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, Value *Addr,
518 uint32_t TypeSize, bool IsWrite,
519 Value *SizeArgument, bool UseCalls,
521 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
522 Value *ShadowValue, uint32_t TypeSize);
523 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
524 bool IsWrite, size_t AccessSizeIndex,
525 Value *SizeArgument, uint32_t Exp);
526 void instrumentMemIntrinsic(MemIntrinsic *MI);
527 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
528 bool runOnFunction(Function &F) override;
529 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
530 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
531 void markEscapedLocalAllocas(Function &F);
532 bool doInitialization(Module &M) override;
533 bool doFinalization(Module &M) override;
534 static char ID; // Pass identification, replacement for typeid
536 DominatorTree &getDominatorTree() const { return *DT; }
539 void initializeCallbacks(Module &M);
541 bool LooksLikeCodeInBug11395(Instruction *I);
542 bool GlobalIsLinkerInitialized(GlobalVariable *G);
543 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
544 uint64_t TypeSize) const;
546 /// Helper to cleanup per-function state.
547 struct FunctionStateRAII {
548 AddressSanitizer *Pass;
549 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
550 assert(Pass->ProcessedAllocas.empty() &&
551 "last pass forgot to clear cache");
552 assert(!Pass->LocalDynamicShadow);
554 ~FunctionStateRAII() {
555 Pass->LocalDynamicShadow = nullptr;
556 Pass->ProcessedAllocas.clear();
567 ShadowMapping Mapping;
569 Function *AsanCtorFunction = nullptr;
570 Function *AsanInitFunction = nullptr;
571 Function *AsanHandleNoReturnFunc;
572 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
573 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
574 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
575 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
576 // This array is indexed by AccessIsWrite and Experiment.
577 Function *AsanErrorCallbackSized[2][2];
578 Function *AsanMemoryAccessCallbackSized[2][2];
579 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
581 Value *LocalDynamicShadow;
582 GlobalsMetadata GlobalsMD;
583 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
585 friend struct FunctionStackPoisoner;
588 class AddressSanitizerModule : public ModulePass {
590 explicit AddressSanitizerModule(bool CompileKernel = false,
591 bool Recover = false)
592 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
593 Recover(Recover || ClRecover) {}
594 bool runOnModule(Module &M) override;
595 static char ID; // Pass identification, replacement for typeid
596 StringRef getPassName() const override { return "AddressSanitizerModule"; }
599 void initializeCallbacks(Module &M);
601 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
602 bool ShouldInstrumentGlobal(GlobalVariable *G);
603 bool ShouldUseMachOGlobalsSection() const;
604 StringRef getGlobalMetadataSection() const;
605 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
606 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
607 size_t MinRedzoneSizeForGlobal() const {
608 return RedzoneSizeForScale(Mapping.Scale);
611 GlobalsMetadata GlobalsMD;
617 ShadowMapping Mapping;
618 Function *AsanPoisonGlobals;
619 Function *AsanUnpoisonGlobals;
620 Function *AsanRegisterGlobals;
621 Function *AsanUnregisterGlobals;
622 Function *AsanRegisterImageGlobals;
623 Function *AsanUnregisterImageGlobals;
626 // Stack poisoning does not play well with exception handling.
627 // When an exception is thrown, we essentially bypass the code
628 // that unpoisones the stack. This is why the run-time library has
629 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
630 // stack in the interceptor. This however does not work inside the
631 // actual function which catches the exception. Most likely because the
632 // compiler hoists the load of the shadow value somewhere too high.
633 // This causes asan to report a non-existing bug on 453.povray.
634 // It sounds like an LLVM bug.
635 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
637 AddressSanitizer &ASan;
642 ShadowMapping Mapping;
644 SmallVector<AllocaInst *, 16> AllocaVec;
645 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
646 SmallVector<Instruction *, 8> RetVec;
647 unsigned StackAlignment;
649 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
650 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
651 Function *AsanSetShadowFunc[0x100] = {};
652 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
653 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
655 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
656 struct AllocaPoisonCall {
657 IntrinsicInst *InsBefore;
662 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
663 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
665 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
666 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
667 AllocaInst *DynamicAllocaLayout = nullptr;
668 IntrinsicInst *LocalEscapeCall = nullptr;
670 // Maps Value to an AllocaInst from which the Value is originated.
671 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
672 AllocaForValueMapTy AllocaForValue;
674 bool HasNonEmptyInlineAsm = false;
675 bool HasReturnsTwiceCall = false;
676 std::unique_ptr<CallInst> EmptyInlineAsm;
678 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
681 DIB(*F.getParent(), /*AllowUnresolved*/ false),
683 IntptrTy(ASan.IntptrTy),
684 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
685 Mapping(ASan.Mapping),
686 StackAlignment(1 << Mapping.Scale),
687 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
689 bool runOnFunction() {
690 if (!ClStack) return false;
691 // Collect alloca, ret, lifetime instructions etc.
692 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
694 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
696 initializeCallbacks(*F.getParent());
698 processDynamicAllocas();
699 processStaticAllocas();
707 // Finds all Alloca instructions and puts
708 // poisoned red zones around all of them.
709 // Then unpoison everything back before the function returns.
710 void processStaticAllocas();
711 void processDynamicAllocas();
713 void createDynamicAllocasInitStorage();
715 // ----------------------- Visitors.
716 /// \brief Collect all Ret instructions.
717 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
719 /// \brief Collect all Resume instructions.
720 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
722 /// \brief Collect all CatchReturnInst instructions.
723 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
725 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
727 IRBuilder<> IRB(InstBefore);
728 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
729 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
730 // need to adjust extracted SP to compute the address of the most recent
731 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
733 if (!isa<ReturnInst>(InstBefore)) {
734 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
735 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
738 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
740 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
744 IRB.CreateCall(AsanAllocasUnpoisonFunc,
745 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
748 // Unpoison dynamic allocas redzones.
749 void unpoisonDynamicAllocas() {
750 for (auto &Ret : RetVec)
751 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
753 for (auto &StackRestoreInst : StackRestoreVec)
754 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
755 StackRestoreInst->getOperand(0));
758 // Deploy and poison redzones around dynamic alloca call. To do this, we
759 // should replace this call with another one with changed parameters and
760 // replace all its uses with new address, so
761 // addr = alloca type, old_size, align
763 // new_size = (old_size + additional_size) * sizeof(type)
764 // tmp = alloca i8, new_size, max(align, 32)
765 // addr = tmp + 32 (first 32 bytes are for the left redzone).
766 // Additional_size is added to make new memory allocation contain not only
767 // requested memory, but also left, partial and right redzones.
768 void handleDynamicAllocaCall(AllocaInst *AI);
770 /// \brief Collect Alloca instructions we want (and can) handle.
771 void visitAllocaInst(AllocaInst &AI) {
772 if (!ASan.isInterestingAlloca(AI)) {
773 if (AI.isStaticAlloca()) {
774 // Skip over allocas that are present *before* the first instrumented
775 // alloca, we don't want to move those around.
776 if (AllocaVec.empty())
779 StaticAllocasToMoveUp.push_back(&AI);
784 StackAlignment = std::max(StackAlignment, AI.getAlignment());
785 if (!AI.isStaticAlloca())
786 DynamicAllocaVec.push_back(&AI);
788 AllocaVec.push_back(&AI);
791 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
793 void visitIntrinsicInst(IntrinsicInst &II) {
794 Intrinsic::ID ID = II.getIntrinsicID();
795 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
796 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
797 if (!ASan.UseAfterScope)
799 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
801 // Found lifetime intrinsic, add ASan instrumentation if necessary.
802 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
803 // If size argument is undefined, don't do anything.
804 if (Size->isMinusOne()) return;
805 // Check that size doesn't saturate uint64_t and can
806 // be stored in IntptrTy.
807 const uint64_t SizeValue = Size->getValue().getLimitedValue();
808 if (SizeValue == ~0ULL ||
809 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
811 // Find alloca instruction that corresponds to llvm.lifetime argument.
812 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
813 if (!AI || !ASan.isInterestingAlloca(*AI))
815 bool DoPoison = (ID == Intrinsic::lifetime_end);
816 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
817 if (AI->isStaticAlloca())
818 StaticAllocaPoisonCallVec.push_back(APC);
819 else if (ClInstrumentDynamicAllocas)
820 DynamicAllocaPoisonCallVec.push_back(APC);
823 void visitCallSite(CallSite CS) {
824 Instruction *I = CS.getInstruction();
825 if (CallInst *CI = dyn_cast<CallInst>(I)) {
826 HasNonEmptyInlineAsm |=
827 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
828 HasReturnsTwiceCall |= CI->canReturnTwice();
832 // ---------------------- Helpers.
833 void initializeCallbacks(Module &M);
835 bool doesDominateAllExits(const Instruction *I) const {
836 for (auto Ret : RetVec) {
837 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
842 /// Finds alloca where the value comes from.
843 AllocaInst *findAllocaForValue(Value *V);
845 // Copies bytes from ShadowBytes into shadow memory for indexes where
846 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
847 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
848 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
849 IRBuilder<> &IRB, Value *ShadowBase);
850 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
851 size_t Begin, size_t End, IRBuilder<> &IRB,
853 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
854 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
855 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
857 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
859 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
861 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
862 Instruction *ThenTerm, Value *ValueIfFalse);
865 } // anonymous namespace
867 char AddressSanitizer::ID = 0;
868 INITIALIZE_PASS_BEGIN(
869 AddressSanitizer, "asan",
870 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
872 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
873 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
875 AddressSanitizer, "asan",
876 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
878 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
880 bool UseAfterScope) {
881 assert(!CompileKernel || Recover);
882 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
885 char AddressSanitizerModule::ID = 0;
887 AddressSanitizerModule, "asan-module",
888 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
891 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
893 assert(!CompileKernel || Recover);
894 return new AddressSanitizerModule(CompileKernel, Recover);
897 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
898 size_t Res = countTrailingZeros(TypeSize / 8);
899 assert(Res < kNumberOfAccessSizes);
903 // \brief Create a constant for Str so that we can pass it to the run-time lib.
904 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
906 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
907 // We use private linkage for module-local strings. If they can be merged
908 // with another one, we set the unnamed_addr attribute.
910 new GlobalVariable(M, StrConst->getType(), true,
911 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
912 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
913 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
917 /// \brief Create a global describing a source location.
918 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
919 LocationMetadata MD) {
920 Constant *LocData[] = {
921 createPrivateGlobalForString(M, MD.Filename, true),
922 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
923 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
925 auto LocStruct = ConstantStruct::getAnon(LocData);
926 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
927 GlobalValue::PrivateLinkage, LocStruct,
929 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
933 /// \brief Check if \p G has been created by a trusted compiler pass.
934 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
935 // Do not instrument asan globals.
936 if (G->getName().startswith(kAsanGenPrefix) ||
937 G->getName().startswith(kSanCovGenPrefix) ||
938 G->getName().startswith(kODRGenPrefix))
941 // Do not instrument gcov counter arrays.
942 if (G->getName() == "__llvm_gcov_ctr")
948 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
950 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
951 if (Mapping.Offset == 0) return Shadow;
952 // (Shadow >> scale) | offset
954 if (LocalDynamicShadow)
955 ShadowBase = LocalDynamicShadow;
957 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
958 if (Mapping.OrShadowOffset)
959 return IRB.CreateOr(Shadow, ShadowBase);
961 return IRB.CreateAdd(Shadow, ShadowBase);
964 // Instrument memset/memmove/memcpy
965 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
967 if (isa<MemTransferInst>(MI)) {
969 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
970 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
971 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
972 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
973 } else if (isa<MemSetInst>(MI)) {
976 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
977 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
978 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
980 MI->eraseFromParent();
983 /// Check if we want (and can) handle this alloca.
984 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
985 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
987 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
988 return PreviouslySeenAllocaInfo->getSecond();
991 (AI.getAllocatedType()->isSized() &&
992 // alloca() may be called with 0 size, ignore it.
993 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
994 // We are only interested in allocas not promotable to registers.
995 // Promotable allocas are common under -O0.
996 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
997 // inalloca allocas are not treated as static, and we don't want
998 // dynamic alloca instrumentation for them as well.
999 !AI.isUsedWithInAlloca());
1001 ProcessedAllocas[&AI] = IsInteresting;
1002 return IsInteresting;
1005 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1008 unsigned *Alignment,
1009 Value **MaybeMask) {
1010 // Skip memory accesses inserted by another instrumentation.
1011 if (I->getMetadata("nosanitize")) return nullptr;
1013 // Do not instrument the load fetching the dynamic shadow address.
1014 if (LocalDynamicShadow == I)
1017 Value *PtrOperand = nullptr;
1018 const DataLayout &DL = I->getModule()->getDataLayout();
1019 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1020 if (!ClInstrumentReads) return nullptr;
1022 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1023 *Alignment = LI->getAlignment();
1024 PtrOperand = LI->getPointerOperand();
1025 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1026 if (!ClInstrumentWrites) return nullptr;
1028 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1029 *Alignment = SI->getAlignment();
1030 PtrOperand = SI->getPointerOperand();
1031 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1032 if (!ClInstrumentAtomics) return nullptr;
1034 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1036 PtrOperand = RMW->getPointerOperand();
1037 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1038 if (!ClInstrumentAtomics) return nullptr;
1040 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1042 PtrOperand = XCHG->getPointerOperand();
1043 } else if (auto CI = dyn_cast<CallInst>(I)) {
1044 auto *F = dyn_cast<Function>(CI->getCalledValue());
1045 if (F && (F->getName().startswith("llvm.masked.load.") ||
1046 F->getName().startswith("llvm.masked.store."))) {
1047 unsigned OpOffset = 0;
1048 if (F->getName().startswith("llvm.masked.store.")) {
1049 if (!ClInstrumentWrites)
1051 // Masked store has an initial operand for the value.
1055 if (!ClInstrumentReads)
1059 // Only instrument if the mask is constant for now.
1060 if (isa<ConstantVector>(CI->getOperand(2 + OpOffset))) {
1061 auto BasePtr = CI->getOperand(0 + OpOffset);
1062 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1063 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1064 if (auto AlignmentConstant =
1065 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1066 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1068 *Alignment = 1; // No alignment guarantees. We probably got Undef
1070 *MaybeMask = CI->getOperand(2 + OpOffset);
1071 PtrOperand = BasePtr;
1076 // Do not instrument acesses from different address spaces; we cannot deal
1079 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1080 if (PtrTy->getPointerAddressSpace() != 0)
1084 // Treat memory accesses to promotable allocas as non-interesting since they
1085 // will not cause memory violations. This greatly speeds up the instrumented
1086 // executable at -O0.
1087 if (ClSkipPromotableAllocas)
1088 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1089 return isInterestingAlloca(*AI) ? AI : nullptr;
1094 static bool isPointerOperand(Value *V) {
1095 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1098 // This is a rough heuristic; it may cause both false positives and
1099 // false negatives. The proper implementation requires cooperation with
1101 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1102 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1103 if (!Cmp->isRelational()) return false;
1104 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1105 if (BO->getOpcode() != Instruction::Sub) return false;
1109 return isPointerOperand(I->getOperand(0)) &&
1110 isPointerOperand(I->getOperand(1));
1113 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1114 // If a global variable does not have dynamic initialization we don't
1115 // have to instrument it. However, if a global does not have initializer
1116 // at all, we assume it has dynamic initializer (in other TU).
1117 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1120 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1123 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1124 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1125 for (Value *&i : Param) {
1126 if (i->getType()->isPointerTy())
1127 i = IRB.CreatePointerCast(i, IntptrTy);
1129 IRB.CreateCall(F, Param);
1132 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1133 Value *Addr, unsigned Alignment,
1134 unsigned Granularity, uint32_t TypeSize,
1135 bool IsWrite, Value *SizeArgument,
1136 bool UseCalls, uint32_t Exp) {
1137 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1138 // if the data is properly aligned.
1139 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1141 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1142 return Pass->instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr,
1144 Pass->instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
1148 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1149 const DataLayout &DL, Type *IntptrTy,
1150 ConstantVector *Mask, Instruction *I,
1151 Value *Addr, unsigned Alignment,
1152 unsigned Granularity, uint32_t TypeSize,
1153 bool IsWrite, Value *SizeArgument,
1154 bool UseCalls, uint32_t Exp) {
1155 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1156 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1157 unsigned Num = VTy->getVectorNumElements();
1158 auto Zero = ConstantInt::get(IntptrTy, 0);
1159 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1160 // dyn_cast as we might get UndefValue
1161 auto Masked = dyn_cast<ConstantInt>(Mask->getOperand(Idx));
1162 if (Masked && Masked->isAllOnesValue()) {
1164 auto InstrumentedAddress =
1165 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1166 doInstrumentAddress(Pass, I, InstrumentedAddress, Alignment, Granularity,
1167 ElemTypeSize, IsWrite, SizeArgument, UseCalls, Exp);
1172 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1173 Instruction *I, bool UseCalls,
1174 const DataLayout &DL) {
1175 bool IsWrite = false;
1176 unsigned Alignment = 0;
1177 uint64_t TypeSize = 0;
1178 Value *MaybeMask = nullptr;
1180 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1183 // Optimization experiments.
1184 // The experiments can be used to evaluate potential optimizations that remove
1185 // instrumentation (assess false negatives). Instead of completely removing
1186 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1187 // experiments that want to remove instrumentation of this instruction).
1188 // If Exp is non-zero, this pass will emit special calls into runtime
1189 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1190 // make runtime terminate the program in a special way (with a different
1191 // exit status). Then you run the new compiler on a buggy corpus, collect
1192 // the special terminations (ideally, you don't see them at all -- no false
1193 // negatives) and make the decision on the optimization.
1194 uint32_t Exp = ClForceExperiment;
1196 if (ClOpt && ClOptGlobals) {
1197 // If initialization order checking is disabled, a simple access to a
1198 // dynamically initialized global is always valid.
1199 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1200 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1201 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1202 NumOptimizedAccessesToGlobalVar++;
1207 if (ClOpt && ClOptStack) {
1208 // A direct inbounds access to a stack variable is always valid.
1209 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1210 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1211 NumOptimizedAccessesToStackVar++;
1217 NumInstrumentedWrites++;
1219 NumInstrumentedReads++;
1221 unsigned Granularity = 1 << Mapping.Scale;
1223 auto Mask = cast<ConstantVector>(MaybeMask);
1224 instrumentMaskedLoadOrStore(this, DL, IntptrTy, Mask, I, Addr, Alignment,
1225 Granularity, TypeSize, IsWrite, nullptr,
1228 doInstrumentAddress(this, I, Addr, Alignment, Granularity, TypeSize,
1229 IsWrite, nullptr, UseCalls, Exp);
1233 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1234 Value *Addr, bool IsWrite,
1235 size_t AccessSizeIndex,
1236 Value *SizeArgument,
1238 IRBuilder<> IRB(InsertBefore);
1239 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1240 CallInst *Call = nullptr;
1243 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1244 {Addr, SizeArgument});
1246 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1247 {Addr, SizeArgument, ExpVal});
1251 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1253 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1257 // We don't do Call->setDoesNotReturn() because the BB already has
1258 // UnreachableInst at the end.
1259 // This EmptyAsm is required to avoid callback merge.
1260 IRB.CreateCall(EmptyAsm, {});
1264 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1266 uint32_t TypeSize) {
1267 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1268 // Addr & (Granularity - 1)
1269 Value *LastAccessedByte =
1270 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1271 // (Addr & (Granularity - 1)) + size - 1
1272 if (TypeSize / 8 > 1)
1273 LastAccessedByte = IRB.CreateAdd(
1274 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1275 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1277 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1278 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1279 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1282 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1283 Instruction *InsertBefore, Value *Addr,
1284 uint32_t TypeSize, bool IsWrite,
1285 Value *SizeArgument, bool UseCalls,
1287 IRBuilder<> IRB(InsertBefore);
1288 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1289 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1293 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1296 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1297 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1302 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1303 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1304 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1305 Value *CmpVal = Constant::getNullValue(ShadowTy);
1306 Value *ShadowValue =
1307 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1309 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1310 size_t Granularity = 1ULL << Mapping.Scale;
1311 TerminatorInst *CrashTerm = nullptr;
1313 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1314 // We use branch weights for the slow path check, to indicate that the slow
1315 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1316 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1317 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1318 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1319 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1320 IRB.SetInsertPoint(CheckTerm);
1321 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1323 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1325 BasicBlock *CrashBlock =
1326 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1327 CrashTerm = new UnreachableInst(*C, CrashBlock);
1328 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1329 ReplaceInstWithInst(CheckTerm, NewTerm);
1332 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1335 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1336 AccessSizeIndex, SizeArgument, Exp);
1337 Crash->setDebugLoc(OrigIns->getDebugLoc());
1340 // Instrument unusual size or unusual alignment.
1341 // We can not do it with a single check, so we do 1-byte check for the first
1342 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1343 // to report the actual access size.
1344 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1345 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1346 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1348 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1349 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1352 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1355 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1356 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1358 Value *LastByte = IRB.CreateIntToPtr(
1359 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1361 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1362 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1366 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1367 GlobalValue *ModuleName) {
1368 // Set up the arguments to our poison/unpoison functions.
1369 IRBuilder<> IRB(&GlobalInit.front(),
1370 GlobalInit.front().getFirstInsertionPt());
1372 // Add a call to poison all external globals before the given function starts.
1373 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1374 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1376 // Add calls to unpoison all globals before each return instruction.
1377 for (auto &BB : GlobalInit.getBasicBlockList())
1378 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1379 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1382 void AddressSanitizerModule::createInitializerPoisonCalls(
1383 Module &M, GlobalValue *ModuleName) {
1384 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1386 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1387 for (Use &OP : CA->operands()) {
1388 if (isa<ConstantAggregateZero>(OP)) continue;
1389 ConstantStruct *CS = cast<ConstantStruct>(OP);
1391 // Must have a function or null ptr.
1392 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1393 if (F->getName() == kAsanModuleCtorName) continue;
1394 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1395 // Don't instrument CTORs that will run before asan.module_ctor.
1396 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1397 poisonOneInitializer(*F, ModuleName);
1402 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1403 Type *Ty = G->getValueType();
1404 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1406 if (GlobalsMD.get(G).IsBlacklisted) return false;
1407 if (!Ty->isSized()) return false;
1408 if (!G->hasInitializer()) return false;
1409 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1410 // Touch only those globals that will not be defined in other modules.
1411 // Don't handle ODR linkage types and COMDATs since other modules may be built
1413 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1414 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1415 G->getLinkage() != GlobalVariable::InternalLinkage)
1417 if (G->hasComdat()) return false;
1418 // Two problems with thread-locals:
1419 // - The address of the main thread's copy can't be computed at link-time.
1420 // - Need to poison all copies, not just the main thread's one.
1421 if (G->isThreadLocal()) return false;
1422 // For now, just ignore this Global if the alignment is large.
1423 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1425 if (G->hasSection()) {
1426 StringRef Section = G->getSection();
1428 // Globals from llvm.metadata aren't emitted, do not instrument them.
1429 if (Section == "llvm.metadata") return false;
1430 // Do not instrument globals from special LLVM sections.
1431 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1433 // Do not instrument function pointers to initialization and termination
1434 // routines: dynamic linker will not properly handle redzones.
1435 if (Section.startswith(".preinit_array") ||
1436 Section.startswith(".init_array") ||
1437 Section.startswith(".fini_array")) {
1441 // Callbacks put into the CRT initializer/terminator sections
1442 // should not be instrumented.
1443 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1444 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1445 if (Section.startswith(".CRT")) {
1446 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1450 if (TargetTriple.isOSBinFormatMachO()) {
1451 StringRef ParsedSegment, ParsedSection;
1452 unsigned TAA = 0, StubSize = 0;
1454 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1455 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1456 assert(ErrorCode.empty() && "Invalid section specifier.");
1458 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1459 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1461 if (ParsedSegment == "__OBJC" ||
1462 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1463 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1466 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1467 // Constant CFString instances are compiled in the following way:
1468 // -- the string buffer is emitted into
1469 // __TEXT,__cstring,cstring_literals
1470 // -- the constant NSConstantString structure referencing that buffer
1471 // is placed into __DATA,__cfstring
1472 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1473 // Moreover, it causes the linker to crash on OS X 10.7
1474 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1475 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1478 // The linker merges the contents of cstring_literals and removes the
1480 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1481 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1490 // On Mach-O platforms, we emit global metadata in a separate section of the
1491 // binary in order to allow the linker to properly dead strip. This is only
1492 // supported on recent versions of ld64.
1493 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1494 if (!ClUseMachOGlobalsSection)
1497 if (!TargetTriple.isOSBinFormatMachO())
1500 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1502 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1504 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1510 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1511 switch (TargetTriple.getObjectFormat()) {
1512 case Triple::COFF: return ".ASAN$GL";
1513 case Triple::ELF: return "asan_globals";
1514 case Triple::MachO: return "__DATA,__asan_globals,regular";
1517 llvm_unreachable("unsupported object format");
1520 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1521 IRBuilder<> IRB(*C);
1523 // Declare our poisoning and unpoisoning functions.
1524 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1525 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1526 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1527 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1528 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1529 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1531 // Declare functions that register/unregister globals.
1532 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1533 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1534 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1535 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1536 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1537 IntptrTy, IntptrTy, nullptr));
1538 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1540 // Declare the functions that find globals in a shared object and then invoke
1541 // the (un)register function on them.
1542 AsanRegisterImageGlobals = checkSanitizerInterfaceFunction(
1543 M.getOrInsertFunction(kAsanRegisterImageGlobalsName,
1544 IRB.getVoidTy(), IntptrTy, nullptr));
1545 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1547 AsanUnregisterImageGlobals = checkSanitizerInterfaceFunction(
1548 M.getOrInsertFunction(kAsanUnregisterImageGlobalsName,
1549 IRB.getVoidTy(), IntptrTy, nullptr));
1550 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1553 // This function replaces all global variables with new variables that have
1554 // trailing redzones. It also creates a function that poisons
1555 // redzones and inserts this function into llvm.global_ctors.
1556 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1559 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1561 for (auto &G : M.globals()) {
1562 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1565 size_t n = GlobalsToChange.size();
1566 if (n == 0) return false;
1568 auto &DL = M.getDataLayout();
1569 bool UseComdatMetadata = TargetTriple.isOSBinFormatCOFF();
1570 bool UseMachOGlobalsSection = ShouldUseMachOGlobalsSection();
1571 bool UseMetadataArray = !(UseComdatMetadata || UseMachOGlobalsSection);
1573 // A global is described by a structure
1576 // size_t size_with_redzone;
1577 // const char *name;
1578 // const char *module_name;
1579 // size_t has_dynamic_init;
1580 // void *source_location;
1581 // size_t odr_indicator;
1582 // We initialize an array of such structures and pass it to a run-time call.
1583 StructType *GlobalStructTy =
1584 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1585 IntptrTy, IntptrTy, IntptrTy, nullptr);
1586 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(GlobalStructTy);
1587 assert((isPowerOf2_32(SizeOfGlobalStruct) ||
1588 !TargetTriple.isOSBinFormatCOFF()) &&
1589 "global metadata will not be padded appropriately");
1590 SmallVector<Constant *, 16> Initializers(UseMetadataArray ? n : 0);
1592 // On recent Mach-O platforms, use a structure which binds the liveness of
1593 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1594 // created to be added to llvm.compiler.used
1595 StructType *LivenessTy = nullptr;
1596 if (UseMachOGlobalsSection)
1597 LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
1598 SmallVector<GlobalValue *, 16> LivenessGlobals(
1599 UseMachOGlobalsSection ? n : 0);
1601 bool HasDynamicallyInitializedGlobals = false;
1603 // We shouldn't merge same module names, as this string serves as unique
1604 // module ID in runtime.
1605 GlobalVariable *ModuleName = createPrivateGlobalForString(
1606 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1608 for (size_t i = 0; i < n; i++) {
1609 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1610 GlobalVariable *G = GlobalsToChange[i];
1612 auto MD = GlobalsMD.get(G);
1613 StringRef NameForGlobal = G->getName();
1614 // Create string holding the global name (use global name from metadata
1615 // if it's available, otherwise just write the name of global variable).
1616 GlobalVariable *Name = createPrivateGlobalForString(
1617 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1618 /*AllowMerging*/ true);
1620 Type *Ty = G->getValueType();
1621 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1622 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1623 // MinRZ <= RZ <= kMaxGlobalRedzone
1624 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1625 uint64_t RZ = std::max(
1626 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1627 uint64_t RightRedzoneSize = RZ;
1628 // Round up to MinRZ
1629 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1630 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1631 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1633 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1634 Constant *NewInitializer =
1635 ConstantStruct::get(NewTy, G->getInitializer(),
1636 Constant::getNullValue(RightRedZoneTy), nullptr);
1638 // Create a new global variable with enough space for a redzone.
1639 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1640 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1641 Linkage = GlobalValue::InternalLinkage;
1642 GlobalVariable *NewGlobal =
1643 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1644 "", G, G->getThreadLocalMode());
1645 NewGlobal->copyAttributesFrom(G);
1646 NewGlobal->setAlignment(MinRZ);
1648 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1649 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1651 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1652 if (Seq && Seq->isCString())
1653 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1656 // Transfer the debug info. The payload starts at offset zero so we can
1657 // copy the debug info over as is.
1658 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1659 G->getDebugInfo(GVs);
1660 for (auto *GV : GVs)
1661 NewGlobal->addDebugInfo(GV);
1664 Indices2[0] = IRB.getInt32(0);
1665 Indices2[1] = IRB.getInt32(0);
1667 G->replaceAllUsesWith(
1668 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1669 NewGlobal->takeName(G);
1670 G->eraseFromParent();
1673 if (UseComdatMetadata) {
1674 // Get or create a COMDAT for G so that we can use it with our metadata.
1675 Comdat *C = G->getComdat();
1677 if (!G->hasName()) {
1678 // If G is unnamed, it must be internal. Give it an artificial name
1679 // so we can put it in a comdat.
1680 assert(G->hasLocalLinkage());
1681 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1683 C = M.getOrInsertComdat(G->getName());
1684 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1685 if (TargetTriple.isOSBinFormatCOFF())
1686 C->setSelectionKind(Comdat::NoDuplicates);
1691 Constant *SourceLoc;
1692 if (!MD.SourceLoc.empty()) {
1693 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1694 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1696 SourceLoc = ConstantInt::get(IntptrTy, 0);
1699 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
1700 GlobalValue *InstrumentedGlobal = NewGlobal;
1702 bool CanUsePrivateAliases =
1703 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO();
1704 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
1705 // Create local alias for NewGlobal to avoid crash on ODR between
1706 // instrumented and non-instrumented libraries.
1707 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
1708 NameForGlobal + M.getName(), NewGlobal);
1710 // With local aliases, we need to provide another externally visible
1711 // symbol __odr_asan_XXX to detect ODR violation.
1712 auto *ODRIndicatorSym =
1713 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
1714 Constant::getNullValue(IRB.getInt8Ty()),
1715 kODRGenPrefix + NameForGlobal, nullptr,
1716 NewGlobal->getThreadLocalMode());
1718 // Set meaningful attributes for indicator symbol.
1719 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
1720 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
1721 ODRIndicatorSym->setAlignment(1);
1722 ODRIndicator = ODRIndicatorSym;
1723 InstrumentedGlobal = GA;
1726 Constant *Initializer = ConstantStruct::get(
1728 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
1729 ConstantInt::get(IntptrTy, SizeInBytes),
1730 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1731 ConstantExpr::getPointerCast(Name, IntptrTy),
1732 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1733 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
1734 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
1736 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1738 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1740 // If we aren't using separate metadata globals, add it to the initializer
1741 // list and continue.
1742 if (UseMetadataArray) {
1743 Initializers[i] = Initializer;
1747 // Create a separate metadata global and put it in the appropriate ASan
1748 // global registration section.
1749 GlobalVariable *Metadata = new GlobalVariable(
1750 M, GlobalStructTy, false, GlobalVariable::InternalLinkage,
1751 Initializer, Twine("__asan_global_") +
1752 GlobalValue::getRealLinkageName(G->getName()));
1753 Metadata->setSection(getGlobalMetadataSection());
1755 // The MSVC linker always inserts padding when linking incrementally. We
1756 // cope with that by aligning each struct to its size, which must be a power
1758 if (TargetTriple.isOSBinFormatCOFF())
1759 Metadata->setAlignment(SizeOfGlobalStruct);
1761 Metadata->setAlignment(1); // Don't leave padding in between.
1763 // On platforms that support comdats, put the metadata and the
1764 // instrumented global in the same group. This ensures that the metadata
1765 // is discarded if the instrumented global is discarded.
1766 if (UseComdatMetadata) {
1767 assert(G->hasComdat());
1768 Metadata->setComdat(G->getComdat());
1771 assert(UseMachOGlobalsSection);
1773 // On recent Mach-O platforms, we emit the global metadata in a way that
1774 // allows the linker to properly strip dead globals.
1775 auto LivenessBinder = ConstantStruct::get(
1776 LivenessTy, Initializer->getAggregateElement(0u),
1777 ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr);
1778 GlobalVariable *Liveness = new GlobalVariable(
1779 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1780 Twine("__asan_binder_") + G->getName());
1781 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1782 LivenessGlobals[i] = Liveness;
1785 // Create calls for poisoning before initializers run and unpoisoning after.
1786 if (HasDynamicallyInitializedGlobals)
1787 createInitializerPoisonCalls(M, ModuleName);
1789 // Platforms with a dedicated metadata section don't need to emit any more
1791 if (UseComdatMetadata)
1794 GlobalVariable *AllGlobals = nullptr;
1795 GlobalVariable *RegisteredFlag = nullptr;
1797 if (UseMachOGlobalsSection) {
1798 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1799 // to look up the loaded image that contains it. Second, we can store in it
1800 // whether registration has already occurred, to prevent duplicate
1803 // common linkage ensures that there is only one global per shared library.
1804 RegisteredFlag = new GlobalVariable(
1805 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1806 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1808 // Update llvm.compiler.used, adding the new liveness globals. This is
1809 // needed so that during LTO these variables stay alive. The alternative
1810 // would be to have the linker handling the LTO symbols, but libLTO
1811 // current API does not expose access to the section for each symbol.
1812 if (!LivenessGlobals.empty())
1813 appendToCompilerUsed(M, LivenessGlobals);
1814 } else if (UseMetadataArray) {
1815 // On platforms that don't have a custom metadata section, we emit an array
1816 // of global metadata structures.
1817 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1818 AllGlobals = new GlobalVariable(
1819 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1820 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1823 // Create a call to register the globals with the runtime.
1824 if (UseMachOGlobalsSection) {
1825 IRB.CreateCall(AsanRegisterImageGlobals,
1826 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1828 IRB.CreateCall(AsanRegisterGlobals,
1829 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1830 ConstantInt::get(IntptrTy, n)});
1833 // We also need to unregister globals at the end, e.g., when a shared library
1835 Function *AsanDtorFunction =
1836 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1837 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1838 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1839 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1841 if (UseMachOGlobalsSection) {
1842 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1843 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1845 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1846 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1847 ConstantInt::get(IntptrTy, n)});
1850 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1856 bool AddressSanitizerModule::runOnModule(Module &M) {
1857 C = &(M.getContext());
1858 int LongSize = M.getDataLayout().getPointerSizeInBits();
1859 IntptrTy = Type::getIntNTy(*C, LongSize);
1860 TargetTriple = Triple(M.getTargetTriple());
1861 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1862 initializeCallbacks(M);
1864 bool Changed = false;
1866 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1867 if (ClGlobals && !CompileKernel) {
1868 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1870 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1871 Changed |= InstrumentGlobals(IRB, M);
1877 void AddressSanitizer::initializeCallbacks(Module &M) {
1878 IRBuilder<> IRB(*C);
1879 // Create __asan_report* callbacks.
1880 // IsWrite, TypeSize and Exp are encoded in the function name.
1881 for (int Exp = 0; Exp < 2; Exp++) {
1882 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1883 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1884 const std::string ExpStr = Exp ? "exp_" : "";
1885 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1886 const std::string EndingStr = Recover ? "_noabort" : "";
1887 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1888 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1889 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1890 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
1891 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1892 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1893 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1894 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1895 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1896 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1897 AccessSizeIndex++) {
1898 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
1899 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1900 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1901 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
1902 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1903 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1904 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1905 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1906 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1911 const std::string MemIntrinCallbackPrefix =
1912 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1913 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1914 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1915 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1916 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1917 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1918 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1919 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1920 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1921 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1923 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1924 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1926 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1927 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1928 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1929 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1930 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1931 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1932 StringRef(""), StringRef(""),
1933 /*hasSideEffects=*/true);
1937 bool AddressSanitizer::doInitialization(Module &M) {
1938 // Initialize the private fields. No one has accessed them before.
1942 C = &(M.getContext());
1943 LongSize = M.getDataLayout().getPointerSizeInBits();
1944 IntptrTy = Type::getIntNTy(*C, LongSize);
1945 TargetTriple = Triple(M.getTargetTriple());
1947 if (!CompileKernel) {
1948 std::tie(AsanCtorFunction, AsanInitFunction) =
1949 createSanitizerCtorAndInitFunctions(
1950 M, kAsanModuleCtorName, kAsanInitName,
1951 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1952 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1954 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1958 bool AddressSanitizer::doFinalization(Module &M) {
1963 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1964 // For each NSObject descendant having a +load method, this method is invoked
1965 // by the ObjC runtime before any of the static constructors is called.
1966 // Therefore we need to instrument such methods with a call to __asan_init
1967 // at the beginning in order to initialize our runtime before any access to
1968 // the shadow memory.
1969 // We cannot just ignore these methods, because they may call other
1970 // instrumented functions.
1971 if (F.getName().find(" load]") != std::string::npos) {
1972 IRBuilder<> IRB(&F.front(), F.front().begin());
1973 IRB.CreateCall(AsanInitFunction, {});
1979 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
1980 // Generate code only when dynamic addressing is needed.
1981 if (Mapping.Offset != kDynamicShadowSentinel)
1984 IRBuilder<> IRB(&F.front().front());
1985 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
1986 kAsanShadowMemoryDynamicAddress, IntptrTy);
1987 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
1990 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1991 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1992 // to it as uninteresting. This assumes we haven't started processing allocas
1993 // yet. This check is done up front because iterating the use list in
1994 // isInterestingAlloca would be algorithmically slower.
1995 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1997 // Try to get the declaration of llvm.localescape. If it's not in the module,
1998 // we can exit early.
1999 if (!F.getParent()->getFunction("llvm.localescape")) return;
2001 // Look for a call to llvm.localescape call in the entry block. It can't be in
2003 for (Instruction &I : F.getEntryBlock()) {
2004 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2005 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2006 // We found a call. Mark all the allocas passed in as uninteresting.
2007 for (Value *Arg : II->arg_operands()) {
2008 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2009 assert(AI && AI->isStaticAlloca() &&
2010 "non-static alloca arg to localescape");
2011 ProcessedAllocas[AI] = false;
2018 bool AddressSanitizer::runOnFunction(Function &F) {
2019 if (&F == AsanCtorFunction) return false;
2020 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2021 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2022 if (F.getName().startswith("__asan_")) return false;
2024 bool FunctionModified = false;
2026 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2027 // This function needs to be called even if the function body is not
2029 if (maybeInsertAsanInitAtFunctionEntry(F))
2030 FunctionModified = true;
2032 // Leave if the function doesn't need instrumentation.
2033 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2035 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2037 initializeCallbacks(*F.getParent());
2038 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2040 FunctionStateRAII CleanupObj(this);
2042 maybeInsertDynamicShadowAtFunctionEntry(F);
2044 // We can't instrument allocas used with llvm.localescape. Only static allocas
2045 // can be passed to that intrinsic.
2046 markEscapedLocalAllocas(F);
2048 // We want to instrument every address only once per basic block (unless there
2049 // are calls between uses).
2050 SmallSet<Value *, 16> TempsToInstrument;
2051 SmallVector<Instruction *, 16> ToInstrument;
2052 SmallVector<Instruction *, 8> NoReturnCalls;
2053 SmallVector<BasicBlock *, 16> AllBlocks;
2054 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2059 const TargetLibraryInfo *TLI =
2060 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2062 // Fill the set of memory operations to instrument.
2063 for (auto &BB : F) {
2064 AllBlocks.push_back(&BB);
2065 TempsToInstrument.clear();
2066 int NumInsnsPerBB = 0;
2067 for (auto &Inst : BB) {
2068 if (LooksLikeCodeInBug11395(&Inst)) return false;
2069 Value *MaybeMask = nullptr;
2070 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2071 &Alignment, &MaybeMask)) {
2072 if (ClOpt && ClOptSameTemp) {
2073 // If we have a mask, skip instrumentation if we've already
2074 // instrumented the full object. But don't add to TempsToInstrument
2075 // because we might get another load/store with a different mask.
2077 if (TempsToInstrument.count(Addr))
2078 continue; // We've seen this (whole) temp in the current BB.
2080 if (!TempsToInstrument.insert(Addr).second)
2081 continue; // We've seen this temp in the current BB.
2084 } else if (ClInvalidPointerPairs &&
2085 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2086 PointerComparisonsOrSubtracts.push_back(&Inst);
2088 } else if (isa<MemIntrinsic>(Inst)) {
2091 if (isa<AllocaInst>(Inst)) NumAllocas++;
2094 // A call inside BB.
2095 TempsToInstrument.clear();
2096 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2098 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2099 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2102 ToInstrument.push_back(&Inst);
2104 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2110 (ClInstrumentationWithCallsThreshold >= 0 &&
2111 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2112 const DataLayout &DL = F.getParent()->getDataLayout();
2113 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
2114 /*RoundToAlign=*/true);
2117 int NumInstrumented = 0;
2118 for (auto Inst : ToInstrument) {
2119 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2120 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2121 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2122 instrumentMop(ObjSizeVis, Inst, UseCalls,
2123 F.getParent()->getDataLayout());
2125 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2130 FunctionStackPoisoner FSP(F, *this);
2131 bool ChangedStack = FSP.runOnFunction();
2133 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2134 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2135 for (auto CI : NoReturnCalls) {
2136 IRBuilder<> IRB(CI);
2137 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2140 for (auto Inst : PointerComparisonsOrSubtracts) {
2141 instrumentPointerComparisonOrSubtraction(Inst);
2145 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2146 FunctionModified = true;
2148 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2151 return FunctionModified;
2154 // Workaround for bug 11395: we don't want to instrument stack in functions
2155 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2156 // FIXME: remove once the bug 11395 is fixed.
2157 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2158 if (LongSize != 32) return false;
2159 CallInst *CI = dyn_cast<CallInst>(I);
2160 if (!CI || !CI->isInlineAsm()) return false;
2161 if (CI->getNumArgOperands() <= 5) return false;
2162 // We have inline assembly with quite a few arguments.
2166 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2167 IRBuilder<> IRB(*C);
2168 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2169 std::string Suffix = itostr(i);
2170 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2171 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2172 IntptrTy, nullptr));
2173 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2174 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2175 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2177 if (ASan.UseAfterScope) {
2178 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2179 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2180 IntptrTy, IntptrTy, nullptr));
2181 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2182 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2183 IntptrTy, IntptrTy, nullptr));
2186 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2187 std::ostringstream Name;
2188 Name << kAsanSetShadowPrefix;
2189 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2190 AsanSetShadowFunc[Val] =
2191 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2192 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2195 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2196 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2197 AsanAllocasUnpoisonFunc =
2198 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2199 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2202 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2203 ArrayRef<uint8_t> ShadowBytes,
2204 size_t Begin, size_t End,
2206 Value *ShadowBase) {
2210 const size_t LargestStoreSizeInBytes =
2211 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2213 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2215 // Poison given range in shadow using larges store size with out leading and
2216 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2217 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2218 // middle of a store.
2219 for (size_t i = Begin; i < End;) {
2220 if (!ShadowMask[i]) {
2221 assert(!ShadowBytes[i]);
2226 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2227 // Fit store size into the range.
2228 while (StoreSizeInBytes > End - i)
2229 StoreSizeInBytes /= 2;
2231 // Minimize store size by trimming trailing zeros.
2232 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2233 while (j <= StoreSizeInBytes / 2)
2234 StoreSizeInBytes /= 2;
2238 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2240 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2242 Val = (Val << 8) | ShadowBytes[i + j];
2245 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2246 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2247 IRB.CreateAlignedStore(
2248 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2250 i += StoreSizeInBytes;
2254 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2255 ArrayRef<uint8_t> ShadowBytes,
2256 IRBuilder<> &IRB, Value *ShadowBase) {
2257 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2260 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2261 ArrayRef<uint8_t> ShadowBytes,
2262 size_t Begin, size_t End,
2263 IRBuilder<> &IRB, Value *ShadowBase) {
2264 assert(ShadowMask.size() == ShadowBytes.size());
2265 size_t Done = Begin;
2266 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2267 if (!ShadowMask[i]) {
2268 assert(!ShadowBytes[i]);
2271 uint8_t Val = ShadowBytes[i];
2272 if (!AsanSetShadowFunc[Val])
2275 // Skip same values.
2276 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2279 if (j - i >= ClMaxInlinePoisoningSize) {
2280 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2281 IRB.CreateCall(AsanSetShadowFunc[Val],
2282 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2283 ConstantInt::get(IntptrTy, j - i)});
2288 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2291 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2292 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2293 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2294 assert(LocalStackSize <= kMaxStackMallocSize);
2295 uint64_t MaxSize = kMinStackMallocSize;
2296 for (int i = 0;; i++, MaxSize *= 2)
2297 if (LocalStackSize <= MaxSize) return i;
2298 llvm_unreachable("impossible LocalStackSize");
2301 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2303 Instruction *ThenTerm,
2304 Value *ValueIfFalse) {
2305 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2306 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2307 PHI->addIncoming(ValueIfFalse, CondBlock);
2308 BasicBlock *ThenBlock = ThenTerm->getParent();
2309 PHI->addIncoming(ValueIfTrue, ThenBlock);
2313 Value *FunctionStackPoisoner::createAllocaForLayout(
2314 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2317 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2318 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2321 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2322 nullptr, "MyAlloca");
2323 assert(Alloca->isStaticAlloca());
2325 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2326 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2327 Alloca->setAlignment(FrameAlignment);
2328 return IRB.CreatePointerCast(Alloca, IntptrTy);
2331 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2332 BasicBlock &FirstBB = *F.begin();
2333 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2334 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2335 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2336 DynamicAllocaLayout->setAlignment(32);
2339 void FunctionStackPoisoner::processDynamicAllocas() {
2340 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2341 assert(DynamicAllocaPoisonCallVec.empty());
2345 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2346 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2347 assert(APC.InsBefore);
2349 assert(ASan.isInterestingAlloca(*APC.AI));
2350 assert(!APC.AI->isStaticAlloca());
2352 IRBuilder<> IRB(APC.InsBefore);
2353 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2354 // Dynamic allocas will be unpoisoned unconditionally below in
2355 // unpoisonDynamicAllocas.
2356 // Flag that we need unpoison static allocas.
2359 // Handle dynamic allocas.
2360 createDynamicAllocasInitStorage();
2361 for (auto &AI : DynamicAllocaVec)
2362 handleDynamicAllocaCall(AI);
2363 unpoisonDynamicAllocas();
2366 void FunctionStackPoisoner::processStaticAllocas() {
2367 if (AllocaVec.empty()) {
2368 assert(StaticAllocaPoisonCallVec.empty());
2372 int StackMallocIdx = -1;
2373 DebugLoc EntryDebugLocation;
2374 if (auto SP = F.getSubprogram())
2375 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2377 Instruction *InsBefore = AllocaVec[0];
2378 IRBuilder<> IRB(InsBefore);
2379 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2381 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2382 // debug info is broken, because only entry-block allocas are treated as
2383 // regular stack slots.
2384 auto InsBeforeB = InsBefore->getParent();
2385 assert(InsBeforeB == &F.getEntryBlock());
2386 for (auto *AI : StaticAllocasToMoveUp)
2387 if (AI->getParent() == InsBeforeB)
2388 AI->moveBefore(InsBefore);
2390 // If we have a call to llvm.localescape, keep it in the entry block.
2391 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2393 SmallVector<ASanStackVariableDescription, 16> SVD;
2394 SVD.reserve(AllocaVec.size());
2395 for (AllocaInst *AI : AllocaVec) {
2396 ASanStackVariableDescription D = {AI->getName().data(),
2397 ASan.getAllocaSizeInBytes(*AI),
2406 // Minimal header size (left redzone) is 4 pointers,
2407 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2408 size_t MinHeaderSize = ASan.LongSize / 2;
2409 const ASanStackFrameLayout &L =
2410 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2412 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2413 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2414 for (auto &Desc : SVD)
2415 AllocaToSVDMap[Desc.AI] = &Desc;
2417 // Update SVD with information from lifetime intrinsics.
2418 for (const auto &APC : StaticAllocaPoisonCallVec) {
2419 assert(APC.InsBefore);
2421 assert(ASan.isInterestingAlloca(*APC.AI));
2422 assert(APC.AI->isStaticAlloca());
2424 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2425 Desc.LifetimeSize = Desc.Size;
2426 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2427 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2428 if (LifetimeLoc->getFile() == FnLoc->getFile())
2429 if (unsigned Line = LifetimeLoc->getLine())
2430 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2435 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2436 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2437 uint64_t LocalStackSize = L.FrameSize;
2438 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2439 LocalStackSize <= kMaxStackMallocSize;
2440 bool DoDynamicAlloca = ClDynamicAllocaStack;
2441 // Don't do dynamic alloca or stack malloc if:
2442 // 1) There is inline asm: too often it makes assumptions on which registers
2444 // 2) There is a returns_twice call (typically setjmp), which is
2445 // optimization-hostile, and doesn't play well with introduced indirect
2446 // register-relative calculation of local variable addresses.
2447 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2448 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2450 Value *StaticAlloca =
2451 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2454 Value *LocalStackBase;
2456 if (DoStackMalloc) {
2457 // void *FakeStack = __asan_option_detect_stack_use_after_return
2458 // ? __asan_stack_malloc_N(LocalStackSize)
2460 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2461 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2462 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2463 Value *UseAfterReturnIsEnabled =
2464 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2465 Constant::getNullValue(IRB.getInt32Ty()));
2467 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2468 IRBuilder<> IRBIf(Term);
2469 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2470 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2471 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2472 Value *FakeStackValue =
2473 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2474 ConstantInt::get(IntptrTy, LocalStackSize));
2475 IRB.SetInsertPoint(InsBefore);
2476 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2477 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2478 ConstantInt::get(IntptrTy, 0));
2480 Value *NoFakeStack =
2481 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2482 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2483 IRBIf.SetInsertPoint(Term);
2484 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2485 Value *AllocaValue =
2486 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2487 IRB.SetInsertPoint(InsBefore);
2488 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2489 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2491 // void *FakeStack = nullptr;
2492 // void *LocalStackBase = alloca(LocalStackSize);
2493 FakeStack = ConstantInt::get(IntptrTy, 0);
2495 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2498 // Replace Alloca instructions with base+offset.
2499 for (const auto &Desc : SVD) {
2500 AllocaInst *AI = Desc.AI;
2501 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2502 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2504 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
2505 AI->replaceAllUsesWith(NewAllocaPtr);
2508 // The left-most redzone has enough space for at least 4 pointers.
2509 // Write the Magic value to redzone[0].
2510 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2511 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2513 // Write the frame description constant to redzone[1].
2514 Value *BasePlus1 = IRB.CreateIntToPtr(
2515 IRB.CreateAdd(LocalStackBase,
2516 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2518 GlobalVariable *StackDescriptionGlobal =
2519 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2520 /*AllowMerging*/ true);
2521 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2522 IRB.CreateStore(Description, BasePlus1);
2523 // Write the PC to redzone[2].
2524 Value *BasePlus2 = IRB.CreateIntToPtr(
2525 IRB.CreateAdd(LocalStackBase,
2526 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2528 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2530 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2532 // Poison the stack red zones at the entry.
2533 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2534 // As mask we must use most poisoned case: red zones and after scope.
2535 // As bytes we can use either the same or just red zones only.
2536 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2538 if (!StaticAllocaPoisonCallVec.empty()) {
2539 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2541 // Poison static allocas near lifetime intrinsics.
2542 for (const auto &APC : StaticAllocaPoisonCallVec) {
2543 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2544 assert(Desc.Offset % L.Granularity == 0);
2545 size_t Begin = Desc.Offset / L.Granularity;
2546 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2548 IRBuilder<> IRB(APC.InsBefore);
2549 copyToShadow(ShadowAfterScope,
2550 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2555 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2556 SmallVector<uint8_t, 64> ShadowAfterReturn;
2558 // (Un)poison the stack before all ret instructions.
2559 for (auto Ret : RetVec) {
2560 IRBuilder<> IRBRet(Ret);
2561 // Mark the current frame as retired.
2562 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2564 if (DoStackMalloc) {
2565 assert(StackMallocIdx >= 0);
2566 // if FakeStack != 0 // LocalStackBase == FakeStack
2567 // // In use-after-return mode, poison the whole stack frame.
2568 // if StackMallocIdx <= 4
2569 // // For small sizes inline the whole thing:
2570 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2571 // **SavedFlagPtr(FakeStack) = 0
2573 // __asan_stack_free_N(FakeStack, LocalStackSize)
2575 // <This is not a fake stack; unpoison the redzones>
2577 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2578 TerminatorInst *ThenTerm, *ElseTerm;
2579 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2581 IRBuilder<> IRBPoison(ThenTerm);
2582 if (StackMallocIdx <= 4) {
2583 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2584 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2585 kAsanStackUseAfterReturnMagic);
2586 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2588 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2590 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2591 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2592 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2593 IRBPoison.CreateStore(
2594 Constant::getNullValue(IRBPoison.getInt8Ty()),
2595 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2597 // For larger frames call __asan_stack_free_*.
2598 IRBPoison.CreateCall(
2599 AsanStackFreeFunc[StackMallocIdx],
2600 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2603 IRBuilder<> IRBElse(ElseTerm);
2604 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2606 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2610 // We are done. Remove the old unused alloca instructions.
2611 for (auto AI : AllocaVec) AI->eraseFromParent();
2614 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2615 IRBuilder<> &IRB, bool DoPoison) {
2616 // For now just insert the call to ASan runtime.
2617 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2618 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2620 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2621 {AddrArg, SizeArg});
2624 // Handling llvm.lifetime intrinsics for a given %alloca:
2625 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2626 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2627 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2628 // could be poisoned by previous llvm.lifetime.end instruction, as the
2629 // variable may go in and out of scope several times, e.g. in loops).
2630 // (3) if we poisoned at least one %alloca in a function,
2631 // unpoison the whole stack frame at function exit.
2633 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2634 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2635 // We're interested only in allocas we can handle.
2636 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2637 // See if we've already calculated (or started to calculate) alloca for a
2639 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2640 if (I != AllocaForValue.end()) return I->second;
2641 // Store 0 while we're calculating alloca for value V to avoid
2642 // infinite recursion if the value references itself.
2643 AllocaForValue[V] = nullptr;
2644 AllocaInst *Res = nullptr;
2645 if (CastInst *CI = dyn_cast<CastInst>(V))
2646 Res = findAllocaForValue(CI->getOperand(0));
2647 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2648 for (Value *IncValue : PN->incoming_values()) {
2649 // Allow self-referencing phi-nodes.
2650 if (IncValue == PN) continue;
2651 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2652 // AI for incoming values should exist and should all be equal.
2653 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2657 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2658 Res = findAllocaForValue(EP->getPointerOperand());
2660 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2662 if (Res) AllocaForValue[V] = Res;
2666 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2667 IRBuilder<> IRB(AI);
2669 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2670 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2672 Value *Zero = Constant::getNullValue(IntptrTy);
2673 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2674 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2676 // Since we need to extend alloca with additional memory to locate
2677 // redzones, and OldSize is number of allocated blocks with
2678 // ElementSize size, get allocated memory size in bytes by
2679 // OldSize * ElementSize.
2680 const unsigned ElementSize =
2681 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2683 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2684 ConstantInt::get(IntptrTy, ElementSize));
2686 // PartialSize = OldSize % 32
2687 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2689 // Misalign = kAllocaRzSize - PartialSize;
2690 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2692 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2693 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2694 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2696 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2697 // Align is added to locate left redzone, PartialPadding for possible
2698 // partial redzone and kAllocaRzSize for right redzone respectively.
2699 Value *AdditionalChunkSize = IRB.CreateAdd(
2700 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2702 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2704 // Insert new alloca with new NewSize and Align params.
2705 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2706 NewAlloca->setAlignment(Align);
2708 // NewAddress = Address + Align
2709 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2710 ConstantInt::get(IntptrTy, Align));
2712 // Insert __asan_alloca_poison call for new created alloca.
2713 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2715 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2716 // for unpoisoning stuff.
2717 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2719 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2721 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2722 AI->replaceAllUsesWith(NewAddressPtr);
2724 // We are done. Erase old alloca from parent.
2725 AI->eraseFromParent();
2728 // isSafeAccess returns true if Addr is always inbounds with respect to its
2729 // base object. For example, it is a field access or an array access with
2730 // constant inbounds index.
2731 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2732 Value *Addr, uint64_t TypeSize) const {
2733 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2734 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2735 uint64_t Size = SizeOffset.first.getZExtValue();
2736 int64_t Offset = SizeOffset.second.getSExtValue();
2737 // Three checks are required to ensure safety:
2738 // . Offset >= 0 (since the offset is given from the base ptr)
2739 // . Size >= Offset (unsigned)
2740 // . Size - Offset >= NeededSize (unsigned)
2741 return Offset >= 0 && Size >= uint64_t(Offset) &&
2742 Size - uint64_t(Offset) >= TypeSize / 8;