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/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/IR/Type.h"
37 #include "llvm/InstVisitor.h"
38 #include "llvm/Support/CallSite.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/DataTypes.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/raw_ostream.h"
43 #include "llvm/Support/system_error.h"
44 #include "llvm/Target/TargetMachine.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/BlackList.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/Transforms/Utils/ModuleUtils.h"
49 #include <algorithm>
50 #include <string>
51
52 using namespace llvm;
53
54 static const uint64_t kDefaultShadowScale = 3;
55 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
56 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
57 static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
58 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
59
60 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
61 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
62 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
63
64 static const char *kAsanModuleCtorName = "asan.module_ctor";
65 static const char *kAsanModuleDtorName = "asan.module_dtor";
66 static const int kAsanCtorAndCtorPriority = 1;
67 static const char *kAsanReportErrorTemplate = "__asan_report_";
68 static const char *kAsanReportLoadN = "__asan_report_load_n";
69 static const char *kAsanReportStoreN = "__asan_report_store_n";
70 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
71 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
72 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
73 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
74 static const char *kAsanInitName = "__asan_init_v2";
75 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
76 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
77 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
78 static const char *kAsanStackMallocName = "__asan_stack_malloc";
79 static const char *kAsanStackFreeName = "__asan_stack_free";
80 static const char *kAsanGenPrefix = "__asan_gen_";
81 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
82 static const char *kAsanUnpoisonStackMemoryName =
83 "__asan_unpoison_stack_memory";
84
85 static const int kAsanStackLeftRedzoneMagic = 0xf1;
86 static const int kAsanStackMidRedzoneMagic = 0xf2;
87 static const int kAsanStackRightRedzoneMagic = 0xf3;
88 static const int kAsanStackPartialRedzoneMagic = 0xf4;
89
90 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
91 static const size_t kNumberOfAccessSizes = 5;
92
93 // Command-line flags.
94
95 // This flag may need to be replaced with -f[no-]asan-reads.
96 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
97 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
98 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
99 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
100 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
101 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
102 cl::Hidden, cl::init(true));
103 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
104 cl::desc("use instrumentation with slow path for all accesses"),
105 cl::Hidden, cl::init(false));
106 // This flag limits the number of instructions to be instrumented
107 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
108 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
109 // set it to 10000.
110 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
111 cl::init(10000),
112 cl::desc("maximal number of instructions to instrument in any given BB"),
113 cl::Hidden);
114 // This flag may need to be replaced with -f[no]asan-stack.
115 static cl::opt<bool> ClStack("asan-stack",
116 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
117 // This flag may need to be replaced with -f[no]asan-use-after-return.
118 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
119 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
120 // This flag may need to be replaced with -f[no]asan-globals.
121 static cl::opt<bool> ClGlobals("asan-globals",
122 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClInitializers("asan-initialization-order",
124 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
125 static cl::opt<bool> ClMemIntrin("asan-memintrin",
126 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
127 static cl::opt<bool> ClRealignStack("asan-realign-stack",
128 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
129 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
130 cl::desc("File containing the list of objects to ignore "
131 "during instrumentation"), cl::Hidden);
132
133 // These flags allow to change the shadow mapping.
134 // The shadow mapping looks like
135 // Shadow = (Mem >> scale) + (1 << offset_log)
136 static cl::opt<int> ClMappingScale("asan-mapping-scale",
137 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
138 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
139 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
140 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
141 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
142 cl::Hidden, cl::init(true));
143
144 // Optimization flags. Not user visible, used mostly for testing
145 // and benchmarking the tool.
146 static cl::opt<bool> ClOpt("asan-opt",
147 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
148 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
149 cl::desc("Instrument the same temp just once"), cl::Hidden,
150 cl::init(true));
151 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
152 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
153
154 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
155 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
156 cl::Hidden, cl::init(false));
157
158 // Debug flags.
159 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
160 cl::init(0));
161 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
162 cl::Hidden, cl::init(0));
163 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
164 cl::Hidden, cl::desc("Debug func"));
165 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
166 cl::Hidden, cl::init(-1));
167 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
168 cl::Hidden, cl::init(-1));
169
170 namespace {
171 /// A set of dynamically initialized globals extracted from metadata.
172 class SetOfDynamicallyInitializedGlobals {
173 public:
Init(Module & M)174 void Init(Module& M) {
175 // Clang generates metadata identifying all dynamically initialized globals.
176 NamedMDNode *DynamicGlobals =
177 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
178 if (!DynamicGlobals)
179 return;
180 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
181 MDNode *MDN = DynamicGlobals->getOperand(i);
182 assert(MDN->getNumOperands() == 1);
183 Value *VG = MDN->getOperand(0);
184 // The optimizer may optimize away a global entirely, in which case we
185 // cannot instrument access to it.
186 if (!VG)
187 continue;
188 DynInitGlobals.insert(cast<GlobalVariable>(VG));
189 }
190 }
Contains(GlobalVariable * G)191 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
192 private:
193 SmallSet<GlobalValue*, 32> DynInitGlobals;
194 };
195
196 /// This struct defines the shadow mapping using the rule:
197 /// shadow = (mem >> Scale) ADD-or-OR Offset.
198 struct ShadowMapping {
199 int Scale;
200 uint64_t Offset;
201 bool OrShadowOffset;
202 };
203
getShadowMapping(const Module & M,int LongSize,bool ZeroBaseShadow)204 static ShadowMapping getShadowMapping(const Module &M, int LongSize,
205 bool ZeroBaseShadow) {
206 llvm::Triple TargetTriple(M.getTargetTriple());
207 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
208 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
209 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
210 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
211
212 ShadowMapping Mapping;
213
214 // OR-ing shadow offset if more efficient (at least on x86),
215 // but on ppc64 we have to use add since the shadow offset is not neccesary
216 // 1/8-th of the address space.
217 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
218
219 Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
220 (LongSize == 32 ? kDefaultShadowOffset32 :
221 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
222 if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
223 assert(LongSize == 64);
224 Mapping.Offset = kDefaultShort64bitShadowOffset;
225 }
226 if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
227 // Zero offset log is the special case.
228 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
229 }
230
231 Mapping.Scale = kDefaultShadowScale;
232 if (ClMappingScale) {
233 Mapping.Scale = ClMappingScale;
234 }
235
236 return Mapping;
237 }
238
RedzoneSizeForScale(int MappingScale)239 static size_t RedzoneSizeForScale(int MappingScale) {
240 // Redzone used for stack and globals is at least 32 bytes.
241 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
242 return std::max(32U, 1U << MappingScale);
243 }
244
245 /// AddressSanitizer: instrument the code in module to find memory bugs.
246 struct AddressSanitizer : public FunctionPass {
AddressSanitizer__anonff7727180111::AddressSanitizer247 AddressSanitizer(bool CheckInitOrder = true,
248 bool CheckUseAfterReturn = false,
249 bool CheckLifetime = false,
250 StringRef BlacklistFile = StringRef(),
251 bool ZeroBaseShadow = false)
252 : FunctionPass(ID),
253 CheckInitOrder(CheckInitOrder || ClInitializers),
254 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
255 CheckLifetime(CheckLifetime || ClCheckLifetime),
256 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
257 : BlacklistFile),
258 ZeroBaseShadow(ZeroBaseShadow) {}
getPassName__anonff7727180111::AddressSanitizer259 virtual const char *getPassName() const {
260 return "AddressSanitizerFunctionPass";
261 }
262 void instrumentMop(Instruction *I);
263 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
264 Value *Addr, uint32_t TypeSize, bool IsWrite,
265 Value *SizeArgument);
266 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
267 Value *ShadowValue, uint32_t TypeSize);
268 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
269 bool IsWrite, size_t AccessSizeIndex,
270 Value *SizeArgument);
271 bool instrumentMemIntrinsic(MemIntrinsic *MI);
272 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
273 Value *Size,
274 Instruction *InsertBefore, bool IsWrite);
275 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
276 bool runOnFunction(Function &F);
277 void createInitializerPoisonCalls(Module &M,
278 Value *FirstAddr, Value *LastAddr);
279 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
280 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
281 virtual bool doInitialization(Module &M);
282 static char ID; // Pass identification, replacement for typeid
283
284 private:
285 void initializeCallbacks(Module &M);
286
287 bool ShouldInstrumentGlobal(GlobalVariable *G);
288 bool LooksLikeCodeInBug11395(Instruction *I);
289 void FindDynamicInitializers(Module &M);
290
291 bool CheckInitOrder;
292 bool CheckUseAfterReturn;
293 bool CheckLifetime;
294 SmallString<64> BlacklistFile;
295 bool ZeroBaseShadow;
296
297 LLVMContext *C;
298 DataLayout *TD;
299 int LongSize;
300 Type *IntptrTy;
301 ShadowMapping Mapping;
302 Function *AsanCtorFunction;
303 Function *AsanInitFunction;
304 Function *AsanHandleNoReturnFunc;
305 OwningPtr<BlackList> BL;
306 // This array is indexed by AccessIsWrite and log2(AccessSize).
307 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
308 // This array is indexed by AccessIsWrite.
309 Function *AsanErrorCallbackSized[2];
310 InlineAsm *EmptyAsm;
311 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
312
313 friend struct FunctionStackPoisoner;
314 };
315
316 class AddressSanitizerModule : public ModulePass {
317 public:
AddressSanitizerModule(bool CheckInitOrder=true,StringRef BlacklistFile=StringRef (),bool ZeroBaseShadow=false)318 AddressSanitizerModule(bool CheckInitOrder = true,
319 StringRef BlacklistFile = StringRef(),
320 bool ZeroBaseShadow = false)
321 : ModulePass(ID),
322 CheckInitOrder(CheckInitOrder || ClInitializers),
323 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
324 : BlacklistFile),
325 ZeroBaseShadow(ZeroBaseShadow) {}
326 bool runOnModule(Module &M);
327 static char ID; // Pass identification, replacement for typeid
getPassName() const328 virtual const char *getPassName() const {
329 return "AddressSanitizerModule";
330 }
331
332 private:
333 void initializeCallbacks(Module &M);
334
335 bool ShouldInstrumentGlobal(GlobalVariable *G);
336 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
337 Value *LastAddr);
RedzoneSize() const338 size_t RedzoneSize() const {
339 return RedzoneSizeForScale(Mapping.Scale);
340 }
341
342 bool CheckInitOrder;
343 SmallString<64> BlacklistFile;
344 bool ZeroBaseShadow;
345
346 OwningPtr<BlackList> BL;
347 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
348 Type *IntptrTy;
349 LLVMContext *C;
350 DataLayout *TD;
351 ShadowMapping Mapping;
352 Function *AsanPoisonGlobals;
353 Function *AsanUnpoisonGlobals;
354 Function *AsanRegisterGlobals;
355 Function *AsanUnregisterGlobals;
356 };
357
358 // Stack poisoning does not play well with exception handling.
359 // When an exception is thrown, we essentially bypass the code
360 // that unpoisones the stack. This is why the run-time library has
361 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
362 // stack in the interceptor. This however does not work inside the
363 // actual function which catches the exception. Most likely because the
364 // compiler hoists the load of the shadow value somewhere too high.
365 // This causes asan to report a non-existing bug on 453.povray.
366 // It sounds like an LLVM bug.
367 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
368 Function &F;
369 AddressSanitizer &ASan;
370 DIBuilder DIB;
371 LLVMContext *C;
372 Type *IntptrTy;
373 Type *IntptrPtrTy;
374 ShadowMapping Mapping;
375
376 SmallVector<AllocaInst*, 16> AllocaVec;
377 SmallVector<Instruction*, 8> RetVec;
378 uint64_t TotalStackSize;
379 unsigned StackAlignment;
380
381 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
382 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
383
384 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
385 struct AllocaPoisonCall {
386 IntrinsicInst *InsBefore;
387 uint64_t Size;
388 bool DoPoison;
389 };
390 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
391
392 // Maps Value to an AllocaInst from which the Value is originated.
393 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
394 AllocaForValueMapTy AllocaForValue;
395
FunctionStackPoisoner__anonff7727180111::FunctionStackPoisoner396 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
397 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
398 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
399 Mapping(ASan.Mapping),
400 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
401
runOnFunction__anonff7727180111::FunctionStackPoisoner402 bool runOnFunction() {
403 if (!ClStack) return false;
404 // Collect alloca, ret, lifetime instructions etc.
405 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
406 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
407 BasicBlock *BB = *DI;
408 visit(*BB);
409 }
410 if (AllocaVec.empty()) return false;
411
412 initializeCallbacks(*F.getParent());
413
414 poisonStack();
415
416 if (ClDebugStack) {
417 DEBUG(dbgs() << F);
418 }
419 return true;
420 }
421
422 // Finds all static Alloca instructions and puts
423 // poisoned red zones around all of them.
424 // Then unpoison everything back before the function returns.
425 void poisonStack();
426
427 // ----------------------- Visitors.
428 /// \brief Collect all Ret instructions.
visitReturnInst__anonff7727180111::FunctionStackPoisoner429 void visitReturnInst(ReturnInst &RI) {
430 RetVec.push_back(&RI);
431 }
432
433 /// \brief Collect Alloca instructions we want (and can) handle.
visitAllocaInst__anonff7727180111::FunctionStackPoisoner434 void visitAllocaInst(AllocaInst &AI) {
435 if (!isInterestingAlloca(AI)) return;
436
437 StackAlignment = std::max(StackAlignment, AI.getAlignment());
438 AllocaVec.push_back(&AI);
439 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
440 TotalStackSize += AlignedSize;
441 }
442
443 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
444 /// errors.
visitIntrinsicInst__anonff7727180111::FunctionStackPoisoner445 void visitIntrinsicInst(IntrinsicInst &II) {
446 if (!ASan.CheckLifetime) return;
447 Intrinsic::ID ID = II.getIntrinsicID();
448 if (ID != Intrinsic::lifetime_start &&
449 ID != Intrinsic::lifetime_end)
450 return;
451 // Found lifetime intrinsic, add ASan instrumentation if necessary.
452 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
453 // If size argument is undefined, don't do anything.
454 if (Size->isMinusOne()) return;
455 // Check that size doesn't saturate uint64_t and can
456 // be stored in IntptrTy.
457 const uint64_t SizeValue = Size->getValue().getLimitedValue();
458 if (SizeValue == ~0ULL ||
459 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
460 return;
461 // Find alloca instruction that corresponds to llvm.lifetime argument.
462 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
463 if (!AI) return;
464 bool DoPoison = (ID == Intrinsic::lifetime_end);
465 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
466 AllocaPoisonCallVec.push_back(APC);
467 }
468
469 // ---------------------- Helpers.
470 void initializeCallbacks(Module &M);
471
472 // Check if we want (and can) handle this alloca.
isInterestingAlloca__anonff7727180111::FunctionStackPoisoner473 bool isInterestingAlloca(AllocaInst &AI) {
474 return (!AI.isArrayAllocation() &&
475 AI.isStaticAlloca() &&
476 AI.getAllocatedType()->isSized());
477 }
478
RedzoneSize__anonff7727180111::FunctionStackPoisoner479 size_t RedzoneSize() const {
480 return RedzoneSizeForScale(Mapping.Scale);
481 }
getAllocaSizeInBytes__anonff7727180111::FunctionStackPoisoner482 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
483 Type *Ty = AI->getAllocatedType();
484 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
485 return SizeInBytes;
486 }
getAlignedSize__anonff7727180111::FunctionStackPoisoner487 uint64_t getAlignedSize(uint64_t SizeInBytes) {
488 size_t RZ = RedzoneSize();
489 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
490 }
getAlignedAllocaSize__anonff7727180111::FunctionStackPoisoner491 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
492 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
493 return getAlignedSize(SizeInBytes);
494 }
495 /// Finds alloca where the value comes from.
496 AllocaInst *findAllocaForValue(Value *V);
497 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
498 Value *ShadowBase, bool DoPoison);
499 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
500 };
501
502 } // namespace
503
504 char AddressSanitizer::ID = 0;
505 INITIALIZE_PASS(AddressSanitizer, "asan",
506 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
507 false, false)
createAddressSanitizerFunctionPass(bool CheckInitOrder,bool CheckUseAfterReturn,bool CheckLifetime,StringRef BlacklistFile,bool ZeroBaseShadow)508 FunctionPass *llvm::createAddressSanitizerFunctionPass(
509 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
510 StringRef BlacklistFile, bool ZeroBaseShadow) {
511 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
512 CheckLifetime, BlacklistFile, ZeroBaseShadow);
513 }
514
515 char AddressSanitizerModule::ID = 0;
516 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
517 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
518 "ModulePass", false, false)
createAddressSanitizerModulePass(bool CheckInitOrder,StringRef BlacklistFile,bool ZeroBaseShadow)519 ModulePass *llvm::createAddressSanitizerModulePass(
520 bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
521 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
522 ZeroBaseShadow);
523 }
524
TypeSizeToSizeIndex(uint32_t TypeSize)525 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
526 size_t Res = CountTrailingZeros_32(TypeSize / 8);
527 assert(Res < kNumberOfAccessSizes);
528 return Res;
529 }
530
531 // Create a constant for Str so that we can pass it to the run-time lib.
createPrivateGlobalForString(Module & M,StringRef Str)532 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
533 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
534 GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
535 GlobalValue::PrivateLinkage, StrConst,
536 kAsanGenPrefix);
537 GV->setUnnamedAddr(true); // Ok to merge these.
538 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
539 return GV;
540 }
541
GlobalWasGeneratedByAsan(GlobalVariable * G)542 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
543 return G->getName().find(kAsanGenPrefix) == 0;
544 }
545
memToShadow(Value * Shadow,IRBuilder<> & IRB)546 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
547 // Shadow >> scale
548 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
549 if (Mapping.Offset == 0)
550 return Shadow;
551 // (Shadow >> scale) | offset
552 if (Mapping.OrShadowOffset)
553 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
554 else
555 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
556 }
557
instrumentMemIntrinsicParam(Instruction * OrigIns,Value * Addr,Value * Size,Instruction * InsertBefore,bool IsWrite)558 void AddressSanitizer::instrumentMemIntrinsicParam(
559 Instruction *OrigIns,
560 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
561 IRBuilder<> IRB(InsertBefore);
562 if (Size->getType() != IntptrTy)
563 Size = IRB.CreateIntCast(Size, IntptrTy, false);
564 // Check the first byte.
565 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
566 // Check the last byte.
567 IRB.SetInsertPoint(InsertBefore);
568 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
569 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
570 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
571 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
572 }
573
574 // Instrument memset/memmove/memcpy
instrumentMemIntrinsic(MemIntrinsic * MI)575 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
576 Value *Dst = MI->getDest();
577 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
578 Value *Src = MemTran ? MemTran->getSource() : 0;
579 Value *Length = MI->getLength();
580
581 Constant *ConstLength = dyn_cast<Constant>(Length);
582 Instruction *InsertBefore = MI;
583 if (ConstLength) {
584 if (ConstLength->isNullValue()) return false;
585 } else {
586 // The size is not a constant so it could be zero -- check at run-time.
587 IRBuilder<> IRB(InsertBefore);
588
589 Value *Cmp = IRB.CreateICmpNE(Length,
590 Constant::getNullValue(Length->getType()));
591 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
592 }
593
594 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
595 if (Src)
596 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
597 return true;
598 }
599
600 // If I is an interesting memory access, return the PointerOperand
601 // and set IsWrite. Otherwise return NULL.
isInterestingMemoryAccess(Instruction * I,bool * IsWrite)602 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
603 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
604 if (!ClInstrumentReads) return NULL;
605 *IsWrite = false;
606 return LI->getPointerOperand();
607 }
608 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
609 if (!ClInstrumentWrites) return NULL;
610 *IsWrite = true;
611 return SI->getPointerOperand();
612 }
613 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
614 if (!ClInstrumentAtomics) return NULL;
615 *IsWrite = true;
616 return RMW->getPointerOperand();
617 }
618 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
619 if (!ClInstrumentAtomics) return NULL;
620 *IsWrite = true;
621 return XCHG->getPointerOperand();
622 }
623 return NULL;
624 }
625
instrumentMop(Instruction * I)626 void AddressSanitizer::instrumentMop(Instruction *I) {
627 bool IsWrite = false;
628 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
629 assert(Addr);
630 if (ClOpt && ClOptGlobals) {
631 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
632 // If initialization order checking is disabled, a simple access to a
633 // dynamically initialized global is always valid.
634 if (!CheckInitOrder)
635 return;
636 // If a global variable does not have dynamic initialization we don't
637 // have to instrument it. However, if a global does not have initailizer
638 // at all, we assume it has dynamic initializer (in other TU).
639 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
640 return;
641 }
642 }
643
644 Type *OrigPtrTy = Addr->getType();
645 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
646
647 assert(OrigTy->isSized());
648 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
649
650 assert((TypeSize % 8) == 0);
651
652 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
653 if (TypeSize == 8 || TypeSize == 16 ||
654 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
655 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
656 // Instrument unusual size (but still multiple of 8).
657 // We can not do it with a single check, so we do 1-byte check for the first
658 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
659 // to report the actual access size.
660 IRBuilder<> IRB(I);
661 Value *LastByte = IRB.CreateIntToPtr(
662 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
663 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
664 OrigPtrTy);
665 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
666 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
667 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
668 }
669
670 // Validate the result of Module::getOrInsertFunction called for an interface
671 // function of AddressSanitizer. If the instrumented module defines a function
672 // with the same name, their prototypes must match, otherwise
673 // getOrInsertFunction returns a bitcast.
checkInterfaceFunction(Constant * FuncOrBitcast)674 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
675 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
676 FuncOrBitcast->dump();
677 report_fatal_error("trying to redefine an AddressSanitizer "
678 "interface function");
679 }
680
generateCrashCode(Instruction * InsertBefore,Value * Addr,bool IsWrite,size_t AccessSizeIndex,Value * SizeArgument)681 Instruction *AddressSanitizer::generateCrashCode(
682 Instruction *InsertBefore, Value *Addr,
683 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
684 IRBuilder<> IRB(InsertBefore);
685 CallInst *Call = SizeArgument
686 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
687 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
688
689 // We don't do Call->setDoesNotReturn() because the BB already has
690 // UnreachableInst at the end.
691 // This EmptyAsm is required to avoid callback merge.
692 IRB.CreateCall(EmptyAsm);
693 return Call;
694 }
695
createSlowPathCmp(IRBuilder<> & IRB,Value * AddrLong,Value * ShadowValue,uint32_t TypeSize)696 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
697 Value *ShadowValue,
698 uint32_t TypeSize) {
699 size_t Granularity = 1 << Mapping.Scale;
700 // Addr & (Granularity - 1)
701 Value *LastAccessedByte = IRB.CreateAnd(
702 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
703 // (Addr & (Granularity - 1)) + size - 1
704 if (TypeSize / 8 > 1)
705 LastAccessedByte = IRB.CreateAdd(
706 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
707 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
708 LastAccessedByte = IRB.CreateIntCast(
709 LastAccessedByte, ShadowValue->getType(), false);
710 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
711 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
712 }
713
instrumentAddress(Instruction * OrigIns,Instruction * InsertBefore,Value * Addr,uint32_t TypeSize,bool IsWrite,Value * SizeArgument)714 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
715 Instruction *InsertBefore,
716 Value *Addr, uint32_t TypeSize,
717 bool IsWrite, Value *SizeArgument) {
718 IRBuilder<> IRB(InsertBefore);
719 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
720
721 Type *ShadowTy = IntegerType::get(
722 *C, std::max(8U, TypeSize >> Mapping.Scale));
723 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
724 Value *ShadowPtr = memToShadow(AddrLong, IRB);
725 Value *CmpVal = Constant::getNullValue(ShadowTy);
726 Value *ShadowValue = IRB.CreateLoad(
727 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
728
729 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
730 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
731 size_t Granularity = 1 << Mapping.Scale;
732 TerminatorInst *CrashTerm = 0;
733
734 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
735 TerminatorInst *CheckTerm =
736 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
737 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
738 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
739 IRB.SetInsertPoint(CheckTerm);
740 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
741 BasicBlock *CrashBlock =
742 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
743 CrashTerm = new UnreachableInst(*C, CrashBlock);
744 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
745 ReplaceInstWithInst(CheckTerm, NewTerm);
746 } else {
747 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
748 }
749
750 Instruction *Crash = generateCrashCode(
751 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
752 Crash->setDebugLoc(OrigIns->getDebugLoc());
753 }
754
createInitializerPoisonCalls(Module & M,Value * FirstAddr,Value * LastAddr)755 void AddressSanitizerModule::createInitializerPoisonCalls(
756 Module &M, Value *FirstAddr, Value *LastAddr) {
757 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
758 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
759 // If that function is not present, this TU contains no globals, or they have
760 // all been optimized away
761 if (!GlobalInit)
762 return;
763
764 // Set up the arguments to our poison/unpoison functions.
765 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
766
767 // Add a call to poison all external globals before the given function starts.
768 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
769
770 // Add calls to unpoison all globals before each return instruction.
771 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
772 I != E; ++I) {
773 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
774 CallInst::Create(AsanUnpoisonGlobals, "", RI);
775 }
776 }
777 }
778
ShouldInstrumentGlobal(GlobalVariable * G)779 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
780 Type *Ty = cast<PointerType>(G->getType())->getElementType();
781 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
782
783 if (BL->isIn(*G)) return false;
784 if (!Ty->isSized()) return false;
785 if (!G->hasInitializer()) return false;
786 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
787 // Touch only those globals that will not be defined in other modules.
788 // Don't handle ODR type linkages since other modules may be built w/o asan.
789 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
790 G->getLinkage() != GlobalVariable::PrivateLinkage &&
791 G->getLinkage() != GlobalVariable::InternalLinkage)
792 return false;
793 // Two problems with thread-locals:
794 // - The address of the main thread's copy can't be computed at link-time.
795 // - Need to poison all copies, not just the main thread's one.
796 if (G->isThreadLocal())
797 return false;
798 // For now, just ignore this Alloca if the alignment is large.
799 if (G->getAlignment() > RedzoneSize()) return false;
800
801 // Ignore all the globals with the names starting with "\01L_OBJC_".
802 // Many of those are put into the .cstring section. The linker compresses
803 // that section by removing the spare \0s after the string terminator, so
804 // our redzones get broken.
805 if ((G->getName().find("\01L_OBJC_") == 0) ||
806 (G->getName().find("\01l_OBJC_") == 0)) {
807 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
808 return false;
809 }
810
811 if (G->hasSection()) {
812 StringRef Section(G->getSection());
813 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
814 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
815 // them.
816 if ((Section.find("__OBJC,") == 0) ||
817 (Section.find("__DATA, __objc_") == 0)) {
818 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
819 return false;
820 }
821 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
822 // Constant CFString instances are compiled in the following way:
823 // -- the string buffer is emitted into
824 // __TEXT,__cstring,cstring_literals
825 // -- the constant NSConstantString structure referencing that buffer
826 // is placed into __DATA,__cfstring
827 // Therefore there's no point in placing redzones into __DATA,__cfstring.
828 // Moreover, it causes the linker to crash on OS X 10.7
829 if (Section.find("__DATA,__cfstring") == 0) {
830 DEBUG(dbgs() << "Ignoring CFString: " << *G);
831 return false;
832 }
833 }
834
835 return true;
836 }
837
initializeCallbacks(Module & M)838 void AddressSanitizerModule::initializeCallbacks(Module &M) {
839 IRBuilder<> IRB(*C);
840 // Declare our poisoning and unpoisoning functions.
841 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
842 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
843 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
844 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
845 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
846 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
847 // Declare functions that register/unregister globals.
848 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
849 kAsanRegisterGlobalsName, IRB.getVoidTy(),
850 IntptrTy, IntptrTy, NULL));
851 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
852 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
853 kAsanUnregisterGlobalsName,
854 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
855 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
856 }
857
858 // This function replaces all global variables with new variables that have
859 // trailing redzones. It also creates a function that poisons
860 // redzones and inserts this function into llvm.global_ctors.
runOnModule(Module & M)861 bool AddressSanitizerModule::runOnModule(Module &M) {
862 if (!ClGlobals) return false;
863 TD = getAnalysisIfAvailable<DataLayout>();
864 if (!TD)
865 return false;
866 BL.reset(new BlackList(BlacklistFile));
867 if (BL->isIn(M)) return false;
868 C = &(M.getContext());
869 int LongSize = TD->getPointerSizeInBits();
870 IntptrTy = Type::getIntNTy(*C, LongSize);
871 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
872 initializeCallbacks(M);
873 DynamicallyInitializedGlobals.Init(M);
874
875 SmallVector<GlobalVariable *, 16> GlobalsToChange;
876
877 for (Module::GlobalListType::iterator G = M.global_begin(),
878 E = M.global_end(); G != E; ++G) {
879 if (ShouldInstrumentGlobal(G))
880 GlobalsToChange.push_back(G);
881 }
882
883 size_t n = GlobalsToChange.size();
884 if (n == 0) return false;
885
886 // A global is described by a structure
887 // size_t beg;
888 // size_t size;
889 // size_t size_with_redzone;
890 // const char *name;
891 // const char *module_name;
892 // size_t has_dynamic_init;
893 // We initialize an array of such structures and pass it to a run-time call.
894 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
895 IntptrTy, IntptrTy,
896 IntptrTy, IntptrTy, NULL);
897 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
898
899
900 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
901 assert(CtorFunc);
902 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
903
904 // The addresses of the first and last dynamically initialized globals in
905 // this TU. Used in initialization order checking.
906 Value *FirstDynamic = 0, *LastDynamic = 0;
907
908 GlobalVariable *ModuleName = createPrivateGlobalForString(
909 M, M.getModuleIdentifier());
910
911 for (size_t i = 0; i < n; i++) {
912 static const uint64_t kMaxGlobalRedzone = 1 << 18;
913 GlobalVariable *G = GlobalsToChange[i];
914 PointerType *PtrTy = cast<PointerType>(G->getType());
915 Type *Ty = PtrTy->getElementType();
916 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
917 uint64_t MinRZ = RedzoneSize();
918 // MinRZ <= RZ <= kMaxGlobalRedzone
919 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
920 uint64_t RZ = std::max(MinRZ,
921 std::min(kMaxGlobalRedzone,
922 (SizeInBytes / MinRZ / 4) * MinRZ));
923 uint64_t RightRedzoneSize = RZ;
924 // Round up to MinRZ
925 if (SizeInBytes % MinRZ)
926 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
927 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
928 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
929 // Determine whether this global should be poisoned in initialization.
930 bool GlobalHasDynamicInitializer =
931 DynamicallyInitializedGlobals.Contains(G);
932 // Don't check initialization order if this global is blacklisted.
933 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
934
935 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
936 Constant *NewInitializer = ConstantStruct::get(
937 NewTy, G->getInitializer(),
938 Constant::getNullValue(RightRedZoneTy), NULL);
939
940 GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
941
942 // Create a new global variable with enough space for a redzone.
943 GlobalVariable *NewGlobal = new GlobalVariable(
944 M, NewTy, G->isConstant(), G->getLinkage(),
945 NewInitializer, "", G, G->getThreadLocalMode());
946 NewGlobal->copyAttributesFrom(G);
947 NewGlobal->setAlignment(MinRZ);
948
949 Value *Indices2[2];
950 Indices2[0] = IRB.getInt32(0);
951 Indices2[1] = IRB.getInt32(0);
952
953 G->replaceAllUsesWith(
954 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
955 NewGlobal->takeName(G);
956 G->eraseFromParent();
957
958 Initializers[i] = ConstantStruct::get(
959 GlobalStructTy,
960 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
961 ConstantInt::get(IntptrTy, SizeInBytes),
962 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
963 ConstantExpr::getPointerCast(Name, IntptrTy),
964 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
965 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
966 NULL);
967
968 // Populate the first and last globals declared in this TU.
969 if (CheckInitOrder && GlobalHasDynamicInitializer) {
970 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
971 if (FirstDynamic == 0)
972 FirstDynamic = LastDynamic;
973 }
974
975 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
976 }
977
978 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
979 GlobalVariable *AllGlobals = new GlobalVariable(
980 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
981 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
982
983 // Create calls for poisoning before initializers run and unpoisoning after.
984 if (CheckInitOrder && FirstDynamic && LastDynamic)
985 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
986 IRB.CreateCall2(AsanRegisterGlobals,
987 IRB.CreatePointerCast(AllGlobals, IntptrTy),
988 ConstantInt::get(IntptrTy, n));
989
990 // We also need to unregister globals at the end, e.g. when a shared library
991 // gets closed.
992 Function *AsanDtorFunction = Function::Create(
993 FunctionType::get(Type::getVoidTy(*C), false),
994 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
995 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
996 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
997 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
998 IRB.CreatePointerCast(AllGlobals, IntptrTy),
999 ConstantInt::get(IntptrTy, n));
1000 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1001
1002 DEBUG(dbgs() << M);
1003 return true;
1004 }
1005
initializeCallbacks(Module & M)1006 void AddressSanitizer::initializeCallbacks(Module &M) {
1007 IRBuilder<> IRB(*C);
1008 // Create __asan_report* callbacks.
1009 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1010 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1011 AccessSizeIndex++) {
1012 // IsWrite and TypeSize are encoded in the function name.
1013 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1014 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1015 // If we are merging crash callbacks, they have two parameters.
1016 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1017 checkInterfaceFunction(M.getOrInsertFunction(
1018 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1019 }
1020 }
1021 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1022 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1023 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1024 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1025
1026 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1027 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1028 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1029 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1030 StringRef(""), StringRef(""),
1031 /*hasSideEffects=*/true);
1032 }
1033
emitShadowMapping(Module & M,IRBuilder<> & IRB) const1034 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1035 // Tell the values of mapping offset and scale to the run-time.
1036 GlobalValue *asan_mapping_offset =
1037 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1038 ConstantInt::get(IntptrTy, Mapping.Offset),
1039 kAsanMappingOffsetName);
1040 // Read the global, otherwise it may be optimized away.
1041 IRB.CreateLoad(asan_mapping_offset, true);
1042
1043 GlobalValue *asan_mapping_scale =
1044 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1045 ConstantInt::get(IntptrTy, Mapping.Scale),
1046 kAsanMappingScaleName);
1047 // Read the global, otherwise it may be optimized away.
1048 IRB.CreateLoad(asan_mapping_scale, true);
1049 }
1050
1051 // virtual
doInitialization(Module & M)1052 bool AddressSanitizer::doInitialization(Module &M) {
1053 // Initialize the private fields. No one has accessed them before.
1054 TD = getAnalysisIfAvailable<DataLayout>();
1055
1056 if (!TD)
1057 return false;
1058 BL.reset(new BlackList(BlacklistFile));
1059 DynamicallyInitializedGlobals.Init(M);
1060
1061 C = &(M.getContext());
1062 LongSize = TD->getPointerSizeInBits();
1063 IntptrTy = Type::getIntNTy(*C, LongSize);
1064
1065 AsanCtorFunction = Function::Create(
1066 FunctionType::get(Type::getVoidTy(*C), false),
1067 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1068 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1069 // call __asan_init in the module ctor.
1070 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1071 AsanInitFunction = checkInterfaceFunction(
1072 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1073 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1074 IRB.CreateCall(AsanInitFunction);
1075
1076 Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1077 emitShadowMapping(M, IRB);
1078
1079 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1080 return true;
1081 }
1082
maybeInsertAsanInitAtFunctionEntry(Function & F)1083 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1084 // For each NSObject descendant having a +load method, this method is invoked
1085 // by the ObjC runtime before any of the static constructors is called.
1086 // Therefore we need to instrument such methods with a call to __asan_init
1087 // at the beginning in order to initialize our runtime before any access to
1088 // the shadow memory.
1089 // We cannot just ignore these methods, because they may call other
1090 // instrumented functions.
1091 if (F.getName().find(" load]") != std::string::npos) {
1092 IRBuilder<> IRB(F.begin()->begin());
1093 IRB.CreateCall(AsanInitFunction);
1094 return true;
1095 }
1096 return false;
1097 }
1098
runOnFunction(Function & F)1099 bool AddressSanitizer::runOnFunction(Function &F) {
1100 if (BL->isIn(F)) return false;
1101 if (&F == AsanCtorFunction) return false;
1102 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1103 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1104 initializeCallbacks(*F.getParent());
1105
1106 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1107 maybeInsertAsanInitAtFunctionEntry(F);
1108
1109 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1110 Attribute::SanitizeAddress))
1111 return false;
1112
1113 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1114 return false;
1115
1116 // We want to instrument every address only once per basic block (unless there
1117 // are calls between uses).
1118 SmallSet<Value*, 16> TempsToInstrument;
1119 SmallVector<Instruction*, 16> ToInstrument;
1120 SmallVector<Instruction*, 8> NoReturnCalls;
1121 bool IsWrite;
1122
1123 // Fill the set of memory operations to instrument.
1124 for (Function::iterator FI = F.begin(), FE = F.end();
1125 FI != FE; ++FI) {
1126 TempsToInstrument.clear();
1127 int NumInsnsPerBB = 0;
1128 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1129 BI != BE; ++BI) {
1130 if (LooksLikeCodeInBug11395(BI)) return false;
1131 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1132 if (ClOpt && ClOptSameTemp) {
1133 if (!TempsToInstrument.insert(Addr))
1134 continue; // We've seen this temp in the current BB.
1135 }
1136 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1137 // ok, take it.
1138 } else {
1139 CallSite CS(BI);
1140 if (CS) {
1141 // A call inside BB.
1142 TempsToInstrument.clear();
1143 if (CS.doesNotReturn())
1144 NoReturnCalls.push_back(CS.getInstruction());
1145 }
1146 continue;
1147 }
1148 ToInstrument.push_back(BI);
1149 NumInsnsPerBB++;
1150 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1151 break;
1152 }
1153 }
1154
1155 // Instrument.
1156 int NumInstrumented = 0;
1157 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1158 Instruction *Inst = ToInstrument[i];
1159 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1160 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1161 if (isInterestingMemoryAccess(Inst, &IsWrite))
1162 instrumentMop(Inst);
1163 else
1164 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1165 }
1166 NumInstrumented++;
1167 }
1168
1169 FunctionStackPoisoner FSP(F, *this);
1170 bool ChangedStack = FSP.runOnFunction();
1171
1172 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1173 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1174 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1175 Instruction *CI = NoReturnCalls[i];
1176 IRBuilder<> IRB(CI);
1177 IRB.CreateCall(AsanHandleNoReturnFunc);
1178 }
1179 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1180
1181 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1182 }
1183
ValueForPoison(uint64_t PoisonByte,size_t ShadowRedzoneSize)1184 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1185 if (ShadowRedzoneSize == 1) return PoisonByte;
1186 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1187 if (ShadowRedzoneSize == 4)
1188 return (PoisonByte << 24) + (PoisonByte << 16) +
1189 (PoisonByte << 8) + (PoisonByte);
1190 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1191 }
1192
PoisonShadowPartialRightRedzone(uint8_t * Shadow,size_t Size,size_t RZSize,size_t ShadowGranularity,uint8_t Magic)1193 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1194 size_t Size,
1195 size_t RZSize,
1196 size_t ShadowGranularity,
1197 uint8_t Magic) {
1198 for (size_t i = 0; i < RZSize;
1199 i+= ShadowGranularity, Shadow++) {
1200 if (i + ShadowGranularity <= Size) {
1201 *Shadow = 0; // fully addressable
1202 } else if (i >= Size) {
1203 *Shadow = Magic; // unaddressable
1204 } else {
1205 *Shadow = Size - i; // first Size-i bytes are addressable
1206 }
1207 }
1208 }
1209
1210 // Workaround for bug 11395: we don't want to instrument stack in functions
1211 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1212 // FIXME: remove once the bug 11395 is fixed.
LooksLikeCodeInBug11395(Instruction * I)1213 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1214 if (LongSize != 32) return false;
1215 CallInst *CI = dyn_cast<CallInst>(I);
1216 if (!CI || !CI->isInlineAsm()) return false;
1217 if (CI->getNumArgOperands() <= 5) return false;
1218 // We have inline assembly with quite a few arguments.
1219 return true;
1220 }
1221
initializeCallbacks(Module & M)1222 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1223 IRBuilder<> IRB(*C);
1224 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1225 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1226 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1227 kAsanStackFreeName, IRB.getVoidTy(),
1228 IntptrTy, IntptrTy, IntptrTy, NULL));
1229 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1230 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1231 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1232 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1233 }
1234
poisonRedZones(const ArrayRef<AllocaInst * > & AllocaVec,IRBuilder<> IRB,Value * ShadowBase,bool DoPoison)1235 void FunctionStackPoisoner::poisonRedZones(
1236 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1237 bool DoPoison) {
1238 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1239 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1240 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1241 Type *RZPtrTy = PointerType::get(RZTy, 0);
1242
1243 Value *PoisonLeft = ConstantInt::get(RZTy,
1244 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1245 Value *PoisonMid = ConstantInt::get(RZTy,
1246 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1247 Value *PoisonRight = ConstantInt::get(RZTy,
1248 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1249
1250 // poison the first red zone.
1251 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1252
1253 // poison all other red zones.
1254 uint64_t Pos = RedzoneSize();
1255 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1256 AllocaInst *AI = AllocaVec[i];
1257 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1258 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1259 assert(AlignedSize - SizeInBytes < RedzoneSize());
1260 Value *Ptr = NULL;
1261
1262 Pos += AlignedSize;
1263
1264 assert(ShadowBase->getType() == IntptrTy);
1265 if (SizeInBytes < AlignedSize) {
1266 // Poison the partial redzone at right
1267 Ptr = IRB.CreateAdd(
1268 ShadowBase, ConstantInt::get(IntptrTy,
1269 (Pos >> Mapping.Scale) - ShadowRZSize));
1270 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1271 uint32_t Poison = 0;
1272 if (DoPoison) {
1273 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1274 RedzoneSize(),
1275 1ULL << Mapping.Scale,
1276 kAsanStackPartialRedzoneMagic);
1277 }
1278 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1279 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1280 }
1281
1282 // Poison the full redzone at right.
1283 Ptr = IRB.CreateAdd(ShadowBase,
1284 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1285 bool LastAlloca = (i == AllocaVec.size() - 1);
1286 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1287 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1288
1289 Pos += RedzoneSize();
1290 }
1291 }
1292
poisonStack()1293 void FunctionStackPoisoner::poisonStack() {
1294 uint64_t LocalStackSize = TotalStackSize +
1295 (AllocaVec.size() + 1) * RedzoneSize();
1296
1297 bool DoStackMalloc = ASan.CheckUseAfterReturn
1298 && LocalStackSize <= kMaxStackMallocSize;
1299
1300 assert(AllocaVec.size() > 0);
1301 Instruction *InsBefore = AllocaVec[0];
1302 IRBuilder<> IRB(InsBefore);
1303
1304
1305 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1306 AllocaInst *MyAlloca =
1307 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1308 if (ClRealignStack && StackAlignment < RedzoneSize())
1309 StackAlignment = RedzoneSize();
1310 MyAlloca->setAlignment(StackAlignment);
1311 assert(MyAlloca->isStaticAlloca());
1312 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1313 Value *LocalStackBase = OrigStackBase;
1314
1315 if (DoStackMalloc) {
1316 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1317 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1318 }
1319
1320 // This string will be parsed by the run-time (DescribeStackAddress).
1321 SmallString<2048> StackDescriptionStorage;
1322 raw_svector_ostream StackDescription(StackDescriptionStorage);
1323 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1324
1325 // Insert poison calls for lifetime intrinsics for alloca.
1326 bool HavePoisonedAllocas = false;
1327 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1328 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1329 IntrinsicInst *II = APC.InsBefore;
1330 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1331 assert(AI);
1332 IRBuilder<> IRB(II);
1333 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1334 HavePoisonedAllocas |= APC.DoPoison;
1335 }
1336
1337 uint64_t Pos = RedzoneSize();
1338 // Replace Alloca instructions with base+offset.
1339 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1340 AllocaInst *AI = AllocaVec[i];
1341 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1342 StringRef Name = AI->getName();
1343 StackDescription << Pos << " " << SizeInBytes << " "
1344 << Name.size() << " " << Name << " ";
1345 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1346 assert((AlignedSize % RedzoneSize()) == 0);
1347 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1348 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1349 AI->getType());
1350 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1351 AI->replaceAllUsesWith(NewAllocaPtr);
1352 Pos += AlignedSize + RedzoneSize();
1353 }
1354 assert(Pos == LocalStackSize);
1355
1356 // Write the Magic value and the frame description constant to the redzone.
1357 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1358 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1359 BasePlus0);
1360 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1361 ConstantInt::get(IntptrTy,
1362 ASan.LongSize/8));
1363 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1364 GlobalVariable *StackDescriptionGlobal =
1365 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1366 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1367 IntptrTy);
1368 IRB.CreateStore(Description, BasePlus1);
1369
1370 // Poison the stack redzones at the entry.
1371 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1372 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1373
1374 // Unpoison the stack before all ret instructions.
1375 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1376 Instruction *Ret = RetVec[i];
1377 IRBuilder<> IRBRet(Ret);
1378 // Mark the current frame as retired.
1379 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1380 BasePlus0);
1381 // Unpoison the stack.
1382 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1383 if (DoStackMalloc) {
1384 // In use-after-return mode, mark the whole stack frame unaddressable.
1385 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1386 ConstantInt::get(IntptrTy, LocalStackSize),
1387 OrigStackBase);
1388 } else if (HavePoisonedAllocas) {
1389 // If we poisoned some allocas in llvm.lifetime analysis,
1390 // unpoison whole stack frame now.
1391 assert(LocalStackBase == OrigStackBase);
1392 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1393 }
1394 }
1395
1396 // We are done. Remove the old unused alloca instructions.
1397 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1398 AllocaVec[i]->eraseFromParent();
1399 }
1400
poisonAlloca(Value * V,uint64_t Size,IRBuilder<> IRB,bool DoPoison)1401 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1402 IRBuilder<> IRB, bool DoPoison) {
1403 // For now just insert the call to ASan runtime.
1404 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1405 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1406 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1407 : AsanUnpoisonStackMemoryFunc,
1408 AddrArg, SizeArg);
1409 }
1410
1411 // Handling llvm.lifetime intrinsics for a given %alloca:
1412 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1413 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1414 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1415 // could be poisoned by previous llvm.lifetime.end instruction, as the
1416 // variable may go in and out of scope several times, e.g. in loops).
1417 // (3) if we poisoned at least one %alloca in a function,
1418 // unpoison the whole stack frame at function exit.
1419
findAllocaForValue(Value * V)1420 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1421 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1422 // We're intested only in allocas we can handle.
1423 return isInterestingAlloca(*AI) ? AI : 0;
1424 // See if we've already calculated (or started to calculate) alloca for a
1425 // given value.
1426 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1427 if (I != AllocaForValue.end())
1428 return I->second;
1429 // Store 0 while we're calculating alloca for value V to avoid
1430 // infinite recursion if the value references itself.
1431 AllocaForValue[V] = 0;
1432 AllocaInst *Res = 0;
1433 if (CastInst *CI = dyn_cast<CastInst>(V))
1434 Res = findAllocaForValue(CI->getOperand(0));
1435 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1436 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1437 Value *IncValue = PN->getIncomingValue(i);
1438 // Allow self-referencing phi-nodes.
1439 if (IncValue == PN) continue;
1440 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1441 // AI for incoming values should exist and should all be equal.
1442 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1443 return 0;
1444 Res = IncValueAI;
1445 }
1446 }
1447 if (Res != 0)
1448 AllocaForValue[V] = Res;
1449 return Res;
1450 }
1451