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/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/DepthFirstIterator.h"
19 #include "llvm/ADT/SetVector.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/ADT/StringExtras.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/Analysis/MemoryBuiltins.h"
26 #include "llvm/Analysis/TargetLibraryInfo.h"
27 #include "llvm/Analysis/ValueTracking.h"
28 #include "llvm/IR/CallSite.h"
29 #include "llvm/IR/DIBuilder.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/Dominators.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/IRBuilder.h"
34 #include "llvm/IR/InlineAsm.h"
35 #include "llvm/IR/InstVisitor.h"
36 #include "llvm/IR/IntrinsicInst.h"
37 #include "llvm/IR/LLVMContext.h"
38 #include "llvm/IR/MDBuilder.h"
39 #include "llvm/IR/Module.h"
40 #include "llvm/IR/Type.h"
41 #include "llvm/MC/MCSectionMachO.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/DataTypes.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/Support/Endian.h"
46 #include "llvm/Support/SwapByteOrder.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include "llvm/Transforms/Instrumentation.h"
49 #include "llvm/Transforms/Scalar.h"
50 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
51 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
52 #include "llvm/Transforms/Utils/Cloning.h"
53 #include "llvm/Transforms/Utils/Local.h"
54 #include "llvm/Transforms/Utils/ModuleUtils.h"
55 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
61 #include <system_error>
65 #define DEBUG_TYPE "asan"
67 static const uint64_t kDefaultShadowScale = 3;
68 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
69 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
70 static const uint64_t kDynamicShadowSentinel = ~(uint64_t)0;
71 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
72 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
73 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
74 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
75 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
76 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
77 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
78 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
79 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
80 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
81 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
82 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
83 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
84 // The shadow memory space is dynamically allocated.
85 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
87 static const size_t kMinStackMallocSize = 1 << 6; // 64B
88 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
89 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
90 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
92 static const char *const kAsanModuleCtorName = "asan.module_ctor";
93 static const char *const kAsanModuleDtorName = "asan.module_dtor";
94 static const uint64_t kAsanCtorAndDtorPriority = 1;
95 static const char *const kAsanReportErrorTemplate = "__asan_report_";
96 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
97 static const char *const kAsanUnregisterGlobalsName =
98 "__asan_unregister_globals";
99 static const char *const kAsanRegisterImageGlobalsName =
100 "__asan_register_image_globals";
101 static const char *const kAsanUnregisterImageGlobalsName =
102 "__asan_unregister_image_globals";
103 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
104 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
105 static const char *const kAsanInitName = "__asan_init";
106 static const char *const kAsanVersionCheckName =
107 "__asan_version_mismatch_check_v8";
108 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
109 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
110 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
111 static const int kMaxAsanStackMallocSizeClass = 10;
112 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
113 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
114 static const char *const kAsanGenPrefix = "__asan_gen_";
115 static const char *const kODRGenPrefix = "__odr_asan_gen_";
116 static const char *const kSanCovGenPrefix = "__sancov_gen_";
117 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
118 static const char *const kAsanPoisonStackMemoryName =
119 "__asan_poison_stack_memory";
120 static const char *const kAsanUnpoisonStackMemoryName =
121 "__asan_unpoison_stack_memory";
122 static const char *const kAsanGlobalsRegisteredFlagName =
123 "__asan_globals_registered";
125 static const char *const kAsanOptionDetectUseAfterReturn =
126 "__asan_option_detect_stack_use_after_return";
128 static const char *const kAsanShadowMemoryDynamicAddress =
129 "__asan_shadow_memory_dynamic_address";
131 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
132 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
134 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
135 static const size_t kNumberOfAccessSizes = 5;
137 static const unsigned kAllocaRzSize = 32;
139 // Command-line flags.
140 static cl::opt<bool> ClEnableKasan(
141 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
142 cl::Hidden, cl::init(false));
143 static cl::opt<bool> ClRecover(
145 cl::desc("Enable recovery mode (continue-after-error)."),
146 cl::Hidden, cl::init(false));
148 // This flag may need to be replaced with -f[no-]asan-reads.
149 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
150 cl::desc("instrument read instructions"),
151 cl::Hidden, cl::init(true));
152 static cl::opt<bool> ClInstrumentWrites(
153 "asan-instrument-writes", cl::desc("instrument write instructions"),
154 cl::Hidden, cl::init(true));
155 static cl::opt<bool> ClInstrumentAtomics(
156 "asan-instrument-atomics",
157 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
159 static cl::opt<bool> ClAlwaysSlowPath(
160 "asan-always-slow-path",
161 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
163 static cl::opt<bool> ClForceDynamicShadow(
164 "asan-force-dynamic-shadow",
165 cl::desc("Load shadow address into a local variable for each function"),
166 cl::Hidden, cl::init(false));
168 // This flag limits the number of instructions to be instrumented
169 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
170 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
172 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
173 "asan-max-ins-per-bb", cl::init(10000),
174 cl::desc("maximal number of instructions to instrument in any given BB"),
176 // This flag may need to be replaced with -f[no]asan-stack.
177 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
178 cl::Hidden, cl::init(true));
179 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
180 "asan-max-inline-poisoning-size",
182 "Inline shadow poisoning for blocks up to the given size in bytes."),
183 cl::Hidden, cl::init(64));
184 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
185 cl::desc("Check stack-use-after-return"),
186 cl::Hidden, cl::init(true));
187 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
188 cl::desc("Check stack-use-after-scope"),
189 cl::Hidden, cl::init(false));
190 // This flag may need to be replaced with -f[no]asan-globals.
191 static cl::opt<bool> ClGlobals("asan-globals",
192 cl::desc("Handle global objects"), cl::Hidden,
194 static cl::opt<bool> ClInitializers("asan-initialization-order",
195 cl::desc("Handle C++ initializer order"),
196 cl::Hidden, cl::init(true));
197 static cl::opt<bool> ClInvalidPointerPairs(
198 "asan-detect-invalid-pointer-pair",
199 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
201 static cl::opt<unsigned> ClRealignStack(
202 "asan-realign-stack",
203 cl::desc("Realign stack to the value of this flag (power of two)"),
204 cl::Hidden, cl::init(32));
205 static cl::opt<int> ClInstrumentationWithCallsThreshold(
206 "asan-instrumentation-with-call-threshold",
208 "If the function being instrumented contains more than "
209 "this number of memory accesses, use callbacks instead of "
210 "inline checks (-1 means never use callbacks)."),
211 cl::Hidden, cl::init(7000));
212 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
213 "asan-memory-access-callback-prefix",
214 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
215 cl::init("__asan_"));
217 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
218 cl::desc("instrument dynamic allocas"),
219 cl::Hidden, cl::init(true));
220 static cl::opt<bool> ClSkipPromotableAllocas(
221 "asan-skip-promotable-allocas",
222 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
225 // These flags allow to change the shadow mapping.
226 // The shadow mapping looks like
227 // Shadow = (Mem >> scale) + offset
228 static cl::opt<int> ClMappingScale("asan-mapping-scale",
229 cl::desc("scale of asan shadow mapping"),
230 cl::Hidden, cl::init(0));
231 static cl::opt<unsigned long long> ClMappingOffset(
232 "asan-mapping-offset",
233 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
236 // Optimization flags. Not user visible, used mostly for testing
237 // and benchmarking the tool.
238 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
239 cl::Hidden, cl::init(true));
240 static cl::opt<bool> ClOptSameTemp(
241 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
242 cl::Hidden, cl::init(true));
243 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
244 cl::desc("Don't instrument scalar globals"),
245 cl::Hidden, cl::init(true));
246 static cl::opt<bool> ClOptStack(
247 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
248 cl::Hidden, cl::init(false));
250 static cl::opt<bool> ClDynamicAllocaStack(
251 "asan-stack-dynamic-alloca",
252 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
255 static cl::opt<uint32_t> ClForceExperiment(
256 "asan-force-experiment",
257 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
261 ClUsePrivateAliasForGlobals("asan-use-private-alias",
262 cl::desc("Use private aliases for global"
264 cl::Hidden, cl::init(false));
267 ClUseMachOGlobalsSection("asan-globals-live-support",
268 cl::desc("Use linker features to support dead "
269 "code stripping of globals "
271 cl::Hidden, cl::init(true));
274 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
276 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
277 cl::Hidden, cl::init(0));
278 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
279 cl::desc("Debug func"));
280 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
281 cl::Hidden, cl::init(-1));
282 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
283 cl::Hidden, cl::init(-1));
285 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
286 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
287 STATISTIC(NumOptimizedAccessesToGlobalVar,
288 "Number of optimized accesses to global vars");
289 STATISTIC(NumOptimizedAccessesToStackVar,
290 "Number of optimized accesses to stack vars");
293 /// Frontend-provided metadata for source location.
294 struct LocationMetadata {
299 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
301 bool empty() const { return Filename.empty(); }
303 void parse(MDNode *MDN) {
304 assert(MDN->getNumOperands() == 3);
305 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
306 Filename = DIFilename->getString();
308 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
310 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
314 /// Frontend-provided metadata for global variables.
315 class GlobalsMetadata {
318 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
319 LocationMetadata SourceLoc;
325 GlobalsMetadata() : inited_(false) {}
332 void init(Module &M) {
335 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
336 if (!Globals) return;
337 for (auto MDN : Globals->operands()) {
338 // Metadata node contains the global and the fields of "Entry".
339 assert(MDN->getNumOperands() == 5);
340 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
341 // The optimizer may optimize away a global entirely.
343 // We can already have an entry for GV if it was merged with another
345 Entry &E = Entries[GV];
346 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
347 E.SourceLoc.parse(Loc);
348 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
349 E.Name = Name->getString();
350 ConstantInt *IsDynInit =
351 mdconst::extract<ConstantInt>(MDN->getOperand(3));
352 E.IsDynInit |= IsDynInit->isOne();
353 ConstantInt *IsBlacklisted =
354 mdconst::extract<ConstantInt>(MDN->getOperand(4));
355 E.IsBlacklisted |= IsBlacklisted->isOne();
359 /// Returns metadata entry for a given global.
360 Entry get(GlobalVariable *G) const {
361 auto Pos = Entries.find(G);
362 return (Pos != Entries.end()) ? Pos->second : Entry();
367 DenseMap<GlobalVariable *, Entry> Entries;
370 /// This struct defines the shadow mapping using the rule:
371 /// shadow = (mem >> Scale) ADD-or-OR Offset.
372 struct ShadowMapping {
378 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
380 bool IsAndroid = TargetTriple.isAndroid();
381 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
382 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
383 bool IsLinux = TargetTriple.isOSLinux();
384 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
385 TargetTriple.getArch() == llvm::Triple::ppc64le;
386 bool IsSystemZ = TargetTriple.getArch() == llvm::Triple::systemz;
387 bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86;
388 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
389 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
390 TargetTriple.getArch() == llvm::Triple::mipsel;
391 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
392 TargetTriple.getArch() == llvm::Triple::mips64el;
393 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
394 bool IsWindows = TargetTriple.isOSWindows();
396 ShadowMapping Mapping;
398 if (LongSize == 32) {
399 // Android is always PIE, which means that the beginning of the address
400 // space is always available.
404 Mapping.Offset = kMIPS32_ShadowOffset32;
406 Mapping.Offset = kFreeBSD_ShadowOffset32;
408 // If we're targeting iOS and x86, the binary is built for iOS simulator.
409 Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
411 Mapping.Offset = kWindowsShadowOffset32;
413 Mapping.Offset = kDefaultShadowOffset32;
414 } else { // LongSize == 64
416 Mapping.Offset = kPPC64_ShadowOffset64;
418 Mapping.Offset = kSystemZ_ShadowOffset64;
420 Mapping.Offset = kFreeBSD_ShadowOffset64;
421 else if (IsLinux && IsX86_64) {
423 Mapping.Offset = kLinuxKasan_ShadowOffset64;
425 Mapping.Offset = kSmallX86_64ShadowOffset;
426 } else if (IsWindows && IsX86_64) {
427 Mapping.Offset = kWindowsShadowOffset64;
429 Mapping.Offset = kMIPS64_ShadowOffset64;
431 // If we're targeting iOS and x86, the binary is built for iOS simulator.
432 // We are using dynamic shadow offset on the 64-bit devices.
434 IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
436 Mapping.Offset = kAArch64_ShadowOffset64;
438 Mapping.Offset = kDefaultShadowOffset64;
441 if (ClForceDynamicShadow) {
442 Mapping.Offset = kDynamicShadowSentinel;
445 Mapping.Scale = kDefaultShadowScale;
446 if (ClMappingScale.getNumOccurrences() > 0) {
447 Mapping.Scale = ClMappingScale;
450 if (ClMappingOffset.getNumOccurrences() > 0) {
451 Mapping.Offset = ClMappingOffset;
454 // OR-ing shadow offset if more efficient (at least on x86) if the offset
455 // is a power of two, but on ppc64 we have to use add since the shadow
456 // offset is not necessary 1/8-th of the address space. On SystemZ,
457 // we could OR the constant in a single instruction, but it's more
458 // efficient to load it once and use indexed addressing.
459 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ
460 && !(Mapping.Offset & (Mapping.Offset - 1))
461 && Mapping.Offset != kDynamicShadowSentinel;
466 static size_t RedzoneSizeForScale(int MappingScale) {
467 // Redzone used for stack and globals is at least 32 bytes.
468 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
469 return std::max(32U, 1U << MappingScale);
472 /// AddressSanitizer: instrument the code in module to find memory bugs.
473 struct AddressSanitizer : public FunctionPass {
474 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false,
475 bool UseAfterScope = false)
476 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
477 Recover(Recover || ClRecover),
478 UseAfterScope(UseAfterScope || ClUseAfterScope),
479 LocalDynamicShadow(nullptr) {
480 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
482 StringRef getPassName() const override {
483 return "AddressSanitizerFunctionPass";
485 void getAnalysisUsage(AnalysisUsage &AU) const override {
486 AU.addRequired<DominatorTreeWrapperPass>();
487 AU.addRequired<TargetLibraryInfoWrapperPass>();
489 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
490 uint64_t ArraySize = 1;
491 if (AI.isArrayAllocation()) {
492 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
493 assert(CI && "non-constant array size");
494 ArraySize = CI->getZExtValue();
496 Type *Ty = AI.getAllocatedType();
497 uint64_t SizeInBytes =
498 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
499 return SizeInBytes * ArraySize;
501 /// Check if we want (and can) handle this alloca.
502 bool isInterestingAlloca(const AllocaInst &AI);
504 /// If it is an interesting memory access, return the PointerOperand
505 /// and set IsWrite/Alignment. Otherwise return nullptr.
506 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
507 /// masked load/store.
508 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
509 uint64_t *TypeSize, unsigned *Alignment,
510 Value **MaybeMask = nullptr);
511 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
512 bool UseCalls, const DataLayout &DL);
513 void instrumentPointerComparisonOrSubtraction(Instruction *I);
514 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
515 Value *Addr, uint32_t TypeSize, bool IsWrite,
516 Value *SizeArgument, bool UseCalls, uint32_t Exp);
517 void instrumentUnusualSizeOrAlignment(Instruction *I,
518 Instruction *InsertBefore, Value *Addr,
519 uint32_t TypeSize, bool IsWrite,
520 Value *SizeArgument, bool UseCalls,
522 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
523 Value *ShadowValue, uint32_t TypeSize);
524 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
525 bool IsWrite, size_t AccessSizeIndex,
526 Value *SizeArgument, uint32_t Exp);
527 void instrumentMemIntrinsic(MemIntrinsic *MI);
528 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
529 bool runOnFunction(Function &F) override;
530 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
531 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
532 void markEscapedLocalAllocas(Function &F);
533 bool doInitialization(Module &M) override;
534 bool doFinalization(Module &M) override;
535 static char ID; // Pass identification, replacement for typeid
537 DominatorTree &getDominatorTree() const { return *DT; }
540 void initializeCallbacks(Module &M);
542 bool LooksLikeCodeInBug11395(Instruction *I);
543 bool GlobalIsLinkerInitialized(GlobalVariable *G);
544 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
545 uint64_t TypeSize) const;
547 /// Helper to cleanup per-function state.
548 struct FunctionStateRAII {
549 AddressSanitizer *Pass;
550 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
551 assert(Pass->ProcessedAllocas.empty() &&
552 "last pass forgot to clear cache");
553 assert(!Pass->LocalDynamicShadow);
555 ~FunctionStateRAII() {
556 Pass->LocalDynamicShadow = nullptr;
557 Pass->ProcessedAllocas.clear();
568 ShadowMapping Mapping;
570 Function *AsanCtorFunction = nullptr;
571 Function *AsanInitFunction = nullptr;
572 Function *AsanHandleNoReturnFunc;
573 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
574 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
575 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
576 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
577 // This array is indexed by AccessIsWrite and Experiment.
578 Function *AsanErrorCallbackSized[2][2];
579 Function *AsanMemoryAccessCallbackSized[2][2];
580 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
582 Value *LocalDynamicShadow;
583 GlobalsMetadata GlobalsMD;
584 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
586 friend struct FunctionStackPoisoner;
589 class AddressSanitizerModule : public ModulePass {
591 explicit AddressSanitizerModule(bool CompileKernel = false,
592 bool Recover = false)
593 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
594 Recover(Recover || ClRecover) {}
595 bool runOnModule(Module &M) override;
596 static char ID; // Pass identification, replacement for typeid
597 StringRef getPassName() const override { return "AddressSanitizerModule"; }
600 void initializeCallbacks(Module &M);
602 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
603 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
604 ArrayRef<GlobalVariable *> ExtendedGlobals,
605 ArrayRef<Constant *> MetadataInitializers);
606 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
607 ArrayRef<GlobalVariable *> ExtendedGlobals,
608 ArrayRef<Constant *> MetadataInitializers);
610 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
611 ArrayRef<GlobalVariable *> ExtendedGlobals,
612 ArrayRef<Constant *> MetadataInitializers);
614 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
615 StringRef OriginalName);
616 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata);
617 IRBuilder<> CreateAsanModuleDtor(Module &M);
619 bool ShouldInstrumentGlobal(GlobalVariable *G);
620 bool ShouldUseMachOGlobalsSection() const;
621 StringRef getGlobalMetadataSection() const;
622 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
623 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
624 size_t MinRedzoneSizeForGlobal() const {
625 return RedzoneSizeForScale(Mapping.Scale);
628 GlobalsMetadata GlobalsMD;
634 ShadowMapping Mapping;
635 Function *AsanPoisonGlobals;
636 Function *AsanUnpoisonGlobals;
637 Function *AsanRegisterGlobals;
638 Function *AsanUnregisterGlobals;
639 Function *AsanRegisterImageGlobals;
640 Function *AsanUnregisterImageGlobals;
643 // Stack poisoning does not play well with exception handling.
644 // When an exception is thrown, we essentially bypass the code
645 // that unpoisones the stack. This is why the run-time library has
646 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
647 // stack in the interceptor. This however does not work inside the
648 // actual function which catches the exception. Most likely because the
649 // compiler hoists the load of the shadow value somewhere too high.
650 // This causes asan to report a non-existing bug on 453.povray.
651 // It sounds like an LLVM bug.
652 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
654 AddressSanitizer &ASan;
659 ShadowMapping Mapping;
661 SmallVector<AllocaInst *, 16> AllocaVec;
662 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
663 SmallVector<Instruction *, 8> RetVec;
664 unsigned StackAlignment;
666 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
667 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
668 Function *AsanSetShadowFunc[0x100] = {};
669 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
670 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
672 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
673 struct AllocaPoisonCall {
674 IntrinsicInst *InsBefore;
679 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
680 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
682 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
683 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
684 AllocaInst *DynamicAllocaLayout = nullptr;
685 IntrinsicInst *LocalEscapeCall = nullptr;
687 // Maps Value to an AllocaInst from which the Value is originated.
688 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
689 AllocaForValueMapTy AllocaForValue;
691 bool HasNonEmptyInlineAsm = false;
692 bool HasReturnsTwiceCall = false;
693 std::unique_ptr<CallInst> EmptyInlineAsm;
695 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
698 DIB(*F.getParent(), /*AllowUnresolved*/ false),
700 IntptrTy(ASan.IntptrTy),
701 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
702 Mapping(ASan.Mapping),
703 StackAlignment(1 << Mapping.Scale),
704 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
706 bool runOnFunction() {
707 if (!ClStack) return false;
708 // Collect alloca, ret, lifetime instructions etc.
709 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
711 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
713 initializeCallbacks(*F.getParent());
715 processDynamicAllocas();
716 processStaticAllocas();
724 // Finds all Alloca instructions and puts
725 // poisoned red zones around all of them.
726 // Then unpoison everything back before the function returns.
727 void processStaticAllocas();
728 void processDynamicAllocas();
730 void createDynamicAllocasInitStorage();
732 // ----------------------- Visitors.
733 /// \brief Collect all Ret instructions.
734 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
736 /// \brief Collect all Resume instructions.
737 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
739 /// \brief Collect all CatchReturnInst instructions.
740 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
742 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
744 IRBuilder<> IRB(InstBefore);
745 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
746 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
747 // need to adjust extracted SP to compute the address of the most recent
748 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
750 if (!isa<ReturnInst>(InstBefore)) {
751 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
752 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
755 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
757 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
761 IRB.CreateCall(AsanAllocasUnpoisonFunc,
762 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
765 // Unpoison dynamic allocas redzones.
766 void unpoisonDynamicAllocas() {
767 for (auto &Ret : RetVec)
768 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
770 for (auto &StackRestoreInst : StackRestoreVec)
771 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
772 StackRestoreInst->getOperand(0));
775 // Deploy and poison redzones around dynamic alloca call. To do this, we
776 // should replace this call with another one with changed parameters and
777 // replace all its uses with new address, so
778 // addr = alloca type, old_size, align
780 // new_size = (old_size + additional_size) * sizeof(type)
781 // tmp = alloca i8, new_size, max(align, 32)
782 // addr = tmp + 32 (first 32 bytes are for the left redzone).
783 // Additional_size is added to make new memory allocation contain not only
784 // requested memory, but also left, partial and right redzones.
785 void handleDynamicAllocaCall(AllocaInst *AI);
787 /// \brief Collect Alloca instructions we want (and can) handle.
788 void visitAllocaInst(AllocaInst &AI) {
789 if (!ASan.isInterestingAlloca(AI)) {
790 if (AI.isStaticAlloca()) {
791 // Skip over allocas that are present *before* the first instrumented
792 // alloca, we don't want to move those around.
793 if (AllocaVec.empty())
796 StaticAllocasToMoveUp.push_back(&AI);
801 StackAlignment = std::max(StackAlignment, AI.getAlignment());
802 if (!AI.isStaticAlloca())
803 DynamicAllocaVec.push_back(&AI);
805 AllocaVec.push_back(&AI);
808 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
810 void visitIntrinsicInst(IntrinsicInst &II) {
811 Intrinsic::ID ID = II.getIntrinsicID();
812 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
813 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
814 if (!ASan.UseAfterScope)
816 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
818 // Found lifetime intrinsic, add ASan instrumentation if necessary.
819 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
820 // If size argument is undefined, don't do anything.
821 if (Size->isMinusOne()) return;
822 // Check that size doesn't saturate uint64_t and can
823 // be stored in IntptrTy.
824 const uint64_t SizeValue = Size->getValue().getLimitedValue();
825 if (SizeValue == ~0ULL ||
826 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
828 // Find alloca instruction that corresponds to llvm.lifetime argument.
829 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
830 if (!AI || !ASan.isInterestingAlloca(*AI))
832 bool DoPoison = (ID == Intrinsic::lifetime_end);
833 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
834 if (AI->isStaticAlloca())
835 StaticAllocaPoisonCallVec.push_back(APC);
836 else if (ClInstrumentDynamicAllocas)
837 DynamicAllocaPoisonCallVec.push_back(APC);
840 void visitCallSite(CallSite CS) {
841 Instruction *I = CS.getInstruction();
842 if (CallInst *CI = dyn_cast<CallInst>(I)) {
843 HasNonEmptyInlineAsm |=
844 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
845 HasReturnsTwiceCall |= CI->canReturnTwice();
849 // ---------------------- Helpers.
850 void initializeCallbacks(Module &M);
852 bool doesDominateAllExits(const Instruction *I) const {
853 for (auto Ret : RetVec) {
854 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
859 /// Finds alloca where the value comes from.
860 AllocaInst *findAllocaForValue(Value *V);
862 // Copies bytes from ShadowBytes into shadow memory for indexes where
863 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
864 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
865 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
866 IRBuilder<> &IRB, Value *ShadowBase);
867 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
868 size_t Begin, size_t End, IRBuilder<> &IRB,
870 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
871 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
872 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
874 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
876 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
878 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
879 Instruction *ThenTerm, Value *ValueIfFalse);
882 } // anonymous namespace
884 char AddressSanitizer::ID = 0;
885 INITIALIZE_PASS_BEGIN(
886 AddressSanitizer, "asan",
887 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
889 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
890 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
892 AddressSanitizer, "asan",
893 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
895 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
897 bool UseAfterScope) {
898 assert(!CompileKernel || Recover);
899 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
902 char AddressSanitizerModule::ID = 0;
904 AddressSanitizerModule, "asan-module",
905 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
908 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
910 assert(!CompileKernel || Recover);
911 return new AddressSanitizerModule(CompileKernel, Recover);
914 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
915 size_t Res = countTrailingZeros(TypeSize / 8);
916 assert(Res < kNumberOfAccessSizes);
920 // \brief Create a constant for Str so that we can pass it to the run-time lib.
921 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
923 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
924 // We use private linkage for module-local strings. If they can be merged
925 // with another one, we set the unnamed_addr attribute.
927 new GlobalVariable(M, StrConst->getType(), true,
928 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
929 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
930 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
934 /// \brief Create a global describing a source location.
935 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
936 LocationMetadata MD) {
937 Constant *LocData[] = {
938 createPrivateGlobalForString(M, MD.Filename, true),
939 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
940 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
942 auto LocStruct = ConstantStruct::getAnon(LocData);
943 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
944 GlobalValue::PrivateLinkage, LocStruct,
946 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
950 /// \brief Check if \p G has been created by a trusted compiler pass.
951 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
952 // Do not instrument asan globals.
953 if (G->getName().startswith(kAsanGenPrefix) ||
954 G->getName().startswith(kSanCovGenPrefix) ||
955 G->getName().startswith(kODRGenPrefix))
958 // Do not instrument gcov counter arrays.
959 if (G->getName() == "__llvm_gcov_ctr")
965 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
967 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
968 if (Mapping.Offset == 0) return Shadow;
969 // (Shadow >> scale) | offset
971 if (LocalDynamicShadow)
972 ShadowBase = LocalDynamicShadow;
974 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
975 if (Mapping.OrShadowOffset)
976 return IRB.CreateOr(Shadow, ShadowBase);
978 return IRB.CreateAdd(Shadow, ShadowBase);
981 // Instrument memset/memmove/memcpy
982 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
984 if (isa<MemTransferInst>(MI)) {
986 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
987 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
988 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
989 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
990 } else if (isa<MemSetInst>(MI)) {
993 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
994 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
995 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
997 MI->eraseFromParent();
1000 /// Check if we want (and can) handle this alloca.
1001 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1002 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1004 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1005 return PreviouslySeenAllocaInfo->getSecond();
1007 bool IsInteresting =
1008 (AI.getAllocatedType()->isSized() &&
1009 // alloca() may be called with 0 size, ignore it.
1010 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1011 // We are only interested in allocas not promotable to registers.
1012 // Promotable allocas are common under -O0.
1013 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1014 // inalloca allocas are not treated as static, and we don't want
1015 // dynamic alloca instrumentation for them as well.
1016 !AI.isUsedWithInAlloca() &&
1017 // swifterror allocas are register promoted by ISel
1018 !AI.isSwiftError());
1020 ProcessedAllocas[&AI] = IsInteresting;
1021 return IsInteresting;
1024 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1027 unsigned *Alignment,
1028 Value **MaybeMask) {
1029 // Skip memory accesses inserted by another instrumentation.
1030 if (I->getMetadata("nosanitize")) return nullptr;
1032 // Do not instrument the load fetching the dynamic shadow address.
1033 if (LocalDynamicShadow == I)
1036 Value *PtrOperand = nullptr;
1037 const DataLayout &DL = I->getModule()->getDataLayout();
1038 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1039 if (!ClInstrumentReads) return nullptr;
1041 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1042 *Alignment = LI->getAlignment();
1043 PtrOperand = LI->getPointerOperand();
1044 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1045 if (!ClInstrumentWrites) return nullptr;
1047 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1048 *Alignment = SI->getAlignment();
1049 PtrOperand = SI->getPointerOperand();
1050 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1051 if (!ClInstrumentAtomics) return nullptr;
1053 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1055 PtrOperand = RMW->getPointerOperand();
1056 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1057 if (!ClInstrumentAtomics) return nullptr;
1059 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1061 PtrOperand = XCHG->getPointerOperand();
1062 } else if (auto CI = dyn_cast<CallInst>(I)) {
1063 auto *F = dyn_cast<Function>(CI->getCalledValue());
1064 if (F && (F->getName().startswith("llvm.masked.load.") ||
1065 F->getName().startswith("llvm.masked.store."))) {
1066 unsigned OpOffset = 0;
1067 if (F->getName().startswith("llvm.masked.store.")) {
1068 if (!ClInstrumentWrites)
1070 // Masked store has an initial operand for the value.
1074 if (!ClInstrumentReads)
1079 auto BasePtr = CI->getOperand(0 + OpOffset);
1080 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1081 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1082 if (auto AlignmentConstant =
1083 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1084 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1086 *Alignment = 1; // No alignment guarantees. We probably got Undef
1088 *MaybeMask = CI->getOperand(2 + OpOffset);
1089 PtrOperand = BasePtr;
1094 // Do not instrument acesses from different address spaces; we cannot deal
1096 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1097 if (PtrTy->getPointerAddressSpace() != 0)
1100 // Ignore swifterror addresses.
1101 // swifterror memory addresses are mem2reg promoted by instruction
1102 // selection. As such they cannot have regular uses like an instrumentation
1103 // function and it makes no sense to track them as memory.
1104 if (PtrOperand->isSwiftError())
1108 // Treat memory accesses to promotable allocas as non-interesting since they
1109 // will not cause memory violations. This greatly speeds up the instrumented
1110 // executable at -O0.
1111 if (ClSkipPromotableAllocas)
1112 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1113 return isInterestingAlloca(*AI) ? AI : nullptr;
1118 static bool isPointerOperand(Value *V) {
1119 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1122 // This is a rough heuristic; it may cause both false positives and
1123 // false negatives. The proper implementation requires cooperation with
1125 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1126 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1127 if (!Cmp->isRelational()) return false;
1128 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1129 if (BO->getOpcode() != Instruction::Sub) return false;
1133 return isPointerOperand(I->getOperand(0)) &&
1134 isPointerOperand(I->getOperand(1));
1137 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1138 // If a global variable does not have dynamic initialization we don't
1139 // have to instrument it. However, if a global does not have initializer
1140 // at all, we assume it has dynamic initializer (in other TU).
1141 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1144 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1147 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1148 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1149 for (Value *&i : Param) {
1150 if (i->getType()->isPointerTy())
1151 i = IRB.CreatePointerCast(i, IntptrTy);
1153 IRB.CreateCall(F, Param);
1156 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1157 Instruction *InsertBefore, Value *Addr,
1158 unsigned Alignment, unsigned Granularity,
1159 uint32_t TypeSize, bool IsWrite,
1160 Value *SizeArgument, bool UseCalls,
1162 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1163 // if the data is properly aligned.
1164 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1166 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1167 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1168 nullptr, UseCalls, Exp);
1169 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1170 IsWrite, nullptr, UseCalls, Exp);
1173 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1174 const DataLayout &DL, Type *IntptrTy,
1175 Value *Mask, Instruction *I,
1176 Value *Addr, unsigned Alignment,
1177 unsigned Granularity, uint32_t TypeSize,
1178 bool IsWrite, Value *SizeArgument,
1179 bool UseCalls, uint32_t Exp) {
1180 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1181 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1182 unsigned Num = VTy->getVectorNumElements();
1183 auto Zero = ConstantInt::get(IntptrTy, 0);
1184 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1185 Value *InstrumentedAddress = nullptr;
1186 Instruction *InsertBefore = I;
1187 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1188 // dyn_cast as we might get UndefValue
1189 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1190 if (Masked->isNullValue())
1191 // Mask is constant false, so no instrumentation needed.
1193 // If we have a true or undef value, fall through to doInstrumentAddress
1194 // with InsertBefore == I
1198 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1199 TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1200 InsertBefore = ThenTerm;
1203 IRBuilder<> IRB(InsertBefore);
1204 InstrumentedAddress =
1205 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1206 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1207 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1212 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1213 Instruction *I, bool UseCalls,
1214 const DataLayout &DL) {
1215 bool IsWrite = false;
1216 unsigned Alignment = 0;
1217 uint64_t TypeSize = 0;
1218 Value *MaybeMask = nullptr;
1220 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1223 // Optimization experiments.
1224 // The experiments can be used to evaluate potential optimizations that remove
1225 // instrumentation (assess false negatives). Instead of completely removing
1226 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1227 // experiments that want to remove instrumentation of this instruction).
1228 // If Exp is non-zero, this pass will emit special calls into runtime
1229 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1230 // make runtime terminate the program in a special way (with a different
1231 // exit status). Then you run the new compiler on a buggy corpus, collect
1232 // the special terminations (ideally, you don't see them at all -- no false
1233 // negatives) and make the decision on the optimization.
1234 uint32_t Exp = ClForceExperiment;
1236 if (ClOpt && ClOptGlobals) {
1237 // If initialization order checking is disabled, a simple access to a
1238 // dynamically initialized global is always valid.
1239 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1240 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1241 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1242 NumOptimizedAccessesToGlobalVar++;
1247 if (ClOpt && ClOptStack) {
1248 // A direct inbounds access to a stack variable is always valid.
1249 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1250 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1251 NumOptimizedAccessesToStackVar++;
1257 NumInstrumentedWrites++;
1259 NumInstrumentedReads++;
1261 unsigned Granularity = 1 << Mapping.Scale;
1263 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1264 Alignment, Granularity, TypeSize, IsWrite,
1265 nullptr, UseCalls, Exp);
1267 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1268 IsWrite, nullptr, UseCalls, Exp);
1272 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1273 Value *Addr, bool IsWrite,
1274 size_t AccessSizeIndex,
1275 Value *SizeArgument,
1277 IRBuilder<> IRB(InsertBefore);
1278 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1279 CallInst *Call = nullptr;
1282 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1283 {Addr, SizeArgument});
1285 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1286 {Addr, SizeArgument, ExpVal});
1290 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1292 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1296 // We don't do Call->setDoesNotReturn() because the BB already has
1297 // UnreachableInst at the end.
1298 // This EmptyAsm is required to avoid callback merge.
1299 IRB.CreateCall(EmptyAsm, {});
1303 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1305 uint32_t TypeSize) {
1306 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1307 // Addr & (Granularity - 1)
1308 Value *LastAccessedByte =
1309 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1310 // (Addr & (Granularity - 1)) + size - 1
1311 if (TypeSize / 8 > 1)
1312 LastAccessedByte = IRB.CreateAdd(
1313 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1314 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1316 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1317 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1318 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1321 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1322 Instruction *InsertBefore, Value *Addr,
1323 uint32_t TypeSize, bool IsWrite,
1324 Value *SizeArgument, bool UseCalls,
1326 IRBuilder<> IRB(InsertBefore);
1327 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1328 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1332 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1335 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1336 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1341 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1342 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1343 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1344 Value *CmpVal = Constant::getNullValue(ShadowTy);
1345 Value *ShadowValue =
1346 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1348 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1349 size_t Granularity = 1ULL << Mapping.Scale;
1350 TerminatorInst *CrashTerm = nullptr;
1352 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1353 // We use branch weights for the slow path check, to indicate that the slow
1354 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1355 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1356 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1357 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1358 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1359 IRB.SetInsertPoint(CheckTerm);
1360 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1362 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1364 BasicBlock *CrashBlock =
1365 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1366 CrashTerm = new UnreachableInst(*C, CrashBlock);
1367 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1368 ReplaceInstWithInst(CheckTerm, NewTerm);
1371 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1374 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1375 AccessSizeIndex, SizeArgument, Exp);
1376 Crash->setDebugLoc(OrigIns->getDebugLoc());
1379 // Instrument unusual size or unusual alignment.
1380 // We can not do it with a single check, so we do 1-byte check for the first
1381 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1382 // to report the actual access size.
1383 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1384 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1385 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1386 IRBuilder<> IRB(InsertBefore);
1387 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1388 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1391 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1394 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1395 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1397 Value *LastByte = IRB.CreateIntToPtr(
1398 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1400 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1401 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1405 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1406 GlobalValue *ModuleName) {
1407 // Set up the arguments to our poison/unpoison functions.
1408 IRBuilder<> IRB(&GlobalInit.front(),
1409 GlobalInit.front().getFirstInsertionPt());
1411 // Add a call to poison all external globals before the given function starts.
1412 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1413 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1415 // Add calls to unpoison all globals before each return instruction.
1416 for (auto &BB : GlobalInit.getBasicBlockList())
1417 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1418 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1421 void AddressSanitizerModule::createInitializerPoisonCalls(
1422 Module &M, GlobalValue *ModuleName) {
1423 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1425 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1426 for (Use &OP : CA->operands()) {
1427 if (isa<ConstantAggregateZero>(OP)) continue;
1428 ConstantStruct *CS = cast<ConstantStruct>(OP);
1430 // Must have a function or null ptr.
1431 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1432 if (F->getName() == kAsanModuleCtorName) continue;
1433 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1434 // Don't instrument CTORs that will run before asan.module_ctor.
1435 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1436 poisonOneInitializer(*F, ModuleName);
1441 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1442 Type *Ty = G->getValueType();
1443 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1445 if (GlobalsMD.get(G).IsBlacklisted) return false;
1446 if (!Ty->isSized()) return false;
1447 if (!G->hasInitializer()) return false;
1448 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1449 // Touch only those globals that will not be defined in other modules.
1450 // Don't handle ODR linkage types and COMDATs since other modules may be built
1452 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1453 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1454 G->getLinkage() != GlobalVariable::InternalLinkage)
1456 if (G->hasComdat()) return false;
1457 // Two problems with thread-locals:
1458 // - The address of the main thread's copy can't be computed at link-time.
1459 // - Need to poison all copies, not just the main thread's one.
1460 if (G->isThreadLocal()) return false;
1461 // For now, just ignore this Global if the alignment is large.
1462 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1464 if (G->hasSection()) {
1465 StringRef Section = G->getSection();
1467 // Globals from llvm.metadata aren't emitted, do not instrument them.
1468 if (Section == "llvm.metadata") return false;
1469 // Do not instrument globals from special LLVM sections.
1470 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1472 // Do not instrument function pointers to initialization and termination
1473 // routines: dynamic linker will not properly handle redzones.
1474 if (Section.startswith(".preinit_array") ||
1475 Section.startswith(".init_array") ||
1476 Section.startswith(".fini_array")) {
1480 // Callbacks put into the CRT initializer/terminator sections
1481 // should not be instrumented.
1482 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1483 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1484 if (Section.startswith(".CRT")) {
1485 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1489 if (TargetTriple.isOSBinFormatMachO()) {
1490 StringRef ParsedSegment, ParsedSection;
1491 unsigned TAA = 0, StubSize = 0;
1493 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1494 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1495 assert(ErrorCode.empty() && "Invalid section specifier.");
1497 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1498 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1500 if (ParsedSegment == "__OBJC" ||
1501 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1502 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1505 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1506 // Constant CFString instances are compiled in the following way:
1507 // -- the string buffer is emitted into
1508 // __TEXT,__cstring,cstring_literals
1509 // -- the constant NSConstantString structure referencing that buffer
1510 // is placed into __DATA,__cfstring
1511 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1512 // Moreover, it causes the linker to crash on OS X 10.7
1513 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1514 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1517 // The linker merges the contents of cstring_literals and removes the
1519 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1520 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1529 // On Mach-O platforms, we emit global metadata in a separate section of the
1530 // binary in order to allow the linker to properly dead strip. This is only
1531 // supported on recent versions of ld64.
1532 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1533 if (!ClUseMachOGlobalsSection)
1536 if (!TargetTriple.isOSBinFormatMachO())
1539 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1541 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1543 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1549 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1550 switch (TargetTriple.getObjectFormat()) {
1551 case Triple::COFF: return ".ASAN$GL";
1552 case Triple::ELF: return "asan_globals";
1553 case Triple::MachO: return "__DATA,__asan_globals,regular";
1556 llvm_unreachable("unsupported object format");
1559 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1560 IRBuilder<> IRB(*C);
1562 // Declare our poisoning and unpoisoning functions.
1563 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1564 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1565 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1566 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1567 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1568 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1570 // Declare functions that register/unregister globals.
1571 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1572 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1573 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1574 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1575 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1576 IntptrTy, IntptrTy, nullptr));
1577 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1579 // Declare the functions that find globals in a shared object and then invoke
1580 // the (un)register function on them.
1581 AsanRegisterImageGlobals =
1582 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1583 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1584 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1586 AsanUnregisterImageGlobals =
1587 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1588 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1589 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1592 // Put the metadata and the instrumented global in the same group. This ensures
1593 // that the metadata is discarded if the instrumented global is discarded.
1594 void AddressSanitizerModule::SetComdatForGlobalMetadata(
1595 GlobalVariable *G, GlobalVariable *Metadata) {
1596 Module &M = *G->getParent();
1597 Comdat *C = G->getComdat();
1599 if (!G->hasName()) {
1600 // If G is unnamed, it must be internal. Give it an artificial name
1601 // so we can put it in a comdat.
1602 assert(G->hasLocalLinkage());
1603 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1605 C = M.getOrInsertComdat(G->getName());
1606 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1607 if (TargetTriple.isOSBinFormatCOFF())
1608 C->setSelectionKind(Comdat::NoDuplicates);
1612 assert(G->hasComdat());
1613 Metadata->setComdat(G->getComdat());
1616 // Create a separate metadata global and put it in the appropriate ASan
1617 // global registration section.
1619 AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
1620 StringRef OriginalName) {
1621 GlobalVariable *Metadata =
1622 new GlobalVariable(M, Initializer->getType(), false,
1623 GlobalVariable::InternalLinkage, Initializer,
1624 Twine("__asan_global_") +
1625 GlobalValue::getRealLinkageName(OriginalName));
1626 Metadata->setSection(getGlobalMetadataSection());
1630 IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) {
1631 Function *AsanDtorFunction =
1632 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1633 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1634 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1635 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1637 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
1640 void AddressSanitizerModule::InstrumentGlobalsCOFF(
1641 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1642 ArrayRef<Constant *> MetadataInitializers) {
1643 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1644 auto &DL = M.getDataLayout();
1646 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1647 Constant *Initializer = MetadataInitializers[i];
1648 GlobalVariable *G = ExtendedGlobals[i];
1649 GlobalVariable *Metadata =
1650 CreateMetadataGlobal(M, Initializer, G->getName());
1652 // The MSVC linker always inserts padding when linking incrementally. We
1653 // cope with that by aligning each struct to its size, which must be a power
1655 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
1656 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
1657 "global metadata will not be padded appropriately");
1658 Metadata->setAlignment(SizeOfGlobalStruct);
1660 SetComdatForGlobalMetadata(G, Metadata);
1664 void AddressSanitizerModule::InstrumentGlobalsMachO(
1665 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1666 ArrayRef<Constant *> MetadataInitializers) {
1667 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1669 // On recent Mach-O platforms, use a structure which binds the liveness of
1670 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1671 // created to be added to llvm.compiler.used
1672 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
1673 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
1675 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1676 Constant *Initializer = MetadataInitializers[i];
1677 GlobalVariable *G = ExtendedGlobals[i];
1678 GlobalVariable *Metadata =
1679 CreateMetadataGlobal(M, Initializer, G->getName());
1681 // On recent Mach-O platforms, we emit the global metadata in a way that
1682 // allows the linker to properly strip dead globals.
1683 auto LivenessBinder = ConstantStruct::get(
1684 LivenessTy, Initializer->getAggregateElement(0u),
1685 ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr);
1686 GlobalVariable *Liveness = new GlobalVariable(
1687 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1688 Twine("__asan_binder_") + G->getName());
1689 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1690 LivenessGlobals[i] = Liveness;
1693 // Update llvm.compiler.used, adding the new liveness globals. This is
1694 // needed so that during LTO these variables stay alive. The alternative
1695 // would be to have the linker handling the LTO symbols, but libLTO
1696 // current API does not expose access to the section for each symbol.
1697 if (!LivenessGlobals.empty())
1698 appendToCompilerUsed(M, LivenessGlobals);
1700 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1701 // to look up the loaded image that contains it. Second, we can store in it
1702 // whether registration has already occurred, to prevent duplicate
1705 // common linkage ensures that there is only one global per shared library.
1706 GlobalVariable *RegisteredFlag = new GlobalVariable(
1707 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1708 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1709 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1711 IRB.CreateCall(AsanRegisterImageGlobals,
1712 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1714 // We also need to unregister globals at the end, e.g., when a shared library
1716 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1717 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1718 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1721 void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
1722 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1723 ArrayRef<Constant *> MetadataInitializers) {
1724 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1725 unsigned N = ExtendedGlobals.size();
1728 // On platforms that don't have a custom metadata section, we emit an array
1729 // of global metadata structures.
1730 ArrayType *ArrayOfGlobalStructTy =
1731 ArrayType::get(MetadataInitializers[0]->getType(), N);
1732 auto AllGlobals = new GlobalVariable(
1733 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1734 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
1736 IRB.CreateCall(AsanRegisterGlobals,
1737 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1738 ConstantInt::get(IntptrTy, N)});
1740 // We also need to unregister globals at the end, e.g., when a shared library
1742 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1743 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1744 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1745 ConstantInt::get(IntptrTy, N)});
1748 // This function replaces all global variables with new variables that have
1749 // trailing redzones. It also creates a function that poisons
1750 // redzones and inserts this function into llvm.global_ctors.
1751 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1754 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1756 for (auto &G : M.globals()) {
1757 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1760 size_t n = GlobalsToChange.size();
1761 if (n == 0) return false;
1763 auto &DL = M.getDataLayout();
1765 // A global is described by a structure
1768 // size_t size_with_redzone;
1769 // const char *name;
1770 // const char *module_name;
1771 // size_t has_dynamic_init;
1772 // void *source_location;
1773 // size_t odr_indicator;
1774 // We initialize an array of such structures and pass it to a run-time call.
1775 StructType *GlobalStructTy =
1776 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1777 IntptrTy, IntptrTy, IntptrTy, nullptr);
1778 SmallVector<GlobalVariable *, 16> NewGlobals(n);
1779 SmallVector<Constant *, 16> Initializers(n);
1781 bool HasDynamicallyInitializedGlobals = false;
1783 // We shouldn't merge same module names, as this string serves as unique
1784 // module ID in runtime.
1785 GlobalVariable *ModuleName = createPrivateGlobalForString(
1786 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1788 for (size_t i = 0; i < n; i++) {
1789 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1790 GlobalVariable *G = GlobalsToChange[i];
1792 auto MD = GlobalsMD.get(G);
1793 StringRef NameForGlobal = G->getName();
1794 // Create string holding the global name (use global name from metadata
1795 // if it's available, otherwise just write the name of global variable).
1796 GlobalVariable *Name = createPrivateGlobalForString(
1797 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1798 /*AllowMerging*/ true);
1800 Type *Ty = G->getValueType();
1801 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1802 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1803 // MinRZ <= RZ <= kMaxGlobalRedzone
1804 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1805 uint64_t RZ = std::max(
1806 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1807 uint64_t RightRedzoneSize = RZ;
1808 // Round up to MinRZ
1809 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1810 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1811 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1813 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1814 Constant *NewInitializer =
1815 ConstantStruct::get(NewTy, G->getInitializer(),
1816 Constant::getNullValue(RightRedZoneTy), nullptr);
1818 // Create a new global variable with enough space for a redzone.
1819 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1820 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1821 Linkage = GlobalValue::InternalLinkage;
1822 GlobalVariable *NewGlobal =
1823 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1824 "", G, G->getThreadLocalMode());
1825 NewGlobal->copyAttributesFrom(G);
1826 NewGlobal->setAlignment(MinRZ);
1828 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1829 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1831 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1832 if (Seq && Seq->isCString())
1833 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1836 // Transfer the debug info. The payload starts at offset zero so we can
1837 // copy the debug info over as is.
1838 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1839 G->getDebugInfo(GVs);
1840 for (auto *GV : GVs)
1841 NewGlobal->addDebugInfo(GV);
1844 Indices2[0] = IRB.getInt32(0);
1845 Indices2[1] = IRB.getInt32(0);
1847 G->replaceAllUsesWith(
1848 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1849 NewGlobal->takeName(G);
1850 G->eraseFromParent();
1851 NewGlobals[i] = NewGlobal;
1853 Constant *SourceLoc;
1854 if (!MD.SourceLoc.empty()) {
1855 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1856 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1858 SourceLoc = ConstantInt::get(IntptrTy, 0);
1861 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
1862 GlobalValue *InstrumentedGlobal = NewGlobal;
1864 bool CanUsePrivateAliases =
1865 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO();
1866 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
1867 // Create local alias for NewGlobal to avoid crash on ODR between
1868 // instrumented and non-instrumented libraries.
1869 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
1870 NameForGlobal + M.getName(), NewGlobal);
1872 // With local aliases, we need to provide another externally visible
1873 // symbol __odr_asan_XXX to detect ODR violation.
1874 auto *ODRIndicatorSym =
1875 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
1876 Constant::getNullValue(IRB.getInt8Ty()),
1877 kODRGenPrefix + NameForGlobal, nullptr,
1878 NewGlobal->getThreadLocalMode());
1880 // Set meaningful attributes for indicator symbol.
1881 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
1882 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
1883 ODRIndicatorSym->setAlignment(1);
1884 ODRIndicator = ODRIndicatorSym;
1885 InstrumentedGlobal = GA;
1888 Constant *Initializer = ConstantStruct::get(
1890 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
1891 ConstantInt::get(IntptrTy, SizeInBytes),
1892 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1893 ConstantExpr::getPointerCast(Name, IntptrTy),
1894 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1895 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
1896 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
1898 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1900 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1902 Initializers[i] = Initializer;
1905 if (TargetTriple.isOSBinFormatCOFF()) {
1906 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
1907 } else if (ShouldUseMachOGlobalsSection()) {
1908 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
1910 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
1913 // Create calls for poisoning before initializers run and unpoisoning after.
1914 if (HasDynamicallyInitializedGlobals)
1915 createInitializerPoisonCalls(M, ModuleName);
1921 bool AddressSanitizerModule::runOnModule(Module &M) {
1922 C = &(M.getContext());
1923 int LongSize = M.getDataLayout().getPointerSizeInBits();
1924 IntptrTy = Type::getIntNTy(*C, LongSize);
1925 TargetTriple = Triple(M.getTargetTriple());
1926 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1927 initializeCallbacks(M);
1929 bool Changed = false;
1931 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1932 if (ClGlobals && !CompileKernel) {
1933 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1935 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1936 Changed |= InstrumentGlobals(IRB, M);
1942 void AddressSanitizer::initializeCallbacks(Module &M) {
1943 IRBuilder<> IRB(*C);
1944 // Create __asan_report* callbacks.
1945 // IsWrite, TypeSize and Exp are encoded in the function name.
1946 for (int Exp = 0; Exp < 2; Exp++) {
1947 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1948 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1949 const std::string ExpStr = Exp ? "exp_" : "";
1950 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1951 const std::string EndingStr = Recover ? "_noabort" : "";
1952 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1953 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1954 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1955 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
1956 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1957 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1958 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1959 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1960 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1961 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1962 AccessSizeIndex++) {
1963 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
1964 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1965 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1966 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
1967 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1968 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1969 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1970 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1971 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1976 const std::string MemIntrinCallbackPrefix =
1977 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1978 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1979 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1980 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1981 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1982 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1983 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1984 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1985 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1986 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1988 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1989 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1991 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1992 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1993 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1994 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1995 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1996 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1997 StringRef(""), StringRef(""),
1998 /*hasSideEffects=*/true);
2002 bool AddressSanitizer::doInitialization(Module &M) {
2003 // Initialize the private fields. No one has accessed them before.
2007 C = &(M.getContext());
2008 LongSize = M.getDataLayout().getPointerSizeInBits();
2009 IntptrTy = Type::getIntNTy(*C, LongSize);
2010 TargetTriple = Triple(M.getTargetTriple());
2012 if (!CompileKernel) {
2013 std::tie(AsanCtorFunction, AsanInitFunction) =
2014 createSanitizerCtorAndInitFunctions(
2015 M, kAsanModuleCtorName, kAsanInitName,
2016 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
2017 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
2019 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2023 bool AddressSanitizer::doFinalization(Module &M) {
2028 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2029 // For each NSObject descendant having a +load method, this method is invoked
2030 // by the ObjC runtime before any of the static constructors is called.
2031 // Therefore we need to instrument such methods with a call to __asan_init
2032 // at the beginning in order to initialize our runtime before any access to
2033 // the shadow memory.
2034 // We cannot just ignore these methods, because they may call other
2035 // instrumented functions.
2036 if (F.getName().find(" load]") != std::string::npos) {
2037 IRBuilder<> IRB(&F.front(), F.front().begin());
2038 IRB.CreateCall(AsanInitFunction, {});
2044 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2045 // Generate code only when dynamic addressing is needed.
2046 if (Mapping.Offset != kDynamicShadowSentinel)
2049 IRBuilder<> IRB(&F.front().front());
2050 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2051 kAsanShadowMemoryDynamicAddress, IntptrTy);
2052 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
2055 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2056 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2057 // to it as uninteresting. This assumes we haven't started processing allocas
2058 // yet. This check is done up front because iterating the use list in
2059 // isInterestingAlloca would be algorithmically slower.
2060 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2062 // Try to get the declaration of llvm.localescape. If it's not in the module,
2063 // we can exit early.
2064 if (!F.getParent()->getFunction("llvm.localescape")) return;
2066 // Look for a call to llvm.localescape call in the entry block. It can't be in
2068 for (Instruction &I : F.getEntryBlock()) {
2069 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2070 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2071 // We found a call. Mark all the allocas passed in as uninteresting.
2072 for (Value *Arg : II->arg_operands()) {
2073 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2074 assert(AI && AI->isStaticAlloca() &&
2075 "non-static alloca arg to localescape");
2076 ProcessedAllocas[AI] = false;
2083 bool AddressSanitizer::runOnFunction(Function &F) {
2084 if (&F == AsanCtorFunction) return false;
2085 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2086 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2087 if (F.getName().startswith("__asan_")) return false;
2089 bool FunctionModified = false;
2091 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2092 // This function needs to be called even if the function body is not
2094 if (maybeInsertAsanInitAtFunctionEntry(F))
2095 FunctionModified = true;
2097 // Leave if the function doesn't need instrumentation.
2098 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2100 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2102 initializeCallbacks(*F.getParent());
2103 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2105 FunctionStateRAII CleanupObj(this);
2107 maybeInsertDynamicShadowAtFunctionEntry(F);
2109 // We can't instrument allocas used with llvm.localescape. Only static allocas
2110 // can be passed to that intrinsic.
2111 markEscapedLocalAllocas(F);
2113 // We want to instrument every address only once per basic block (unless there
2114 // are calls between uses).
2115 SmallSet<Value *, 16> TempsToInstrument;
2116 SmallVector<Instruction *, 16> ToInstrument;
2117 SmallVector<Instruction *, 8> NoReturnCalls;
2118 SmallVector<BasicBlock *, 16> AllBlocks;
2119 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2124 const TargetLibraryInfo *TLI =
2125 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2127 // Fill the set of memory operations to instrument.
2128 for (auto &BB : F) {
2129 AllBlocks.push_back(&BB);
2130 TempsToInstrument.clear();
2131 int NumInsnsPerBB = 0;
2132 for (auto &Inst : BB) {
2133 if (LooksLikeCodeInBug11395(&Inst)) return false;
2134 Value *MaybeMask = nullptr;
2135 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2136 &Alignment, &MaybeMask)) {
2137 if (ClOpt && ClOptSameTemp) {
2138 // If we have a mask, skip instrumentation if we've already
2139 // instrumented the full object. But don't add to TempsToInstrument
2140 // because we might get another load/store with a different mask.
2142 if (TempsToInstrument.count(Addr))
2143 continue; // We've seen this (whole) temp in the current BB.
2145 if (!TempsToInstrument.insert(Addr).second)
2146 continue; // We've seen this temp in the current BB.
2149 } else if (ClInvalidPointerPairs &&
2150 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2151 PointerComparisonsOrSubtracts.push_back(&Inst);
2153 } else if (isa<MemIntrinsic>(Inst)) {
2156 if (isa<AllocaInst>(Inst)) NumAllocas++;
2159 // A call inside BB.
2160 TempsToInstrument.clear();
2161 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2163 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2164 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2167 ToInstrument.push_back(&Inst);
2169 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2175 (ClInstrumentationWithCallsThreshold >= 0 &&
2176 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2177 const DataLayout &DL = F.getParent()->getDataLayout();
2178 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
2179 /*RoundToAlign=*/true);
2182 int NumInstrumented = 0;
2183 for (auto Inst : ToInstrument) {
2184 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2185 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2186 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2187 instrumentMop(ObjSizeVis, Inst, UseCalls,
2188 F.getParent()->getDataLayout());
2190 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2195 FunctionStackPoisoner FSP(F, *this);
2196 bool ChangedStack = FSP.runOnFunction();
2198 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2199 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2200 for (auto CI : NoReturnCalls) {
2201 IRBuilder<> IRB(CI);
2202 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2205 for (auto Inst : PointerComparisonsOrSubtracts) {
2206 instrumentPointerComparisonOrSubtraction(Inst);
2210 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2211 FunctionModified = true;
2213 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2216 return FunctionModified;
2219 // Workaround for bug 11395: we don't want to instrument stack in functions
2220 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2221 // FIXME: remove once the bug 11395 is fixed.
2222 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2223 if (LongSize != 32) return false;
2224 CallInst *CI = dyn_cast<CallInst>(I);
2225 if (!CI || !CI->isInlineAsm()) return false;
2226 if (CI->getNumArgOperands() <= 5) return false;
2227 // We have inline assembly with quite a few arguments.
2231 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2232 IRBuilder<> IRB(*C);
2233 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2234 std::string Suffix = itostr(i);
2235 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2236 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2237 IntptrTy, nullptr));
2238 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2239 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2240 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2242 if (ASan.UseAfterScope) {
2243 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2244 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2245 IntptrTy, IntptrTy, nullptr));
2246 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2247 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2248 IntptrTy, IntptrTy, nullptr));
2251 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2252 std::ostringstream Name;
2253 Name << kAsanSetShadowPrefix;
2254 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2255 AsanSetShadowFunc[Val] =
2256 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2257 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2260 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2261 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2262 AsanAllocasUnpoisonFunc =
2263 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2264 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2267 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2268 ArrayRef<uint8_t> ShadowBytes,
2269 size_t Begin, size_t End,
2271 Value *ShadowBase) {
2275 const size_t LargestStoreSizeInBytes =
2276 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2278 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2280 // Poison given range in shadow using larges store size with out leading and
2281 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2282 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2283 // middle of a store.
2284 for (size_t i = Begin; i < End;) {
2285 if (!ShadowMask[i]) {
2286 assert(!ShadowBytes[i]);
2291 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2292 // Fit store size into the range.
2293 while (StoreSizeInBytes > End - i)
2294 StoreSizeInBytes /= 2;
2296 // Minimize store size by trimming trailing zeros.
2297 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2298 while (j <= StoreSizeInBytes / 2)
2299 StoreSizeInBytes /= 2;
2303 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2305 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2307 Val = (Val << 8) | ShadowBytes[i + j];
2310 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2311 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2312 IRB.CreateAlignedStore(
2313 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2315 i += StoreSizeInBytes;
2319 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2320 ArrayRef<uint8_t> ShadowBytes,
2321 IRBuilder<> &IRB, Value *ShadowBase) {
2322 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2325 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2326 ArrayRef<uint8_t> ShadowBytes,
2327 size_t Begin, size_t End,
2328 IRBuilder<> &IRB, Value *ShadowBase) {
2329 assert(ShadowMask.size() == ShadowBytes.size());
2330 size_t Done = Begin;
2331 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2332 if (!ShadowMask[i]) {
2333 assert(!ShadowBytes[i]);
2336 uint8_t Val = ShadowBytes[i];
2337 if (!AsanSetShadowFunc[Val])
2340 // Skip same values.
2341 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2344 if (j - i >= ClMaxInlinePoisoningSize) {
2345 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2346 IRB.CreateCall(AsanSetShadowFunc[Val],
2347 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2348 ConstantInt::get(IntptrTy, j - i)});
2353 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2356 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2357 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2358 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2359 assert(LocalStackSize <= kMaxStackMallocSize);
2360 uint64_t MaxSize = kMinStackMallocSize;
2361 for (int i = 0;; i++, MaxSize *= 2)
2362 if (LocalStackSize <= MaxSize) return i;
2363 llvm_unreachable("impossible LocalStackSize");
2366 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2368 Instruction *ThenTerm,
2369 Value *ValueIfFalse) {
2370 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2371 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2372 PHI->addIncoming(ValueIfFalse, CondBlock);
2373 BasicBlock *ThenBlock = ThenTerm->getParent();
2374 PHI->addIncoming(ValueIfTrue, ThenBlock);
2378 Value *FunctionStackPoisoner::createAllocaForLayout(
2379 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2382 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2383 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2386 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2387 nullptr, "MyAlloca");
2388 assert(Alloca->isStaticAlloca());
2390 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2391 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2392 Alloca->setAlignment(FrameAlignment);
2393 return IRB.CreatePointerCast(Alloca, IntptrTy);
2396 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2397 BasicBlock &FirstBB = *F.begin();
2398 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2399 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2400 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2401 DynamicAllocaLayout->setAlignment(32);
2404 void FunctionStackPoisoner::processDynamicAllocas() {
2405 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2406 assert(DynamicAllocaPoisonCallVec.empty());
2410 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2411 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2412 assert(APC.InsBefore);
2414 assert(ASan.isInterestingAlloca(*APC.AI));
2415 assert(!APC.AI->isStaticAlloca());
2417 IRBuilder<> IRB(APC.InsBefore);
2418 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2419 // Dynamic allocas will be unpoisoned unconditionally below in
2420 // unpoisonDynamicAllocas.
2421 // Flag that we need unpoison static allocas.
2424 // Handle dynamic allocas.
2425 createDynamicAllocasInitStorage();
2426 for (auto &AI : DynamicAllocaVec)
2427 handleDynamicAllocaCall(AI);
2428 unpoisonDynamicAllocas();
2431 void FunctionStackPoisoner::processStaticAllocas() {
2432 if (AllocaVec.empty()) {
2433 assert(StaticAllocaPoisonCallVec.empty());
2437 int StackMallocIdx = -1;
2438 DebugLoc EntryDebugLocation;
2439 if (auto SP = F.getSubprogram())
2440 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2442 Instruction *InsBefore = AllocaVec[0];
2443 IRBuilder<> IRB(InsBefore);
2444 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2446 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2447 // debug info is broken, because only entry-block allocas are treated as
2448 // regular stack slots.
2449 auto InsBeforeB = InsBefore->getParent();
2450 assert(InsBeforeB == &F.getEntryBlock());
2451 for (auto *AI : StaticAllocasToMoveUp)
2452 if (AI->getParent() == InsBeforeB)
2453 AI->moveBefore(InsBefore);
2455 // If we have a call to llvm.localescape, keep it in the entry block.
2456 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2458 SmallVector<ASanStackVariableDescription, 16> SVD;
2459 SVD.reserve(AllocaVec.size());
2460 for (AllocaInst *AI : AllocaVec) {
2461 ASanStackVariableDescription D = {AI->getName().data(),
2462 ASan.getAllocaSizeInBytes(*AI),
2471 // Minimal header size (left redzone) is 4 pointers,
2472 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2473 size_t MinHeaderSize = ASan.LongSize / 2;
2474 const ASanStackFrameLayout &L =
2475 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2477 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2478 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2479 for (auto &Desc : SVD)
2480 AllocaToSVDMap[Desc.AI] = &Desc;
2482 // Update SVD with information from lifetime intrinsics.
2483 for (const auto &APC : StaticAllocaPoisonCallVec) {
2484 assert(APC.InsBefore);
2486 assert(ASan.isInterestingAlloca(*APC.AI));
2487 assert(APC.AI->isStaticAlloca());
2489 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2490 Desc.LifetimeSize = Desc.Size;
2491 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2492 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2493 if (LifetimeLoc->getFile() == FnLoc->getFile())
2494 if (unsigned Line = LifetimeLoc->getLine())
2495 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2500 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2501 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2502 uint64_t LocalStackSize = L.FrameSize;
2503 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2504 LocalStackSize <= kMaxStackMallocSize;
2505 bool DoDynamicAlloca = ClDynamicAllocaStack;
2506 // Don't do dynamic alloca or stack malloc if:
2507 // 1) There is inline asm: too often it makes assumptions on which registers
2509 // 2) There is a returns_twice call (typically setjmp), which is
2510 // optimization-hostile, and doesn't play well with introduced indirect
2511 // register-relative calculation of local variable addresses.
2512 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2513 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2515 Value *StaticAlloca =
2516 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2519 Value *LocalStackBase;
2521 if (DoStackMalloc) {
2522 // void *FakeStack = __asan_option_detect_stack_use_after_return
2523 // ? __asan_stack_malloc_N(LocalStackSize)
2525 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2526 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2527 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2528 Value *UseAfterReturnIsEnabled =
2529 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2530 Constant::getNullValue(IRB.getInt32Ty()));
2532 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2533 IRBuilder<> IRBIf(Term);
2534 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2535 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2536 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2537 Value *FakeStackValue =
2538 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2539 ConstantInt::get(IntptrTy, LocalStackSize));
2540 IRB.SetInsertPoint(InsBefore);
2541 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2542 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2543 ConstantInt::get(IntptrTy, 0));
2545 Value *NoFakeStack =
2546 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2547 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2548 IRBIf.SetInsertPoint(Term);
2549 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2550 Value *AllocaValue =
2551 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2552 IRB.SetInsertPoint(InsBefore);
2553 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2554 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2556 // void *FakeStack = nullptr;
2557 // void *LocalStackBase = alloca(LocalStackSize);
2558 FakeStack = ConstantInt::get(IntptrTy, 0);
2560 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2563 // Replace Alloca instructions with base+offset.
2564 for (const auto &Desc : SVD) {
2565 AllocaInst *AI = Desc.AI;
2566 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2567 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2569 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
2570 AI->replaceAllUsesWith(NewAllocaPtr);
2573 // The left-most redzone has enough space for at least 4 pointers.
2574 // Write the Magic value to redzone[0].
2575 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2576 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2578 // Write the frame description constant to redzone[1].
2579 Value *BasePlus1 = IRB.CreateIntToPtr(
2580 IRB.CreateAdd(LocalStackBase,
2581 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2583 GlobalVariable *StackDescriptionGlobal =
2584 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2585 /*AllowMerging*/ true);
2586 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2587 IRB.CreateStore(Description, BasePlus1);
2588 // Write the PC to redzone[2].
2589 Value *BasePlus2 = IRB.CreateIntToPtr(
2590 IRB.CreateAdd(LocalStackBase,
2591 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2593 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2595 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2597 // Poison the stack red zones at the entry.
2598 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2599 // As mask we must use most poisoned case: red zones and after scope.
2600 // As bytes we can use either the same or just red zones only.
2601 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2603 if (!StaticAllocaPoisonCallVec.empty()) {
2604 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2606 // Poison static allocas near lifetime intrinsics.
2607 for (const auto &APC : StaticAllocaPoisonCallVec) {
2608 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2609 assert(Desc.Offset % L.Granularity == 0);
2610 size_t Begin = Desc.Offset / L.Granularity;
2611 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2613 IRBuilder<> IRB(APC.InsBefore);
2614 copyToShadow(ShadowAfterScope,
2615 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2620 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2621 SmallVector<uint8_t, 64> ShadowAfterReturn;
2623 // (Un)poison the stack before all ret instructions.
2624 for (auto Ret : RetVec) {
2625 IRBuilder<> IRBRet(Ret);
2626 // Mark the current frame as retired.
2627 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2629 if (DoStackMalloc) {
2630 assert(StackMallocIdx >= 0);
2631 // if FakeStack != 0 // LocalStackBase == FakeStack
2632 // // In use-after-return mode, poison the whole stack frame.
2633 // if StackMallocIdx <= 4
2634 // // For small sizes inline the whole thing:
2635 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2636 // **SavedFlagPtr(FakeStack) = 0
2638 // __asan_stack_free_N(FakeStack, LocalStackSize)
2640 // <This is not a fake stack; unpoison the redzones>
2642 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2643 TerminatorInst *ThenTerm, *ElseTerm;
2644 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2646 IRBuilder<> IRBPoison(ThenTerm);
2647 if (StackMallocIdx <= 4) {
2648 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2649 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2650 kAsanStackUseAfterReturnMagic);
2651 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2653 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2655 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2656 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2657 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2658 IRBPoison.CreateStore(
2659 Constant::getNullValue(IRBPoison.getInt8Ty()),
2660 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2662 // For larger frames call __asan_stack_free_*.
2663 IRBPoison.CreateCall(
2664 AsanStackFreeFunc[StackMallocIdx],
2665 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2668 IRBuilder<> IRBElse(ElseTerm);
2669 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2671 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2675 // We are done. Remove the old unused alloca instructions.
2676 for (auto AI : AllocaVec) AI->eraseFromParent();
2679 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2680 IRBuilder<> &IRB, bool DoPoison) {
2681 // For now just insert the call to ASan runtime.
2682 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2683 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2685 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2686 {AddrArg, SizeArg});
2689 // Handling llvm.lifetime intrinsics for a given %alloca:
2690 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2691 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2692 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2693 // could be poisoned by previous llvm.lifetime.end instruction, as the
2694 // variable may go in and out of scope several times, e.g. in loops).
2695 // (3) if we poisoned at least one %alloca in a function,
2696 // unpoison the whole stack frame at function exit.
2698 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2699 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2700 // We're interested only in allocas we can handle.
2701 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2702 // See if we've already calculated (or started to calculate) alloca for a
2704 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2705 if (I != AllocaForValue.end()) return I->second;
2706 // Store 0 while we're calculating alloca for value V to avoid
2707 // infinite recursion if the value references itself.
2708 AllocaForValue[V] = nullptr;
2709 AllocaInst *Res = nullptr;
2710 if (CastInst *CI = dyn_cast<CastInst>(V))
2711 Res = findAllocaForValue(CI->getOperand(0));
2712 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2713 for (Value *IncValue : PN->incoming_values()) {
2714 // Allow self-referencing phi-nodes.
2715 if (IncValue == PN) continue;
2716 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2717 // AI for incoming values should exist and should all be equal.
2718 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2722 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2723 Res = findAllocaForValue(EP->getPointerOperand());
2725 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2727 if (Res) AllocaForValue[V] = Res;
2731 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2732 IRBuilder<> IRB(AI);
2734 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2735 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2737 Value *Zero = Constant::getNullValue(IntptrTy);
2738 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2739 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2741 // Since we need to extend alloca with additional memory to locate
2742 // redzones, and OldSize is number of allocated blocks with
2743 // ElementSize size, get allocated memory size in bytes by
2744 // OldSize * ElementSize.
2745 const unsigned ElementSize =
2746 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2748 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2749 ConstantInt::get(IntptrTy, ElementSize));
2751 // PartialSize = OldSize % 32
2752 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2754 // Misalign = kAllocaRzSize - PartialSize;
2755 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2757 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2758 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2759 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2761 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2762 // Align is added to locate left redzone, PartialPadding for possible
2763 // partial redzone and kAllocaRzSize for right redzone respectively.
2764 Value *AdditionalChunkSize = IRB.CreateAdd(
2765 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2767 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2769 // Insert new alloca with new NewSize and Align params.
2770 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2771 NewAlloca->setAlignment(Align);
2773 // NewAddress = Address + Align
2774 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2775 ConstantInt::get(IntptrTy, Align));
2777 // Insert __asan_alloca_poison call for new created alloca.
2778 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2780 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2781 // for unpoisoning stuff.
2782 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2784 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2786 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2787 AI->replaceAllUsesWith(NewAddressPtr);
2789 // We are done. Erase old alloca from parent.
2790 AI->eraseFromParent();
2793 // isSafeAccess returns true if Addr is always inbounds with respect to its
2794 // base object. For example, it is a field access or an array access with
2795 // constant inbounds index.
2796 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2797 Value *Addr, uint64_t TypeSize) const {
2798 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2799 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2800 uint64_t Size = SizeOffset.first.getZExtValue();
2801 int64_t Offset = SizeOffset.second.getSExtValue();
2802 // Three checks are required to ensure safety:
2803 // . Offset >= 0 (since the offset is given from the base ptr)
2804 // . Size >= Offset (unsigned)
2805 // . Size - Offset >= NeededSize (unsigned)
2806 return Offset >= 0 && Size >= uint64_t(Offset) &&
2807 Size - uint64_t(Offset) >= TypeSize / 8;