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/Scalar.h"
44 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Cloning.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/Transforms/Utils/ModuleUtils.h"
51 #include <system_error>
55 #define DEBUG_TYPE "asan"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
60 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
61 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
62 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
63 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
64 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
65 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
67 static const size_t kMinStackMallocSize = 1 << 6; // 64B
68 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
69 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
70 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
72 static const char *const kAsanModuleCtorName = "asan.module_ctor";
73 static const char *const kAsanModuleDtorName = "asan.module_dtor";
74 static const int kAsanCtorAndDtorPriority = 1;
75 static const char *const kAsanReportErrorTemplate = "__asan_report_";
76 static const char *const kAsanReportLoadN = "__asan_report_load_n";
77 static const char *const kAsanReportStoreN = "__asan_report_store_n";
78 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
79 static const char *const kAsanUnregisterGlobalsName =
80 "__asan_unregister_globals";
81 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
82 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
83 static const char *const kAsanInitName = "__asan_init_v4";
84 static const char *const kAsanCovModuleInitName = "__sanitizer_cov_module_init";
85 static const char *const kAsanCovName = "__sanitizer_cov";
86 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
87 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
88 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
89 static const int kMaxAsanStackMallocSizeClass = 10;
90 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
91 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
92 static const char *const kAsanGenPrefix = "__asan_gen_";
93 static const char *const kAsanPoisonStackMemoryName =
94 "__asan_poison_stack_memory";
95 static const char *const kAsanUnpoisonStackMemoryName =
96 "__asan_unpoison_stack_memory";
98 static const char *const kAsanOptionDetectUAR =
99 "__asan_option_detect_stack_use_after_return";
102 static const int kAsanStackAfterReturnMagic = 0xf5;
105 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
106 static const size_t kNumberOfAccessSizes = 5;
108 // Command-line flags.
110 // This flag may need to be replaced with -f[no-]asan-reads.
111 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
112 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
114 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
115 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
116 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
117 cl::Hidden, cl::init(true));
118 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
119 cl::desc("use instrumentation with slow path for all accesses"),
120 cl::Hidden, cl::init(false));
121 // This flag limits the number of instructions to be instrumented
122 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
123 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
125 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
127 cl::desc("maximal number of instructions to instrument in any given BB"),
129 // This flag may need to be replaced with -f[no]asan-stack.
130 static cl::opt<bool> ClStack("asan-stack",
131 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
132 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
134 // This flag may need to be replaced with -f[no]asan-globals.
135 static cl::opt<bool> ClGlobals("asan-globals",
136 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
137 static cl::opt<int> ClCoverage("asan-coverage",
138 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks, "
139 "3: all blocks and critical edges"),
140 cl::Hidden, cl::init(false));
141 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
142 cl::desc("Add coverage instrumentation only to the entry block if there "
143 "are more than this number of blocks."),
144 cl::Hidden, cl::init(1500));
145 static cl::opt<bool> ClInitializers("asan-initialization-order",
146 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
147 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
148 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
149 cl::Hidden, cl::init(false));
150 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
151 cl::desc("Realign stack to the value of this flag (power of two)"),
152 cl::Hidden, cl::init(32));
153 static cl::opt<int> ClInstrumentationWithCallsThreshold(
154 "asan-instrumentation-with-call-threshold",
155 cl::desc("If the function being instrumented contains more than "
156 "this number of memory accesses, use callbacks instead of "
157 "inline checks (-1 means never use callbacks)."),
158 cl::Hidden, cl::init(7000));
159 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
160 "asan-memory-access-callback-prefix",
161 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
162 cl::init("__asan_"));
164 // This is an experimental feature that will allow to choose between
165 // instrumented and non-instrumented code at link-time.
166 // If this option is on, just before instrumenting a function we create its
167 // clone; if the function is not changed by asan the clone is deleted.
168 // If we end up with a clone, we put the instrumented function into a section
169 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
171 // This is still a prototype, we need to figure out a way to keep two copies of
172 // a function so that the linker can easily choose one of them.
173 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
174 cl::desc("Keep uninstrumented copies of functions"),
175 cl::Hidden, cl::init(false));
177 // These flags allow to change the shadow mapping.
178 // The shadow mapping looks like
179 // Shadow = (Mem >> scale) + (1 << offset_log)
180 static cl::opt<int> ClMappingScale("asan-mapping-scale",
181 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
183 // Optimization flags. Not user visible, used mostly for testing
184 // and benchmarking the tool.
185 static cl::opt<bool> ClOpt("asan-opt",
186 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
187 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
188 cl::desc("Instrument the same temp just once"), cl::Hidden,
190 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
191 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
193 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
194 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
195 cl::Hidden, cl::init(false));
198 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
200 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
201 cl::Hidden, cl::init(0));
202 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
203 cl::Hidden, cl::desc("Debug func"));
204 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
205 cl::Hidden, cl::init(-1));
206 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
207 cl::Hidden, cl::init(-1));
209 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
210 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
211 STATISTIC(NumOptimizedAccessesToGlobalArray,
212 "Number of optimized accesses to global arrays");
213 STATISTIC(NumOptimizedAccessesToGlobalVar,
214 "Number of optimized accesses to global vars");
217 /// Frontend-provided metadata for source location.
218 struct LocationMetadata {
223 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
225 bool empty() const { return Filename.empty(); }
227 void parse(MDNode *MDN) {
228 assert(MDN->getNumOperands() == 3);
229 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
230 Filename = MDFilename->getString();
231 LineNo = cast<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
232 ColumnNo = cast<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
236 /// Frontend-provided metadata for global variables.
237 class GlobalsMetadata {
241 : SourceLoc(), Name(), IsDynInit(false),
242 IsBlacklisted(false) {}
243 LocationMetadata SourceLoc;
249 GlobalsMetadata() : inited_(false) {}
251 void init(Module& M) {
254 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
257 for (auto MDN : Globals->operands()) {
258 // Metadata node contains the global and the fields of "Entry".
259 assert(MDN->getNumOperands() == 5);
260 Value *V = MDN->getOperand(0);
261 // The optimizer may optimize away a global entirely.
264 GlobalVariable *GV = cast<GlobalVariable>(V);
265 // We can already have an entry for GV if it was merged with another
267 Entry &E = Entries[GV];
268 if (Value *Loc = MDN->getOperand(1))
269 E.SourceLoc.parse(cast<MDNode>(Loc));
270 if (Value *Name = MDN->getOperand(2)) {
271 MDString *MDName = cast<MDString>(Name);
272 E.Name = MDName->getString();
274 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
275 E.IsDynInit |= IsDynInit->isOne();
276 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
277 E.IsBlacklisted |= IsBlacklisted->isOne();
281 /// Returns metadata entry for a given global.
282 Entry get(GlobalVariable *G) const {
283 auto Pos = Entries.find(G);
284 return (Pos != Entries.end()) ? Pos->second : Entry();
289 DenseMap<GlobalVariable*, Entry> Entries;
292 /// This struct defines the shadow mapping using the rule:
293 /// shadow = (mem >> Scale) ADD-or-OR Offset.
294 struct ShadowMapping {
300 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
301 llvm::Triple TargetTriple(M.getTargetTriple());
302 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
303 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
304 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
305 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
306 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
307 TargetTriple.getArch() == llvm::Triple::ppc64le;
308 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
309 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
310 TargetTriple.getArch() == llvm::Triple::mipsel;
312 ShadowMapping Mapping;
314 if (LongSize == 32) {
318 Mapping.Offset = kMIPS32_ShadowOffset32;
320 Mapping.Offset = kFreeBSD_ShadowOffset32;
322 Mapping.Offset = kIOSShadowOffset32;
324 Mapping.Offset = kDefaultShadowOffset32;
325 } else { // LongSize == 64
327 Mapping.Offset = kPPC64_ShadowOffset64;
329 Mapping.Offset = kFreeBSD_ShadowOffset64;
330 else if (IsLinux && IsX86_64)
331 Mapping.Offset = kSmallX86_64ShadowOffset;
333 Mapping.Offset = kDefaultShadowOffset64;
336 Mapping.Scale = kDefaultShadowScale;
337 if (ClMappingScale) {
338 Mapping.Scale = ClMappingScale;
341 // OR-ing shadow offset if more efficient (at least on x86) if the offset
342 // is a power of two, but on ppc64 we have to use add since the shadow
343 // offset is not necessary 1/8-th of the address space.
344 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
349 static size_t RedzoneSizeForScale(int MappingScale) {
350 // Redzone used for stack and globals is at least 32 bytes.
351 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
352 return std::max(32U, 1U << MappingScale);
355 /// AddressSanitizer: instrument the code in module to find memory bugs.
356 struct AddressSanitizer : public FunctionPass {
357 AddressSanitizer() : FunctionPass(ID) {
358 initializeBreakCriticalEdgesPass(*PassRegistry::getPassRegistry());
360 const char *getPassName() const override {
361 return "AddressSanitizerFunctionPass";
363 void instrumentMop(Instruction *I, bool UseCalls);
364 void instrumentPointerComparisonOrSubtraction(Instruction *I);
365 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
366 Value *Addr, uint32_t TypeSize, bool IsWrite,
367 Value *SizeArgument, bool UseCalls);
368 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
369 Value *ShadowValue, uint32_t TypeSize);
370 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
371 bool IsWrite, size_t AccessSizeIndex,
372 Value *SizeArgument);
373 void instrumentMemIntrinsic(MemIntrinsic *MI);
374 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
375 bool runOnFunction(Function &F) override;
376 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
377 bool doInitialization(Module &M) override;
378 static char ID; // Pass identification, replacement for typeid
380 void getAnalysisUsage(AnalysisUsage &AU) const override {
382 AU.addRequiredID(BreakCriticalEdgesID);
386 void initializeCallbacks(Module &M);
388 bool LooksLikeCodeInBug11395(Instruction *I);
389 bool GlobalIsLinkerInitialized(GlobalVariable *G);
390 bool InjectCoverage(Function &F, ArrayRef<BasicBlock*> AllBlocks);
391 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
394 const DataLayout *DL;
397 ShadowMapping Mapping;
398 Function *AsanCtorFunction;
399 Function *AsanInitFunction;
400 Function *AsanHandleNoReturnFunc;
401 Function *AsanCovFunction;
402 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
403 // This array is indexed by AccessIsWrite and log2(AccessSize).
404 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
405 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
406 // This array is indexed by AccessIsWrite.
407 Function *AsanErrorCallbackSized[2],
408 *AsanMemoryAccessCallbackSized[2];
409 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
411 GlobalsMetadata GlobalsMD;
413 friend struct FunctionStackPoisoner;
416 class AddressSanitizerModule : public ModulePass {
418 AddressSanitizerModule() : ModulePass(ID) {}
419 bool runOnModule(Module &M) override;
420 static char ID; // Pass identification, replacement for typeid
421 const char *getPassName() const override {
422 return "AddressSanitizerModule";
426 void initializeCallbacks(Module &M);
428 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
429 bool ShouldInstrumentGlobal(GlobalVariable *G);
430 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
431 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
432 size_t MinRedzoneSizeForGlobal() const {
433 return RedzoneSizeForScale(Mapping.Scale);
436 GlobalsMetadata GlobalsMD;
439 const DataLayout *DL;
440 ShadowMapping Mapping;
441 Function *AsanPoisonGlobals;
442 Function *AsanUnpoisonGlobals;
443 Function *AsanRegisterGlobals;
444 Function *AsanUnregisterGlobals;
445 Function *AsanCovModuleInit;
448 // Stack poisoning does not play well with exception handling.
449 // When an exception is thrown, we essentially bypass the code
450 // that unpoisones the stack. This is why the run-time library has
451 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
452 // stack in the interceptor. This however does not work inside the
453 // actual function which catches the exception. Most likely because the
454 // compiler hoists the load of the shadow value somewhere too high.
455 // This causes asan to report a non-existing bug on 453.povray.
456 // It sounds like an LLVM bug.
457 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
459 AddressSanitizer &ASan;
464 ShadowMapping Mapping;
466 SmallVector<AllocaInst*, 16> AllocaVec;
467 SmallVector<Instruction*, 8> RetVec;
468 unsigned StackAlignment;
470 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
471 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
472 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
474 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
475 struct AllocaPoisonCall {
476 IntrinsicInst *InsBefore;
481 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
483 // Maps Value to an AllocaInst from which the Value is originated.
484 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
485 AllocaForValueMapTy AllocaForValue;
487 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
488 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
489 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
490 Mapping(ASan.Mapping),
491 StackAlignment(1 << Mapping.Scale) {}
493 bool runOnFunction() {
494 if (!ClStack) return false;
495 // Collect alloca, ret, lifetime instructions etc.
496 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
499 if (AllocaVec.empty()) return false;
501 initializeCallbacks(*F.getParent());
511 // Finds all static Alloca instructions and puts
512 // poisoned red zones around all of them.
513 // Then unpoison everything back before the function returns.
516 // ----------------------- Visitors.
517 /// \brief Collect all Ret instructions.
518 void visitReturnInst(ReturnInst &RI) {
519 RetVec.push_back(&RI);
522 /// \brief Collect Alloca instructions we want (and can) handle.
523 void visitAllocaInst(AllocaInst &AI) {
524 if (!isInterestingAlloca(AI)) return;
526 StackAlignment = std::max(StackAlignment, AI.getAlignment());
527 AllocaVec.push_back(&AI);
530 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
532 void visitIntrinsicInst(IntrinsicInst &II) {
533 if (!ClCheckLifetime) return;
534 Intrinsic::ID ID = II.getIntrinsicID();
535 if (ID != Intrinsic::lifetime_start &&
536 ID != Intrinsic::lifetime_end)
538 // Found lifetime intrinsic, add ASan instrumentation if necessary.
539 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
540 // If size argument is undefined, don't do anything.
541 if (Size->isMinusOne()) return;
542 // Check that size doesn't saturate uint64_t and can
543 // be stored in IntptrTy.
544 const uint64_t SizeValue = Size->getValue().getLimitedValue();
545 if (SizeValue == ~0ULL ||
546 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
548 // Find alloca instruction that corresponds to llvm.lifetime argument.
549 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
551 bool DoPoison = (ID == Intrinsic::lifetime_end);
552 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
553 AllocaPoisonCallVec.push_back(APC);
556 // ---------------------- Helpers.
557 void initializeCallbacks(Module &M);
559 // Check if we want (and can) handle this alloca.
560 bool isInterestingAlloca(AllocaInst &AI) const {
561 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
562 AI.getAllocatedType()->isSized() &&
563 // alloca() may be called with 0 size, ignore it.
564 getAllocaSizeInBytes(&AI) > 0);
567 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
568 Type *Ty = AI->getAllocatedType();
569 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
572 /// Finds alloca where the value comes from.
573 AllocaInst *findAllocaForValue(Value *V);
574 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
575 Value *ShadowBase, bool DoPoison);
576 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
578 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
584 char AddressSanitizer::ID = 0;
585 INITIALIZE_PASS(AddressSanitizer, "asan",
586 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
588 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
589 return new AddressSanitizer();
592 char AddressSanitizerModule::ID = 0;
593 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
594 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
595 "ModulePass", false, false)
596 ModulePass *llvm::createAddressSanitizerModulePass() {
597 return new AddressSanitizerModule();
600 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
601 size_t Res = countTrailingZeros(TypeSize / 8);
602 assert(Res < kNumberOfAccessSizes);
606 // \brief Create a constant for Str so that we can pass it to the run-time lib.
607 static GlobalVariable *createPrivateGlobalForString(
608 Module &M, StringRef Str, bool AllowMerging) {
609 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
610 // We use private linkage for module-local strings. If they can be merged
611 // with another one, we set the unnamed_addr attribute.
613 new GlobalVariable(M, StrConst->getType(), true,
614 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
616 GV->setUnnamedAddr(true);
617 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
621 /// \brief Create a global describing a source location.
622 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
623 LocationMetadata MD) {
624 Constant *LocData[] = {
625 createPrivateGlobalForString(M, MD.Filename, true),
626 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
627 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
629 auto LocStruct = ConstantStruct::getAnon(LocData);
630 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
631 GlobalValue::PrivateLinkage, LocStruct,
633 GV->setUnnamedAddr(true);
637 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
638 return G->getName().find(kAsanGenPrefix) == 0;
641 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
643 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
644 if (Mapping.Offset == 0)
646 // (Shadow >> scale) | offset
647 if (Mapping.OrShadowOffset)
648 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
650 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
653 // Instrument memset/memmove/memcpy
654 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
656 if (isa<MemTransferInst>(MI)) {
658 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
659 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
660 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
661 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
662 } else if (isa<MemSetInst>(MI)) {
665 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
666 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
667 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
669 MI->eraseFromParent();
672 // If I is an interesting memory access, return the PointerOperand
673 // and set IsWrite/Alignment. Otherwise return NULL.
674 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
675 unsigned *Alignment) {
676 // Skip memory accesses inserted by another instrumentation.
677 if (I->getMetadata("nosanitize"))
679 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
680 if (!ClInstrumentReads) return nullptr;
682 *Alignment = LI->getAlignment();
683 return LI->getPointerOperand();
685 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
686 if (!ClInstrumentWrites) return nullptr;
688 *Alignment = SI->getAlignment();
689 return SI->getPointerOperand();
691 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
692 if (!ClInstrumentAtomics) return nullptr;
695 return RMW->getPointerOperand();
697 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
698 if (!ClInstrumentAtomics) return nullptr;
701 return XCHG->getPointerOperand();
706 static bool isPointerOperand(Value *V) {
707 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
710 // This is a rough heuristic; it may cause both false positives and
711 // false negatives. The proper implementation requires cooperation with
713 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
714 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
715 if (!Cmp->isRelational())
717 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
718 if (BO->getOpcode() != Instruction::Sub)
723 if (!isPointerOperand(I->getOperand(0)) ||
724 !isPointerOperand(I->getOperand(1)))
729 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
730 // If a global variable does not have dynamic initialization we don't
731 // have to instrument it. However, if a global does not have initializer
732 // at all, we assume it has dynamic initializer (in other TU).
733 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
737 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
739 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
740 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
741 for (int i = 0; i < 2; i++) {
742 if (Param[i]->getType()->isPointerTy())
743 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
745 IRB.CreateCall2(F, Param[0], Param[1]);
748 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
749 bool IsWrite = false;
750 unsigned Alignment = 0;
751 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
753 if (ClOpt && ClOptGlobals) {
754 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
755 // If initialization order checking is disabled, a simple access to a
756 // dynamically initialized global is always valid.
757 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
758 NumOptimizedAccessesToGlobalVar++;
762 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
763 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
764 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
765 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
766 NumOptimizedAccessesToGlobalArray++;
773 Type *OrigPtrTy = Addr->getType();
774 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
776 assert(OrigTy->isSized());
777 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
779 assert((TypeSize % 8) == 0);
782 NumInstrumentedWrites++;
784 NumInstrumentedReads++;
786 unsigned Granularity = 1 << Mapping.Scale;
787 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
788 // if the data is properly aligned.
789 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
791 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
792 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
793 // Instrument unusual size or unusual alignment.
794 // We can not do it with a single check, so we do 1-byte check for the first
795 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
796 // to report the actual access size.
798 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
799 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
801 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
803 Value *LastByte = IRB.CreateIntToPtr(
804 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
806 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
807 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
811 // Validate the result of Module::getOrInsertFunction called for an interface
812 // function of AddressSanitizer. If the instrumented module defines a function
813 // with the same name, their prototypes must match, otherwise
814 // getOrInsertFunction returns a bitcast.
815 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
816 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
817 FuncOrBitcast->dump();
818 report_fatal_error("trying to redefine an AddressSanitizer "
819 "interface function");
822 Instruction *AddressSanitizer::generateCrashCode(
823 Instruction *InsertBefore, Value *Addr,
824 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
825 IRBuilder<> IRB(InsertBefore);
826 CallInst *Call = SizeArgument
827 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
828 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
830 // We don't do Call->setDoesNotReturn() because the BB already has
831 // UnreachableInst at the end.
832 // This EmptyAsm is required to avoid callback merge.
833 IRB.CreateCall(EmptyAsm);
837 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
840 size_t Granularity = 1 << Mapping.Scale;
841 // Addr & (Granularity - 1)
842 Value *LastAccessedByte = IRB.CreateAnd(
843 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
844 // (Addr & (Granularity - 1)) + size - 1
845 if (TypeSize / 8 > 1)
846 LastAccessedByte = IRB.CreateAdd(
847 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
848 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
849 LastAccessedByte = IRB.CreateIntCast(
850 LastAccessedByte, ShadowValue->getType(), false);
851 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
852 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
855 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
856 Instruction *InsertBefore, Value *Addr,
857 uint32_t TypeSize, bool IsWrite,
858 Value *SizeArgument, bool UseCalls) {
859 IRBuilder<> IRB(InsertBefore);
860 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
861 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
864 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
869 Type *ShadowTy = IntegerType::get(
870 *C, std::max(8U, TypeSize >> Mapping.Scale));
871 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
872 Value *ShadowPtr = memToShadow(AddrLong, IRB);
873 Value *CmpVal = Constant::getNullValue(ShadowTy);
874 Value *ShadowValue = IRB.CreateLoad(
875 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
877 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
878 size_t Granularity = 1 << Mapping.Scale;
879 TerminatorInst *CrashTerm = nullptr;
881 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
882 // We use branch weights for the slow path check, to indicate that the slow
883 // path is rarely taken. This seems to be the case for SPEC benchmarks.
884 TerminatorInst *CheckTerm =
885 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
886 MDBuilder(*C).createBranchWeights(1, 100000));
887 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
888 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
889 IRB.SetInsertPoint(CheckTerm);
890 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
891 BasicBlock *CrashBlock =
892 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
893 CrashTerm = new UnreachableInst(*C, CrashBlock);
894 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
895 ReplaceInstWithInst(CheckTerm, NewTerm);
897 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
900 Instruction *Crash = generateCrashCode(
901 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
902 Crash->setDebugLoc(OrigIns->getDebugLoc());
905 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
906 GlobalValue *ModuleName) {
907 // Set up the arguments to our poison/unpoison functions.
908 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
910 // Add a call to poison all external globals before the given function starts.
911 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
912 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
914 // Add calls to unpoison all globals before each return instruction.
915 for (auto &BB : GlobalInit.getBasicBlockList())
916 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
917 CallInst::Create(AsanUnpoisonGlobals, "", RI);
920 void AddressSanitizerModule::createInitializerPoisonCalls(
921 Module &M, GlobalValue *ModuleName) {
922 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
924 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
925 for (Use &OP : CA->operands()) {
926 if (isa<ConstantAggregateZero>(OP))
928 ConstantStruct *CS = cast<ConstantStruct>(OP);
930 // Must have a function or null ptr.
931 // (CS->getOperand(0) is the init priority.)
932 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
933 if (F->getName() != kAsanModuleCtorName)
934 poisonOneInitializer(*F, ModuleName);
939 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
940 Type *Ty = cast<PointerType>(G->getType())->getElementType();
941 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
943 if (GlobalsMD.get(G).IsBlacklisted) return false;
944 if (!Ty->isSized()) return false;
945 if (!G->hasInitializer()) return false;
946 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
947 // Touch only those globals that will not be defined in other modules.
948 // Don't handle ODR linkage types and COMDATs since other modules may be built
950 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
951 G->getLinkage() != GlobalVariable::PrivateLinkage &&
952 G->getLinkage() != GlobalVariable::InternalLinkage)
956 // Two problems with thread-locals:
957 // - The address of the main thread's copy can't be computed at link-time.
958 // - Need to poison all copies, not just the main thread's one.
959 if (G->isThreadLocal())
961 // For now, just ignore this Global if the alignment is large.
962 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
964 // Ignore all the globals with the names starting with "\01L_OBJC_".
965 // Many of those are put into the .cstring section. The linker compresses
966 // that section by removing the spare \0s after the string terminator, so
967 // our redzones get broken.
968 if ((G->getName().find("\01L_OBJC_") == 0) ||
969 (G->getName().find("\01l_OBJC_") == 0)) {
970 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
974 if (G->hasSection()) {
975 StringRef Section(G->getSection());
976 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
977 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
979 if (Section.startswith("__OBJC,") ||
980 Section.startswith("__DATA, __objc_")) {
981 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
984 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
985 // Constant CFString instances are compiled in the following way:
986 // -- the string buffer is emitted into
987 // __TEXT,__cstring,cstring_literals
988 // -- the constant NSConstantString structure referencing that buffer
989 // is placed into __DATA,__cfstring
990 // Therefore there's no point in placing redzones into __DATA,__cfstring.
991 // Moreover, it causes the linker to crash on OS X 10.7
992 if (Section.startswith("__DATA,__cfstring")) {
993 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
996 // The linker merges the contents of cstring_literals and removes the
998 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
999 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1003 // Callbacks put into the CRT initializer/terminator sections
1004 // should not be instrumented.
1005 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1006 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1007 if (Section.startswith(".CRT")) {
1008 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1012 // Globals from llvm.metadata aren't emitted, do not instrument them.
1013 if (Section == "llvm.metadata") return false;
1019 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1020 IRBuilder<> IRB(*C);
1021 // Declare our poisoning and unpoisoning functions.
1022 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1023 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
1024 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1025 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1026 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
1027 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1028 // Declare functions that register/unregister globals.
1029 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1030 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1031 IntptrTy, IntptrTy, NULL));
1032 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1033 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1034 kAsanUnregisterGlobalsName,
1035 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1036 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1037 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
1038 kAsanCovModuleInitName,
1039 IRB.getVoidTy(), IntptrTy, NULL));
1040 AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
1043 // This function replaces all global variables with new variables that have
1044 // trailing redzones. It also creates a function that poisons
1045 // redzones and inserts this function into llvm.global_ctors.
1046 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1049 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1051 for (auto &G : M.globals()) {
1052 if (ShouldInstrumentGlobal(&G))
1053 GlobalsToChange.push_back(&G);
1056 size_t n = GlobalsToChange.size();
1057 if (n == 0) return false;
1059 // A global is described by a structure
1062 // size_t size_with_redzone;
1063 // const char *name;
1064 // const char *module_name;
1065 // size_t has_dynamic_init;
1066 // void *source_location;
1067 // We initialize an array of such structures and pass it to a run-time call.
1068 StructType *GlobalStructTy =
1069 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1070 IntptrTy, IntptrTy, NULL);
1071 SmallVector<Constant *, 16> Initializers(n);
1073 bool HasDynamicallyInitializedGlobals = false;
1075 // We shouldn't merge same module names, as this string serves as unique
1076 // module ID in runtime.
1077 GlobalVariable *ModuleName = createPrivateGlobalForString(
1078 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1080 for (size_t i = 0; i < n; i++) {
1081 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1082 GlobalVariable *G = GlobalsToChange[i];
1084 auto MD = GlobalsMD.get(G);
1085 // Create string holding the global name (use global name from metadata
1086 // if it's available, otherwise just write the name of global variable).
1087 GlobalVariable *Name = createPrivateGlobalForString(
1088 M, MD.Name.empty() ? G->getName() : MD.Name,
1089 /*AllowMerging*/ true);
1091 PointerType *PtrTy = cast<PointerType>(G->getType());
1092 Type *Ty = PtrTy->getElementType();
1093 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1094 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1095 // MinRZ <= RZ <= kMaxGlobalRedzone
1096 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1097 uint64_t RZ = std::max(MinRZ,
1098 std::min(kMaxGlobalRedzone,
1099 (SizeInBytes / MinRZ / 4) * MinRZ));
1100 uint64_t RightRedzoneSize = RZ;
1101 // Round up to MinRZ
1102 if (SizeInBytes % MinRZ)
1103 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1104 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1105 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1107 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1108 Constant *NewInitializer = ConstantStruct::get(
1109 NewTy, G->getInitializer(),
1110 Constant::getNullValue(RightRedZoneTy), NULL);
1112 // Create a new global variable with enough space for a redzone.
1113 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1114 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1115 Linkage = GlobalValue::InternalLinkage;
1116 GlobalVariable *NewGlobal = new GlobalVariable(
1117 M, NewTy, G->isConstant(), Linkage,
1118 NewInitializer, "", G, G->getThreadLocalMode());
1119 NewGlobal->copyAttributesFrom(G);
1120 NewGlobal->setAlignment(MinRZ);
1123 Indices2[0] = IRB.getInt32(0);
1124 Indices2[1] = IRB.getInt32(0);
1126 G->replaceAllUsesWith(
1127 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1128 NewGlobal->takeName(G);
1129 G->eraseFromParent();
1131 Constant *SourceLoc;
1132 if (!MD.SourceLoc.empty()) {
1133 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1134 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1136 SourceLoc = ConstantInt::get(IntptrTy, 0);
1139 Initializers[i] = ConstantStruct::get(
1140 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1141 ConstantInt::get(IntptrTy, SizeInBytes),
1142 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1143 ConstantExpr::getPointerCast(Name, IntptrTy),
1144 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1145 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, NULL);
1147 if (ClInitializers && MD.IsDynInit)
1148 HasDynamicallyInitializedGlobals = true;
1150 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1153 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1154 GlobalVariable *AllGlobals = new GlobalVariable(
1155 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1156 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1158 // Create calls for poisoning before initializers run and unpoisoning after.
1159 if (HasDynamicallyInitializedGlobals)
1160 createInitializerPoisonCalls(M, ModuleName);
1161 IRB.CreateCall2(AsanRegisterGlobals,
1162 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1163 ConstantInt::get(IntptrTy, n));
1165 // We also need to unregister globals at the end, e.g. when a shared library
1167 Function *AsanDtorFunction = Function::Create(
1168 FunctionType::get(Type::getVoidTy(*C), false),
1169 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1170 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1171 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1172 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1173 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1174 ConstantInt::get(IntptrTy, n));
1175 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1181 bool AddressSanitizerModule::runOnModule(Module &M) {
1182 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1185 DL = &DLP->getDataLayout();
1186 C = &(M.getContext());
1187 int LongSize = DL->getPointerSizeInBits();
1188 IntptrTy = Type::getIntNTy(*C, LongSize);
1189 Mapping = getShadowMapping(M, LongSize);
1190 initializeCallbacks(M);
1192 bool Changed = false;
1194 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1196 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1198 if (ClCoverage > 0) {
1199 Function *CovFunc = M.getFunction(kAsanCovName);
1200 int nCov = CovFunc ? CovFunc->getNumUses() : 0;
1201 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
1206 Changed |= InstrumentGlobals(IRB, M);
1211 void AddressSanitizer::initializeCallbacks(Module &M) {
1212 IRBuilder<> IRB(*C);
1213 // Create __asan_report* callbacks.
1214 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1215 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1216 AccessSizeIndex++) {
1217 // IsWrite and TypeSize are encoded in the function name.
1218 std::string Suffix =
1219 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1220 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1221 checkInterfaceFunction(
1222 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1223 IRB.getVoidTy(), IntptrTy, NULL));
1224 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1225 checkInterfaceFunction(
1226 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1227 IRB.getVoidTy(), IntptrTy, NULL));
1230 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1231 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1232 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1233 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1235 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1236 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1237 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1238 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1239 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1240 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1242 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1243 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1244 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1245 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1246 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1247 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1248 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1249 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1250 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1252 AsanHandleNoReturnFunc = checkInterfaceFunction(
1253 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1254 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1255 kAsanCovName, IRB.getVoidTy(), NULL));
1256 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1257 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1258 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1259 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1260 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1261 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1262 StringRef(""), StringRef(""),
1263 /*hasSideEffects=*/true);
1267 bool AddressSanitizer::doInitialization(Module &M) {
1268 // Initialize the private fields. No one has accessed them before.
1269 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1271 report_fatal_error("data layout missing");
1272 DL = &DLP->getDataLayout();
1276 C = &(M.getContext());
1277 LongSize = DL->getPointerSizeInBits();
1278 IntptrTy = Type::getIntNTy(*C, LongSize);
1280 AsanCtorFunction = Function::Create(
1281 FunctionType::get(Type::getVoidTy(*C), false),
1282 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1283 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1284 // call __asan_init in the module ctor.
1285 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1286 AsanInitFunction = checkInterfaceFunction(
1287 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1288 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1289 IRB.CreateCall(AsanInitFunction);
1291 Mapping = getShadowMapping(M, LongSize);
1293 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1297 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1298 // For each NSObject descendant having a +load method, this method is invoked
1299 // by the ObjC runtime before any of the static constructors is called.
1300 // Therefore we need to instrument such methods with a call to __asan_init
1301 // at the beginning in order to initialize our runtime before any access to
1302 // the shadow memory.
1303 // We cannot just ignore these methods, because they may call other
1304 // instrumented functions.
1305 if (F.getName().find(" load]") != std::string::npos) {
1306 IRBuilder<> IRB(F.begin()->begin());
1307 IRB.CreateCall(AsanInitFunction);
1313 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1314 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1315 // Skip static allocas at the top of the entry block so they don't become
1316 // dynamic when we split the block. If we used our optimized stack layout,
1317 // then there will only be one alloca and it will come first.
1318 for (; IP != BE; ++IP) {
1319 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1320 if (!AI || !AI->isStaticAlloca())
1324 DebugLoc EntryLoc = IP->getDebugLoc().getFnDebugLoc(*C);
1325 IRBuilder<> IRB(IP);
1326 IRB.SetCurrentDebugLocation(EntryLoc);
1327 Type *Int8Ty = IRB.getInt8Ty();
1328 GlobalVariable *Guard = new GlobalVariable(
1329 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1330 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1331 LoadInst *Load = IRB.CreateLoad(Guard);
1332 Load->setAtomic(Monotonic);
1333 Load->setAlignment(1);
1334 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1335 Instruction *Ins = SplitBlockAndInsertIfThen(
1336 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1337 IRB.SetInsertPoint(Ins);
1338 IRB.SetCurrentDebugLocation(EntryLoc);
1339 // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
1340 IRB.CreateCall(AsanCovFunction);
1341 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1342 Store->setAtomic(Monotonic);
1343 Store->setAlignment(1);
1346 // Poor man's coverage that works with ASan.
1347 // We create a Guard boolean variable with the same linkage
1348 // as the function and inject this code into the entry block (-asan-coverage=1)
1349 // or all blocks (-asan-coverage=2):
1351 // __sanitizer_cov();
1354 // The accesses to Guard are atomic. The rest of the logic is
1355 // in __sanitizer_cov (it's fine to call it more than once).
1357 // This coverage implementation provides very limited data:
1358 // it only tells if a given function (block) was ever executed.
1359 // No counters, no per-edge data.
1360 // But for many use cases this is what we need and the added slowdown
1361 // is negligible. This simple implementation will probably be obsoleted
1362 // by the upcoming Clang-based coverage implementation.
1363 // By having it here and now we hope to
1364 // a) get the functionality to users earlier and
1365 // b) collect usage statistics to help improve Clang coverage design.
1366 bool AddressSanitizer::InjectCoverage(Function &F,
1367 ArrayRef<BasicBlock *> AllBlocks) {
1368 if (!ClCoverage) return false;
1370 if (ClCoverage == 1 ||
1371 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1372 InjectCoverageAtBlock(F, F.getEntryBlock());
1374 for (auto BB : AllBlocks)
1375 InjectCoverageAtBlock(F, *BB);
1380 bool AddressSanitizer::runOnFunction(Function &F) {
1381 if (&F == AsanCtorFunction) return false;
1382 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1383 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1384 initializeCallbacks(*F.getParent());
1386 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1387 maybeInsertAsanInitAtFunctionEntry(F);
1389 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1392 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1395 // We want to instrument every address only once per basic block (unless there
1396 // are calls between uses).
1397 SmallSet<Value*, 16> TempsToInstrument;
1398 SmallVector<Instruction*, 16> ToInstrument;
1399 SmallVector<Instruction*, 8> NoReturnCalls;
1400 SmallVector<BasicBlock*, 16> AllBlocks;
1401 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1406 // Fill the set of memory operations to instrument.
1407 for (auto &BB : F) {
1408 AllBlocks.push_back(&BB);
1409 TempsToInstrument.clear();
1410 int NumInsnsPerBB = 0;
1411 for (auto &Inst : BB) {
1412 if (LooksLikeCodeInBug11395(&Inst)) return false;
1414 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1415 if (ClOpt && ClOptSameTemp) {
1416 if (!TempsToInstrument.insert(Addr))
1417 continue; // We've seen this temp in the current BB.
1419 } else if (ClInvalidPointerPairs &&
1420 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1421 PointerComparisonsOrSubtracts.push_back(&Inst);
1423 } else if (isa<MemIntrinsic>(Inst)) {
1426 if (isa<AllocaInst>(Inst))
1430 // A call inside BB.
1431 TempsToInstrument.clear();
1432 if (CS.doesNotReturn())
1433 NoReturnCalls.push_back(CS.getInstruction());
1437 ToInstrument.push_back(&Inst);
1439 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1444 Function *UninstrumentedDuplicate = nullptr;
1445 bool LikelyToInstrument =
1446 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1447 if (ClKeepUninstrumented && LikelyToInstrument) {
1448 ValueToValueMapTy VMap;
1449 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1450 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1451 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1452 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1455 bool UseCalls = false;
1456 if (ClInstrumentationWithCallsThreshold >= 0 &&
1457 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1461 int NumInstrumented = 0;
1462 for (auto Inst : ToInstrument) {
1463 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1464 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1465 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1466 instrumentMop(Inst, UseCalls);
1468 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1473 FunctionStackPoisoner FSP(F, *this);
1474 bool ChangedStack = FSP.runOnFunction();
1476 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1477 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1478 for (auto CI : NoReturnCalls) {
1479 IRBuilder<> IRB(CI);
1480 IRB.CreateCall(AsanHandleNoReturnFunc);
1483 for (auto Inst : PointerComparisonsOrSubtracts) {
1484 instrumentPointerComparisonOrSubtraction(Inst);
1488 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1490 if (InjectCoverage(F, AllBlocks))
1493 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1495 if (ClKeepUninstrumented) {
1497 // No instrumentation is done, no need for the duplicate.
1498 if (UninstrumentedDuplicate)
1499 UninstrumentedDuplicate->eraseFromParent();
1501 // The function was instrumented. We must have the duplicate.
1502 assert(UninstrumentedDuplicate);
1503 UninstrumentedDuplicate->setSection("NOASAN");
1504 assert(!F.hasSection());
1505 F.setSection("ASAN");
1512 // Workaround for bug 11395: we don't want to instrument stack in functions
1513 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1514 // FIXME: remove once the bug 11395 is fixed.
1515 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1516 if (LongSize != 32) return false;
1517 CallInst *CI = dyn_cast<CallInst>(I);
1518 if (!CI || !CI->isInlineAsm()) return false;
1519 if (CI->getNumArgOperands() <= 5) return false;
1520 // We have inline assembly with quite a few arguments.
1524 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1525 IRBuilder<> IRB(*C);
1526 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1527 std::string Suffix = itostr(i);
1528 AsanStackMallocFunc[i] = checkInterfaceFunction(
1529 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1530 IntptrTy, IntptrTy, NULL));
1531 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1532 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1533 IntptrTy, IntptrTy, NULL));
1535 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1536 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1537 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1538 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1542 FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1543 IRBuilder<> &IRB, Value *ShadowBase,
1545 size_t n = ShadowBytes.size();
1547 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1548 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1549 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1550 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1551 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1552 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1554 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1555 if (ASan.DL->isLittleEndian())
1556 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1558 Val = (Val << 8) | ShadowBytes[i + j];
1561 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1562 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1563 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1564 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1569 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1570 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1571 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1572 assert(LocalStackSize <= kMaxStackMallocSize);
1573 uint64_t MaxSize = kMinStackMallocSize;
1574 for (int i = 0; ; i++, MaxSize *= 2)
1575 if (LocalStackSize <= MaxSize)
1577 llvm_unreachable("impossible LocalStackSize");
1580 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1581 // We can not use MemSet intrinsic because it may end up calling the actual
1582 // memset. Size is a multiple of 8.
1583 // Currently this generates 8-byte stores on x86_64; it may be better to
1584 // generate wider stores.
1585 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1586 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1587 assert(!(Size % 8));
1588 assert(kAsanStackAfterReturnMagic == 0xf5);
1589 for (int i = 0; i < Size; i += 8) {
1590 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1591 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1592 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1596 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1597 for (const auto &Inst : F.getEntryBlock())
1598 if (!isa<AllocaInst>(Inst))
1599 return Inst.getDebugLoc();
1603 void FunctionStackPoisoner::poisonStack() {
1604 int StackMallocIdx = -1;
1605 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1607 assert(AllocaVec.size() > 0);
1608 Instruction *InsBefore = AllocaVec[0];
1609 IRBuilder<> IRB(InsBefore);
1610 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1612 SmallVector<ASanStackVariableDescription, 16> SVD;
1613 SVD.reserve(AllocaVec.size());
1614 for (AllocaInst *AI : AllocaVec) {
1615 ASanStackVariableDescription D = { AI->getName().data(),
1616 getAllocaSizeInBytes(AI),
1617 AI->getAlignment(), AI, 0};
1620 // Minimal header size (left redzone) is 4 pointers,
1621 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1622 size_t MinHeaderSize = ASan.LongSize / 2;
1623 ASanStackFrameLayout L;
1624 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1625 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1626 uint64_t LocalStackSize = L.FrameSize;
1627 bool DoStackMalloc =
1628 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1630 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1631 AllocaInst *MyAlloca =
1632 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1633 MyAlloca->setDebugLoc(EntryDebugLocation);
1634 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1635 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1636 MyAlloca->setAlignment(FrameAlignment);
1637 assert(MyAlloca->isStaticAlloca());
1638 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1639 Value *LocalStackBase = OrigStackBase;
1641 if (DoStackMalloc) {
1642 // LocalStackBase = OrigStackBase
1643 // if (__asan_option_detect_stack_use_after_return)
1644 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1645 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1646 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1647 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1648 kAsanOptionDetectUAR, IRB.getInt32Ty());
1649 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1650 Constant::getNullValue(IRB.getInt32Ty()));
1651 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1652 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1653 IRBuilder<> IRBIf(Term);
1654 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1655 LocalStackBase = IRBIf.CreateCall2(
1656 AsanStackMallocFunc[StackMallocIdx],
1657 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1658 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1659 IRB.SetInsertPoint(InsBefore);
1660 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1661 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1662 Phi->addIncoming(OrigStackBase, CmpBlock);
1663 Phi->addIncoming(LocalStackBase, SetBlock);
1664 LocalStackBase = Phi;
1667 // Insert poison calls for lifetime intrinsics for alloca.
1668 bool HavePoisonedAllocas = false;
1669 for (const auto &APC : AllocaPoisonCallVec) {
1670 assert(APC.InsBefore);
1672 IRBuilder<> IRB(APC.InsBefore);
1673 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1674 HavePoisonedAllocas |= APC.DoPoison;
1677 // Replace Alloca instructions with base+offset.
1678 for (const auto &Desc : SVD) {
1679 AllocaInst *AI = Desc.AI;
1680 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1681 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1683 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1684 AI->replaceAllUsesWith(NewAllocaPtr);
1687 // The left-most redzone has enough space for at least 4 pointers.
1688 // Write the Magic value to redzone[0].
1689 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1690 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1692 // Write the frame description constant to redzone[1].
1693 Value *BasePlus1 = IRB.CreateIntToPtr(
1694 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1696 GlobalVariable *StackDescriptionGlobal =
1697 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1698 /*AllowMerging*/true);
1699 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1701 IRB.CreateStore(Description, BasePlus1);
1702 // Write the PC to redzone[2].
1703 Value *BasePlus2 = IRB.CreateIntToPtr(
1704 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1705 2 * ASan.LongSize/8)),
1707 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1709 // Poison the stack redzones at the entry.
1710 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1711 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1713 // (Un)poison the stack before all ret instructions.
1714 for (auto Ret : RetVec) {
1715 IRBuilder<> IRBRet(Ret);
1716 // Mark the current frame as retired.
1717 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1719 if (DoStackMalloc) {
1720 assert(StackMallocIdx >= 0);
1721 // if LocalStackBase != OrigStackBase:
1722 // // In use-after-return mode, poison the whole stack frame.
1723 // if StackMallocIdx <= 4
1724 // // For small sizes inline the whole thing:
1725 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1726 // **SavedFlagPtr(LocalStackBase) = 0
1728 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1730 // <This is not a fake stack; unpoison the redzones>
1731 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1732 TerminatorInst *ThenTerm, *ElseTerm;
1733 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1735 IRBuilder<> IRBPoison(ThenTerm);
1736 if (StackMallocIdx <= 4) {
1737 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1738 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1739 ClassSize >> Mapping.Scale);
1740 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1742 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1743 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1744 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1745 IRBPoison.CreateStore(
1746 Constant::getNullValue(IRBPoison.getInt8Ty()),
1747 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1749 // For larger frames call __asan_stack_free_*.
1750 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1751 ConstantInt::get(IntptrTy, LocalStackSize),
1755 IRBuilder<> IRBElse(ElseTerm);
1756 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1757 } else if (HavePoisonedAllocas) {
1758 // If we poisoned some allocas in llvm.lifetime analysis,
1759 // unpoison whole stack frame now.
1760 assert(LocalStackBase == OrigStackBase);
1761 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1763 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1767 // We are done. Remove the old unused alloca instructions.
1768 for (auto AI : AllocaVec)
1769 AI->eraseFromParent();
1772 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1773 IRBuilder<> &IRB, bool DoPoison) {
1774 // For now just insert the call to ASan runtime.
1775 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1776 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1777 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1778 : AsanUnpoisonStackMemoryFunc,
1782 // Handling llvm.lifetime intrinsics for a given %alloca:
1783 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1784 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1785 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1786 // could be poisoned by previous llvm.lifetime.end instruction, as the
1787 // variable may go in and out of scope several times, e.g. in loops).
1788 // (3) if we poisoned at least one %alloca in a function,
1789 // unpoison the whole stack frame at function exit.
1791 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1792 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1793 // We're intested only in allocas we can handle.
1794 return isInterestingAlloca(*AI) ? AI : nullptr;
1795 // See if we've already calculated (or started to calculate) alloca for a
1797 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1798 if (I != AllocaForValue.end())
1800 // Store 0 while we're calculating alloca for value V to avoid
1801 // infinite recursion if the value references itself.
1802 AllocaForValue[V] = nullptr;
1803 AllocaInst *Res = nullptr;
1804 if (CastInst *CI = dyn_cast<CastInst>(V))
1805 Res = findAllocaForValue(CI->getOperand(0));
1806 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1807 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1808 Value *IncValue = PN->getIncomingValue(i);
1809 // Allow self-referencing phi-nodes.
1810 if (IncValue == PN) continue;
1811 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1812 // AI for incoming values should exist and should all be equal.
1813 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1819 AllocaForValue[V] = Res;