAsanModuleCtorName = "asan.module_ctor";
72 static const char *const kAsanModuleDtorName = "asan.module_dtor";
73 static const int kAsanCtorAndDtorPriority = 1;
74 static const char *const kAsanReportErrorTemplate = "__asan_report_";
75 static const char *const kAsanReportLoadN = "__asan_report_load_n";
76 static const char *const kAsanReportStoreN = "__asan_report_store_n";
77 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
78 static const char *const kAsanUnregisterGlobalsName =
79 "__asan_unregister_globals";
80 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
81 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
82 static const char *const kAsanInitName = "__asan_init_v4";
83 static const char *const kAsanCovModuleInitName = "__sanitizer_cov_module_init";
84 static const char *const kAsanCovName = "__sanitizer_cov";
85 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
86 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
87 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
88 static const int kMaxAsanStackMallocSizeClass = 10;
89 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
90 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
91 static const char *const kAsanGenPrefix = "__asan_gen_";
92 static const char *const kAsanPoisonStackMemoryName =
93 "__asan_poison_stack_memory";
94 static const char *const kAsanUnpoisonStackMemoryName =
95 "__asan_unpoison_stack_memory";
97 static const char *const kAsanOptionDetectUAR =
98 "__asan_option_detect_stack_use_after_return";
101 static const int kAsanStackAfterReturnMagic = 0xf5;
104 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105 static const size_t kNumberOfAccessSizes = 5;
107 // Command-line flags.
109 // This flag may need to be replaced with -f[no-]asan-reads.
110 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
111 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
112 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
113 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
114 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
115 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
116 cl::Hidden, cl::init(true));
117 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
118 cl::desc("use instrumentation with slow path for all accesses"),
119 cl::Hidden, cl::init(false));
120 // This flag limits the number of instructions to be instrumented
121 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
122 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
124 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
126 cl::desc("maximal number of instructions to instrument in any given BB"),
128 // This flag may need to be replaced with -f[no]asan-stack.
129 static cl::opt<bool> ClStack("asan-stack",
130 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
131 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
132 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
133 // This flag may need to be replaced with -f[no]asan-globals.
134 static cl::opt<bool> ClGlobals("asan-globals",
135 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
136 static cl::opt<int> ClCoverage("asan-coverage",
137 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
138 cl::Hidden, cl::init(false));
139 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
140 cl::desc("Add coverage instrumentation only to the entry block if there "
141 "are more than this number of blocks."),
142 cl::Hidden, cl::init(1500));
143 static cl::opt<bool> ClInitializers("asan-initialization-order",
144 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
145 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
146 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
147 cl::Hidden, cl::init(false));
148 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
149 cl::desc("Realign stack to the value of this flag (power of two)"),
150 cl::Hidden, cl::init(32));
151 static cl::opt<int> ClInstrumentationWithCallsThreshold(
152 "asan-instrumentation-with-call-threshold",
153 cl::desc("If the function being instrumented contains more than "
154 "this number of memory accesses, use callbacks instead of "
155 "inline checks (-1 means never use callbacks)."),
156 cl::Hidden, cl::init(7000));
157 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
158 "asan-memory-access-callback-prefix",
159 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
160 cl::init("__asan_"));
162 // This is an experimental feature that will allow to choose between
163 // instrumented and non-instrumented code at link-time.
164 // If this option is on, just before instrumenting a function we create its
165 // clone; if the function is not changed by asan the clone is deleted.
166 // If we end up with a clone, we put the instrumented function into a section
167 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
169 // This is still a prototype, we need to figure out a way to keep two copies of
170 // a function so that the linker can easily choose one of them.
171 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
172 cl::desc("Keep uninstrumented copies of functions"),
173 cl::Hidden, cl::init(false));
175 // These flags allow to change the shadow mapping.
176 // The shadow mapping looks like
177 // Shadow = (Mem >> scale) + (1 << offset_log)
178 static cl::opt<int> ClMappingScale("asan-mapping-scale",
179 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
181 // Optimization flags. Not user visible, used mostly for testing
182 // and benchmarking the tool.
183 static cl::opt<bool> ClOpt("asan-opt",
184 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
185 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
186 cl::desc("Instrument the same temp just once"), cl::Hidden,
188 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
189 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
191 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
192 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
193 cl::Hidden, cl::init(false));
196 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
198 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
199 cl::Hidden, cl::init(0));
200 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
201 cl::Hidden, cl::desc("Debug func"));
202 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
203 cl::Hidden, cl::init(-1));
204 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
205 cl::Hidden, cl::init(-1));
207 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
208 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
209 STATISTIC(NumOptimizedAccessesToGlobalArray,
210 "Number of optimized accesses to global arrays");
211 STATISTIC(NumOptimizedAccessesToGlobalVar,
212 "Number of optimized accesses to global vars");
215 /// Frontend-provided metadata for source location.
216 struct LocationMetadata {
221 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
223 bool empty() const { return Filename.empty(); }
225 void parse(MDNode *MDN) {
226 assert(MDN->getNumOperands() == 3);
227 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
228 Filename = MDFilename->getString();
229 LineNo = cast<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
230 ColumnNo = cast<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
234 /// Frontend-provided metadata for global variables.
235 class GlobalsMetadata {
239 : SourceLoc(), Name(), IsDynInit(false),
240 IsBlacklisted(false) {}
241 LocationMetadata SourceLoc;
247 GlobalsMetadata() : inited_(false) {}
249 void init(Module& M) {
252 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
255 for (auto MDN : Globals->operands()) {
256 // Metadata node contains the global and the fields of "Entry".
257 assert(MDN->getNumOperands() == 5);
258 Value *V = MDN->getOperand(0);
259 // The optimizer may optimize away a global entirely.
262 GlobalVariable *GV = cast<GlobalVariable>(V);
263 // We can already have an entry for GV if it was merged with another
265 Entry &E = Entries[GV];
266 if (Value *Loc = MDN->getOperand(1))
267 E.SourceLoc.parse(cast<MDNode>(Loc));
268 if (Value *Name = MDN->getOperand(2)) {
269 MDString *MDName = cast<MDString>(Name);
270 E.Name = MDName->getString();
272 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
273 E.IsDynInit |= IsDynInit->isOne();
274 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
275 E.IsBlacklisted |= IsBlacklisted->isOne();
279 /// Returns metadata entry for a given global.
280 Entry get(GlobalVariable *G) const {
281 auto Pos = Entries.find(G);
282 return (Pos != Entries.end()) ? Pos->second : Entry();
287 DenseMap<GlobalVariable*, Entry> Entries;
290 /// This struct defines the shadow mapping using the rule:
291 /// shadow = (mem >> Scale) ADD-or-OR Offset.
292 struct ShadowMapping {
298 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
299 llvm::Triple TargetTriple(M.getTargetTriple());
300 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
301 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
302 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
303 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
304 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
305 TargetTriple.getArch() == llvm::Triple::ppc64le;
306 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
307 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
308 TargetTriple.getArch() == llvm::Triple::mipsel;
310 ShadowMapping Mapping;
312 if (LongSize == 32) {
316 Mapping.Offset = kMIPS32_ShadowOffset32;
318 Mapping.Offset = kFreeBSD_ShadowOffset32;
320 Mapping.Offset = kIOSShadowOffset32;
322 Mapping.Offset = kDefaultShadowOffset32;
323 } else { // LongSize == 64
325 Mapping.Offset = kPPC64_ShadowOffset64;
327 Mapping.Offset = kFreeBSD_ShadowOffset64;
328 else if (IsLinux && IsX86_64)
329 Mapping.Offset = kSmallX86_64ShadowOffset;
331 Mapping.Offset = kDefaultShadowOffset64;
334 Mapping.Scale = kDefaultShadowScale;
335 if (ClMappingScale) {
336 Mapping.Scale = ClMappingScale;
339 // OR-ing shadow offset if more efficient (at least on x86) if the offset
340 // is a power of two, but on ppc64 we have to use add since the shadow
341 // offset is not necessary 1/8-th of the address space.
342 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
347 static size_t RedzoneSizeForScale(int MappingScale) {
348 // Redzone used for stack and globals is at least 32 bytes.
349 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
350 return std::max(32U, 1U << MappingScale);
353 /// AddressSanitizer: instrument the code in module to find memory bugs.
354 struct AddressSanitizer : public FunctionPass {
355 AddressSanitizer() : FunctionPass(ID) {}
356 const char *getPassName() const override {
357 return "AddressSanitizerFunctionPass";
359 void instrumentMop(Instruction *I, bool UseCalls);
360 void instrumentPointerComparisonOrSubtraction(Instruction *I);
361 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
362 Value *Addr, uint32_t TypeSize, bool IsWrite,
363 Value *SizeArgument, bool UseCalls);
364 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
365 Value *ShadowValue, uint32_t TypeSize);
366 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
367 bool IsWrite, size_t AccessSizeIndex,
368 Value *SizeArgument);
369 void instrumentMemIntrinsic(MemIntrinsic *MI);
370 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
371 bool runOnFunction(Function &F) override;
372 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
373 bool doInitialization(Module &M) override;
374 static char ID; // Pass identification, replacement for typeid
377 void initializeCallbacks(Module &M);
379 bool LooksLikeCodeInBug11395(Instruction *I);
380 bool GlobalIsLinkerInitialized(GlobalVariable *G);
381 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
382 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
385 const DataLayout *DL;
388 ShadowMapping Mapping;
389 Function *AsanCtorFunction;
390 Function *AsanInitFunction;
391 Function *AsanHandleNoReturnFunc;
392 Function *AsanCovFunction;
393 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
394 // This array is indexed by AccessIsWrite and log2(AccessSize).
395 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
396 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
397 // This array is indexed by AccessIsWrite.
398 Function *AsanErrorCallbackSized[2],
399 *AsanMemoryAccessCallbackSized[2];
400 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
402 GlobalsMetadata GlobalsMD;
404 friend struct FunctionStackPoisoner;
407 class AddressSanitizerModule : public ModulePass {
409 AddressSanitizerModule() : ModulePass(ID) {}
410 bool runOnModule(Module &M) override;
411 static char ID; // Pass identification, replacement for typeid
412 const char *getPassName() const override {
413 return "AddressSanitizerModule";
417 void initializeCallbacks(Module &M);
419 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
420 bool ShouldInstrumentGlobal(GlobalVariable *G);
421 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
422 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
423 size_t MinRedzoneSizeForGlobal() const {
424 return RedzoneSizeForScale(Mapping.Scale);
427 GlobalsMetadata GlobalsMD;
430 const DataLayout *DL;
431 ShadowMapping Mapping;
432 Function *AsanPoisonGlobals;
433 Function *AsanUnpoisonGlobals;
434 Function *AsanRegisterGlobals;
435 Function *AsanUnregisterGlobals;
436 Function *AsanCovModuleInit;
439 // Stack poisoning does not play well with exception handling.
440 // When an exception is thrown, we essentially bypass the code
441 // that unpoisones the stack. This is why the run-time library has
442 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
443 // stack in the interceptor. This however does not work inside the
444 // actual function which catches the exception. Most likely because the
445 // compiler hoists the load of the shadow value somewhere too high.
446 // This causes asan to report a non-existing bug on 453.povray.
447 // It sounds like an LLVM bug.
448 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
450 AddressSanitizer &ASan;
455 ShadowMapping Mapping;
457 SmallVector<AllocaInst*, 16> AllocaVec;
458 SmallVector<Instruction*, 8> RetVec;
459 unsigned StackAlignment;
461 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
462 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
463 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
465 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
466 struct AllocaPoisonCall {
467 IntrinsicInst *InsBefore;
472 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
474 // Maps Value to an AllocaInst from which the Value is originated.
475 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
476 AllocaForValueMapTy AllocaForValue;
478 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
479 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
480 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
481 Mapping(ASan.Mapping),
482 StackAlignment(1 << Mapping.Scale) {}
484 bool runOnFunction() {
485 if (!ClStack) return false;
486 // Collect alloca, ret, lifetime instructions etc.
487 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
490 if (AllocaVec.empty()) return false;
492 initializeCallbacks(*F.getParent());
502 // Finds all static Alloca instructions and puts
503 // poisoned red zones around all of them.
504 // Then unpoison everything back before the function returns.
507 // ----------------------- Visitors.
508 /// \brief Collect all Ret instructions.
509 void visitReturnInst(ReturnInst &RI) {
510 RetVec.push_back(&RI);
513 /// \brief Collect Alloca instructions we want (and can) handle.
514 void visitAllocaInst(AllocaInst &AI) {
515 if (!isInterestingAlloca(AI)) return;
517 StackAlignment = std::max(StackAlignment, AI.getAlignment());
518 AllocaVec.push_back(&AI);
521 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
523 void visitIntrinsicInst(IntrinsicInst &II) {
524 if (!ClCheckLifetime) return;
525 Intrinsic::ID ID = II.getIntrinsicID();
526 if (ID != Intrinsic::lifetime_start &&
527 ID != Intrinsic::lifetime_end)
529 // Found lifetime intrinsic, add ASan instrumentation if necessary.
530 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
531 // If size argument is undefined, don't do anything.
532 if (Size->isMinusOne()) return;
533 // Check that size doesn't saturate uint64_t and can
534 // be stored in IntptrTy.
535 const uint64_t SizeValue = Size->getValue().getLimitedValue();
536 if (SizeValue == ~0ULL ||
537 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
539 // Find alloca instruction that corresponds to llvm.lifetime argument.
540 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
542 bool DoPoison = (ID == Intrinsic::lifetime_end);
543 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
544 AllocaPoisonCallVec.push_back(APC);
547 // ---------------------- Helpers.
548 void initializeCallbacks(Module &M);
550 // Check if we want (and can) handle this alloca.
551 bool isInterestingAlloca(AllocaInst &AI) const {
552 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
553 AI.getAllocatedType()->isSized() &&
554 // alloca() may be called with 0 size, ignore it.
555 getAllocaSizeInBytes(&AI) > 0);
558 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
559 Type *Ty = AI->getAllocatedType();
560 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
563 /// Finds alloca where the value comes from.
564 AllocaInst *findAllocaForValue(Value *V);
565 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
566 Value *ShadowBase, bool DoPoison);
567 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
569 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
575 char AddressSanitizer::ID = 0;
576 INITIALIZE_PASS(AddressSanitizer, "asan",
577 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
579 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
580 return new AddressSanitizer();
583 char AddressSanitizerModule::ID = 0;
584 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
585 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
586 "ModulePass", false, false)
587 ModulePass *llvm::createAddressSanitizerModulePass() {
588 return new AddressSanitizerModule();
591 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
592 size_t Res = countTrailingZeros(TypeSize / 8);
593 assert(Res < kNumberOfAccessSizes);
597 // \brief Create a constant for Str so that we can pass it to the run-time lib.
598 static GlobalVariable *createPrivateGlobalForString(
599 Module &M, StringRef Str, bool AllowMerging) {
600 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
601 // We use private linkage for module-local strings. If they can be merged
602 // with another one, we set the unnamed_addr attribute.
604 new GlobalVariable(M, StrConst->getType(), true,
605 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
607 GV->setUnnamedAddr(true);
608 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
612 /// \brief Create a global describing a source location.
613 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
614 LocationMetadata MD) {
615 Constant *LocData[] = {
616 createPrivateGlobalForString(M, MD.Filename, true),
617 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
618 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
620 auto LocStruct = ConstantStruct::getAnon(LocData);
621 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
622 GlobalValue::PrivateLinkage, LocStruct,
624 GV->setUnnamedAddr(true);
628 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
629 return G->getName().find(kAsanGenPrefix) == 0;
632 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
634 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
635 if (Mapping.Offset == 0)
637 // (Shadow >> scale) | offset
638 if (Mapping.OrShadowOffset)
639 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
641 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
644 // Instrument memset/memmove/memcpy
645 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
647 if (isa<MemTransferInst>(MI)) {
649 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
650 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
651 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
652 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
653 } else if (isa<MemSetInst>(MI)) {
656 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
657 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
658 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
660 MI->eraseFromParent();
663 // If I is an interesting memory access, return the PointerOperand
664 // and set IsWrite/Alignment. Otherwise return NULL.
665 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
666 unsigned *Alignment) {
667 // Skip memory accesses inserted by another instrumentation.
668 if (I->getMetadata("nosanitize"))
670 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
671 if (!ClInstrumentReads) return nullptr;
673 *Alignment = LI->getAlignment();
674 return LI->getPointerOperand();
676 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
677 if (!ClInstrumentWrites) return nullptr;
679 *Alignment = SI->getAlignment();
680 return SI->getPointerOperand();
682 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
683 if (!ClInstrumentAtomics) return nullptr;
686 return RMW->getPointerOperand();
688 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
689 if (!ClInstrumentAtomics) return nullptr;
692 return XCHG->getPointerOperand();
697 static bool isPointerOperand(Value *V) {
698 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
701 // This is a rough heuristic; it may cause both false positives and
702 // false negatives. The proper implementation requires cooperation with
704 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
705 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
706 if (!Cmp->isRelational())
708 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
709 if (BO->getOpcode() != Instruction::Sub)
714 if (!isPointerOperand(I->getOperand(0)) ||
715 !isPointerOperand(I->getOperand(1)))
720 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
721 // If a global variable does not have dynamic initialization we don't
722 // have to instrument it. However, if a global does not have initializer
723 // at all, we assume it has dynamic initializer (in other TU).
724 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
728 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
730 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
731 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
732 for (int i = 0; i < 2; i++) {
733 if (Param[i]->getType()->isPointerTy())
734 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
736 IRB.CreateCall2(F, Param[0], Param[1]);
739 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
740 bool IsWrite = false;
741 unsigned Alignment = 0;
742 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
744 if (ClOpt && ClOptGlobals) {
745 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
746 // If initialization order checking is disabled, a simple access to a
747 // dynamically initialized global is always valid.
748 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
749 NumOptimizedAccessesToGlobalVar++;
753 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
754 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
755 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
756 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
757 NumOptimizedAccessesToGlobalArray++;
764 Type *OrigPtrTy = Addr->getType();
765 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
767 assert(OrigTy->isSized());
768 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
770 assert((TypeSize % 8) == 0);
773 NumInstrumentedWrites++;
775 NumInstrumentedReads++;
777 unsigned Granularity = 1 << Mapping.Scale;
778 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
779 // if the data is properly aligned.
780 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
782 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
783 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
784 // Instrument unusual size or unusual alignment.
785 // We can not do it with a single check, so we do 1-byte check for the first
786 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
787 // to report the actual access size.
789 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
790 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
792 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
794 Value *LastByte = IRB.CreateIntToPtr(
795 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
797 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
798 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
802 // Validate the result of Module::getOrInsertFunction called for an interface
803 // function of AddressSanitizer. If the instrumented module defines a function
804 // with the same name, their prototypes must match, otherwise
805 // getOrInsertFunction returns a bitcast.
806 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
807 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
808 FuncOrBitcast->dump();
809 report_fatal_error("trying to redefine an AddressSanitizer "
810 "interface function");
813 Instruction *AddressSanitizer::generateCrashCode(
814 Instruction *InsertBefore, Value *Addr,
815 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
816 IRBuilder<> IRB(InsertBefore);
817 CallInst *Call = SizeArgument
818 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
819 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
821 // We don't do Call->setDoesNotReturn() because the BB already has
822 // UnreachableInst at the end.
823 // This EmptyAsm is required to avoid callback merge.
824 IRB.CreateCall(EmptyAsm);
828 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
831 size_t Granularity = 1 << Mapping.Scale;
832 // Addr & (Granularity - 1)
833 Value *LastAccessedByte = IRB.CreateAnd(
834 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
835 // (Addr & (Granularity - 1)) + size - 1
836 if (TypeSize / 8 > 1)
837 LastAccessedByte = IRB.CreateAdd(
838 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
839 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
840 LastAccessedByte = IRB.CreateIntCast(
841 LastAccessedByte, ShadowValue->getType(), false);
842 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
843 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
846 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
847 Instruction *InsertBefore, Value *Addr,
848 uint32_t TypeSize, bool IsWrite,
849 Value *SizeArgument, bool UseCalls) {
850 IRBuilder<> IRB(InsertBefore);
851 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
852 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
855 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
860 Type *ShadowTy = IntegerType::get(
861 *C, std::max(8U, TypeSize >> Mapping.Scale));
862 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
863 Value *ShadowPtr = memToShadow(AddrLong, IRB);
864 Value *CmpVal = Constant::getNullValue(ShadowTy);
865 Value *ShadowValue = IRB.CreateLoad(
866 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
868 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
869 size_t Granularity = 1 << Mapping.Scale;
870 TerminatorInst *CrashTerm = nullptr;
872 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
873 TerminatorInst *CheckTerm =
874 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
875 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
876 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
877 IRB.SetInsertPoint(CheckTerm);
878 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
879 BasicBlock *CrashBlock =
880 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
881 CrashTerm = new UnreachableInst(*C, CrashBlock);
882 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
883 ReplaceInstWithInst(CheckTerm, NewTerm);
885 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
888 Instruction *Crash = generateCrashCode(
889 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
890 Crash->setDebugLoc(OrigIns->getDebugLoc());
893 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
894 GlobalValue *ModuleName) {
895 // Set up the arguments to our poison/unpoison functions.
896 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
898 // Add a call to poison all external globals before the given function starts.
899 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
900 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
902 // Add calls to unpoison all globals before each return instruction.
903 for (auto &BB : GlobalInit.getBasicBlockList())
904 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
905 CallInst::Create(AsanUnpoisonGlobals, "", RI);
908 void AddressSanitizerModule::createInitializerPoisonCalls(
909 Module &M, GlobalValue *ModuleName) {
910 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
912 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
913 for (Use &OP : CA->operands()) {
914 if (isa<ConstantAggregateZero>(OP))
916 ConstantStruct *CS = cast<ConstantStruct>(OP);
918 // Must have a function or null ptr.
919 // (CS->getOperand(0) is the init priority.)
920 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
921 if (F->getName() != kAsanModuleCtorName)
922 poisonOneInitializer(*F, ModuleName);
927 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
928 Type *Ty = cast<PointerType>(G->getType())->getElementType();
929 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
931 if (GlobalsMD.get(G).IsBlacklisted) return false;
932 if (!Ty->isSized()) return false;
933 if (!G->hasInitializer()) return false;
934 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
935 // Touch only those globals that will not be defined in other modules.
936 // Don't handle ODR linkage types and COMDATs since other modules may be built
938 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
939 G->getLinkage() != GlobalVariable::PrivateLinkage &&
940 G->getLinkage() != GlobalVariable::InternalLinkage)
944 // Two problems with thread-locals:
945 // - The address of the main thread's copy can't be computed at link-time.
946 // - Need to poison all copies, not just the main thread's one.
947 if (G->isThreadLocal())
949 // For now, just ignore this Global if the alignment is large.
950 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
952 // Ignore all the globals with the names starting with "\01L_OBJC_".
953 // Many of those are put into the .cstring section. The linker compresses
954 // that section by removing the spare \0s after the string terminator, so
955 // our redzones get broken.
956 if ((G->getName().find("\01L_OBJC_") == 0) ||
957 (G->getName().find("\01l_OBJC_") == 0)) {
958 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
962 if (G->hasSection()) {
963 StringRef Section(G->getSection());
964 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
965 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
967 if (Section.startswith("__OBJC,") ||
968 Section.startswith("__DATA, __objc_")) {
969 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
972 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
973 // Constant CFString instances are compiled in the following way:
974 // -- the string buffer is emitted into
975 // __TEXT,__cstring,cstring_literals
976 // -- the constant NSConstantString structure referencing that buffer
977 // is placed into __DATA,__cfstring
978 // Therefore there's no point in placing redzones into __DATA,__cfstring.
979 // Moreover, it causes the linker to crash on OS X 10.7
980 if (Section.startswith("__DATA,__cfstring")) {
981 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
984 // The linker merges the contents of cstring_literals and removes the
986 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
987 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
991 // Callbacks put into the CRT initializer/terminator sections
992 // should not be instrumented.
993 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
994 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
995 if (Section.startswith(".CRT")) {
996 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1000 // Globals from llvm.metadata aren't emitted, do not instrument them.
1001 if (Section == "llvm.metadata") return false;
1007 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1008 IRBuilder<> IRB(*C);
1009 // Declare our poisoning and unpoisoning functions.
1010 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1011 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
1012 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1013 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1014 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
1015 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1016 // Declare functions that register/unregister globals.
1017 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1018 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1019 IntptrTy, IntptrTy, NULL));
1020 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1021 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1022 kAsanUnregisterGlobalsName,
1023 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1024 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1025 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
1026 kAsanCovModuleInitName,
1027 IRB.getVoidTy(), IntptrTy, NULL));
1028 AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
1031 // This function replaces all global variables with new variables that have
1032 // trailing redzones. It also creates a function that poisons
1033 // redzones and inserts this function into llvm.global_ctors.
1034 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1037 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1039 for (auto &G : M.globals()) {
1040 if (ShouldInstrumentGlobal(&G))
1041 GlobalsToChange.push_back(&G);
1044 size_t n = GlobalsToChange.size();
1045 if (n == 0) return false;
1047 // A global is described by a structure
1050 // size_t size_with_redzone;
1051 // const char *name;
1052 // const char *module_name;
1053 // size_t has_dynamic_init;
1054 // void *source_location;
1055 // We initialize an array of such structures and pass it to a run-time call.
1056 StructType *GlobalStructTy =
1057 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1058 IntptrTy, IntptrTy, NULL);
1059 SmallVector<Constant *, 16> Initializers(n);
1061 bool HasDynamicallyInitializedGlobals = false;
1063 // We shouldn't merge same module names, as this string serves as unique
1064 // module ID in runtime.
1065 GlobalVariable *ModuleName = createPrivateGlobalForString(
1066 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1068 for (size_t i = 0; i < n; i++) {
1069 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1070 GlobalVariable *G = GlobalsToChange[i];
1072 auto MD = GlobalsMD.get(G);
1073 // Create string holding the global name (use global name from metadata
1074 // if it's available, otherwise just write the name of global variable).
1075 GlobalVariable *Name = createPrivateGlobalForString(
1076 M, MD.Name.empty() ? G->getName() : MD.Name,
1077 /*AllowMerging*/ true);
1079 PointerType *PtrTy = cast<PointerType>(G->getType());
1080 Type *Ty = PtrTy->getElementType();
1081 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1082 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1083 // MinRZ <= RZ <= kMaxGlobalRedzone
1084 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1085 uint64_t RZ = std::max(MinRZ,
1086 std::min(kMaxGlobalRedzone,
1087 (SizeInBytes / MinRZ / 4) * MinRZ));
1088 uint64_t RightRedzoneSize = RZ;
1089 // Round up to MinRZ
1090 if (SizeInBytes % MinRZ)
1091 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1092 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1093 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1095 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1096 Constant *NewInitializer = ConstantStruct::get(
1097 NewTy, G->getInitializer(),
1098 Constant::getNullValue(RightRedZoneTy), NULL);
1100 // Create a new global variable with enough space for a redzone.
1101 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1102 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1103 Linkage = GlobalValue::InternalLinkage;
1104 GlobalVariable *NewGlobal = new GlobalVariable(
1105 M, NewTy, G->isConstant(), Linkage,
1106 NewInitializer, "", G, G->getThreadLocalMode());
1107 NewGlobal->copyAttributesFrom(G);
1108 NewGlobal->setAlignment(MinRZ);
1111 Indices2[0] = IRB.getInt32(0);
1112 Indices2[1] = IRB.getInt32(0);
1114 G->replaceAllUsesWith(
1115 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1116 NewGlobal->takeName(G);
1117 G->eraseFromParent();
1119 Constant *SourceLoc;
1120 if (!MD.SourceLoc.empty()) {
1121 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1122 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1124 SourceLoc = ConstantInt::get(IntptrTy, 0);
1127 Initializers[i] = ConstantStruct::get(
1128 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1129 ConstantInt::get(IntptrTy, SizeInBytes),
1130 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1131 ConstantExpr::getPointerCast(Name, IntptrTy),
1132 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1133 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, NULL);
1135 if (ClInitializers && MD.IsDynInit)
1136 HasDynamicallyInitializedGlobals = true;
1138 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1141 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1142 GlobalVariable *AllGlobals = new GlobalVariable(
1143 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1144 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1146 // Create calls for poisoning before initializers run and unpoisoning after.
1147 if (HasDynamicallyInitializedGlobals)
1148 createInitializerPoisonCalls(M, ModuleName);
1149 IRB.CreateCall2(AsanRegisterGlobals,
1150 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1151 ConstantInt::get(IntptrTy, n));
1153 // We also need to unregister globals at the end, e.g. when a shared library
1155 Function *AsanDtorFunction = Function::Create(
1156 FunctionType::get(Type::getVoidTy(*C), false),
1157 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1158 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1159 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1160 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1161 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1162 ConstantInt::get(IntptrTy, n));
1163 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1169 bool AddressSanitizerModule::runOnModule(Module &M) {
1170 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1173 DL = &DLP->getDataLayout();
1174 C = &(M.getContext());
1175 int LongSize = DL->getPointerSizeInBits();
1176 IntptrTy = Type::getIntNTy(*C, LongSize);
1177 Mapping = getShadowMapping(M, LongSize);
1178 initializeCallbacks(M);
1180 bool Changed = false;
1182 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1184 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1186 if (ClCoverage > 0) {
1187 Function *CovFunc = M.getFunction(kAsanCovName);
1188 int nCov = CovFunc ? CovFunc->getNumUses() : 0;
1189 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
1194 Changed |= InstrumentGlobals(IRB, M);
1199 void AddressSanitizer::initializeCallbacks(Module &M) {
1200 IRBuilder<> IRB(*C);
1201 // Create __asan_report* callbacks.
1202 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1203 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1204 AccessSizeIndex++) {
1205 // IsWrite and TypeSize are encoded in the function name.
1206 std::string Suffix =
1207 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1208 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1209 checkInterfaceFunction(
1210 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1211 IRB.getVoidTy(), IntptrTy, NULL));
1212 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1213 checkInterfaceFunction(
1214 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1215 IRB.getVoidTy(), IntptrTy, NULL));
1218 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1219 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1220 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1221 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1223 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1224 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1225 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1226 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1227 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1228 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1230 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1231 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1232 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1233 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1234 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1235 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1236 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1237 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1238 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1240 AsanHandleNoReturnFunc = checkInterfaceFunction(
1241 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1242 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1243 kAsanCovName, IRB.getVoidTy(), NULL));
1244 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1245 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1246 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1247 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1248 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1249 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1250 StringRef(""), StringRef(""),
1251 /*hasSideEffects=*/true);
1255 bool AddressSanitizer::doInitialization(Module &M) {
1256 // Initialize the private fields. No one has accessed them before.
1257 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1259 report_fatal_error("data layout missing");
1260 DL = &DLP->getDataLayout();
1264 C = &(M.getContext());
1265 LongSize = DL->getPointerSizeInBits();
1266 IntptrTy = Type::getIntNTy(*C, LongSize);
1268 AsanCtorFunction = Function::Create(
1269 FunctionType::get(Type::getVoidTy(*C), false),
1270 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1271 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1272 // call __asan_init in the module ctor.
1273 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1274 AsanInitFunction = checkInterfaceFunction(
1275 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1276 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1277 IRB.CreateCall(AsanInitFunction);
1279 Mapping = getShadowMapping(M, LongSize);
1281 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1285 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1286 // For each NSObject descendant having a +load method, this method is invoked
1287 // by the ObjC runtime before any of the static constructors is called.
1288 // Therefore we need to instrument such methods with a call to __asan_init
1289 // at the beginning in order to initialize our runtime before any access to
1290 // the shadow memory.
1291 // We cannot just ignore these methods, because they may call other
1292 // instrumented functions.
1293 if (F.getName().find(" load]") != std::string::npos) {
1294 IRBuilder<> IRB(F.begin()->begin());
1295 IRB.CreateCall(AsanInitFunction);
1301 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1302 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1303 // Skip static allocas at the top of the entry block so they don't become
1304 // dynamic when we split the block. If we used our optimized stack layout,
1305 // then there will only be one alloca and it will come first.
1306 for (; IP != BE; ++IP) {
1307 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1308 if (!AI || !AI->isStaticAlloca())
1312 DebugLoc EntryLoc = IP->getDebugLoc().getFnDebugLoc(*C);
1313 IRBuilder<> IRB(IP);
1314 IRB.SetCurrentDebugLocation(EntryLoc);
1315 Type *Int8Ty = IRB.getInt8Ty();
1316 GlobalVariable *Guard = new GlobalVariable(
1317 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1318 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1319 LoadInst *Load = IRB.CreateLoad(Guard);
1320 Load->setAtomic(Monotonic);
1321 Load->setAlignment(1);
1322 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1323 Instruction *Ins = SplitBlockAndInsertIfThen(
1324 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1325 IRB.SetInsertPoint(Ins);
1326 IRB.SetCurrentDebugLocation(EntryLoc);
1327 // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
1328 IRB.CreateCall(AsanCovFunction);
1329 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1330 Store->setAtomic(Monotonic);
1331 Store->setAlignment(1);
1334 // Poor man's coverage that works with ASan.
1335 // We create a Guard boolean variable with the same linkage
1336 // as the function and inject this code into the entry block (-asan-coverage=1)
1337 // or all blocks (-asan-coverage=2):
1339 // __sanitizer_cov();
1342 // The accesses to Guard are atomic. The rest of the logic is
1343 // in __sanitizer_cov (it's fine to call it more than once).
1345 // This coverage implementation provides very limited data:
1346 // it only tells if a given function (block) was ever executed.
1347 // No counters, no per-edge data.
1348 // But for many use cases this is what we need and the added slowdown
1349 // is negligible. This simple implementation will probably be obsoleted
1350 // by the upcoming Clang-based coverage implementation.
1351 // By having it here and now we hope to
1352 // a) get the functionality to users earlier and
1353 // b) collect usage statistics to help improve Clang coverage design.
1354 bool AddressSanitizer::InjectCoverage(Function &F,
1355 const ArrayRef<BasicBlock *> AllBlocks) {
1356 if (!ClCoverage) return false;
1358 if (ClCoverage == 1 ||
1359 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1360 InjectCoverageAtBlock(F, F.getEntryBlock());
1362 for (auto BB : AllBlocks)
1363 InjectCoverageAtBlock(F, *BB);
1368 bool AddressSanitizer::runOnFunction(Function &F) {
1369 if (&F == AsanCtorFunction) return false;
1370 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1371 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1372 initializeCallbacks(*F.getParent());
1374 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1375 maybeInsertAsanInitAtFunctionEntry(F);
1377 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1380 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1383 // We want to instrument every address only once per basic block (unless there
1384 // are calls between uses).
1385 SmallSet<Value*, 16> TempsToInstrument;
1386 SmallVector<Instruction*, 16> ToInstrument;
1387 SmallVector<Instruction*, 8> NoReturnCalls;
1388 SmallVector<BasicBlock*, 16> AllBlocks;
1389 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1394 // Fill the set of memory operations to instrument.
1395 for (auto &BB : F) {
1396 AllBlocks.push_back(&BB);
1397 TempsToInstrument.clear();
1398 int NumInsnsPerBB = 0;
1399 for (auto &Inst : BB) {
1400 if (LooksLikeCodeInBug11395(&Inst)) return false;
1402 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1403 if (ClOpt && ClOptSameTemp) {
1404 if (!TempsToInstrument.insert(Addr))
1405 continue; // We've seen this temp in the current BB.
1407 } else if (ClInvalidPointerPairs &&
1408 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1409 PointerComparisonsOrSubtracts.push_back(&Inst);
1411 } else if (isa<MemIntrinsic>(Inst)) {
1414 if (isa<AllocaInst>(Inst))
1418 // A call inside BB.
1419 TempsToInstrument.clear();
1420 if (CS.doesNotReturn())
1421 NoReturnCalls.push_back(CS.getInstruction());
1425 ToInstrument.push_back(&Inst);
1427 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1432 Function *UninstrumentedDuplicate = nullptr;
1433 bool LikelyToInstrument =
1434 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1435 if (ClKeepUninstrumented && LikelyToInstrument) {
1436 ValueToValueMapTy VMap;
1437 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1438 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1439 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1440 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1443 bool UseCalls = false;
1444 if (ClInstrumentationWithCallsThreshold >= 0 &&
1445 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1449 int NumInstrumented = 0;
1450 for (auto Inst : ToInstrument) {
1451 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1452 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1453 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1454 instrumentMop(Inst, UseCalls);
1456 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1461 FunctionStackPoisoner FSP(F, *this);
1462 bool ChangedStack = FSP.runOnFunction();
1464 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1465 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1466 for (auto CI : NoReturnCalls) {
1467 IRBuilder<> IRB(CI);
1468 IRB.CreateCall(AsanHandleNoReturnFunc);
1471 for (auto Inst : PointerComparisonsOrSubtracts) {
1472 instrumentPointerComparisonOrSubtraction(Inst);
1476 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1478 if (InjectCoverage(F, AllBlocks))
1481 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1483 if (ClKeepUninstrumented) {
1485 // No instrumentation is done, no need for the duplicate.
1486 if (UninstrumentedDuplicate)
1487 UninstrumentedDuplicate->eraseFromParent();
1489 // The function was instrumented. We must have the duplicate.
1490 assert(UninstrumentedDuplicate);
1491 UninstrumentedDuplicate->setSection("NOASAN");
1492 assert(!F.hasSection());
1493 F.setSection("ASAN");
1500 // Workaround for bug 11395: we don't want to instrument stack in functions
1501 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1502 // FIXME: remove once the bug 11395 is fixed.
1503 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1504 if (LongSize != 32) return false;
1505 CallInst *CI = dyn_cast<CallInst>(I);
1506 if (!CI || !CI->isInlineAsm()) return false;
1507 if (CI->getNumArgOperands() <= 5) return false;
1508 // We have inline assembly with quite a few arguments.
1512 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1513 IRBuilder<> IRB(*C);
1514 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1515 std::string Suffix = itostr(i);
1516 AsanStackMallocFunc[i] = checkInterfaceFunction(
1517 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1518 IntptrTy, IntptrTy, NULL));
1519 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1520 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1521 IntptrTy, IntptrTy, NULL));
1523 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1524 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1525 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1526 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1530 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1531 IRBuilder<> &IRB, Value *ShadowBase,
1533 size_t n = ShadowBytes.size();
1535 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1536 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1537 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1538 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1539 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1540 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1542 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1543 if (ASan.DL->isLittleEndian())
1544 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1546 Val = (Val << 8) | ShadowBytes[i + j];
1549 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1550 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1551 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1552 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1557 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1558 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1559 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1560 assert(LocalStackSize <= kMaxStackMallocSize);
1561 uint64_t MaxSize = kMinStackMallocSize;
1562 for (int i = 0; ; i++, MaxSize *= 2)
1563 if (LocalStackSize <= MaxSize)
1565 llvm_unreachable("impossible LocalStackSize");
1568 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1569 // We can not use MemSet intrinsic because it may end up calling the actual
1570 // memset. Size is a multiple of 8.
1571 // Currently this generates 8-byte stores on x86_64; it may be better to
1572 // generate wider stores.
1573 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1574 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1575 assert(!(Size % 8));
1576 assert(kAsanStackAfterReturnMagic == 0xf5);
1577 for (int i = 0; i < Size; i += 8) {
1578 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1579 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1580 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1584 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1585 for (const auto &Inst : F.getEntryBlock())
1586 if (!isa<AllocaInst>(Inst))
1587 return Inst.getDebugLoc();
1591 void FunctionStackPoisoner::poisonStack() {
1592 int StackMallocIdx = -1;
1593 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1595 assert(AllocaVec.size() > 0);
1596 Instruction *InsBefore = AllocaVec[0];
1597 IRBuilder<> IRB(InsBefore);
1598 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1600 SmallVector<ASanStackVariableDescription, 16> SVD;
1601 SVD.reserve(AllocaVec.size());
1602 for (AllocaInst *AI : AllocaVec) {
1603 ASanStackVariableDescription D = { AI->getName().data(),
1604 getAllocaSizeInBytes(AI),
1605 AI->getAlignment(), AI, 0};
1608 // Minimal header size (left redzone) is 4 pointers,
1609 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1610 size_t MinHeaderSize = ASan.LongSize / 2;
1611 ASanStackFrameLayout L;
1612 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1613 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1614 uint64_t LocalStackSize = L.FrameSize;
1615 bool DoStackMalloc =
1616 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1618 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1619 AllocaInst *MyAlloca =
1620 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1621 MyAlloca->setDebugLoc(EntryDebugLocation);
1622 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1623 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1624 MyAlloca->setAlignment(FrameAlignment);
1625 assert(MyAlloca->isStaticAlloca());
1626 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1627 Value *LocalStackBase = OrigStackBase;
1629 if (DoStackMalloc) {
1630 // LocalStackBase = OrigStackBase
1631 // if (__asan_option_detect_stack_use_after_return)
1632 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1633 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1634 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1635 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1636 kAsanOptionDetectUAR, IRB.getInt32Ty());
1637 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1638 Constant::getNullValue(IRB.getInt32Ty()));
1639 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1640 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1641 IRBuilder<> IRBIf(Term);
1642 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1643 LocalStackBase = IRBIf.CreateCall2(
1644 AsanStackMallocFunc[StackMallocIdx],
1645 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1646 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1647 IRB.SetInsertPoint(InsBefore);
1648 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1649 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1650 Phi->addIncoming(OrigStackBase, CmpBlock);
1651 Phi->addIncoming(LocalStackBase, SetBlock);
1652 LocalStackBase = Phi;
1655 // Insert poison calls for lifetime intrinsics for alloca.
1656 bool HavePoisonedAllocas = false;
1657 for (const auto &APC : AllocaPoisonCallVec) {
1658 assert(APC.InsBefore);
1660 IRBuilder<> IRB(APC.InsBefore);
1661 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1662 HavePoisonedAllocas |= APC.DoPoison;
1665 // Replace Alloca instructions with base+offset.
1666 for (const auto &Desc : SVD) {
1667 AllocaInst *AI = Desc.AI;
1668 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1669 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1671 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1672 AI->replaceAllUsesWith(NewAllocaPtr);
1675 // The left-most redzone has enough space for at least 4 pointers.
1676 // Write the Magic value to redzone[0].
1677 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1678 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1680 // Write the frame description constant to redzone[1].
1681 Value *BasePlus1 = IRB.CreateIntToPtr(
1682 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1684 GlobalVariable *StackDescriptionGlobal =
1685 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1686 /*AllowMerging*/true);
1687 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1689 IRB.CreateStore(Description, BasePlus1);
1690 // Write the PC to redzone[2].
1691 Value *BasePlus2 = IRB.CreateIntToPtr(
1692 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1693 2 * ASan.LongSize/8)),
1695 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1697 // Poison the stack redzones at the entry.
1698 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1699 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1701 // (Un)poison the stack before all ret instructions.
1702 for (auto Ret : RetVec) {
1703 IRBuilder<> IRBRet(Ret);
1704 // Mark the current frame as retired.
1705 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1707 if (DoStackMalloc) {
1708 assert(StackMallocIdx >= 0);
1709 // if LocalStackBase != OrigStackBase:
1710 // // In use-after-return mode, poison the whole stack frame.
1711 // if StackMallocIdx <= 4
1712 // // For small sizes inline the whole thing:
1713 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1714 // **SavedFlagPtr(LocalStackBase) = 0
1716 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1718 // <This is not a fake stack; unpoison the redzones>
1719 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1720 TerminatorInst *ThenTerm, *ElseTerm;
1721 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1723 IRBuilder<> IRBPoison(ThenTerm);
1724 if (StackMallocIdx <= 4) {
1725 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1726 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1727 ClassSize >> Mapping.Scale);
1728 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1730 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1731 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1732 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1733 IRBPoison.CreateStore(
1734 Constant::getNullValue(IRBPoison.getInt8Ty()),
1735 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1737 // For larger frames call __asan_stack_free_*.
1738 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1739 ConstantInt::get(IntptrTy, LocalStackSize),
1743 IRBuilder<> IRBElse(ElseTerm);
1744 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1745 } else if (HavePoisonedAllocas) {
1746 // If we poisoned some allocas in llvm.lifetime analysis,
1747 // unpoison whole stack frame now.
1748 assert(LocalStackBase == OrigStackBase);
1749 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1751 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1755 // We are done. Remove the old unused alloca instructions.
1756 for (auto AI : AllocaVec)
1757 AI->eraseFromParent();
1760 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1761 IRBuilder<> &IRB, bool DoPoison) {
1762 // For now just insert the call to ASan runtime.
1763 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1764 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1765 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1766 : AsanUnpoisonStackMemoryFunc,
1770 // Handling llvm.lifetime intrinsics for a given %alloca:
1771 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1772 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1773 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1774 // could be poisoned by previous llvm.lifetime.end instruction, as the
1775 // variable may go in and out of scope several times, e.g. in loops).
1776 // (3) if we poisoned at least one %alloca in a function,
1777 // unpoison the whole stack frame at function exit.
1779 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1780 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1781 // We're intested only in allocas we can handle.
1782 return isInterestingAlloca(*AI) ? AI : nullptr;
1783 // See if we've already calculated (or started to calculate) alloca for a
1785 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1786 if (I != AllocaForValue.end())
1788 // Store 0 while we're calculating alloca for value V to avoid
1789 // infinite recursion if the value references itself.
1790 AllocaForValue[V] = nullptr;
1791 AllocaInst *Res = nullptr;
1792 if (CastInst *CI = dyn_cast<CastInst>(V))
1793 Res = findAllocaForValue(CI->getOperand(0));
1794 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1795 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1796 Value *IncValue = PN->getIncomingValue(i);
1797 // Allow self-referencing phi-nodes.
1798 if (IncValue == PN) continue;
1799 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1800 // AI for incoming values should exist and should all be equal.
1801 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1807 AllocaForValue[V] = Res;