AddressSanitizer.cpp revision 8cc5f7cd59c69250ab3b6a68e38405dcdb6a4b25
1//===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 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 13// 14//===----------------------------------------------------------------------===// 15 16#define DEBUG_TYPE "asan" 17 18#include "llvm/Transforms/Instrumentation.h" 19#include "llvm/ADT/ArrayRef.h" 20#include "llvm/ADT/DenseMap.h" 21#include "llvm/ADT/DepthFirstIterator.h" 22#include "llvm/ADT/OwningPtr.h" 23#include "llvm/ADT/SmallSet.h" 24#include "llvm/ADT/SmallString.h" 25#include "llvm/ADT/SmallVector.h" 26#include "llvm/ADT/Statistic.h" 27#include "llvm/ADT/StringExtras.h" 28#include "llvm/ADT/Triple.h" 29#include "llvm/DIBuilder.h" 30#include "llvm/IR/DataLayout.h" 31#include "llvm/IR/Function.h" 32#include "llvm/IR/IRBuilder.h" 33#include "llvm/IR/InlineAsm.h" 34#include "llvm/IR/IntrinsicInst.h" 35#include "llvm/IR/LLVMContext.h" 36#include "llvm/IR/Module.h" 37#include "llvm/IR/Type.h" 38#include "llvm/InstVisitor.h" 39#include "llvm/Support/CallSite.h" 40#include "llvm/Support/CommandLine.h" 41#include "llvm/Support/DataTypes.h" 42#include "llvm/Support/Debug.h" 43#include "llvm/Support/Endian.h" 44#include "llvm/Support/raw_ostream.h" 45#include "llvm/Support/system_error.h" 46#include "llvm/Transforms/Utils/BasicBlockUtils.h" 47#include "llvm/Transforms/Utils/Cloning.h" 48#include "llvm/Transforms/Utils/Local.h" 49#include "llvm/Transforms/Utils/ModuleUtils.h" 50#include "llvm/Transforms/Utils/SpecialCaseList.h" 51#include <algorithm> 52#include <string> 53 54using namespace llvm; 55 56static const uint64_t kDefaultShadowScale = 3; 57static const uint64_t kDefaultShadowOffset32 = 1ULL << 29; 58static const uint64_t kDefaultShadowOffset64 = 1ULL << 44; 59static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G. 60static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41; 61static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000; 62 63static const size_t kMinStackMallocSize = 1 << 6; // 64B 64static const size_t kMaxStackMallocSize = 1 << 16; // 64K 65static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3; 66static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E; 67 68static const char *const kAsanModuleCtorName = "asan.module_ctor"; 69static const char *const kAsanModuleDtorName = "asan.module_dtor"; 70static const int kAsanCtorAndCtorPriority = 1; 71static const char *const kAsanReportErrorTemplate = "__asan_report_"; 72static const char *const kAsanReportLoadN = "__asan_report_load_n"; 73static const char *const kAsanReportStoreN = "__asan_report_store_n"; 74static const char *const kAsanRegisterGlobalsName = "__asan_register_globals"; 75static const char *const kAsanUnregisterGlobalsName = 76 "__asan_unregister_globals"; 77static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init"; 78static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init"; 79static const char *const kAsanInitName = "__asan_init_v3"; 80static const char *const kAsanCovName = "__sanitizer_cov"; 81static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return"; 82static const char *const kAsanMappingOffsetName = "__asan_mapping_offset"; 83static const char *const kAsanMappingScaleName = "__asan_mapping_scale"; 84static const int kMaxAsanStackMallocSizeClass = 10; 85static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_"; 86static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_"; 87static const char *const kAsanGenPrefix = "__asan_gen_"; 88static const char *const kAsanPoisonStackMemoryName = 89 "__asan_poison_stack_memory"; 90static const char *const kAsanUnpoisonStackMemoryName = 91 "__asan_unpoison_stack_memory"; 92 93static const char *const kAsanOptionDetectUAR = 94 "__asan_option_detect_stack_use_after_return"; 95 96// These constants must match the definitions in the run-time library. 97static const int kAsanStackLeftRedzoneMagic = 0xf1; 98static const int kAsanStackMidRedzoneMagic = 0xf2; 99static const int kAsanStackRightRedzoneMagic = 0xf3; 100static const int kAsanStackPartialRedzoneMagic = 0xf4; 101#ifndef NDEBUG 102static const int kAsanStackAfterReturnMagic = 0xf5; 103#endif 104 105// Accesses sizes are powers of two: 1, 2, 4, 8, 16. 106static const size_t kNumberOfAccessSizes = 5; 107 108// Command-line flags. 109 110// This flag may need to be replaced with -f[no-]asan-reads. 111static cl::opt<bool> ClInstrumentReads("asan-instrument-reads", 112 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true)); 113static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes", 114 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true)); 115static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics", 116 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), 117 cl::Hidden, cl::init(true)); 118static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path", 119 cl::desc("use instrumentation with slow path for all accesses"), 120 cl::Hidden, cl::init(false)); 121// This flag limits the number of instructions to be instrumented 122// in any given BB. Normally, this should be set to unlimited (INT_MAX), 123// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary 124// set it to 10000. 125static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb", 126 cl::init(10000), 127 cl::desc("maximal number of instructions to instrument in any given BB"), 128 cl::Hidden); 129// This flag may need to be replaced with -f[no]asan-stack. 130static cl::opt<bool> ClStack("asan-stack", 131 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true)); 132// This flag may need to be replaced with -f[no]asan-use-after-return. 133static cl::opt<bool> ClUseAfterReturn("asan-use-after-return", 134 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false)); 135// This flag may need to be replaced with -f[no]asan-globals. 136static cl::opt<bool> ClGlobals("asan-globals", 137 cl::desc("Handle global objects"), cl::Hidden, cl::init(true)); 138static cl::opt<bool> ClCoverage("asan-coverage", 139 cl::desc("ASan coverage"), cl::Hidden, cl::init(false)); 140static cl::opt<bool> ClInitializers("asan-initialization-order", 141 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false)); 142static cl::opt<bool> ClMemIntrin("asan-memintrin", 143 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true)); 144static cl::opt<bool> ClRealignStack("asan-realign-stack", 145 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true)); 146static cl::opt<std::string> ClBlacklistFile("asan-blacklist", 147 cl::desc("File containing the list of objects to ignore " 148 "during instrumentation"), cl::Hidden); 149 150// This is an experimental feature that will allow to choose between 151// instrumented and non-instrumented code at link-time. 152// If this option is on, just before instrumenting a function we create its 153// clone; if the function is not changed by asan the clone is deleted. 154// If we end up with a clone, we put the instrumented function into a section 155// called "ASAN" and the uninstrumented function into a section called "NOASAN". 156// 157// This is still a prototype, we need to figure out a way to keep two copies of 158// a function so that the linker can easily choose one of them. 159static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions", 160 cl::desc("Keep uninstrumented copies of functions"), 161 cl::Hidden, cl::init(false)); 162 163// These flags allow to change the shadow mapping. 164// The shadow mapping looks like 165// Shadow = (Mem >> scale) + (1 << offset_log) 166static cl::opt<int> ClMappingScale("asan-mapping-scale", 167 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0)); 168static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log", 169 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1)); 170static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset", 171 cl::desc("Use short immediate constant as the mapping offset for 64bit"), 172 cl::Hidden, cl::init(true)); 173 174// Optimization flags. Not user visible, used mostly for testing 175// and benchmarking the tool. 176static cl::opt<bool> ClOpt("asan-opt", 177 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true)); 178static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp", 179 cl::desc("Instrument the same temp just once"), cl::Hidden, 180 cl::init(true)); 181static cl::opt<bool> ClOptGlobals("asan-opt-globals", 182 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true)); 183 184static cl::opt<bool> ClCheckLifetime("asan-check-lifetime", 185 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), 186 cl::Hidden, cl::init(false)); 187 188// Debug flags. 189static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden, 190 cl::init(0)); 191static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"), 192 cl::Hidden, cl::init(0)); 193static cl::opt<std::string> ClDebugFunc("asan-debug-func", 194 cl::Hidden, cl::desc("Debug func")); 195static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"), 196 cl::Hidden, cl::init(-1)); 197static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"), 198 cl::Hidden, cl::init(-1)); 199 200STATISTIC(NumInstrumentedReads, "Number of instrumented reads"); 201STATISTIC(NumInstrumentedWrites, "Number of instrumented writes"); 202STATISTIC(NumOptimizedAccessesToGlobalArray, 203 "Number of optimized accesses to global arrays"); 204STATISTIC(NumOptimizedAccessesToGlobalVar, 205 "Number of optimized accesses to global vars"); 206 207namespace { 208/// A set of dynamically initialized globals extracted from metadata. 209class SetOfDynamicallyInitializedGlobals { 210 public: 211 void Init(Module& M) { 212 // Clang generates metadata identifying all dynamically initialized globals. 213 NamedMDNode *DynamicGlobals = 214 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals"); 215 if (!DynamicGlobals) 216 return; 217 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) { 218 MDNode *MDN = DynamicGlobals->getOperand(i); 219 assert(MDN->getNumOperands() == 1); 220 Value *VG = MDN->getOperand(0); 221 // The optimizer may optimize away a global entirely, in which case we 222 // cannot instrument access to it. 223 if (!VG) 224 continue; 225 DynInitGlobals.insert(cast<GlobalVariable>(VG)); 226 } 227 } 228 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; } 229 private: 230 SmallSet<GlobalValue*, 32> DynInitGlobals; 231}; 232 233/// This struct defines the shadow mapping using the rule: 234/// shadow = (mem >> Scale) ADD-or-OR Offset. 235struct ShadowMapping { 236 int Scale; 237 uint64_t Offset; 238 bool OrShadowOffset; 239}; 240 241static ShadowMapping getShadowMapping(const Module &M, int LongSize, 242 bool ZeroBaseShadow) { 243 llvm::Triple TargetTriple(M.getTargetTriple()); 244 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android; 245 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX; 246 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 || 247 TargetTriple.getArch() == llvm::Triple::ppc64le; 248 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64; 249 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips || 250 TargetTriple.getArch() == llvm::Triple::mipsel; 251 252 ShadowMapping Mapping; 253 254 // OR-ing shadow offset if more efficient (at least on x86), 255 // but on ppc64 we have to use add since the shadow offset is not neccesary 256 // 1/8-th of the address space. 257 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset; 258 259 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 : 260 (LongSize == 32 ? 261 (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) : 262 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64); 263 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) { 264 assert(LongSize == 64); 265 Mapping.Offset = kDefaultShort64bitShadowOffset; 266 } 267 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) { 268 // Zero offset log is the special case. 269 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog; 270 } 271 272 Mapping.Scale = kDefaultShadowScale; 273 if (ClMappingScale) { 274 Mapping.Scale = ClMappingScale; 275 } 276 277 return Mapping; 278} 279 280static size_t RedzoneSizeForScale(int MappingScale) { 281 // Redzone used for stack and globals is at least 32 bytes. 282 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively. 283 return std::max(32U, 1U << MappingScale); 284} 285 286/// AddressSanitizer: instrument the code in module to find memory bugs. 287struct AddressSanitizer : public FunctionPass { 288 AddressSanitizer(bool CheckInitOrder = true, 289 bool CheckUseAfterReturn = false, 290 bool CheckLifetime = false, 291 StringRef BlacklistFile = StringRef(), 292 bool ZeroBaseShadow = false) 293 : FunctionPass(ID), 294 CheckInitOrder(CheckInitOrder || ClInitializers), 295 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn), 296 CheckLifetime(CheckLifetime || ClCheckLifetime), 297 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile 298 : BlacklistFile), 299 ZeroBaseShadow(ZeroBaseShadow) {} 300 virtual const char *getPassName() const { 301 return "AddressSanitizerFunctionPass"; 302 } 303 void instrumentMop(Instruction *I); 304 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore, 305 Value *Addr, uint32_t TypeSize, bool IsWrite, 306 Value *SizeArgument); 307 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, 308 Value *ShadowValue, uint32_t TypeSize); 309 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr, 310 bool IsWrite, size_t AccessSizeIndex, 311 Value *SizeArgument); 312 bool instrumentMemIntrinsic(MemIntrinsic *MI); 313 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr, 314 Value *Size, 315 Instruction *InsertBefore, bool IsWrite); 316 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB); 317 bool runOnFunction(Function &F); 318 bool maybeInsertAsanInitAtFunctionEntry(Function &F); 319 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const; 320 virtual bool doInitialization(Module &M); 321 static char ID; // Pass identification, replacement for typeid 322 323 private: 324 void initializeCallbacks(Module &M); 325 326 bool ShouldInstrumentGlobal(GlobalVariable *G); 327 bool LooksLikeCodeInBug11395(Instruction *I); 328 void FindDynamicInitializers(Module &M); 329 bool GlobalIsLinkerInitialized(GlobalVariable *G); 330 bool InjectCoverage(Function &F); 331 332 bool CheckInitOrder; 333 bool CheckUseAfterReturn; 334 bool CheckLifetime; 335 SmallString<64> BlacklistFile; 336 bool ZeroBaseShadow; 337 338 LLVMContext *C; 339 DataLayout *TD; 340 int LongSize; 341 Type *IntptrTy; 342 ShadowMapping Mapping; 343 Function *AsanCtorFunction; 344 Function *AsanInitFunction; 345 Function *AsanHandleNoReturnFunc; 346 Function *AsanCovFunction; 347 OwningPtr<SpecialCaseList> BL; 348 // This array is indexed by AccessIsWrite and log2(AccessSize). 349 Function *AsanErrorCallback[2][kNumberOfAccessSizes]; 350 // This array is indexed by AccessIsWrite. 351 Function *AsanErrorCallbackSized[2]; 352 InlineAsm *EmptyAsm; 353 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals; 354 355 friend struct FunctionStackPoisoner; 356}; 357 358class AddressSanitizerModule : public ModulePass { 359 public: 360 AddressSanitizerModule(bool CheckInitOrder = true, 361 StringRef BlacklistFile = StringRef(), 362 bool ZeroBaseShadow = false) 363 : ModulePass(ID), 364 CheckInitOrder(CheckInitOrder || ClInitializers), 365 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile 366 : BlacklistFile), 367 ZeroBaseShadow(ZeroBaseShadow) {} 368 bool runOnModule(Module &M); 369 static char ID; // Pass identification, replacement for typeid 370 virtual const char *getPassName() const { 371 return "AddressSanitizerModule"; 372 } 373 374 private: 375 void initializeCallbacks(Module &M); 376 377 bool ShouldInstrumentGlobal(GlobalVariable *G); 378 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName); 379 size_t RedzoneSize() const { 380 return RedzoneSizeForScale(Mapping.Scale); 381 } 382 383 bool CheckInitOrder; 384 SmallString<64> BlacklistFile; 385 bool ZeroBaseShadow; 386 387 OwningPtr<SpecialCaseList> BL; 388 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals; 389 Type *IntptrTy; 390 LLVMContext *C; 391 DataLayout *TD; 392 ShadowMapping Mapping; 393 Function *AsanPoisonGlobals; 394 Function *AsanUnpoisonGlobals; 395 Function *AsanRegisterGlobals; 396 Function *AsanUnregisterGlobals; 397}; 398 399// Stack poisoning does not play well with exception handling. 400// When an exception is thrown, we essentially bypass the code 401// that unpoisones the stack. This is why the run-time library has 402// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire 403// stack in the interceptor. This however does not work inside the 404// actual function which catches the exception. Most likely because the 405// compiler hoists the load of the shadow value somewhere too high. 406// This causes asan to report a non-existing bug on 453.povray. 407// It sounds like an LLVM bug. 408struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> { 409 Function &F; 410 AddressSanitizer &ASan; 411 DIBuilder DIB; 412 LLVMContext *C; 413 Type *IntptrTy; 414 Type *IntptrPtrTy; 415 ShadowMapping Mapping; 416 417 SmallVector<AllocaInst*, 16> AllocaVec; 418 SmallVector<Instruction*, 8> RetVec; 419 uint64_t TotalStackSize; 420 unsigned StackAlignment; 421 422 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1], 423 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1]; 424 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc; 425 426 // Stores a place and arguments of poisoning/unpoisoning call for alloca. 427 struct AllocaPoisonCall { 428 IntrinsicInst *InsBefore; 429 uint64_t Size; 430 bool DoPoison; 431 }; 432 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec; 433 434 // Maps Value to an AllocaInst from which the Value is originated. 435 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy; 436 AllocaForValueMapTy AllocaForValue; 437 438 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan) 439 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C), 440 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)), 441 Mapping(ASan.Mapping), 442 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {} 443 444 bool runOnFunction() { 445 if (!ClStack) return false; 446 // Collect alloca, ret, lifetime instructions etc. 447 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()), 448 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) { 449 BasicBlock *BB = *DI; 450 visit(*BB); 451 } 452 if (AllocaVec.empty()) return false; 453 454 initializeCallbacks(*F.getParent()); 455 456 poisonStack(); 457 458 if (ClDebugStack) { 459 DEBUG(dbgs() << F); 460 } 461 return true; 462 } 463 464 // Finds all static Alloca instructions and puts 465 // poisoned red zones around all of them. 466 // Then unpoison everything back before the function returns. 467 void poisonStack(); 468 469 // ----------------------- Visitors. 470 /// \brief Collect all Ret instructions. 471 void visitReturnInst(ReturnInst &RI) { 472 RetVec.push_back(&RI); 473 } 474 475 /// \brief Collect Alloca instructions we want (and can) handle. 476 void visitAllocaInst(AllocaInst &AI) { 477 if (!isInterestingAlloca(AI)) return; 478 479 StackAlignment = std::max(StackAlignment, AI.getAlignment()); 480 AllocaVec.push_back(&AI); 481 uint64_t AlignedSize = getAlignedAllocaSize(&AI); 482 TotalStackSize += AlignedSize; 483 } 484 485 /// \brief Collect lifetime intrinsic calls to check for use-after-scope 486 /// errors. 487 void visitIntrinsicInst(IntrinsicInst &II) { 488 if (!ASan.CheckLifetime) return; 489 Intrinsic::ID ID = II.getIntrinsicID(); 490 if (ID != Intrinsic::lifetime_start && 491 ID != Intrinsic::lifetime_end) 492 return; 493 // Found lifetime intrinsic, add ASan instrumentation if necessary. 494 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0)); 495 // If size argument is undefined, don't do anything. 496 if (Size->isMinusOne()) return; 497 // Check that size doesn't saturate uint64_t and can 498 // be stored in IntptrTy. 499 const uint64_t SizeValue = Size->getValue().getLimitedValue(); 500 if (SizeValue == ~0ULL || 501 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) 502 return; 503 // Find alloca instruction that corresponds to llvm.lifetime argument. 504 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1)); 505 if (!AI) return; 506 bool DoPoison = (ID == Intrinsic::lifetime_end); 507 AllocaPoisonCall APC = {&II, SizeValue, DoPoison}; 508 AllocaPoisonCallVec.push_back(APC); 509 } 510 511 // ---------------------- Helpers. 512 void initializeCallbacks(Module &M); 513 514 // Check if we want (and can) handle this alloca. 515 bool isInterestingAlloca(AllocaInst &AI) const { 516 return (!AI.isArrayAllocation() && 517 AI.isStaticAlloca() && 518 AI.getAlignment() <= RedzoneSize() && 519 AI.getAllocatedType()->isSized()); 520 } 521 522 size_t RedzoneSize() const { 523 return RedzoneSizeForScale(Mapping.Scale); 524 } 525 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const { 526 Type *Ty = AI->getAllocatedType(); 527 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty); 528 return SizeInBytes; 529 } 530 uint64_t getAlignedSize(uint64_t SizeInBytes) const { 531 size_t RZ = RedzoneSize(); 532 return ((SizeInBytes + RZ - 1) / RZ) * RZ; 533 } 534 uint64_t getAlignedAllocaSize(AllocaInst *AI) const { 535 uint64_t SizeInBytes = getAllocaSizeInBytes(AI); 536 return getAlignedSize(SizeInBytes); 537 } 538 /// Finds alloca where the value comes from. 539 AllocaInst *findAllocaForValue(Value *V); 540 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB, 541 Value *ShadowBase, bool DoPoison); 542 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison); 543 544 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase, 545 int Size); 546}; 547 548} // namespace 549 550char AddressSanitizer::ID = 0; 551INITIALIZE_PASS(AddressSanitizer, "asan", 552 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", 553 false, false) 554FunctionPass *llvm::createAddressSanitizerFunctionPass( 555 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime, 556 StringRef BlacklistFile, bool ZeroBaseShadow) { 557 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn, 558 CheckLifetime, BlacklistFile, ZeroBaseShadow); 559} 560 561char AddressSanitizerModule::ID = 0; 562INITIALIZE_PASS(AddressSanitizerModule, "asan-module", 563 "AddressSanitizer: detects use-after-free and out-of-bounds bugs." 564 "ModulePass", false, false) 565ModulePass *llvm::createAddressSanitizerModulePass( 566 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) { 567 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile, 568 ZeroBaseShadow); 569} 570 571static size_t TypeSizeToSizeIndex(uint32_t TypeSize) { 572 size_t Res = countTrailingZeros(TypeSize / 8); 573 assert(Res < kNumberOfAccessSizes); 574 return Res; 575} 576 577// \brief Create a constant for Str so that we can pass it to the run-time lib. 578static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) { 579 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str); 580 GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true, 581 GlobalValue::InternalLinkage, StrConst, 582 kAsanGenPrefix); 583 GV->setUnnamedAddr(true); // Ok to merge these. 584 GV->setAlignment(1); // Strings may not be merged w/o setting align 1. 585 return GV; 586} 587 588static bool GlobalWasGeneratedByAsan(GlobalVariable *G) { 589 return G->getName().find(kAsanGenPrefix) == 0; 590} 591 592Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) { 593 // Shadow >> scale 594 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale); 595 if (Mapping.Offset == 0) 596 return Shadow; 597 // (Shadow >> scale) | offset 598 if (Mapping.OrShadowOffset) 599 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); 600 else 601 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); 602} 603 604void AddressSanitizer::instrumentMemIntrinsicParam( 605 Instruction *OrigIns, 606 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) { 607 IRBuilder<> IRB(InsertBefore); 608 if (Size->getType() != IntptrTy) 609 Size = IRB.CreateIntCast(Size, IntptrTy, false); 610 // Check the first byte. 611 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size); 612 // Check the last byte. 613 IRB.SetInsertPoint(InsertBefore); 614 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1)); 615 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); 616 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne); 617 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size); 618} 619 620// Instrument memset/memmove/memcpy 621bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) { 622 Value *Dst = MI->getDest(); 623 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI); 624 Value *Src = MemTran ? MemTran->getSource() : 0; 625 Value *Length = MI->getLength(); 626 627 Constant *ConstLength = dyn_cast<Constant>(Length); 628 Instruction *InsertBefore = MI; 629 if (ConstLength) { 630 if (ConstLength->isNullValue()) return false; 631 } else { 632 // The size is not a constant so it could be zero -- check at run-time. 633 IRBuilder<> IRB(InsertBefore); 634 635 Value *Cmp = IRB.CreateICmpNE(Length, 636 Constant::getNullValue(Length->getType())); 637 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false); 638 } 639 640 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true); 641 if (Src) 642 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false); 643 return true; 644} 645 646// If I is an interesting memory access, return the PointerOperand 647// and set IsWrite. Otherwise return NULL. 648static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) { 649 if (LoadInst *LI = dyn_cast<LoadInst>(I)) { 650 if (!ClInstrumentReads) return NULL; 651 *IsWrite = false; 652 return LI->getPointerOperand(); 653 } 654 if (StoreInst *SI = dyn_cast<StoreInst>(I)) { 655 if (!ClInstrumentWrites) return NULL; 656 *IsWrite = true; 657 return SI->getPointerOperand(); 658 } 659 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) { 660 if (!ClInstrumentAtomics) return NULL; 661 *IsWrite = true; 662 return RMW->getPointerOperand(); 663 } 664 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) { 665 if (!ClInstrumentAtomics) return NULL; 666 *IsWrite = true; 667 return XCHG->getPointerOperand(); 668 } 669 return NULL; 670} 671 672bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) { 673 // If a global variable does not have dynamic initialization we don't 674 // have to instrument it. However, if a global does not have initializer 675 // at all, we assume it has dynamic initializer (in other TU). 676 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G); 677} 678 679void AddressSanitizer::instrumentMop(Instruction *I) { 680 bool IsWrite = false; 681 Value *Addr = isInterestingMemoryAccess(I, &IsWrite); 682 assert(Addr); 683 if (ClOpt && ClOptGlobals) { 684 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) { 685 // If initialization order checking is disabled, a simple access to a 686 // dynamically initialized global is always valid. 687 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) { 688 NumOptimizedAccessesToGlobalVar++; 689 return; 690 } 691 } 692 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr); 693 if (CE && CE->isGEPWithNoNotionalOverIndexing()) { 694 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) { 695 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) { 696 NumOptimizedAccessesToGlobalArray++; 697 return; 698 } 699 } 700 } 701 } 702 703 Type *OrigPtrTy = Addr->getType(); 704 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType(); 705 706 assert(OrigTy->isSized()); 707 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy); 708 709 assert((TypeSize % 8) == 0); 710 711 if (IsWrite) 712 NumInstrumentedWrites++; 713 else 714 NumInstrumentedReads++; 715 716 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check. 717 if (TypeSize == 8 || TypeSize == 16 || 718 TypeSize == 32 || TypeSize == 64 || TypeSize == 128) 719 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0); 720 // Instrument unusual size (but still multiple of 8). 721 // We can not do it with a single check, so we do 1-byte check for the first 722 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able 723 // to report the actual access size. 724 IRBuilder<> IRB(I); 725 Value *LastByte = IRB.CreateIntToPtr( 726 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy), 727 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)), 728 OrigPtrTy); 729 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8); 730 instrumentAddress(I, I, Addr, 8, IsWrite, Size); 731 instrumentAddress(I, I, LastByte, 8, IsWrite, Size); 732} 733 734// Validate the result of Module::getOrInsertFunction called for an interface 735// function of AddressSanitizer. If the instrumented module defines a function 736// with the same name, their prototypes must match, otherwise 737// getOrInsertFunction returns a bitcast. 738static Function *checkInterfaceFunction(Constant *FuncOrBitcast) { 739 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast); 740 FuncOrBitcast->dump(); 741 report_fatal_error("trying to redefine an AddressSanitizer " 742 "interface function"); 743} 744 745Instruction *AddressSanitizer::generateCrashCode( 746 Instruction *InsertBefore, Value *Addr, 747 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) { 748 IRBuilder<> IRB(InsertBefore); 749 CallInst *Call = SizeArgument 750 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument) 751 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr); 752 753 // We don't do Call->setDoesNotReturn() because the BB already has 754 // UnreachableInst at the end. 755 // This EmptyAsm is required to avoid callback merge. 756 IRB.CreateCall(EmptyAsm); 757 return Call; 758} 759 760Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, 761 Value *ShadowValue, 762 uint32_t TypeSize) { 763 size_t Granularity = 1 << Mapping.Scale; 764 // Addr & (Granularity - 1) 765 Value *LastAccessedByte = IRB.CreateAnd( 766 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1)); 767 // (Addr & (Granularity - 1)) + size - 1 768 if (TypeSize / 8 > 1) 769 LastAccessedByte = IRB.CreateAdd( 770 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)); 771 // (uint8_t) ((Addr & (Granularity-1)) + size - 1) 772 LastAccessedByte = IRB.CreateIntCast( 773 LastAccessedByte, ShadowValue->getType(), false); 774 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue 775 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue); 776} 777 778void AddressSanitizer::instrumentAddress(Instruction *OrigIns, 779 Instruction *InsertBefore, 780 Value *Addr, uint32_t TypeSize, 781 bool IsWrite, Value *SizeArgument) { 782 IRBuilder<> IRB(InsertBefore); 783 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); 784 785 Type *ShadowTy = IntegerType::get( 786 *C, std::max(8U, TypeSize >> Mapping.Scale)); 787 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0); 788 Value *ShadowPtr = memToShadow(AddrLong, IRB); 789 Value *CmpVal = Constant::getNullValue(ShadowTy); 790 Value *ShadowValue = IRB.CreateLoad( 791 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy)); 792 793 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal); 794 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize); 795 size_t Granularity = 1 << Mapping.Scale; 796 TerminatorInst *CrashTerm = 0; 797 798 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) { 799 TerminatorInst *CheckTerm = 800 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false); 801 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional()); 802 BasicBlock *NextBB = CheckTerm->getSuccessor(0); 803 IRB.SetInsertPoint(CheckTerm); 804 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize); 805 BasicBlock *CrashBlock = 806 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB); 807 CrashTerm = new UnreachableInst(*C, CrashBlock); 808 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2); 809 ReplaceInstWithInst(CheckTerm, NewTerm); 810 } else { 811 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true); 812 } 813 814 Instruction *Crash = generateCrashCode( 815 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument); 816 Crash->setDebugLoc(OrigIns->getDebugLoc()); 817} 818 819void AddressSanitizerModule::createInitializerPoisonCalls( 820 Module &M, GlobalValue *ModuleName) { 821 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a. 822 Function *GlobalInit = M.getFunction("_GLOBAL__I_a"); 823 // If that function is not present, this TU contains no globals, or they have 824 // all been optimized away 825 if (!GlobalInit) 826 return; 827 828 // Set up the arguments to our poison/unpoison functions. 829 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt()); 830 831 // Add a call to poison all external globals before the given function starts. 832 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy); 833 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr); 834 835 // Add calls to unpoison all globals before each return instruction. 836 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end(); 837 I != E; ++I) { 838 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) { 839 CallInst::Create(AsanUnpoisonGlobals, "", RI); 840 } 841 } 842} 843 844bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) { 845 Type *Ty = cast<PointerType>(G->getType())->getElementType(); 846 DEBUG(dbgs() << "GLOBAL: " << *G << "\n"); 847 848 if (BL->isIn(*G)) return false; 849 if (!Ty->isSized()) return false; 850 if (!G->hasInitializer()) return false; 851 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global. 852 // Touch only those globals that will not be defined in other modules. 853 // Don't handle ODR type linkages since other modules may be built w/o asan. 854 if (G->getLinkage() != GlobalVariable::ExternalLinkage && 855 G->getLinkage() != GlobalVariable::PrivateLinkage && 856 G->getLinkage() != GlobalVariable::InternalLinkage) 857 return false; 858 // Two problems with thread-locals: 859 // - The address of the main thread's copy can't be computed at link-time. 860 // - Need to poison all copies, not just the main thread's one. 861 if (G->isThreadLocal()) 862 return false; 863 // For now, just ignore this Alloca if the alignment is large. 864 if (G->getAlignment() > RedzoneSize()) return false; 865 866 // Ignore all the globals with the names starting with "\01L_OBJC_". 867 // Many of those are put into the .cstring section. The linker compresses 868 // that section by removing the spare \0s after the string terminator, so 869 // our redzones get broken. 870 if ((G->getName().find("\01L_OBJC_") == 0) || 871 (G->getName().find("\01l_OBJC_") == 0)) { 872 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G); 873 return false; 874 } 875 876 if (G->hasSection()) { 877 StringRef Section(G->getSection()); 878 // Ignore the globals from the __OBJC section. The ObjC runtime assumes 879 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to 880 // them. 881 if ((Section.find("__OBJC,") == 0) || 882 (Section.find("__DATA, __objc_") == 0)) { 883 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G); 884 return false; 885 } 886 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32 887 // Constant CFString instances are compiled in the following way: 888 // -- the string buffer is emitted into 889 // __TEXT,__cstring,cstring_literals 890 // -- the constant NSConstantString structure referencing that buffer 891 // is placed into __DATA,__cfstring 892 // Therefore there's no point in placing redzones into __DATA,__cfstring. 893 // Moreover, it causes the linker to crash on OS X 10.7 894 if (Section.find("__DATA,__cfstring") == 0) { 895 DEBUG(dbgs() << "Ignoring CFString: " << *G); 896 return false; 897 } 898 } 899 900 return true; 901} 902 903void AddressSanitizerModule::initializeCallbacks(Module &M) { 904 IRBuilder<> IRB(*C); 905 // Declare our poisoning and unpoisoning functions. 906 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction( 907 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL)); 908 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage); 909 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction( 910 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL)); 911 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage); 912 // Declare functions that register/unregister globals. 913 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction( 914 kAsanRegisterGlobalsName, IRB.getVoidTy(), 915 IntptrTy, IntptrTy, NULL)); 916 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage); 917 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction( 918 kAsanUnregisterGlobalsName, 919 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 920 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage); 921} 922 923// This function replaces all global variables with new variables that have 924// trailing redzones. It also creates a function that poisons 925// redzones and inserts this function into llvm.global_ctors. 926bool AddressSanitizerModule::runOnModule(Module &M) { 927 if (!ClGlobals) return false; 928 TD = getAnalysisIfAvailable<DataLayout>(); 929 if (!TD) 930 return false; 931 BL.reset(SpecialCaseList::createOrDie(BlacklistFile)); 932 if (BL->isIn(M)) return false; 933 C = &(M.getContext()); 934 int LongSize = TD->getPointerSizeInBits(); 935 IntptrTy = Type::getIntNTy(*C, LongSize); 936 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow); 937 initializeCallbacks(M); 938 DynamicallyInitializedGlobals.Init(M); 939 940 SmallVector<GlobalVariable *, 16> GlobalsToChange; 941 942 for (Module::GlobalListType::iterator G = M.global_begin(), 943 E = M.global_end(); G != E; ++G) { 944 if (ShouldInstrumentGlobal(G)) 945 GlobalsToChange.push_back(G); 946 } 947 948 size_t n = GlobalsToChange.size(); 949 if (n == 0) return false; 950 951 // A global is described by a structure 952 // size_t beg; 953 // size_t size; 954 // size_t size_with_redzone; 955 // const char *name; 956 // const char *module_name; 957 // size_t has_dynamic_init; 958 // We initialize an array of such structures and pass it to a run-time call. 959 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy, 960 IntptrTy, IntptrTy, 961 IntptrTy, IntptrTy, NULL); 962 SmallVector<Constant *, 16> Initializers(n); 963 964 Function *CtorFunc = M.getFunction(kAsanModuleCtorName); 965 assert(CtorFunc); 966 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator()); 967 968 bool HasDynamicallyInitializedGlobals = false; 969 970 GlobalVariable *ModuleName = createPrivateGlobalForString( 971 M, M.getModuleIdentifier()); 972 // We shouldn't merge same module names, as this string serves as unique 973 // module ID in runtime. 974 ModuleName->setUnnamedAddr(false); 975 976 for (size_t i = 0; i < n; i++) { 977 static const uint64_t kMaxGlobalRedzone = 1 << 18; 978 GlobalVariable *G = GlobalsToChange[i]; 979 PointerType *PtrTy = cast<PointerType>(G->getType()); 980 Type *Ty = PtrTy->getElementType(); 981 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty); 982 uint64_t MinRZ = RedzoneSize(); 983 // MinRZ <= RZ <= kMaxGlobalRedzone 984 // and trying to make RZ to be ~ 1/4 of SizeInBytes. 985 uint64_t RZ = std::max(MinRZ, 986 std::min(kMaxGlobalRedzone, 987 (SizeInBytes / MinRZ / 4) * MinRZ)); 988 uint64_t RightRedzoneSize = RZ; 989 // Round up to MinRZ 990 if (SizeInBytes % MinRZ) 991 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ); 992 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0); 993 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize); 994 // Determine whether this global should be poisoned in initialization. 995 bool GlobalHasDynamicInitializer = 996 DynamicallyInitializedGlobals.Contains(G); 997 // Don't check initialization order if this global is blacklisted. 998 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init"); 999 1000 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL); 1001 Constant *NewInitializer = ConstantStruct::get( 1002 NewTy, G->getInitializer(), 1003 Constant::getNullValue(RightRedZoneTy), NULL); 1004 1005 GlobalVariable *Name = createPrivateGlobalForString(M, G->getName()); 1006 1007 // Create a new global variable with enough space for a redzone. 1008 GlobalValue::LinkageTypes Linkage = G->getLinkage(); 1009 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage) 1010 Linkage = GlobalValue::InternalLinkage; 1011 GlobalVariable *NewGlobal = new GlobalVariable( 1012 M, NewTy, G->isConstant(), Linkage, 1013 NewInitializer, "", G, G->getThreadLocalMode()); 1014 NewGlobal->copyAttributesFrom(G); 1015 NewGlobal->setAlignment(MinRZ); 1016 1017 Value *Indices2[2]; 1018 Indices2[0] = IRB.getInt32(0); 1019 Indices2[1] = IRB.getInt32(0); 1020 1021 G->replaceAllUsesWith( 1022 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true)); 1023 NewGlobal->takeName(G); 1024 G->eraseFromParent(); 1025 1026 Initializers[i] = ConstantStruct::get( 1027 GlobalStructTy, 1028 ConstantExpr::getPointerCast(NewGlobal, IntptrTy), 1029 ConstantInt::get(IntptrTy, SizeInBytes), 1030 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize), 1031 ConstantExpr::getPointerCast(Name, IntptrTy), 1032 ConstantExpr::getPointerCast(ModuleName, IntptrTy), 1033 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer), 1034 NULL); 1035 1036 // Populate the first and last globals declared in this TU. 1037 if (CheckInitOrder && GlobalHasDynamicInitializer) 1038 HasDynamicallyInitializedGlobals = true; 1039 1040 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n"); 1041 } 1042 1043 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n); 1044 GlobalVariable *AllGlobals = new GlobalVariable( 1045 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage, 1046 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), ""); 1047 1048 // Create calls for poisoning before initializers run and unpoisoning after. 1049 if (CheckInitOrder && HasDynamicallyInitializedGlobals) 1050 createInitializerPoisonCalls(M, ModuleName); 1051 IRB.CreateCall2(AsanRegisterGlobals, 1052 IRB.CreatePointerCast(AllGlobals, IntptrTy), 1053 ConstantInt::get(IntptrTy, n)); 1054 1055 // We also need to unregister globals at the end, e.g. when a shared library 1056 // gets closed. 1057 Function *AsanDtorFunction = Function::Create( 1058 FunctionType::get(Type::getVoidTy(*C), false), 1059 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M); 1060 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction); 1061 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB)); 1062 IRB_Dtor.CreateCall2(AsanUnregisterGlobals, 1063 IRB.CreatePointerCast(AllGlobals, IntptrTy), 1064 ConstantInt::get(IntptrTy, n)); 1065 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority); 1066 1067 DEBUG(dbgs() << M); 1068 return true; 1069} 1070 1071void AddressSanitizer::initializeCallbacks(Module &M) { 1072 IRBuilder<> IRB(*C); 1073 // Create __asan_report* callbacks. 1074 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) { 1075 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes; 1076 AccessSizeIndex++) { 1077 // IsWrite and TypeSize are encoded in the function name. 1078 std::string FunctionName = std::string(kAsanReportErrorTemplate) + 1079 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex); 1080 // If we are merging crash callbacks, they have two parameters. 1081 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] = 1082 checkInterfaceFunction(M.getOrInsertFunction( 1083 FunctionName, IRB.getVoidTy(), IntptrTy, NULL)); 1084 } 1085 } 1086 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction( 1087 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1088 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction( 1089 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1090 1091 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction( 1092 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL)); 1093 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction( 1094 kAsanCovName, IRB.getVoidTy(), IntptrTy, NULL)); 1095 // We insert an empty inline asm after __asan_report* to avoid callback merge. 1096 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 1097 StringRef(""), StringRef(""), 1098 /*hasSideEffects=*/true); 1099} 1100 1101void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const { 1102 // Tell the values of mapping offset and scale to the run-time. 1103 GlobalValue *asan_mapping_offset = 1104 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage, 1105 ConstantInt::get(IntptrTy, Mapping.Offset), 1106 kAsanMappingOffsetName); 1107 // Read the global, otherwise it may be optimized away. 1108 IRB.CreateLoad(asan_mapping_offset, true); 1109 1110 GlobalValue *asan_mapping_scale = 1111 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage, 1112 ConstantInt::get(IntptrTy, Mapping.Scale), 1113 kAsanMappingScaleName); 1114 // Read the global, otherwise it may be optimized away. 1115 IRB.CreateLoad(asan_mapping_scale, true); 1116} 1117 1118// virtual 1119bool AddressSanitizer::doInitialization(Module &M) { 1120 // Initialize the private fields. No one has accessed them before. 1121 TD = getAnalysisIfAvailable<DataLayout>(); 1122 1123 if (!TD) 1124 return false; 1125 BL.reset(SpecialCaseList::createOrDie(BlacklistFile)); 1126 DynamicallyInitializedGlobals.Init(M); 1127 1128 C = &(M.getContext()); 1129 LongSize = TD->getPointerSizeInBits(); 1130 IntptrTy = Type::getIntNTy(*C, LongSize); 1131 1132 AsanCtorFunction = Function::Create( 1133 FunctionType::get(Type::getVoidTy(*C), false), 1134 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M); 1135 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction); 1136 // call __asan_init in the module ctor. 1137 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB)); 1138 AsanInitFunction = checkInterfaceFunction( 1139 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL)); 1140 AsanInitFunction->setLinkage(Function::ExternalLinkage); 1141 IRB.CreateCall(AsanInitFunction); 1142 1143 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow); 1144 emitShadowMapping(M, IRB); 1145 1146 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority); 1147 return true; 1148} 1149 1150bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) { 1151 // For each NSObject descendant having a +load method, this method is invoked 1152 // by the ObjC runtime before any of the static constructors is called. 1153 // Therefore we need to instrument such methods with a call to __asan_init 1154 // at the beginning in order to initialize our runtime before any access to 1155 // the shadow memory. 1156 // We cannot just ignore these methods, because they may call other 1157 // instrumented functions. 1158 if (F.getName().find(" load]") != std::string::npos) { 1159 IRBuilder<> IRB(F.begin()->begin()); 1160 IRB.CreateCall(AsanInitFunction); 1161 return true; 1162 } 1163 return false; 1164} 1165 1166// Poor man's coverage that works with ASan. 1167// We create a Guard boolean variable with the same linkage 1168// as the function and inject this code into the entry block: 1169// if (*Guard) { 1170// __sanitizer_cov(&F); 1171// *Guard = 1; 1172// } 1173// The accesses to Guard are atomic. The rest of the logic is 1174// in __sanitizer_cov (it's fine to call it more than once). 1175// 1176// This coverage implementation provides very limited data: 1177// it only tells if a given function was ever executed. 1178// No counters, no per-basic-block or per-edge data. 1179// But for many use cases this is what we need and the added slowdown 1180// is negligible. This simple implementation will probably be obsoleted 1181// by the upcoming Clang-based coverage implementation. 1182// By having it here and now we hope to 1183// a) get the functionality to users earlier and 1184// b) collect usage statistics to help improve Clang coverage design. 1185bool AddressSanitizer::InjectCoverage(Function &F) { 1186 if (!ClCoverage) return false; 1187 IRBuilder<> IRB(F.getEntryBlock().getFirstInsertionPt()); 1188 Type *Int8Ty = IRB.getInt8Ty(); 1189 GlobalVariable *Guard = new GlobalVariable( 1190 *F.getParent(), Int8Ty, false, F.getLinkage(), 1191 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName()); 1192 LoadInst *Load = IRB.CreateLoad(Guard); 1193 Load->setAtomic(Monotonic); 1194 Load->setAlignment(1); 1195 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load); 1196 Instruction *Ins = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false); 1197 IRB.SetInsertPoint(Ins); 1198 // We pass &F to __sanitizer_cov. We could avoid this and rely on 1199 // GET_CALLER_PC, but having the PC of the first instruction is just nice. 1200 IRB.CreateCall(AsanCovFunction, IRB.CreatePointerCast(&F, IntptrTy)); 1201 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard); 1202 Store->setAtomic(Monotonic); 1203 Store->setAlignment(1); 1204 return true; 1205} 1206 1207bool AddressSanitizer::runOnFunction(Function &F) { 1208 if (BL->isIn(F)) return false; 1209 if (&F == AsanCtorFunction) return false; 1210 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false; 1211 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n"); 1212 initializeCallbacks(*F.getParent()); 1213 1214 // If needed, insert __asan_init before checking for SanitizeAddress attr. 1215 maybeInsertAsanInitAtFunctionEntry(F); 1216 1217 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) 1218 return false; 1219 1220 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) 1221 return false; 1222 1223 // We want to instrument every address only once per basic block (unless there 1224 // are calls between uses). 1225 SmallSet<Value*, 16> TempsToInstrument; 1226 SmallVector<Instruction*, 16> ToInstrument; 1227 SmallVector<Instruction*, 8> NoReturnCalls; 1228 int NumAllocas = 0; 1229 bool IsWrite; 1230 1231 // Fill the set of memory operations to instrument. 1232 for (Function::iterator FI = F.begin(), FE = F.end(); 1233 FI != FE; ++FI) { 1234 TempsToInstrument.clear(); 1235 int NumInsnsPerBB = 0; 1236 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); 1237 BI != BE; ++BI) { 1238 if (LooksLikeCodeInBug11395(BI)) return false; 1239 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) { 1240 if (ClOpt && ClOptSameTemp) { 1241 if (!TempsToInstrument.insert(Addr)) 1242 continue; // We've seen this temp in the current BB. 1243 } 1244 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) { 1245 // ok, take it. 1246 } else { 1247 if (isa<AllocaInst>(BI)) 1248 NumAllocas++; 1249 CallSite CS(BI); 1250 if (CS) { 1251 // A call inside BB. 1252 TempsToInstrument.clear(); 1253 if (CS.doesNotReturn()) 1254 NoReturnCalls.push_back(CS.getInstruction()); 1255 } 1256 continue; 1257 } 1258 ToInstrument.push_back(BI); 1259 NumInsnsPerBB++; 1260 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) 1261 break; 1262 } 1263 } 1264 1265 Function *UninstrumentedDuplicate = 0; 1266 bool LikelyToInstrument = 1267 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0); 1268 if (ClKeepUninstrumented && LikelyToInstrument) { 1269 ValueToValueMapTy VMap; 1270 UninstrumentedDuplicate = CloneFunction(&F, VMap, false); 1271 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress); 1272 UninstrumentedDuplicate->setName("NOASAN_" + F.getName()); 1273 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate); 1274 } 1275 1276 // Instrument. 1277 int NumInstrumented = 0; 1278 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) { 1279 Instruction *Inst = ToInstrument[i]; 1280 if (ClDebugMin < 0 || ClDebugMax < 0 || 1281 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) { 1282 if (isInterestingMemoryAccess(Inst, &IsWrite)) 1283 instrumentMop(Inst); 1284 else 1285 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst)); 1286 } 1287 NumInstrumented++; 1288 } 1289 1290 FunctionStackPoisoner FSP(F, *this); 1291 bool ChangedStack = FSP.runOnFunction(); 1292 1293 // We must unpoison the stack before every NoReturn call (throw, _exit, etc). 1294 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37 1295 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) { 1296 Instruction *CI = NoReturnCalls[i]; 1297 IRBuilder<> IRB(CI); 1298 IRB.CreateCall(AsanHandleNoReturnFunc); 1299 } 1300 1301 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty(); 1302 1303 if (InjectCoverage(F)) 1304 res = true; 1305 1306 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n"); 1307 1308 if (ClKeepUninstrumented) { 1309 if (!res) { 1310 // No instrumentation is done, no need for the duplicate. 1311 if (UninstrumentedDuplicate) 1312 UninstrumentedDuplicate->eraseFromParent(); 1313 } else { 1314 // The function was instrumented. We must have the duplicate. 1315 assert(UninstrumentedDuplicate); 1316 UninstrumentedDuplicate->setSection("NOASAN"); 1317 assert(!F.hasSection()); 1318 F.setSection("ASAN"); 1319 } 1320 } 1321 1322 return res; 1323} 1324 1325static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) { 1326 if (ShadowRedzoneSize == 1) return PoisonByte; 1327 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte; 1328 if (ShadowRedzoneSize == 4) 1329 return (PoisonByte << 24) + (PoisonByte << 16) + 1330 (PoisonByte << 8) + (PoisonByte); 1331 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4"); 1332} 1333 1334static void PoisonShadowPartialRightRedzone(uint8_t *Shadow, 1335 size_t Size, 1336 size_t RZSize, 1337 size_t ShadowGranularity, 1338 uint8_t Magic) { 1339 for (size_t i = 0; i < RZSize; 1340 i+= ShadowGranularity, Shadow++) { 1341 if (i + ShadowGranularity <= Size) { 1342 *Shadow = 0; // fully addressable 1343 } else if (i >= Size) { 1344 *Shadow = Magic; // unaddressable 1345 } else { 1346 *Shadow = Size - i; // first Size-i bytes are addressable 1347 } 1348 } 1349} 1350 1351// Workaround for bug 11395: we don't want to instrument stack in functions 1352// with large assembly blobs (32-bit only), otherwise reg alloc may crash. 1353// FIXME: remove once the bug 11395 is fixed. 1354bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) { 1355 if (LongSize != 32) return false; 1356 CallInst *CI = dyn_cast<CallInst>(I); 1357 if (!CI || !CI->isInlineAsm()) return false; 1358 if (CI->getNumArgOperands() <= 5) return false; 1359 // We have inline assembly with quite a few arguments. 1360 return true; 1361} 1362 1363void FunctionStackPoisoner::initializeCallbacks(Module &M) { 1364 IRBuilder<> IRB(*C); 1365 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) { 1366 std::string Suffix = itostr(i); 1367 AsanStackMallocFunc[i] = checkInterfaceFunction( 1368 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy, 1369 IntptrTy, IntptrTy, NULL)); 1370 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction( 1371 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy, 1372 IntptrTy, IntptrTy, NULL)); 1373 } 1374 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction( 1375 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1376 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction( 1377 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1378} 1379 1380void FunctionStackPoisoner::poisonRedZones( 1381 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB, Value *ShadowBase, 1382 bool DoPoison) { 1383 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale; 1384 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4); 1385 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8); 1386 Type *RZPtrTy = PointerType::get(RZTy, 0); 1387 1388 Value *PoisonLeft = ConstantInt::get(RZTy, 1389 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize)); 1390 Value *PoisonMid = ConstantInt::get(RZTy, 1391 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize)); 1392 Value *PoisonRight = ConstantInt::get(RZTy, 1393 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize)); 1394 1395 // poison the first red zone. 1396 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy)); 1397 1398 // poison all other red zones. 1399 uint64_t Pos = RedzoneSize(); 1400 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) { 1401 AllocaInst *AI = AllocaVec[i]; 1402 uint64_t SizeInBytes = getAllocaSizeInBytes(AI); 1403 uint64_t AlignedSize = getAlignedAllocaSize(AI); 1404 assert(AlignedSize - SizeInBytes < RedzoneSize()); 1405 Value *Ptr = NULL; 1406 1407 Pos += AlignedSize; 1408 1409 assert(ShadowBase->getType() == IntptrTy); 1410 if (SizeInBytes < AlignedSize) { 1411 // Poison the partial redzone at right 1412 Ptr = IRB.CreateAdd( 1413 ShadowBase, ConstantInt::get(IntptrTy, 1414 (Pos >> Mapping.Scale) - ShadowRZSize)); 1415 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes); 1416 uint32_t Poison = 0; 1417 if (DoPoison) { 1418 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes, 1419 RedzoneSize(), 1420 1ULL << Mapping.Scale, 1421 kAsanStackPartialRedzoneMagic); 1422 Poison = 1423 ASan.TD->isLittleEndian() 1424 ? support::endian::byte_swap<uint32_t, support::little>(Poison) 1425 : support::endian::byte_swap<uint32_t, support::big>(Poison); 1426 } 1427 Value *PartialPoison = ConstantInt::get(RZTy, Poison); 1428 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy)); 1429 } 1430 1431 // Poison the full redzone at right. 1432 Ptr = IRB.CreateAdd(ShadowBase, 1433 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale)); 1434 bool LastAlloca = (i == AllocaVec.size() - 1); 1435 Value *Poison = LastAlloca ? PoisonRight : PoisonMid; 1436 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy)); 1437 1438 Pos += RedzoneSize(); 1439 } 1440} 1441 1442// Fake stack allocator (asan_fake_stack.h) has 11 size classes 1443// for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass 1444static int StackMallocSizeClass(uint64_t LocalStackSize) { 1445 assert(LocalStackSize <= kMaxStackMallocSize); 1446 uint64_t MaxSize = kMinStackMallocSize; 1447 for (int i = 0; ; i++, MaxSize *= 2) 1448 if (LocalStackSize <= MaxSize) 1449 return i; 1450 llvm_unreachable("impossible LocalStackSize"); 1451} 1452 1453// Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic. 1454// We can not use MemSet intrinsic because it may end up calling the actual 1455// memset. Size is a multiple of 8. 1456// Currently this generates 8-byte stores on x86_64; it may be better to 1457// generate wider stores. 1458void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined( 1459 IRBuilder<> &IRB, Value *ShadowBase, int Size) { 1460 assert(!(Size % 8)); 1461 assert(kAsanStackAfterReturnMagic == 0xf5); 1462 for (int i = 0; i < Size; i += 8) { 1463 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); 1464 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL), 1465 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo())); 1466 } 1467} 1468 1469void FunctionStackPoisoner::poisonStack() { 1470 uint64_t LocalStackSize = TotalStackSize + 1471 (AllocaVec.size() + 1) * RedzoneSize(); 1472 1473 bool DoStackMalloc = ASan.CheckUseAfterReturn 1474 && LocalStackSize <= kMaxStackMallocSize; 1475 int StackMallocIdx = -1; 1476 1477 assert(AllocaVec.size() > 0); 1478 Instruction *InsBefore = AllocaVec[0]; 1479 IRBuilder<> IRB(InsBefore); 1480 1481 1482 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize); 1483 AllocaInst *MyAlloca = 1484 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore); 1485 if (ClRealignStack && StackAlignment < RedzoneSize()) 1486 StackAlignment = RedzoneSize(); 1487 MyAlloca->setAlignment(StackAlignment); 1488 assert(MyAlloca->isStaticAlloca()); 1489 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy); 1490 Value *LocalStackBase = OrigStackBase; 1491 1492 if (DoStackMalloc) { 1493 // LocalStackBase = OrigStackBase 1494 // if (__asan_option_detect_stack_use_after_return) 1495 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase); 1496 StackMallocIdx = StackMallocSizeClass(LocalStackSize); 1497 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass); 1498 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal( 1499 kAsanOptionDetectUAR, IRB.getInt32Ty()); 1500 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR), 1501 Constant::getNullValue(IRB.getInt32Ty())); 1502 Instruction *Term = 1503 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false); 1504 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent(); 1505 IRBuilder<> IRBIf(Term); 1506 LocalStackBase = IRBIf.CreateCall2( 1507 AsanStackMallocFunc[StackMallocIdx], 1508 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase); 1509 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent(); 1510 IRB.SetInsertPoint(InsBefore); 1511 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2); 1512 Phi->addIncoming(OrigStackBase, CmpBlock); 1513 Phi->addIncoming(LocalStackBase, SetBlock); 1514 LocalStackBase = Phi; 1515 } 1516 1517 // This string will be parsed by the run-time (DescribeAddressIfStack). 1518 SmallString<2048> StackDescriptionStorage; 1519 raw_svector_ostream StackDescription(StackDescriptionStorage); 1520 StackDescription << AllocaVec.size() << " "; 1521 1522 // Insert poison calls for lifetime intrinsics for alloca. 1523 bool HavePoisonedAllocas = false; 1524 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) { 1525 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i]; 1526 IntrinsicInst *II = APC.InsBefore; 1527 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1)); 1528 assert(AI); 1529 IRBuilder<> IRB(II); 1530 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison); 1531 HavePoisonedAllocas |= APC.DoPoison; 1532 } 1533 1534 uint64_t Pos = RedzoneSize(); 1535 // Replace Alloca instructions with base+offset. 1536 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) { 1537 AllocaInst *AI = AllocaVec[i]; 1538 uint64_t SizeInBytes = getAllocaSizeInBytes(AI); 1539 StringRef Name = AI->getName(); 1540 StackDescription << Pos << " " << SizeInBytes << " " 1541 << Name.size() << " " << Name << " "; 1542 uint64_t AlignedSize = getAlignedAllocaSize(AI); 1543 assert((AlignedSize % RedzoneSize()) == 0); 1544 Value *NewAllocaPtr = IRB.CreateIntToPtr( 1545 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)), 1546 AI->getType()); 1547 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB); 1548 AI->replaceAllUsesWith(NewAllocaPtr); 1549 Pos += AlignedSize + RedzoneSize(); 1550 } 1551 assert(Pos == LocalStackSize); 1552 1553 // The left-most redzone has enough space for at least 4 pointers. 1554 // Write the Magic value to redzone[0]. 1555 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy); 1556 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic), 1557 BasePlus0); 1558 // Write the frame description constant to redzone[1]. 1559 Value *BasePlus1 = IRB.CreateIntToPtr( 1560 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)), 1561 IntptrPtrTy); 1562 GlobalVariable *StackDescriptionGlobal = 1563 createPrivateGlobalForString(*F.getParent(), StackDescription.str()); 1564 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, 1565 IntptrTy); 1566 IRB.CreateStore(Description, BasePlus1); 1567 // Write the PC to redzone[2]. 1568 Value *BasePlus2 = IRB.CreateIntToPtr( 1569 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, 1570 2 * ASan.LongSize/8)), 1571 IntptrPtrTy); 1572 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2); 1573 1574 // Poison the stack redzones at the entry. 1575 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB); 1576 poisonRedZones(AllocaVec, IRB, ShadowBase, true); 1577 1578 // Unpoison the stack before all ret instructions. 1579 for (size_t i = 0, n = RetVec.size(); i < n; i++) { 1580 Instruction *Ret = RetVec[i]; 1581 IRBuilder<> IRBRet(Ret); 1582 // Mark the current frame as retired. 1583 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic), 1584 BasePlus0); 1585 // Unpoison the stack. 1586 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false); 1587 if (DoStackMalloc) { 1588 assert(StackMallocIdx >= 0); 1589 // In use-after-return mode, mark the whole stack frame unaddressable. 1590 if (StackMallocIdx <= 4) { 1591 // For small sizes inline the whole thing: 1592 // if LocalStackBase != OrigStackBase: 1593 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize); 1594 // **SavedFlagPtr(LocalStackBase) = 0 1595 // FIXME: if LocalStackBase != OrigStackBase don't call poisonRedZones. 1596 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase); 1597 TerminatorInst *PoisonTerm = 1598 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false); 1599 IRBuilder<> IRBPoison(PoisonTerm); 1600 int ClassSize = kMinStackMallocSize << StackMallocIdx; 1601 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase, 1602 ClassSize >> Mapping.Scale); 1603 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd( 1604 LocalStackBase, 1605 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8)); 1606 Value *SavedFlagPtr = IRBPoison.CreateLoad( 1607 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy)); 1608 IRBPoison.CreateStore( 1609 Constant::getNullValue(IRBPoison.getInt8Ty()), 1610 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy())); 1611 } else { 1612 // For larger frames call __asan_stack_free_*. 1613 IRBRet.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase, 1614 ConstantInt::get(IntptrTy, LocalStackSize), 1615 OrigStackBase); 1616 } 1617 } else if (HavePoisonedAllocas) { 1618 // If we poisoned some allocas in llvm.lifetime analysis, 1619 // unpoison whole stack frame now. 1620 assert(LocalStackBase == OrigStackBase); 1621 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false); 1622 } 1623 } 1624 1625 // We are done. Remove the old unused alloca instructions. 1626 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) 1627 AllocaVec[i]->eraseFromParent(); 1628} 1629 1630void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size, 1631 IRBuilder<> &IRB, bool DoPoison) { 1632 // For now just insert the call to ASan runtime. 1633 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy); 1634 Value *SizeArg = ConstantInt::get(IntptrTy, Size); 1635 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc 1636 : AsanUnpoisonStackMemoryFunc, 1637 AddrArg, SizeArg); 1638} 1639 1640// Handling llvm.lifetime intrinsics for a given %alloca: 1641// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca. 1642// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect 1643// invalid accesses) and unpoison it for llvm.lifetime.start (the memory 1644// could be poisoned by previous llvm.lifetime.end instruction, as the 1645// variable may go in and out of scope several times, e.g. in loops). 1646// (3) if we poisoned at least one %alloca in a function, 1647// unpoison the whole stack frame at function exit. 1648 1649AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) { 1650 if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) 1651 // We're intested only in allocas we can handle. 1652 return isInterestingAlloca(*AI) ? AI : 0; 1653 // See if we've already calculated (or started to calculate) alloca for a 1654 // given value. 1655 AllocaForValueMapTy::iterator I = AllocaForValue.find(V); 1656 if (I != AllocaForValue.end()) 1657 return I->second; 1658 // Store 0 while we're calculating alloca for value V to avoid 1659 // infinite recursion if the value references itself. 1660 AllocaForValue[V] = 0; 1661 AllocaInst *Res = 0; 1662 if (CastInst *CI = dyn_cast<CastInst>(V)) 1663 Res = findAllocaForValue(CI->getOperand(0)); 1664 else if (PHINode *PN = dyn_cast<PHINode>(V)) { 1665 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 1666 Value *IncValue = PN->getIncomingValue(i); 1667 // Allow self-referencing phi-nodes. 1668 if (IncValue == PN) continue; 1669 AllocaInst *IncValueAI = findAllocaForValue(IncValue); 1670 // AI for incoming values should exist and should all be equal. 1671 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res)) 1672 return 0; 1673 Res = IncValueAI; 1674 } 1675 } 1676 if (Res != 0) 1677 AllocaForValue[V] = Res; 1678 return Res; 1679} 1680