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 kPS4CPU_ShadowOffset64 = 1ULL << 40;
84 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
85 // The shadow memory space is dynamically allocated.
86 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
88 static const size_t kMinStackMallocSize = 1 << 6; // 64B
89 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
90 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
91 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
93 static const char *const kAsanModuleCtorName = "asan.module_ctor";
94 static const char *const kAsanModuleDtorName = "asan.module_dtor";
95 static const uint64_t kAsanCtorAndDtorPriority = 1;
96 static const char *const kAsanReportErrorTemplate = "__asan_report_";
97 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
98 static const char *const kAsanUnregisterGlobalsName =
99 "__asan_unregister_globals";
100 static const char *const kAsanRegisterImageGlobalsName =
101 "__asan_register_image_globals";
102 static const char *const kAsanUnregisterImageGlobalsName =
103 "__asan_unregister_image_globals";
104 static const char *const kAsanRegisterElfGlobalsName =
105 "__asan_register_elf_globals";
106 static const char *const kAsanUnregisterElfGlobalsName =
107 "__asan_unregister_elf_globals";
108 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
109 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
110 static const char *const kAsanInitName = "__asan_init";
111 static const char *const kAsanVersionCheckName =
112 "__asan_version_mismatch_check_v8";
113 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
114 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
115 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
116 static const int kMaxAsanStackMallocSizeClass = 10;
117 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
118 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
119 static const char *const kAsanGenPrefix = "__asan_gen_";
120 static const char *const kODRGenPrefix = "__odr_asan_gen_";
121 static const char *const kSanCovGenPrefix = "__sancov_gen_";
122 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
123 static const char *const kAsanPoisonStackMemoryName =
124 "__asan_poison_stack_memory";
125 static const char *const kAsanUnpoisonStackMemoryName =
126 "__asan_unpoison_stack_memory";
128 // ASan version script has __asan_* wildcard. Triple underscore prevents a
129 // linker (gold) warning about attempting to export a local symbol.
130 static const char *const kAsanGlobalsRegisteredFlagName =
131 "___asan_globals_registered";
133 static const char *const kAsanOptionDetectUseAfterReturn =
134 "__asan_option_detect_stack_use_after_return";
136 static const char *const kAsanShadowMemoryDynamicAddress =
137 "__asan_shadow_memory_dynamic_address";
139 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
140 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
142 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
143 static const size_t kNumberOfAccessSizes = 5;
145 static const unsigned kAllocaRzSize = 32;
147 // Command-line flags.
148 static cl::opt<bool> ClEnableKasan(
149 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
150 cl::Hidden, cl::init(false));
151 static cl::opt<bool> ClRecover(
153 cl::desc("Enable recovery mode (continue-after-error)."),
154 cl::Hidden, cl::init(false));
156 // This flag may need to be replaced with -f[no-]asan-reads.
157 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
158 cl::desc("instrument read instructions"),
159 cl::Hidden, cl::init(true));
160 static cl::opt<bool> ClInstrumentWrites(
161 "asan-instrument-writes", cl::desc("instrument write instructions"),
162 cl::Hidden, cl::init(true));
163 static cl::opt<bool> ClInstrumentAtomics(
164 "asan-instrument-atomics",
165 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
167 static cl::opt<bool> ClAlwaysSlowPath(
168 "asan-always-slow-path",
169 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
171 static cl::opt<bool> ClForceDynamicShadow(
172 "asan-force-dynamic-shadow",
173 cl::desc("Load shadow address into a local variable for each function"),
174 cl::Hidden, cl::init(false));
176 // This flag limits the number of instructions to be instrumented
177 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
178 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
180 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
181 "asan-max-ins-per-bb", cl::init(10000),
182 cl::desc("maximal number of instructions to instrument in any given BB"),
184 // This flag may need to be replaced with -f[no]asan-stack.
185 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
186 cl::Hidden, cl::init(true));
187 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
188 "asan-max-inline-poisoning-size",
190 "Inline shadow poisoning for blocks up to the given size in bytes."),
191 cl::Hidden, cl::init(64));
192 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
193 cl::desc("Check stack-use-after-return"),
194 cl::Hidden, cl::init(true));
195 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
196 cl::desc("Check stack-use-after-scope"),
197 cl::Hidden, cl::init(false));
198 // This flag may need to be replaced with -f[no]asan-globals.
199 static cl::opt<bool> ClGlobals("asan-globals",
200 cl::desc("Handle global objects"), cl::Hidden,
202 static cl::opt<bool> ClInitializers("asan-initialization-order",
203 cl::desc("Handle C++ initializer order"),
204 cl::Hidden, cl::init(true));
205 static cl::opt<bool> ClInvalidPointerPairs(
206 "asan-detect-invalid-pointer-pair",
207 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
209 static cl::opt<unsigned> ClRealignStack(
210 "asan-realign-stack",
211 cl::desc("Realign stack to the value of this flag (power of two)"),
212 cl::Hidden, cl::init(32));
213 static cl::opt<int> ClInstrumentationWithCallsThreshold(
214 "asan-instrumentation-with-call-threshold",
216 "If the function being instrumented contains more than "
217 "this number of memory accesses, use callbacks instead of "
218 "inline checks (-1 means never use callbacks)."),
219 cl::Hidden, cl::init(7000));
220 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
221 "asan-memory-access-callback-prefix",
222 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
223 cl::init("__asan_"));
225 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
226 cl::desc("instrument dynamic allocas"),
227 cl::Hidden, cl::init(true));
228 static cl::opt<bool> ClSkipPromotableAllocas(
229 "asan-skip-promotable-allocas",
230 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
233 // These flags allow to change the shadow mapping.
234 // The shadow mapping looks like
235 // Shadow = (Mem >> scale) + offset
236 static cl::opt<int> ClMappingScale("asan-mapping-scale",
237 cl::desc("scale of asan shadow mapping"),
238 cl::Hidden, cl::init(0));
239 static cl::opt<unsigned long long> ClMappingOffset(
240 "asan-mapping-offset",
241 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
244 // Optimization flags. Not user visible, used mostly for testing
245 // and benchmarking the tool.
246 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
247 cl::Hidden, cl::init(true));
248 static cl::opt<bool> ClOptSameTemp(
249 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
250 cl::Hidden, cl::init(true));
251 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
252 cl::desc("Don't instrument scalar globals"),
253 cl::Hidden, cl::init(true));
254 static cl::opt<bool> ClOptStack(
255 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
256 cl::Hidden, cl::init(false));
258 static cl::opt<bool> ClDynamicAllocaStack(
259 "asan-stack-dynamic-alloca",
260 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
263 static cl::opt<uint32_t> ClForceExperiment(
264 "asan-force-experiment",
265 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
269 ClUsePrivateAliasForGlobals("asan-use-private-alias",
270 cl::desc("Use private aliases for global"
272 cl::Hidden, cl::init(false));
275 ClUseGlobalsGC("asan-globals-live-support",
276 cl::desc("Use linker features to support dead "
277 "code stripping of globals"),
278 cl::Hidden, cl::init(true));
280 // This is on by default even though there is a bug in gold:
281 // https://sourceware.org/bugzilla/show_bug.cgi?id=19002
283 ClWithComdat("asan-with-comdat",
284 cl::desc("Place ASan constructors in comdat sections"),
285 cl::Hidden, cl::init(true));
288 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
290 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
291 cl::Hidden, cl::init(0));
292 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
293 cl::desc("Debug func"));
294 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
295 cl::Hidden, cl::init(-1));
296 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
297 cl::Hidden, cl::init(-1));
299 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
300 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
301 STATISTIC(NumOptimizedAccessesToGlobalVar,
302 "Number of optimized accesses to global vars");
303 STATISTIC(NumOptimizedAccessesToStackVar,
304 "Number of optimized accesses to stack vars");
307 /// Frontend-provided metadata for source location.
308 struct LocationMetadata {
313 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
315 bool empty() const { return Filename.empty(); }
317 void parse(MDNode *MDN) {
318 assert(MDN->getNumOperands() == 3);
319 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
320 Filename = DIFilename->getString();
322 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
324 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
328 /// Frontend-provided metadata for global variables.
329 class GlobalsMetadata {
332 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
333 LocationMetadata SourceLoc;
339 GlobalsMetadata() : inited_(false) {}
346 void init(Module &M) {
349 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
350 if (!Globals) return;
351 for (auto MDN : Globals->operands()) {
352 // Metadata node contains the global and the fields of "Entry".
353 assert(MDN->getNumOperands() == 5);
354 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
355 // The optimizer may optimize away a global entirely.
357 // We can already have an entry for GV if it was merged with another
359 Entry &E = Entries[GV];
360 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
361 E.SourceLoc.parse(Loc);
362 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
363 E.Name = Name->getString();
364 ConstantInt *IsDynInit =
365 mdconst::extract<ConstantInt>(MDN->getOperand(3));
366 E.IsDynInit |= IsDynInit->isOne();
367 ConstantInt *IsBlacklisted =
368 mdconst::extract<ConstantInt>(MDN->getOperand(4));
369 E.IsBlacklisted |= IsBlacklisted->isOne();
373 /// Returns metadata entry for a given global.
374 Entry get(GlobalVariable *G) const {
375 auto Pos = Entries.find(G);
376 return (Pos != Entries.end()) ? Pos->second : Entry();
381 DenseMap<GlobalVariable *, Entry> Entries;
384 /// This struct defines the shadow mapping using the rule:
385 /// shadow = (mem >> Scale) ADD-or-OR Offset.
386 struct ShadowMapping {
392 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
394 bool IsAndroid = TargetTriple.isAndroid();
395 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
396 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
397 bool IsPS4CPU = TargetTriple.isPS4CPU();
398 bool IsLinux = TargetTriple.isOSLinux();
399 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
400 TargetTriple.getArch() == llvm::Triple::ppc64le;
401 bool IsSystemZ = TargetTriple.getArch() == llvm::Triple::systemz;
402 bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86;
403 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
404 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
405 TargetTriple.getArch() == llvm::Triple::mipsel;
406 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
407 TargetTriple.getArch() == llvm::Triple::mips64el;
408 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
409 bool IsWindows = TargetTriple.isOSWindows();
410 bool IsFuchsia = TargetTriple.isOSFuchsia();
412 ShadowMapping Mapping;
414 if (LongSize == 32) {
415 // Android is always PIE, which means that the beginning of the address
416 // space is always available.
420 Mapping.Offset = kMIPS32_ShadowOffset32;
422 Mapping.Offset = kFreeBSD_ShadowOffset32;
424 // If we're targeting iOS and x86, the binary is built for iOS simulator.
425 Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
427 Mapping.Offset = kWindowsShadowOffset32;
429 Mapping.Offset = kDefaultShadowOffset32;
430 } else { // LongSize == 64
431 // Fuchsia is always PIE, which means that the beginning of the address
432 // space is always available.
436 Mapping.Offset = kPPC64_ShadowOffset64;
438 Mapping.Offset = kSystemZ_ShadowOffset64;
440 Mapping.Offset = kFreeBSD_ShadowOffset64;
442 Mapping.Offset = kPS4CPU_ShadowOffset64;
443 else if (IsLinux && IsX86_64) {
445 Mapping.Offset = kLinuxKasan_ShadowOffset64;
447 Mapping.Offset = kSmallX86_64ShadowOffset;
448 } else if (IsWindows && IsX86_64) {
449 Mapping.Offset = kWindowsShadowOffset64;
451 Mapping.Offset = kMIPS64_ShadowOffset64;
453 // If we're targeting iOS and x86, the binary is built for iOS simulator.
454 // We are using dynamic shadow offset on the 64-bit devices.
456 IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
458 Mapping.Offset = kAArch64_ShadowOffset64;
460 Mapping.Offset = kDefaultShadowOffset64;
463 if (ClForceDynamicShadow) {
464 Mapping.Offset = kDynamicShadowSentinel;
467 Mapping.Scale = kDefaultShadowScale;
468 if (ClMappingScale.getNumOccurrences() > 0) {
469 Mapping.Scale = ClMappingScale;
472 if (ClMappingOffset.getNumOccurrences() > 0) {
473 Mapping.Offset = ClMappingOffset;
476 // OR-ing shadow offset if more efficient (at least on x86) if the offset
477 // is a power of two, but on ppc64 we have to use add since the shadow
478 // offset is not necessary 1/8-th of the address space. On SystemZ,
479 // we could OR the constant in a single instruction, but it's more
480 // efficient to load it once and use indexed addressing.
481 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
482 !(Mapping.Offset & (Mapping.Offset - 1)) &&
483 Mapping.Offset != kDynamicShadowSentinel;
488 static size_t RedzoneSizeForScale(int MappingScale) {
489 // Redzone used for stack and globals is at least 32 bytes.
490 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
491 return std::max(32U, 1U << MappingScale);
494 /// AddressSanitizer: instrument the code in module to find memory bugs.
495 struct AddressSanitizer : public FunctionPass {
496 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false,
497 bool UseAfterScope = false)
498 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
499 Recover(Recover || ClRecover),
500 UseAfterScope(UseAfterScope || ClUseAfterScope),
501 LocalDynamicShadow(nullptr) {
502 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
504 StringRef getPassName() const override {
505 return "AddressSanitizerFunctionPass";
507 void getAnalysisUsage(AnalysisUsage &AU) const override {
508 AU.addRequired<DominatorTreeWrapperPass>();
509 AU.addRequired<TargetLibraryInfoWrapperPass>();
511 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
512 uint64_t ArraySize = 1;
513 if (AI.isArrayAllocation()) {
514 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
515 assert(CI && "non-constant array size");
516 ArraySize = CI->getZExtValue();
518 Type *Ty = AI.getAllocatedType();
519 uint64_t SizeInBytes =
520 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
521 return SizeInBytes * ArraySize;
523 /// Check if we want (and can) handle this alloca.
524 bool isInterestingAlloca(const AllocaInst &AI);
526 /// If it is an interesting memory access, return the PointerOperand
527 /// and set IsWrite/Alignment. Otherwise return nullptr.
528 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
529 /// masked load/store.
530 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
531 uint64_t *TypeSize, unsigned *Alignment,
532 Value **MaybeMask = nullptr);
533 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
534 bool UseCalls, const DataLayout &DL);
535 void instrumentPointerComparisonOrSubtraction(Instruction *I);
536 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
537 Value *Addr, uint32_t TypeSize, bool IsWrite,
538 Value *SizeArgument, bool UseCalls, uint32_t Exp);
539 void instrumentUnusualSizeOrAlignment(Instruction *I,
540 Instruction *InsertBefore, Value *Addr,
541 uint32_t TypeSize, bool IsWrite,
542 Value *SizeArgument, bool UseCalls,
544 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
545 Value *ShadowValue, uint32_t TypeSize);
546 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
547 bool IsWrite, size_t AccessSizeIndex,
548 Value *SizeArgument, uint32_t Exp);
549 void instrumentMemIntrinsic(MemIntrinsic *MI);
550 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
551 bool runOnFunction(Function &F) override;
552 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
553 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
554 void markEscapedLocalAllocas(Function &F);
555 bool doInitialization(Module &M) override;
556 bool doFinalization(Module &M) override;
557 static char ID; // Pass identification, replacement for typeid
559 DominatorTree &getDominatorTree() const { return *DT; }
562 void initializeCallbacks(Module &M);
564 bool LooksLikeCodeInBug11395(Instruction *I);
565 bool GlobalIsLinkerInitialized(GlobalVariable *G);
566 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
567 uint64_t TypeSize) const;
569 /// Helper to cleanup per-function state.
570 struct FunctionStateRAII {
571 AddressSanitizer *Pass;
572 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
573 assert(Pass->ProcessedAllocas.empty() &&
574 "last pass forgot to clear cache");
575 assert(!Pass->LocalDynamicShadow);
577 ~FunctionStateRAII() {
578 Pass->LocalDynamicShadow = nullptr;
579 Pass->ProcessedAllocas.clear();
590 ShadowMapping Mapping;
592 Function *AsanHandleNoReturnFunc;
593 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
594 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
595 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
596 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
597 // This array is indexed by AccessIsWrite and Experiment.
598 Function *AsanErrorCallbackSized[2][2];
599 Function *AsanMemoryAccessCallbackSized[2][2];
600 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
602 Value *LocalDynamicShadow;
603 GlobalsMetadata GlobalsMD;
604 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
606 friend struct FunctionStackPoisoner;
609 class AddressSanitizerModule : public ModulePass {
611 explicit AddressSanitizerModule(bool CompileKernel = false,
612 bool Recover = false,
613 bool UseGlobalsGC = true)
614 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
615 Recover(Recover || ClRecover),
616 UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC) {}
617 bool runOnModule(Module &M) override;
618 static char ID; // Pass identification, replacement for typeid
619 StringRef getPassName() const override { return "AddressSanitizerModule"; }
622 void initializeCallbacks(Module &M);
624 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat);
625 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
626 ArrayRef<GlobalVariable *> ExtendedGlobals,
627 ArrayRef<Constant *> MetadataInitializers);
628 void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
629 ArrayRef<GlobalVariable *> ExtendedGlobals,
630 ArrayRef<Constant *> MetadataInitializers,
631 const std::string &UniqueModuleId);
632 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
633 ArrayRef<GlobalVariable *> ExtendedGlobals,
634 ArrayRef<Constant *> MetadataInitializers);
636 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
637 ArrayRef<GlobalVariable *> ExtendedGlobals,
638 ArrayRef<Constant *> MetadataInitializers);
640 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
641 StringRef OriginalName);
642 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
643 StringRef InternalSuffix);
644 IRBuilder<> CreateAsanModuleDtor(Module &M);
646 bool ShouldInstrumentGlobal(GlobalVariable *G);
647 bool ShouldUseMachOGlobalsSection() const;
648 StringRef getGlobalMetadataSection() const;
649 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
650 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
651 size_t MinRedzoneSizeForGlobal() const {
652 return RedzoneSizeForScale(Mapping.Scale);
655 GlobalsMetadata GlobalsMD;
662 ShadowMapping Mapping;
663 Function *AsanPoisonGlobals;
664 Function *AsanUnpoisonGlobals;
665 Function *AsanRegisterGlobals;
666 Function *AsanUnregisterGlobals;
667 Function *AsanRegisterImageGlobals;
668 Function *AsanUnregisterImageGlobals;
669 Function *AsanRegisterElfGlobals;
670 Function *AsanUnregisterElfGlobals;
672 Function *AsanCtorFunction = nullptr;
673 Function *AsanDtorFunction = nullptr;
676 // Stack poisoning does not play well with exception handling.
677 // When an exception is thrown, we essentially bypass the code
678 // that unpoisones the stack. This is why the run-time library has
679 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
680 // stack in the interceptor. This however does not work inside the
681 // actual function which catches the exception. Most likely because the
682 // compiler hoists the load of the shadow value somewhere too high.
683 // This causes asan to report a non-existing bug on 453.povray.
684 // It sounds like an LLVM bug.
685 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
687 AddressSanitizer &ASan;
692 ShadowMapping Mapping;
694 SmallVector<AllocaInst *, 16> AllocaVec;
695 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
696 SmallVector<Instruction *, 8> RetVec;
697 unsigned StackAlignment;
699 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
700 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
701 Function *AsanSetShadowFunc[0x100] = {};
702 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
703 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
705 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
706 struct AllocaPoisonCall {
707 IntrinsicInst *InsBefore;
712 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
713 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
715 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
716 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
717 AllocaInst *DynamicAllocaLayout = nullptr;
718 IntrinsicInst *LocalEscapeCall = nullptr;
720 // Maps Value to an AllocaInst from which the Value is originated.
721 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
722 AllocaForValueMapTy AllocaForValue;
724 bool HasNonEmptyInlineAsm = false;
725 bool HasReturnsTwiceCall = false;
726 std::unique_ptr<CallInst> EmptyInlineAsm;
728 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
731 DIB(*F.getParent(), /*AllowUnresolved*/ false),
733 IntptrTy(ASan.IntptrTy),
734 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
735 Mapping(ASan.Mapping),
736 StackAlignment(1 << Mapping.Scale),
737 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
739 bool runOnFunction() {
740 if (!ClStack) return false;
741 // Collect alloca, ret, lifetime instructions etc.
742 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
744 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
746 initializeCallbacks(*F.getParent());
748 processDynamicAllocas();
749 processStaticAllocas();
757 // Finds all Alloca instructions and puts
758 // poisoned red zones around all of them.
759 // Then unpoison everything back before the function returns.
760 void processStaticAllocas();
761 void processDynamicAllocas();
763 void createDynamicAllocasInitStorage();
765 // ----------------------- Visitors.
766 /// \brief Collect all Ret instructions.
767 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
769 /// \brief Collect all Resume instructions.
770 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
772 /// \brief Collect all CatchReturnInst instructions.
773 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
775 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
777 IRBuilder<> IRB(InstBefore);
778 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
779 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
780 // need to adjust extracted SP to compute the address of the most recent
781 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
783 if (!isa<ReturnInst>(InstBefore)) {
784 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
785 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
788 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
790 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
794 IRB.CreateCall(AsanAllocasUnpoisonFunc,
795 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
798 // Unpoison dynamic allocas redzones.
799 void unpoisonDynamicAllocas() {
800 for (auto &Ret : RetVec)
801 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
803 for (auto &StackRestoreInst : StackRestoreVec)
804 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
805 StackRestoreInst->getOperand(0));
808 // Deploy and poison redzones around dynamic alloca call. To do this, we
809 // should replace this call with another one with changed parameters and
810 // replace all its uses with new address, so
811 // addr = alloca type, old_size, align
813 // new_size = (old_size + additional_size) * sizeof(type)
814 // tmp = alloca i8, new_size, max(align, 32)
815 // addr = tmp + 32 (first 32 bytes are for the left redzone).
816 // Additional_size is added to make new memory allocation contain not only
817 // requested memory, but also left, partial and right redzones.
818 void handleDynamicAllocaCall(AllocaInst *AI);
820 /// \brief Collect Alloca instructions we want (and can) handle.
821 void visitAllocaInst(AllocaInst &AI) {
822 if (!ASan.isInterestingAlloca(AI)) {
823 if (AI.isStaticAlloca()) {
824 // Skip over allocas that are present *before* the first instrumented
825 // alloca, we don't want to move those around.
826 if (AllocaVec.empty())
829 StaticAllocasToMoveUp.push_back(&AI);
834 StackAlignment = std::max(StackAlignment, AI.getAlignment());
835 if (!AI.isStaticAlloca())
836 DynamicAllocaVec.push_back(&AI);
838 AllocaVec.push_back(&AI);
841 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
843 void visitIntrinsicInst(IntrinsicInst &II) {
844 Intrinsic::ID ID = II.getIntrinsicID();
845 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
846 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
847 if (!ASan.UseAfterScope)
849 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
851 // Found lifetime intrinsic, add ASan instrumentation if necessary.
852 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
853 // If size argument is undefined, don't do anything.
854 if (Size->isMinusOne()) return;
855 // Check that size doesn't saturate uint64_t and can
856 // be stored in IntptrTy.
857 const uint64_t SizeValue = Size->getValue().getLimitedValue();
858 if (SizeValue == ~0ULL ||
859 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
861 // Find alloca instruction that corresponds to llvm.lifetime argument.
862 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
863 if (!AI || !ASan.isInterestingAlloca(*AI))
865 bool DoPoison = (ID == Intrinsic::lifetime_end);
866 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
867 if (AI->isStaticAlloca())
868 StaticAllocaPoisonCallVec.push_back(APC);
869 else if (ClInstrumentDynamicAllocas)
870 DynamicAllocaPoisonCallVec.push_back(APC);
873 void visitCallSite(CallSite CS) {
874 Instruction *I = CS.getInstruction();
875 if (CallInst *CI = dyn_cast<CallInst>(I)) {
876 HasNonEmptyInlineAsm |=
877 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
878 HasReturnsTwiceCall |= CI->canReturnTwice();
882 // ---------------------- Helpers.
883 void initializeCallbacks(Module &M);
885 bool doesDominateAllExits(const Instruction *I) const {
886 for (auto Ret : RetVec) {
887 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
892 /// Finds alloca where the value comes from.
893 AllocaInst *findAllocaForValue(Value *V);
895 // Copies bytes from ShadowBytes into shadow memory for indexes where
896 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
897 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
898 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
899 IRBuilder<> &IRB, Value *ShadowBase);
900 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
901 size_t Begin, size_t End, IRBuilder<> &IRB,
903 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
904 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
905 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
907 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
909 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
911 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
912 Instruction *ThenTerm, Value *ValueIfFalse);
915 } // anonymous namespace
917 char AddressSanitizer::ID = 0;
918 INITIALIZE_PASS_BEGIN(
919 AddressSanitizer, "asan",
920 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
922 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
923 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
925 AddressSanitizer, "asan",
926 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
928 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
930 bool UseAfterScope) {
931 assert(!CompileKernel || Recover);
932 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
935 char AddressSanitizerModule::ID = 0;
937 AddressSanitizerModule, "asan-module",
938 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
941 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
944 assert(!CompileKernel || Recover);
945 return new AddressSanitizerModule(CompileKernel, Recover, UseGlobalsGC);
948 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
949 size_t Res = countTrailingZeros(TypeSize / 8);
950 assert(Res < kNumberOfAccessSizes);
954 // \brief Create a constant for Str so that we can pass it to the run-time lib.
955 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
957 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
958 // We use private linkage for module-local strings. If they can be merged
959 // with another one, we set the unnamed_addr attribute.
961 new GlobalVariable(M, StrConst->getType(), true,
962 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
963 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
964 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
968 /// \brief Create a global describing a source location.
969 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
970 LocationMetadata MD) {
971 Constant *LocData[] = {
972 createPrivateGlobalForString(M, MD.Filename, true),
973 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
974 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
976 auto LocStruct = ConstantStruct::getAnon(LocData);
977 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
978 GlobalValue::PrivateLinkage, LocStruct,
980 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
984 /// \brief Check if \p G has been created by a trusted compiler pass.
985 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
986 // Do not instrument asan globals.
987 if (G->getName().startswith(kAsanGenPrefix) ||
988 G->getName().startswith(kSanCovGenPrefix) ||
989 G->getName().startswith(kODRGenPrefix))
992 // Do not instrument gcov counter arrays.
993 if (G->getName() == "__llvm_gcov_ctr")
999 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
1001 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
1002 if (Mapping.Offset == 0) return Shadow;
1003 // (Shadow >> scale) | offset
1005 if (LocalDynamicShadow)
1006 ShadowBase = LocalDynamicShadow;
1008 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
1009 if (Mapping.OrShadowOffset)
1010 return IRB.CreateOr(Shadow, ShadowBase);
1012 return IRB.CreateAdd(Shadow, ShadowBase);
1015 // Instrument memset/memmove/memcpy
1016 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
1017 IRBuilder<> IRB(MI);
1018 if (isa<MemTransferInst>(MI)) {
1020 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
1021 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1022 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
1023 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1024 } else if (isa<MemSetInst>(MI)) {
1027 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1028 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
1029 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1031 MI->eraseFromParent();
1034 /// Check if we want (and can) handle this alloca.
1035 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1036 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1038 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1039 return PreviouslySeenAllocaInfo->getSecond();
1041 bool IsInteresting =
1042 (AI.getAllocatedType()->isSized() &&
1043 // alloca() may be called with 0 size, ignore it.
1044 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1045 // We are only interested in allocas not promotable to registers.
1046 // Promotable allocas are common under -O0.
1047 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1048 // inalloca allocas are not treated as static, and we don't want
1049 // dynamic alloca instrumentation for them as well.
1050 !AI.isUsedWithInAlloca() &&
1051 // swifterror allocas are register promoted by ISel
1052 !AI.isSwiftError());
1054 ProcessedAllocas[&AI] = IsInteresting;
1055 return IsInteresting;
1058 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1061 unsigned *Alignment,
1062 Value **MaybeMask) {
1063 // Skip memory accesses inserted by another instrumentation.
1064 if (I->getMetadata("nosanitize")) return nullptr;
1066 // Do not instrument the load fetching the dynamic shadow address.
1067 if (LocalDynamicShadow == I)
1070 Value *PtrOperand = nullptr;
1071 const DataLayout &DL = I->getModule()->getDataLayout();
1072 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1073 if (!ClInstrumentReads) return nullptr;
1075 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1076 *Alignment = LI->getAlignment();
1077 PtrOperand = LI->getPointerOperand();
1078 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1079 if (!ClInstrumentWrites) return nullptr;
1081 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1082 *Alignment = SI->getAlignment();
1083 PtrOperand = SI->getPointerOperand();
1084 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1085 if (!ClInstrumentAtomics) return nullptr;
1087 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1089 PtrOperand = RMW->getPointerOperand();
1090 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1091 if (!ClInstrumentAtomics) return nullptr;
1093 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1095 PtrOperand = XCHG->getPointerOperand();
1096 } else if (auto CI = dyn_cast<CallInst>(I)) {
1097 auto *F = dyn_cast<Function>(CI->getCalledValue());
1098 if (F && (F->getName().startswith("llvm.masked.load.") ||
1099 F->getName().startswith("llvm.masked.store."))) {
1100 unsigned OpOffset = 0;
1101 if (F->getName().startswith("llvm.masked.store.")) {
1102 if (!ClInstrumentWrites)
1104 // Masked store has an initial operand for the value.
1108 if (!ClInstrumentReads)
1113 auto BasePtr = CI->getOperand(0 + OpOffset);
1114 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1115 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1116 if (auto AlignmentConstant =
1117 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1118 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1120 *Alignment = 1; // No alignment guarantees. We probably got Undef
1122 *MaybeMask = CI->getOperand(2 + OpOffset);
1123 PtrOperand = BasePtr;
1128 // Do not instrument acesses from different address spaces; we cannot deal
1130 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1131 if (PtrTy->getPointerAddressSpace() != 0)
1134 // Ignore swifterror addresses.
1135 // swifterror memory addresses are mem2reg promoted by instruction
1136 // selection. As such they cannot have regular uses like an instrumentation
1137 // function and it makes no sense to track them as memory.
1138 if (PtrOperand->isSwiftError())
1142 // Treat memory accesses to promotable allocas as non-interesting since they
1143 // will not cause memory violations. This greatly speeds up the instrumented
1144 // executable at -O0.
1145 if (ClSkipPromotableAllocas)
1146 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1147 return isInterestingAlloca(*AI) ? AI : nullptr;
1152 static bool isPointerOperand(Value *V) {
1153 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1156 // This is a rough heuristic; it may cause both false positives and
1157 // false negatives. The proper implementation requires cooperation with
1159 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1160 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1161 if (!Cmp->isRelational()) return false;
1162 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1163 if (BO->getOpcode() != Instruction::Sub) return false;
1167 return isPointerOperand(I->getOperand(0)) &&
1168 isPointerOperand(I->getOperand(1));
1171 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1172 // If a global variable does not have dynamic initialization we don't
1173 // have to instrument it. However, if a global does not have initializer
1174 // at all, we assume it has dynamic initializer (in other TU).
1175 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1178 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1181 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1182 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1183 for (Value *&i : Param) {
1184 if (i->getType()->isPointerTy())
1185 i = IRB.CreatePointerCast(i, IntptrTy);
1187 IRB.CreateCall(F, Param);
1190 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1191 Instruction *InsertBefore, Value *Addr,
1192 unsigned Alignment, unsigned Granularity,
1193 uint32_t TypeSize, bool IsWrite,
1194 Value *SizeArgument, bool UseCalls,
1196 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1197 // if the data is properly aligned.
1198 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1200 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1201 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1202 nullptr, UseCalls, Exp);
1203 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1204 IsWrite, nullptr, UseCalls, Exp);
1207 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1208 const DataLayout &DL, Type *IntptrTy,
1209 Value *Mask, Instruction *I,
1210 Value *Addr, unsigned Alignment,
1211 unsigned Granularity, uint32_t TypeSize,
1212 bool IsWrite, Value *SizeArgument,
1213 bool UseCalls, uint32_t Exp) {
1214 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1215 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1216 unsigned Num = VTy->getVectorNumElements();
1217 auto Zero = ConstantInt::get(IntptrTy, 0);
1218 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1219 Value *InstrumentedAddress = nullptr;
1220 Instruction *InsertBefore = I;
1221 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1222 // dyn_cast as we might get UndefValue
1223 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1224 if (Masked->isNullValue())
1225 // Mask is constant false, so no instrumentation needed.
1227 // If we have a true or undef value, fall through to doInstrumentAddress
1228 // with InsertBefore == I
1232 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1233 TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1234 InsertBefore = ThenTerm;
1237 IRBuilder<> IRB(InsertBefore);
1238 InstrumentedAddress =
1239 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1240 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1241 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1246 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1247 Instruction *I, bool UseCalls,
1248 const DataLayout &DL) {
1249 bool IsWrite = false;
1250 unsigned Alignment = 0;
1251 uint64_t TypeSize = 0;
1252 Value *MaybeMask = nullptr;
1254 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1257 // Optimization experiments.
1258 // The experiments can be used to evaluate potential optimizations that remove
1259 // instrumentation (assess false negatives). Instead of completely removing
1260 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1261 // experiments that want to remove instrumentation of this instruction).
1262 // If Exp is non-zero, this pass will emit special calls into runtime
1263 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1264 // make runtime terminate the program in a special way (with a different
1265 // exit status). Then you run the new compiler on a buggy corpus, collect
1266 // the special terminations (ideally, you don't see them at all -- no false
1267 // negatives) and make the decision on the optimization.
1268 uint32_t Exp = ClForceExperiment;
1270 if (ClOpt && ClOptGlobals) {
1271 // If initialization order checking is disabled, a simple access to a
1272 // dynamically initialized global is always valid.
1273 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1274 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1275 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1276 NumOptimizedAccessesToGlobalVar++;
1281 if (ClOpt && ClOptStack) {
1282 // A direct inbounds access to a stack variable is always valid.
1283 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1284 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1285 NumOptimizedAccessesToStackVar++;
1291 NumInstrumentedWrites++;
1293 NumInstrumentedReads++;
1295 unsigned Granularity = 1 << Mapping.Scale;
1297 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1298 Alignment, Granularity, TypeSize, IsWrite,
1299 nullptr, UseCalls, Exp);
1301 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1302 IsWrite, nullptr, UseCalls, Exp);
1306 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1307 Value *Addr, bool IsWrite,
1308 size_t AccessSizeIndex,
1309 Value *SizeArgument,
1311 IRBuilder<> IRB(InsertBefore);
1312 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1313 CallInst *Call = nullptr;
1316 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1317 {Addr, SizeArgument});
1319 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1320 {Addr, SizeArgument, ExpVal});
1324 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1326 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1330 // We don't do Call->setDoesNotReturn() because the BB already has
1331 // UnreachableInst at the end.
1332 // This EmptyAsm is required to avoid callback merge.
1333 IRB.CreateCall(EmptyAsm, {});
1337 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1339 uint32_t TypeSize) {
1340 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1341 // Addr & (Granularity - 1)
1342 Value *LastAccessedByte =
1343 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1344 // (Addr & (Granularity - 1)) + size - 1
1345 if (TypeSize / 8 > 1)
1346 LastAccessedByte = IRB.CreateAdd(
1347 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1348 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1350 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1351 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1352 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1355 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1356 Instruction *InsertBefore, Value *Addr,
1357 uint32_t TypeSize, bool IsWrite,
1358 Value *SizeArgument, bool UseCalls,
1360 IRBuilder<> IRB(InsertBefore);
1361 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1362 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1366 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1369 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1370 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1375 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1376 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1377 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1378 Value *CmpVal = Constant::getNullValue(ShadowTy);
1379 Value *ShadowValue =
1380 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1382 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1383 size_t Granularity = 1ULL << Mapping.Scale;
1384 TerminatorInst *CrashTerm = nullptr;
1386 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1387 // We use branch weights for the slow path check, to indicate that the slow
1388 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1389 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1390 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1391 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1392 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1393 IRB.SetInsertPoint(CheckTerm);
1394 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1396 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1398 BasicBlock *CrashBlock =
1399 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1400 CrashTerm = new UnreachableInst(*C, CrashBlock);
1401 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1402 ReplaceInstWithInst(CheckTerm, NewTerm);
1405 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1408 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1409 AccessSizeIndex, SizeArgument, Exp);
1410 Crash->setDebugLoc(OrigIns->getDebugLoc());
1413 // Instrument unusual size or unusual alignment.
1414 // We can not do it with a single check, so we do 1-byte check for the first
1415 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1416 // to report the actual access size.
1417 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1418 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1419 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1420 IRBuilder<> IRB(InsertBefore);
1421 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1422 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1425 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1428 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1429 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1431 Value *LastByte = IRB.CreateIntToPtr(
1432 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1434 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1435 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1439 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1440 GlobalValue *ModuleName) {
1441 // Set up the arguments to our poison/unpoison functions.
1442 IRBuilder<> IRB(&GlobalInit.front(),
1443 GlobalInit.front().getFirstInsertionPt());
1445 // Add a call to poison all external globals before the given function starts.
1446 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1447 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1449 // Add calls to unpoison all globals before each return instruction.
1450 for (auto &BB : GlobalInit.getBasicBlockList())
1451 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1452 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1455 void AddressSanitizerModule::createInitializerPoisonCalls(
1456 Module &M, GlobalValue *ModuleName) {
1457 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1461 ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
1465 for (Use &OP : CA->operands()) {
1466 if (isa<ConstantAggregateZero>(OP)) continue;
1467 ConstantStruct *CS = cast<ConstantStruct>(OP);
1469 // Must have a function or null ptr.
1470 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1471 if (F->getName() == kAsanModuleCtorName) continue;
1472 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1473 // Don't instrument CTORs that will run before asan.module_ctor.
1474 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1475 poisonOneInitializer(*F, ModuleName);
1480 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1481 Type *Ty = G->getValueType();
1482 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1484 if (GlobalsMD.get(G).IsBlacklisted) return false;
1485 if (!Ty->isSized()) return false;
1486 if (!G->hasInitializer()) return false;
1487 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1488 // Touch only those globals that will not be defined in other modules.
1489 // Don't handle ODR linkage types and COMDATs since other modules may be built
1491 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1492 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1493 G->getLinkage() != GlobalVariable::InternalLinkage)
1495 if (G->hasComdat()) return false;
1496 // Two problems with thread-locals:
1497 // - The address of the main thread's copy can't be computed at link-time.
1498 // - Need to poison all copies, not just the main thread's one.
1499 if (G->isThreadLocal()) return false;
1500 // For now, just ignore this Global if the alignment is large.
1501 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1503 if (G->hasSection()) {
1504 StringRef Section = G->getSection();
1506 // Globals from llvm.metadata aren't emitted, do not instrument them.
1507 if (Section == "llvm.metadata") return false;
1508 // Do not instrument globals from special LLVM sections.
1509 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1511 // Do not instrument function pointers to initialization and termination
1512 // routines: dynamic linker will not properly handle redzones.
1513 if (Section.startswith(".preinit_array") ||
1514 Section.startswith(".init_array") ||
1515 Section.startswith(".fini_array")) {
1519 // Callbacks put into the CRT initializer/terminator sections
1520 // should not be instrumented.
1521 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1522 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1523 if (Section.startswith(".CRT")) {
1524 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1528 if (TargetTriple.isOSBinFormatMachO()) {
1529 StringRef ParsedSegment, ParsedSection;
1530 unsigned TAA = 0, StubSize = 0;
1532 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1533 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1534 assert(ErrorCode.empty() && "Invalid section specifier.");
1536 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1537 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1539 if (ParsedSegment == "__OBJC" ||
1540 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1541 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1544 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1545 // Constant CFString instances are compiled in the following way:
1546 // -- the string buffer is emitted into
1547 // __TEXT,__cstring,cstring_literals
1548 // -- the constant NSConstantString structure referencing that buffer
1549 // is placed into __DATA,__cfstring
1550 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1551 // Moreover, it causes the linker to crash on OS X 10.7
1552 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1553 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1556 // The linker merges the contents of cstring_literals and removes the
1558 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1559 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1568 // On Mach-O platforms, we emit global metadata in a separate section of the
1569 // binary in order to allow the linker to properly dead strip. This is only
1570 // supported on recent versions of ld64.
1571 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1572 if (!TargetTriple.isOSBinFormatMachO())
1575 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1577 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1579 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1585 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1586 switch (TargetTriple.getObjectFormat()) {
1587 case Triple::COFF: return ".ASAN$GL";
1588 case Triple::ELF: return "asan_globals";
1589 case Triple::MachO: return "__DATA,__asan_globals,regular";
1592 llvm_unreachable("unsupported object format");
1595 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1596 IRBuilder<> IRB(*C);
1598 // Declare our poisoning and unpoisoning functions.
1599 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1600 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy));
1601 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1602 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1603 kAsanUnpoisonGlobalsName, IRB.getVoidTy()));
1604 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1606 // Declare functions that register/unregister globals.
1607 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1608 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy));
1609 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1610 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1611 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1612 IntptrTy, IntptrTy));
1613 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1615 // Declare the functions that find globals in a shared object and then invoke
1616 // the (un)register function on them.
1617 AsanRegisterImageGlobals =
1618 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1619 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
1620 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1622 AsanUnregisterImageGlobals =
1623 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1624 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
1625 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1627 AsanRegisterElfGlobals = checkSanitizerInterfaceFunction(
1628 M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
1629 IntptrTy, IntptrTy, IntptrTy));
1630 AsanRegisterElfGlobals->setLinkage(Function::ExternalLinkage);
1632 AsanUnregisterElfGlobals = checkSanitizerInterfaceFunction(
1633 M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
1634 IntptrTy, IntptrTy, IntptrTy));
1635 AsanUnregisterElfGlobals->setLinkage(Function::ExternalLinkage);
1638 // Put the metadata and the instrumented global in the same group. This ensures
1639 // that the metadata is discarded if the instrumented global is discarded.
1640 void AddressSanitizerModule::SetComdatForGlobalMetadata(
1641 GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
1642 Module &M = *G->getParent();
1643 Comdat *C = G->getComdat();
1645 if (!G->hasName()) {
1646 // If G is unnamed, it must be internal. Give it an artificial name
1647 // so we can put it in a comdat.
1648 assert(G->hasLocalLinkage());
1649 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1652 if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
1653 std::string Name = G->getName();
1654 Name += InternalSuffix;
1655 C = M.getOrInsertComdat(Name);
1657 C = M.getOrInsertComdat(G->getName());
1660 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1661 if (TargetTriple.isOSBinFormatCOFF())
1662 C->setSelectionKind(Comdat::NoDuplicates);
1666 assert(G->hasComdat());
1667 Metadata->setComdat(G->getComdat());
1670 // Create a separate metadata global and put it in the appropriate ASan
1671 // global registration section.
1673 AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
1674 StringRef OriginalName) {
1675 auto Linkage = TargetTriple.isOSBinFormatMachO()
1676 ? GlobalVariable::InternalLinkage
1677 : GlobalVariable::PrivateLinkage;
1678 GlobalVariable *Metadata = new GlobalVariable(
1679 M, Initializer->getType(), false, Linkage, Initializer,
1680 Twine("__asan_global_") + GlobalValue::getRealLinkageName(OriginalName));
1681 Metadata->setSection(getGlobalMetadataSection());
1685 IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) {
1687 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1688 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1689 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1691 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
1694 void AddressSanitizerModule::InstrumentGlobalsCOFF(
1695 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1696 ArrayRef<Constant *> MetadataInitializers) {
1697 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1698 auto &DL = M.getDataLayout();
1700 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1701 Constant *Initializer = MetadataInitializers[i];
1702 GlobalVariable *G = ExtendedGlobals[i];
1703 GlobalVariable *Metadata =
1704 CreateMetadataGlobal(M, Initializer, G->getName());
1706 // The MSVC linker always inserts padding when linking incrementally. We
1707 // cope with that by aligning each struct to its size, which must be a power
1709 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
1710 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
1711 "global metadata will not be padded appropriately");
1712 Metadata->setAlignment(SizeOfGlobalStruct);
1714 SetComdatForGlobalMetadata(G, Metadata, "");
1718 void AddressSanitizerModule::InstrumentGlobalsELF(
1719 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1720 ArrayRef<Constant *> MetadataInitializers,
1721 const std::string &UniqueModuleId) {
1722 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1724 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
1725 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1726 GlobalVariable *G = ExtendedGlobals[i];
1727 GlobalVariable *Metadata =
1728 CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
1729 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
1730 Metadata->setMetadata(LLVMContext::MD_associated, MD);
1731 MetadataGlobals[i] = Metadata;
1733 SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
1736 // Update llvm.compiler.used, adding the new metadata globals. This is
1737 // needed so that during LTO these variables stay alive.
1738 if (!MetadataGlobals.empty())
1739 appendToCompilerUsed(M, MetadataGlobals);
1741 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1742 // to look up the loaded image that contains it. Second, we can store in it
1743 // whether registration has already occurred, to prevent duplicate
1746 // Common linkage ensures that there is only one global per shared library.
1747 GlobalVariable *RegisteredFlag = new GlobalVariable(
1748 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1749 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1750 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1752 // Create start and stop symbols.
1753 GlobalVariable *StartELFMetadata = new GlobalVariable(
1754 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
1755 "__start_" + getGlobalMetadataSection());
1756 StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
1757 GlobalVariable *StopELFMetadata = new GlobalVariable(
1758 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
1759 "__stop_" + getGlobalMetadataSection());
1760 StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
1762 // Create a call to register the globals with the runtime.
1763 IRB.CreateCall(AsanRegisterElfGlobals,
1764 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
1765 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
1766 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
1768 // We also need to unregister globals at the end, e.g., when a shared library
1770 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1771 IRB_Dtor.CreateCall(AsanUnregisterElfGlobals,
1772 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
1773 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
1774 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
1777 void AddressSanitizerModule::InstrumentGlobalsMachO(
1778 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1779 ArrayRef<Constant *> MetadataInitializers) {
1780 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1782 // On recent Mach-O platforms, use a structure which binds the liveness of
1783 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1784 // created to be added to llvm.compiler.used
1785 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
1786 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
1788 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1789 Constant *Initializer = MetadataInitializers[i];
1790 GlobalVariable *G = ExtendedGlobals[i];
1791 GlobalVariable *Metadata =
1792 CreateMetadataGlobal(M, Initializer, G->getName());
1794 // On recent Mach-O platforms, we emit the global metadata in a way that
1795 // allows the linker to properly strip dead globals.
1796 auto LivenessBinder = ConstantStruct::get(
1797 LivenessTy, Initializer->getAggregateElement(0u),
1798 ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr);
1799 GlobalVariable *Liveness = new GlobalVariable(
1800 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1801 Twine("__asan_binder_") + G->getName());
1802 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1803 LivenessGlobals[i] = Liveness;
1806 // Update llvm.compiler.used, adding the new liveness globals. This is
1807 // needed so that during LTO these variables stay alive. The alternative
1808 // would be to have the linker handling the LTO symbols, but libLTO
1809 // current API does not expose access to the section for each symbol.
1810 if (!LivenessGlobals.empty())
1811 appendToCompilerUsed(M, LivenessGlobals);
1813 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1814 // to look up the loaded image that contains it. Second, we can store in it
1815 // whether registration has already occurred, to prevent duplicate
1818 // common linkage ensures that there is only one global per shared library.
1819 GlobalVariable *RegisteredFlag = new GlobalVariable(
1820 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1821 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1822 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1824 IRB.CreateCall(AsanRegisterImageGlobals,
1825 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1827 // We also need to unregister globals at the end, e.g., when a shared library
1829 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1830 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1831 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1834 void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
1835 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1836 ArrayRef<Constant *> MetadataInitializers) {
1837 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1838 unsigned N = ExtendedGlobals.size();
1841 // On platforms that don't have a custom metadata section, we emit an array
1842 // of global metadata structures.
1843 ArrayType *ArrayOfGlobalStructTy =
1844 ArrayType::get(MetadataInitializers[0]->getType(), N);
1845 auto AllGlobals = new GlobalVariable(
1846 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1847 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
1849 IRB.CreateCall(AsanRegisterGlobals,
1850 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1851 ConstantInt::get(IntptrTy, N)});
1853 // We also need to unregister globals at the end, e.g., when a shared library
1855 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1856 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1857 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1858 ConstantInt::get(IntptrTy, N)});
1861 // This function replaces all global variables with new variables that have
1862 // trailing redzones. It also creates a function that poisons
1863 // redzones and inserts this function into llvm.global_ctors.
1864 // Sets *CtorComdat to true if the global registration code emitted into the
1865 // asan constructor is comdat-compatible.
1866 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat) {
1867 *CtorComdat = false;
1870 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1872 for (auto &G : M.globals()) {
1873 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1876 size_t n = GlobalsToChange.size();
1882 auto &DL = M.getDataLayout();
1884 // A global is described by a structure
1887 // size_t size_with_redzone;
1888 // const char *name;
1889 // const char *module_name;
1890 // size_t has_dynamic_init;
1891 // void *source_location;
1892 // size_t odr_indicator;
1893 // We initialize an array of such structures and pass it to a run-time call.
1894 StructType *GlobalStructTy =
1895 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1896 IntptrTy, IntptrTy, IntptrTy, nullptr);
1897 SmallVector<GlobalVariable *, 16> NewGlobals(n);
1898 SmallVector<Constant *, 16> Initializers(n);
1900 bool HasDynamicallyInitializedGlobals = false;
1902 // We shouldn't merge same module names, as this string serves as unique
1903 // module ID in runtime.
1904 GlobalVariable *ModuleName = createPrivateGlobalForString(
1905 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1907 for (size_t i = 0; i < n; i++) {
1908 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1909 GlobalVariable *G = GlobalsToChange[i];
1911 auto MD = GlobalsMD.get(G);
1912 StringRef NameForGlobal = G->getName();
1913 // Create string holding the global name (use global name from metadata
1914 // if it's available, otherwise just write the name of global variable).
1915 GlobalVariable *Name = createPrivateGlobalForString(
1916 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1917 /*AllowMerging*/ true);
1919 Type *Ty = G->getValueType();
1920 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1921 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1922 // MinRZ <= RZ <= kMaxGlobalRedzone
1923 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1924 uint64_t RZ = std::max(
1925 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1926 uint64_t RightRedzoneSize = RZ;
1927 // Round up to MinRZ
1928 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1929 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1930 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1932 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1933 Constant *NewInitializer =
1934 ConstantStruct::get(NewTy, G->getInitializer(),
1935 Constant::getNullValue(RightRedZoneTy), nullptr);
1937 // Create a new global variable with enough space for a redzone.
1938 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1939 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1940 Linkage = GlobalValue::InternalLinkage;
1941 GlobalVariable *NewGlobal =
1942 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1943 "", G, G->getThreadLocalMode());
1944 NewGlobal->copyAttributesFrom(G);
1945 NewGlobal->setAlignment(MinRZ);
1947 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1948 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1950 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1951 if (Seq && Seq->isCString())
1952 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1955 // Transfer the debug info. The payload starts at offset zero so we can
1956 // copy the debug info over as is.
1957 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1958 G->getDebugInfo(GVs);
1959 for (auto *GV : GVs)
1960 NewGlobal->addDebugInfo(GV);
1963 Indices2[0] = IRB.getInt32(0);
1964 Indices2[1] = IRB.getInt32(0);
1966 G->replaceAllUsesWith(
1967 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1968 NewGlobal->takeName(G);
1969 G->eraseFromParent();
1970 NewGlobals[i] = NewGlobal;
1972 Constant *SourceLoc;
1973 if (!MD.SourceLoc.empty()) {
1974 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1975 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1977 SourceLoc = ConstantInt::get(IntptrTy, 0);
1980 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
1981 GlobalValue *InstrumentedGlobal = NewGlobal;
1983 bool CanUsePrivateAliases =
1984 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
1985 TargetTriple.isOSBinFormatWasm();
1986 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
1987 // Create local alias for NewGlobal to avoid crash on ODR between
1988 // instrumented and non-instrumented libraries.
1989 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
1990 NameForGlobal + M.getName(), NewGlobal);
1992 // With local aliases, we need to provide another externally visible
1993 // symbol __odr_asan_XXX to detect ODR violation.
1994 auto *ODRIndicatorSym =
1995 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
1996 Constant::getNullValue(IRB.getInt8Ty()),
1997 kODRGenPrefix + NameForGlobal, nullptr,
1998 NewGlobal->getThreadLocalMode());
2000 // Set meaningful attributes for indicator symbol.
2001 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
2002 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
2003 ODRIndicatorSym->setAlignment(1);
2004 ODRIndicator = ODRIndicatorSym;
2005 InstrumentedGlobal = GA;
2008 Constant *Initializer = ConstantStruct::get(
2010 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
2011 ConstantInt::get(IntptrTy, SizeInBytes),
2012 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
2013 ConstantExpr::getPointerCast(Name, IntptrTy),
2014 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
2015 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
2016 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
2018 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
2020 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
2022 Initializers[i] = Initializer;
2025 std::string ELFUniqueModuleId =
2026 (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
2029 if (!ELFUniqueModuleId.empty()) {
2030 InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
2032 } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
2033 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
2034 } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
2035 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
2037 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
2040 // Create calls for poisoning before initializers run and unpoisoning after.
2041 if (HasDynamicallyInitializedGlobals)
2042 createInitializerPoisonCalls(M, ModuleName);
2048 bool AddressSanitizerModule::runOnModule(Module &M) {
2049 C = &(M.getContext());
2050 int LongSize = M.getDataLayout().getPointerSizeInBits();
2051 IntptrTy = Type::getIntNTy(*C, LongSize);
2052 TargetTriple = Triple(M.getTargetTriple());
2053 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2054 initializeCallbacks(M);
2059 // Create a module constructor. A destructor is created lazily because not all
2060 // platforms, and not all modules need it.
2061 std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
2062 M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
2063 /*InitArgs=*/{}, kAsanVersionCheckName);
2065 bool CtorComdat = true;
2066 bool Changed = false;
2067 // TODO(glider): temporarily disabled globals instrumentation for KASan.
2069 IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
2070 Changed |= InstrumentGlobals(IRB, M, &CtorComdat);
2073 // Put the constructor and destructor in comdat if both
2074 // (1) global instrumentation is not TU-specific
2075 // (2) target is ELF.
2076 if (ClWithComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
2077 AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
2078 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority,
2080 if (AsanDtorFunction) {
2081 AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
2082 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority,
2086 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
2087 if (AsanDtorFunction)
2088 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
2094 void AddressSanitizer::initializeCallbacks(Module &M) {
2095 IRBuilder<> IRB(*C);
2096 // Create __asan_report* callbacks.
2097 // IsWrite, TypeSize and Exp are encoded in the function name.
2098 for (int Exp = 0; Exp < 2; Exp++) {
2099 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
2100 const std::string TypeStr = AccessIsWrite ? "store" : "load";
2101 const std::string ExpStr = Exp ? "exp_" : "";
2102 const std::string SuffixStr = CompileKernel ? "N" : "_n";
2103 const std::string EndingStr = Recover ? "_noabort" : "";
2105 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
2106 SmallVector<Type *, 2> Args1{1, IntptrTy};
2108 Type *ExpType = Type::getInt32Ty(*C);
2109 Args2.push_back(ExpType);
2110 Args1.push_back(ExpType);
2112 AsanErrorCallbackSized[AccessIsWrite][Exp] =
2113 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2114 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr +
2116 FunctionType::get(IRB.getVoidTy(), Args2, false)));
2118 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
2119 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2120 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
2121 FunctionType::get(IRB.getVoidTy(), Args2, false)));
2123 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
2124 AccessSizeIndex++) {
2125 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
2126 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2127 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2128 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
2129 FunctionType::get(IRB.getVoidTy(), Args1, false)));
2131 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2132 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2133 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
2134 FunctionType::get(IRB.getVoidTy(), Args1, false)));
2139 const std::string MemIntrinCallbackPrefix =
2140 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
2141 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2142 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
2143 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy));
2144 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2145 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
2146 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy));
2147 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2148 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
2149 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy));
2151 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
2152 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy()));
2154 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2155 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy));
2156 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2157 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy));
2158 // We insert an empty inline asm after __asan_report* to avoid callback merge.
2159 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
2160 StringRef(""), StringRef(""),
2161 /*hasSideEffects=*/true);
2165 bool AddressSanitizer::doInitialization(Module &M) {
2166 // Initialize the private fields. No one has accessed them before.
2169 C = &(M.getContext());
2170 LongSize = M.getDataLayout().getPointerSizeInBits();
2171 IntptrTy = Type::getIntNTy(*C, LongSize);
2172 TargetTriple = Triple(M.getTargetTriple());
2174 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2178 bool AddressSanitizer::doFinalization(Module &M) {
2183 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2184 // For each NSObject descendant having a +load method, this method is invoked
2185 // by the ObjC runtime before any of the static constructors is called.
2186 // Therefore we need to instrument such methods with a call to __asan_init
2187 // at the beginning in order to initialize our runtime before any access to
2188 // the shadow memory.
2189 // We cannot just ignore these methods, because they may call other
2190 // instrumented functions.
2191 if (F.getName().find(" load]") != std::string::npos) {
2192 Function *AsanInitFunction =
2193 declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
2194 IRBuilder<> IRB(&F.front(), F.front().begin());
2195 IRB.CreateCall(AsanInitFunction, {});
2201 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2202 // Generate code only when dynamic addressing is needed.
2203 if (Mapping.Offset != kDynamicShadowSentinel)
2206 IRBuilder<> IRB(&F.front().front());
2207 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2208 kAsanShadowMemoryDynamicAddress, IntptrTy);
2209 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
2212 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2213 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2214 // to it as uninteresting. This assumes we haven't started processing allocas
2215 // yet. This check is done up front because iterating the use list in
2216 // isInterestingAlloca would be algorithmically slower.
2217 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2219 // Try to get the declaration of llvm.localescape. If it's not in the module,
2220 // we can exit early.
2221 if (!F.getParent()->getFunction("llvm.localescape")) return;
2223 // Look for a call to llvm.localescape call in the entry block. It can't be in
2225 for (Instruction &I : F.getEntryBlock()) {
2226 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2227 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2228 // We found a call. Mark all the allocas passed in as uninteresting.
2229 for (Value *Arg : II->arg_operands()) {
2230 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2231 assert(AI && AI->isStaticAlloca() &&
2232 "non-static alloca arg to localescape");
2233 ProcessedAllocas[AI] = false;
2240 bool AddressSanitizer::runOnFunction(Function &F) {
2241 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2242 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2243 if (F.getName().startswith("__asan_")) return false;
2245 bool FunctionModified = false;
2247 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2248 // This function needs to be called even if the function body is not
2250 if (maybeInsertAsanInitAtFunctionEntry(F))
2251 FunctionModified = true;
2253 // Leave if the function doesn't need instrumentation.
2254 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2256 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2258 initializeCallbacks(*F.getParent());
2259 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2261 FunctionStateRAII CleanupObj(this);
2263 maybeInsertDynamicShadowAtFunctionEntry(F);
2265 // We can't instrument allocas used with llvm.localescape. Only static allocas
2266 // can be passed to that intrinsic.
2267 markEscapedLocalAllocas(F);
2269 // We want to instrument every address only once per basic block (unless there
2270 // are calls between uses).
2271 SmallSet<Value *, 16> TempsToInstrument;
2272 SmallVector<Instruction *, 16> ToInstrument;
2273 SmallVector<Instruction *, 8> NoReturnCalls;
2274 SmallVector<BasicBlock *, 16> AllBlocks;
2275 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2280 const TargetLibraryInfo *TLI =
2281 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2283 // Fill the set of memory operations to instrument.
2284 for (auto &BB : F) {
2285 AllBlocks.push_back(&BB);
2286 TempsToInstrument.clear();
2287 int NumInsnsPerBB = 0;
2288 for (auto &Inst : BB) {
2289 if (LooksLikeCodeInBug11395(&Inst)) return false;
2290 Value *MaybeMask = nullptr;
2291 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2292 &Alignment, &MaybeMask)) {
2293 if (ClOpt && ClOptSameTemp) {
2294 // If we have a mask, skip instrumentation if we've already
2295 // instrumented the full object. But don't add to TempsToInstrument
2296 // because we might get another load/store with a different mask.
2298 if (TempsToInstrument.count(Addr))
2299 continue; // We've seen this (whole) temp in the current BB.
2301 if (!TempsToInstrument.insert(Addr).second)
2302 continue; // We've seen this temp in the current BB.
2305 } else if (ClInvalidPointerPairs &&
2306 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2307 PointerComparisonsOrSubtracts.push_back(&Inst);
2309 } else if (isa<MemIntrinsic>(Inst)) {
2312 if (isa<AllocaInst>(Inst)) NumAllocas++;
2315 // A call inside BB.
2316 TempsToInstrument.clear();
2317 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2319 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2320 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2323 ToInstrument.push_back(&Inst);
2325 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2331 (ClInstrumentationWithCallsThreshold >= 0 &&
2332 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2333 const DataLayout &DL = F.getParent()->getDataLayout();
2334 ObjectSizeOpts ObjSizeOpts;
2335 ObjSizeOpts.RoundToAlign = true;
2336 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
2339 int NumInstrumented = 0;
2340 for (auto Inst : ToInstrument) {
2341 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2342 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2343 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2344 instrumentMop(ObjSizeVis, Inst, UseCalls,
2345 F.getParent()->getDataLayout());
2347 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2352 FunctionStackPoisoner FSP(F, *this);
2353 bool ChangedStack = FSP.runOnFunction();
2355 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2356 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2357 for (auto CI : NoReturnCalls) {
2358 IRBuilder<> IRB(CI);
2359 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2362 for (auto Inst : PointerComparisonsOrSubtracts) {
2363 instrumentPointerComparisonOrSubtraction(Inst);
2367 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2368 FunctionModified = true;
2370 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2373 return FunctionModified;
2376 // Workaround for bug 11395: we don't want to instrument stack in functions
2377 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2378 // FIXME: remove once the bug 11395 is fixed.
2379 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2380 if (LongSize != 32) return false;
2381 CallInst *CI = dyn_cast<CallInst>(I);
2382 if (!CI || !CI->isInlineAsm()) return false;
2383 if (CI->getNumArgOperands() <= 5) return false;
2384 // We have inline assembly with quite a few arguments.
2388 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2389 IRBuilder<> IRB(*C);
2390 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2391 std::string Suffix = itostr(i);
2392 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2393 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2395 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2396 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2397 IRB.getVoidTy(), IntptrTy, IntptrTy));
2399 if (ASan.UseAfterScope) {
2400 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2401 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2402 IntptrTy, IntptrTy));
2403 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2404 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2405 IntptrTy, IntptrTy));
2408 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2409 std::ostringstream Name;
2410 Name << kAsanSetShadowPrefix;
2411 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2412 AsanSetShadowFunc[Val] =
2413 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2414 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy));
2417 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2418 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy));
2419 AsanAllocasUnpoisonFunc =
2420 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2421 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy));
2424 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2425 ArrayRef<uint8_t> ShadowBytes,
2426 size_t Begin, size_t End,
2428 Value *ShadowBase) {
2432 const size_t LargestStoreSizeInBytes =
2433 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2435 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2437 // Poison given range in shadow using larges store size with out leading and
2438 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2439 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2440 // middle of a store.
2441 for (size_t i = Begin; i < End;) {
2442 if (!ShadowMask[i]) {
2443 assert(!ShadowBytes[i]);
2448 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2449 // Fit store size into the range.
2450 while (StoreSizeInBytes > End - i)
2451 StoreSizeInBytes /= 2;
2453 // Minimize store size by trimming trailing zeros.
2454 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2455 while (j <= StoreSizeInBytes / 2)
2456 StoreSizeInBytes /= 2;
2460 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2462 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2464 Val = (Val << 8) | ShadowBytes[i + j];
2467 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2468 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2469 IRB.CreateAlignedStore(
2470 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2472 i += StoreSizeInBytes;
2476 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2477 ArrayRef<uint8_t> ShadowBytes,
2478 IRBuilder<> &IRB, Value *ShadowBase) {
2479 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2482 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2483 ArrayRef<uint8_t> ShadowBytes,
2484 size_t Begin, size_t End,
2485 IRBuilder<> &IRB, Value *ShadowBase) {
2486 assert(ShadowMask.size() == ShadowBytes.size());
2487 size_t Done = Begin;
2488 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2489 if (!ShadowMask[i]) {
2490 assert(!ShadowBytes[i]);
2493 uint8_t Val = ShadowBytes[i];
2494 if (!AsanSetShadowFunc[Val])
2497 // Skip same values.
2498 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2501 if (j - i >= ClMaxInlinePoisoningSize) {
2502 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2503 IRB.CreateCall(AsanSetShadowFunc[Val],
2504 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2505 ConstantInt::get(IntptrTy, j - i)});
2510 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2513 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2514 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2515 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2516 assert(LocalStackSize <= kMaxStackMallocSize);
2517 uint64_t MaxSize = kMinStackMallocSize;
2518 for (int i = 0;; i++, MaxSize *= 2)
2519 if (LocalStackSize <= MaxSize) return i;
2520 llvm_unreachable("impossible LocalStackSize");
2523 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2525 Instruction *ThenTerm,
2526 Value *ValueIfFalse) {
2527 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2528 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2529 PHI->addIncoming(ValueIfFalse, CondBlock);
2530 BasicBlock *ThenBlock = ThenTerm->getParent();
2531 PHI->addIncoming(ValueIfTrue, ThenBlock);
2535 Value *FunctionStackPoisoner::createAllocaForLayout(
2536 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2539 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2540 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2543 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2544 nullptr, "MyAlloca");
2545 assert(Alloca->isStaticAlloca());
2547 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2548 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2549 Alloca->setAlignment(FrameAlignment);
2550 return IRB.CreatePointerCast(Alloca, IntptrTy);
2553 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2554 BasicBlock &FirstBB = *F.begin();
2555 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2556 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2557 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2558 DynamicAllocaLayout->setAlignment(32);
2561 void FunctionStackPoisoner::processDynamicAllocas() {
2562 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2563 assert(DynamicAllocaPoisonCallVec.empty());
2567 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2568 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2569 assert(APC.InsBefore);
2571 assert(ASan.isInterestingAlloca(*APC.AI));
2572 assert(!APC.AI->isStaticAlloca());
2574 IRBuilder<> IRB(APC.InsBefore);
2575 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2576 // Dynamic allocas will be unpoisoned unconditionally below in
2577 // unpoisonDynamicAllocas.
2578 // Flag that we need unpoison static allocas.
2581 // Handle dynamic allocas.
2582 createDynamicAllocasInitStorage();
2583 for (auto &AI : DynamicAllocaVec)
2584 handleDynamicAllocaCall(AI);
2585 unpoisonDynamicAllocas();
2588 void FunctionStackPoisoner::processStaticAllocas() {
2589 if (AllocaVec.empty()) {
2590 assert(StaticAllocaPoisonCallVec.empty());
2594 int StackMallocIdx = -1;
2595 DebugLoc EntryDebugLocation;
2596 if (auto SP = F.getSubprogram())
2597 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2599 Instruction *InsBefore = AllocaVec[0];
2600 IRBuilder<> IRB(InsBefore);
2601 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2603 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2604 // debug info is broken, because only entry-block allocas are treated as
2605 // regular stack slots.
2606 auto InsBeforeB = InsBefore->getParent();
2607 assert(InsBeforeB == &F.getEntryBlock());
2608 for (auto *AI : StaticAllocasToMoveUp)
2609 if (AI->getParent() == InsBeforeB)
2610 AI->moveBefore(InsBefore);
2612 // If we have a call to llvm.localescape, keep it in the entry block.
2613 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2615 SmallVector<ASanStackVariableDescription, 16> SVD;
2616 SVD.reserve(AllocaVec.size());
2617 for (AllocaInst *AI : AllocaVec) {
2618 ASanStackVariableDescription D = {AI->getName().data(),
2619 ASan.getAllocaSizeInBytes(*AI),
2628 // Minimal header size (left redzone) is 4 pointers,
2629 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2630 size_t MinHeaderSize = ASan.LongSize / 2;
2631 const ASanStackFrameLayout &L =
2632 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2634 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2635 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2636 for (auto &Desc : SVD)
2637 AllocaToSVDMap[Desc.AI] = &Desc;
2639 // Update SVD with information from lifetime intrinsics.
2640 for (const auto &APC : StaticAllocaPoisonCallVec) {
2641 assert(APC.InsBefore);
2643 assert(ASan.isInterestingAlloca(*APC.AI));
2644 assert(APC.AI->isStaticAlloca());
2646 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2647 Desc.LifetimeSize = Desc.Size;
2648 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2649 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2650 if (LifetimeLoc->getFile() == FnLoc->getFile())
2651 if (unsigned Line = LifetimeLoc->getLine())
2652 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2657 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2658 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2659 uint64_t LocalStackSize = L.FrameSize;
2660 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2661 LocalStackSize <= kMaxStackMallocSize;
2662 bool DoDynamicAlloca = ClDynamicAllocaStack;
2663 // Don't do dynamic alloca or stack malloc if:
2664 // 1) There is inline asm: too often it makes assumptions on which registers
2666 // 2) There is a returns_twice call (typically setjmp), which is
2667 // optimization-hostile, and doesn't play well with introduced indirect
2668 // register-relative calculation of local variable addresses.
2669 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2670 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2672 Value *StaticAlloca =
2673 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2676 Value *LocalStackBase;
2678 if (DoStackMalloc) {
2679 // void *FakeStack = __asan_option_detect_stack_use_after_return
2680 // ? __asan_stack_malloc_N(LocalStackSize)
2682 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2683 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2684 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2685 Value *UseAfterReturnIsEnabled =
2686 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2687 Constant::getNullValue(IRB.getInt32Ty()));
2689 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2690 IRBuilder<> IRBIf(Term);
2691 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2692 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2693 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2694 Value *FakeStackValue =
2695 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2696 ConstantInt::get(IntptrTy, LocalStackSize));
2697 IRB.SetInsertPoint(InsBefore);
2698 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2699 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2700 ConstantInt::get(IntptrTy, 0));
2702 Value *NoFakeStack =
2703 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2704 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2705 IRBIf.SetInsertPoint(Term);
2706 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2707 Value *AllocaValue =
2708 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2709 IRB.SetInsertPoint(InsBefore);
2710 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2711 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2713 // void *FakeStack = nullptr;
2714 // void *LocalStackBase = alloca(LocalStackSize);
2715 FakeStack = ConstantInt::get(IntptrTy, 0);
2717 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2720 // Replace Alloca instructions with base+offset.
2721 for (const auto &Desc : SVD) {
2722 AllocaInst *AI = Desc.AI;
2723 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2724 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2726 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, DIExpression::NoDeref);
2727 AI->replaceAllUsesWith(NewAllocaPtr);
2730 // The left-most redzone has enough space for at least 4 pointers.
2731 // Write the Magic value to redzone[0].
2732 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2733 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2735 // Write the frame description constant to redzone[1].
2736 Value *BasePlus1 = IRB.CreateIntToPtr(
2737 IRB.CreateAdd(LocalStackBase,
2738 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2740 GlobalVariable *StackDescriptionGlobal =
2741 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2742 /*AllowMerging*/ true);
2743 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2744 IRB.CreateStore(Description, BasePlus1);
2745 // Write the PC to redzone[2].
2746 Value *BasePlus2 = IRB.CreateIntToPtr(
2747 IRB.CreateAdd(LocalStackBase,
2748 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2750 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2752 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2754 // Poison the stack red zones at the entry.
2755 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2756 // As mask we must use most poisoned case: red zones and after scope.
2757 // As bytes we can use either the same or just red zones only.
2758 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2760 if (!StaticAllocaPoisonCallVec.empty()) {
2761 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2763 // Poison static allocas near lifetime intrinsics.
2764 for (const auto &APC : StaticAllocaPoisonCallVec) {
2765 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2766 assert(Desc.Offset % L.Granularity == 0);
2767 size_t Begin = Desc.Offset / L.Granularity;
2768 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2770 IRBuilder<> IRB(APC.InsBefore);
2771 copyToShadow(ShadowAfterScope,
2772 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2777 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2778 SmallVector<uint8_t, 64> ShadowAfterReturn;
2780 // (Un)poison the stack before all ret instructions.
2781 for (auto Ret : RetVec) {
2782 IRBuilder<> IRBRet(Ret);
2783 // Mark the current frame as retired.
2784 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2786 if (DoStackMalloc) {
2787 assert(StackMallocIdx >= 0);
2788 // if FakeStack != 0 // LocalStackBase == FakeStack
2789 // // In use-after-return mode, poison the whole stack frame.
2790 // if StackMallocIdx <= 4
2791 // // For small sizes inline the whole thing:
2792 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2793 // **SavedFlagPtr(FakeStack) = 0
2795 // __asan_stack_free_N(FakeStack, LocalStackSize)
2797 // <This is not a fake stack; unpoison the redzones>
2799 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2800 TerminatorInst *ThenTerm, *ElseTerm;
2801 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2803 IRBuilder<> IRBPoison(ThenTerm);
2804 if (StackMallocIdx <= 4) {
2805 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2806 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2807 kAsanStackUseAfterReturnMagic);
2808 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2810 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2812 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2813 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2814 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2815 IRBPoison.CreateStore(
2816 Constant::getNullValue(IRBPoison.getInt8Ty()),
2817 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2819 // For larger frames call __asan_stack_free_*.
2820 IRBPoison.CreateCall(
2821 AsanStackFreeFunc[StackMallocIdx],
2822 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2825 IRBuilder<> IRBElse(ElseTerm);
2826 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2828 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2832 // We are done. Remove the old unused alloca instructions.
2833 for (auto AI : AllocaVec) AI->eraseFromParent();
2836 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2837 IRBuilder<> &IRB, bool DoPoison) {
2838 // For now just insert the call to ASan runtime.
2839 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2840 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2842 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2843 {AddrArg, SizeArg});
2846 // Handling llvm.lifetime intrinsics for a given %alloca:
2847 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2848 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2849 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2850 // could be poisoned by previous llvm.lifetime.end instruction, as the
2851 // variable may go in and out of scope several times, e.g. in loops).
2852 // (3) if we poisoned at least one %alloca in a function,
2853 // unpoison the whole stack frame at function exit.
2855 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2856 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2857 // We're interested only in allocas we can handle.
2858 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2859 // See if we've already calculated (or started to calculate) alloca for a
2861 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2862 if (I != AllocaForValue.end()) return I->second;
2863 // Store 0 while we're calculating alloca for value V to avoid
2864 // infinite recursion if the value references itself.
2865 AllocaForValue[V] = nullptr;
2866 AllocaInst *Res = nullptr;
2867 if (CastInst *CI = dyn_cast<CastInst>(V))
2868 Res = findAllocaForValue(CI->getOperand(0));
2869 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2870 for (Value *IncValue : PN->incoming_values()) {
2871 // Allow self-referencing phi-nodes.
2872 if (IncValue == PN) continue;
2873 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2874 // AI for incoming values should exist and should all be equal.
2875 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2879 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2880 Res = findAllocaForValue(EP->getPointerOperand());
2882 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2884 if (Res) AllocaForValue[V] = Res;
2888 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2889 IRBuilder<> IRB(AI);
2891 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2892 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2894 Value *Zero = Constant::getNullValue(IntptrTy);
2895 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2896 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2898 // Since we need to extend alloca with additional memory to locate
2899 // redzones, and OldSize is number of allocated blocks with
2900 // ElementSize size, get allocated memory size in bytes by
2901 // OldSize * ElementSize.
2902 const unsigned ElementSize =
2903 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2905 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2906 ConstantInt::get(IntptrTy, ElementSize));
2908 // PartialSize = OldSize % 32
2909 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2911 // Misalign = kAllocaRzSize - PartialSize;
2912 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2914 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2915 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2916 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2918 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2919 // Align is added to locate left redzone, PartialPadding for possible
2920 // partial redzone and kAllocaRzSize for right redzone respectively.
2921 Value *AdditionalChunkSize = IRB.CreateAdd(
2922 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2924 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2926 // Insert new alloca with new NewSize and Align params.
2927 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2928 NewAlloca->setAlignment(Align);
2930 // NewAddress = Address + Align
2931 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2932 ConstantInt::get(IntptrTy, Align));
2934 // Insert __asan_alloca_poison call for new created alloca.
2935 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2937 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2938 // for unpoisoning stuff.
2939 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2941 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2943 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2944 AI->replaceAllUsesWith(NewAddressPtr);
2946 // We are done. Erase old alloca from parent.
2947 AI->eraseFromParent();
2950 // isSafeAccess returns true if Addr is always inbounds with respect to its
2951 // base object. For example, it is a field access or an array access with
2952 // constant inbounds index.
2953 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2954 Value *Addr, uint64_t TypeSize) const {
2955 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2956 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2957 uint64_t Size = SizeOffset.first.getZExtValue();
2958 int64_t Offset = SizeOffset.second.getSExtValue();
2959 // Three checks are required to ensure safety:
2960 // . Offset >= 0 (since the offset is given from the base ptr)
2961 // . Size >= Offset (unsigned)
2962 // . Size - Offset >= NeededSize (unsigned)
2963 return Offset >= 0 && Size >= uint64_t(Offset) &&
2964 Size - uint64_t(Offset) >= TypeSize / 8;