AddressSanitizer.cpp revision ee548275c63a1eeffda9d3edd2bea04e1dadcc67 
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 "BlackList.h"
19#include "llvm/Function.h"
20#include "llvm/IRBuilder.h"
21#include "llvm/InlineAsm.h"
22#include "llvm/IntrinsicInst.h"
23#include "llvm/LLVMContext.h"
24#include "llvm/Module.h"
25#include "llvm/Type.h"
26#include "llvm/ADT/ArrayRef.h"
27#include "llvm/ADT/OwningPtr.h"
28#include "llvm/ADT/SmallSet.h"
29#include "llvm/ADT/SmallString.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/ADT/StringExtras.h"
32#include "llvm/ADT/Triple.h"
33#include "llvm/Support/CommandLine.h"
34#include "llvm/Support/DataTypes.h"
35#include "llvm/Support/Debug.h"
36#include "llvm/Support/raw_ostream.h"
37#include "llvm/Support/system_error.h"
38#include "llvm/DataLayout.h"
39#include "llvm/Target/TargetMachine.h"
40#include "llvm/Transforms/Instrumentation.h"
41#include "llvm/Transforms/Utils/BasicBlockUtils.h"
42#include "llvm/Transforms/Utils/ModuleUtils.h"
43
44#include <string>
45#include <algorithm>
46
47using namespace llvm;
48
49static const uint64_t kDefaultShadowScale = 3;
50static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
51static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
52static const uint64_t kDefaultShadowOffsetAndroid = 0;
53
54static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
55static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
56static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
57
58static const char *kAsanModuleCtorName = "asan.module_ctor";
59static const char *kAsanModuleDtorName = "asan.module_dtor";
60static const int   kAsanCtorAndCtorPriority = 1;
61static const char *kAsanReportErrorTemplate = "__asan_report_";
62static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
63static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
64static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
65static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
66static const char *kAsanInitName = "__asan_init";
67static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
68static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
69static const char *kAsanMappingScaleName = "__asan_mapping_scale";
70static const char *kAsanStackMallocName = "__asan_stack_malloc";
71static const char *kAsanStackFreeName = "__asan_stack_free";
72static const char *kAsanGenPrefix = "__asan_gen_";
73
74static const int kAsanStackLeftRedzoneMagic = 0xf1;
75static const int kAsanStackMidRedzoneMagic = 0xf2;
76static const int kAsanStackRightRedzoneMagic = 0xf3;
77static const int kAsanStackPartialRedzoneMagic = 0xf4;
78
79// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
80static const size_t kNumberOfAccessSizes = 5;
81
82// Command-line flags.
83
84// This flag may need to be replaced with -f[no-]asan-reads.
85static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
86       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
87static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
88       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
89static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
90       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
91       cl::Hidden, cl::init(true));
92static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
93       cl::desc("use instrumentation with slow path for all accesses"),
94       cl::Hidden, cl::init(false));
95// This flag limits the number of instructions to be instrumented
96// in any given BB. Normally, this should be set to unlimited (INT_MAX),
97// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
98// set it to 10000.
99static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
100       cl::init(10000),
101       cl::desc("maximal number of instructions to instrument in any given BB"),
102       cl::Hidden);
103// This flag may need to be replaced with -f[no]asan-stack.
104static cl::opt<bool> ClStack("asan-stack",
105       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
106// This flag may need to be replaced with -f[no]asan-use-after-return.
107static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
108       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
109// This flag may need to be replaced with -f[no]asan-globals.
110static cl::opt<bool> ClGlobals("asan-globals",
111       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
112static cl::opt<bool> ClInitializers("asan-initialization-order",
113       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
114static cl::opt<bool> ClMemIntrin("asan-memintrin",
115       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
116// This flag may need to be replaced with -fasan-blacklist.
117static cl::opt<std::string>  ClBlackListFile("asan-blacklist",
118       cl::desc("File containing the list of functions to ignore "
119                "during instrumentation"), cl::Hidden);
120
121// These flags allow to change the shadow mapping.
122// The shadow mapping looks like
123//    Shadow = (Mem >> scale) + (1 << offset_log)
124static cl::opt<int> ClMappingScale("asan-mapping-scale",
125       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
126static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
127       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
128
129// Optimization flags. Not user visible, used mostly for testing
130// and benchmarking the tool.
131static cl::opt<bool> ClOpt("asan-opt",
132       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
133static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
134       cl::desc("Instrument the same temp just once"), cl::Hidden,
135       cl::init(true));
136static cl::opt<bool> ClOptGlobals("asan-opt-globals",
137       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
138
139static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
140       cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
141       cl::Hidden, cl::init(false));
142
143// Debug flags.
144static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
145                            cl::init(0));
146static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
147                                 cl::Hidden, cl::init(0));
148static cl::opt<std::string> ClDebugFunc("asan-debug-func",
149                                        cl::Hidden, cl::desc("Debug func"));
150static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
151                               cl::Hidden, cl::init(-1));
152static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
153                               cl::Hidden, cl::init(-1));
154
155namespace {
156/// A set of dynamically initialized globals extracted from metadata.
157class SetOfDynamicallyInitializedGlobals {
158 public:
159  void Init(Module& M) {
160    // Clang generates metadata identifying all dynamically initialized globals.
161    NamedMDNode *DynamicGlobals =
162        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
163    if (!DynamicGlobals)
164      return;
165    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
166      MDNode *MDN = DynamicGlobals->getOperand(i);
167      assert(MDN->getNumOperands() == 1);
168      Value *VG = MDN->getOperand(0);
169      // The optimizer may optimize away a global entirely, in which case we
170      // cannot instrument access to it.
171      if (!VG)
172        continue;
173      DynInitGlobals.insert(cast<GlobalVariable>(VG));
174    }
175  }
176  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
177 private:
178  SmallSet<GlobalValue*, 32> DynInitGlobals;
179};
180
181static int MappingScale() {
182  return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
183}
184
185static size_t RedzoneSize() {
186  // Redzone used for stack and globals is at least 32 bytes.
187  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
188  return std::max(32U, 1U << MappingScale());
189}
190
191/// AddressSanitizer: instrument the code in module to find memory bugs.
192struct AddressSanitizer : public FunctionPass {
193  AddressSanitizer(bool CheckInitOrder = false,
194                   bool CheckUseAfterReturn = false,
195                   bool CheckLifetime = false)
196      : FunctionPass(ID),
197        CheckInitOrder(CheckInitOrder || ClInitializers),
198        CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
199        CheckLifetime(CheckLifetime || ClCheckLifetime) {}
200  virtual const char *getPassName() const {
201    return "AddressSanitizerFunctionPass";
202  }
203  void instrumentMop(Instruction *I);
204  void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
205                         Value *Addr, uint32_t TypeSize, bool IsWrite);
206  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
207                           Value *ShadowValue, uint32_t TypeSize);
208  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
209                                 bool IsWrite, size_t AccessSizeIndex);
210  bool instrumentMemIntrinsic(MemIntrinsic *MI);
211  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
212                                   Value *Size,
213                                   Instruction *InsertBefore, bool IsWrite);
214  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
215  bool runOnFunction(Function &F);
216  void createInitializerPoisonCalls(Module &M,
217                                    Value *FirstAddr, Value *LastAddr);
218  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
219  bool poisonStackInFunction(Function &F);
220  virtual bool doInitialization(Module &M);
221  static char ID;  // Pass identification, replacement for typeid
222
223 private:
224  void initializeCallbacks(Module &M);
225  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
226    Type *Ty = AI->getAllocatedType();
227    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
228    return SizeInBytes;
229  }
230  uint64_t getAlignedSize(uint64_t SizeInBytes) {
231    size_t RZ = RedzoneSize();
232    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
233  }
234  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
235    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
236    return getAlignedSize(SizeInBytes);
237  }
238
239  bool ShouldInstrumentGlobal(GlobalVariable *G);
240  void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
241                   Value *ShadowBase, bool DoPoison);
242  bool LooksLikeCodeInBug11395(Instruction *I);
243  void FindDynamicInitializers(Module &M);
244
245  bool CheckInitOrder;
246  bool CheckUseAfterReturn;
247  bool CheckLifetime;
248  LLVMContext *C;
249  DataLayout *TD;
250  uint64_t MappingOffset;
251  int LongSize;
252  Type *IntptrTy;
253  Type *IntptrPtrTy;
254  Function *AsanCtorFunction;
255  Function *AsanInitFunction;
256  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
257  Function *AsanHandleNoReturnFunc;
258  OwningPtr<BlackList> BL;
259  // This array is indexed by AccessIsWrite and log2(AccessSize).
260  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
261  InlineAsm *EmptyAsm;
262  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
263};
264
265class AddressSanitizerModule : public ModulePass {
266 public:
267  AddressSanitizerModule(bool CheckInitOrder = false)
268      : ModulePass(ID),
269        CheckInitOrder(CheckInitOrder || ClInitializers) {}
270  bool runOnModule(Module &M);
271  static char ID;  // Pass identification, replacement for typeid
272  virtual const char *getPassName() const {
273    return "AddressSanitizerModule";
274  }
275 private:
276  bool ShouldInstrumentGlobal(GlobalVariable *G);
277  void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
278                                    Value *LastAddr);
279
280  bool CheckInitOrder;
281  OwningPtr<BlackList> BL;
282  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
283  Type *IntptrTy;
284  LLVMContext *C;
285  DataLayout *TD;
286};
287
288}  // namespace
289
290char AddressSanitizer::ID = 0;
291INITIALIZE_PASS(AddressSanitizer, "asan",
292    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
293    false, false)
294FunctionPass *llvm::createAddressSanitizerFunctionPass(
295    bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime) {
296  return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
297                              CheckLifetime);
298}
299
300char AddressSanitizerModule::ID = 0;
301INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
302    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
303    "ModulePass", false, false)
304ModulePass *llvm::createAddressSanitizerModulePass(bool CheckInitOrder) {
305  return new AddressSanitizerModule(CheckInitOrder);
306}
307
308static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
309  size_t Res = CountTrailingZeros_32(TypeSize / 8);
310  assert(Res < kNumberOfAccessSizes);
311  return Res;
312}
313
314// Create a constant for Str so that we can pass it to the run-time lib.
315static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
316  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
317  return new GlobalVariable(M, StrConst->getType(), true,
318                            GlobalValue::PrivateLinkage, StrConst,
319                            kAsanGenPrefix);
320}
321
322static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
323  return G->getName().find(kAsanGenPrefix) == 0;
324}
325
326Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
327  // Shadow >> scale
328  Shadow = IRB.CreateLShr(Shadow, MappingScale());
329  if (MappingOffset == 0)
330    return Shadow;
331  // (Shadow >> scale) | offset
332  return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
333                                               MappingOffset));
334}
335
336void AddressSanitizer::instrumentMemIntrinsicParam(
337    Instruction *OrigIns,
338    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
339  // Check the first byte.
340  {
341    IRBuilder<> IRB(InsertBefore);
342    instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
343  }
344  // Check the last byte.
345  {
346    IRBuilder<> IRB(InsertBefore);
347    Value *SizeMinusOne = IRB.CreateSub(
348        Size, ConstantInt::get(Size->getType(), 1));
349    SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
350    Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
351    Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
352    instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
353  }
354}
355
356// Instrument memset/memmove/memcpy
357bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
358  Value *Dst = MI->getDest();
359  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
360  Value *Src = MemTran ? MemTran->getSource() : 0;
361  Value *Length = MI->getLength();
362
363  Constant *ConstLength = dyn_cast<Constant>(Length);
364  Instruction *InsertBefore = MI;
365  if (ConstLength) {
366    if (ConstLength->isNullValue()) return false;
367  } else {
368    // The size is not a constant so it could be zero -- check at run-time.
369    IRBuilder<> IRB(InsertBefore);
370
371    Value *Cmp = IRB.CreateICmpNE(Length,
372                                  Constant::getNullValue(Length->getType()));
373    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
374  }
375
376  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
377  if (Src)
378    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
379  return true;
380}
381
382// If I is an interesting memory access, return the PointerOperand
383// and set IsWrite. Otherwise return NULL.
384static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
385  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
386    if (!ClInstrumentReads) return NULL;
387    *IsWrite = false;
388    return LI->getPointerOperand();
389  }
390  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
391    if (!ClInstrumentWrites) return NULL;
392    *IsWrite = true;
393    return SI->getPointerOperand();
394  }
395  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
396    if (!ClInstrumentAtomics) return NULL;
397    *IsWrite = true;
398    return RMW->getPointerOperand();
399  }
400  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
401    if (!ClInstrumentAtomics) return NULL;
402    *IsWrite = true;
403    return XCHG->getPointerOperand();
404  }
405  return NULL;
406}
407
408void AddressSanitizer::instrumentMop(Instruction *I) {
409  bool IsWrite = false;
410  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
411  assert(Addr);
412  if (ClOpt && ClOptGlobals) {
413    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
414      // If initialization order checking is disabled, a simple access to a
415      // dynamically initialized global is always valid.
416      if (!CheckInitOrder)
417        return;
418      // If a global variable does not have dynamic initialization we don't
419      // have to instrument it.  However, if a global does not have initailizer
420      // at all, we assume it has dynamic initializer (in other TU).
421      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
422        return;
423    }
424  }
425
426  Type *OrigPtrTy = Addr->getType();
427  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
428
429  assert(OrigTy->isSized());
430  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
431
432  if (TypeSize != 8  && TypeSize != 16 &&
433      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
434    // Ignore all unusual sizes.
435    return;
436  }
437
438  IRBuilder<> IRB(I);
439  instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
440}
441
442// Validate the result of Module::getOrInsertFunction called for an interface
443// function of AddressSanitizer. If the instrumented module defines a function
444// with the same name, their prototypes must match, otherwise
445// getOrInsertFunction returns a bitcast.
446static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
447  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
448  FuncOrBitcast->dump();
449  report_fatal_error("trying to redefine an AddressSanitizer "
450                     "interface function");
451}
452
453Instruction *AddressSanitizer::generateCrashCode(
454    Instruction *InsertBefore, Value *Addr,
455    bool IsWrite, size_t AccessSizeIndex) {
456  IRBuilder<> IRB(InsertBefore);
457  CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
458                                  Addr);
459  // We don't do Call->setDoesNotReturn() because the BB already has
460  // UnreachableInst at the end.
461  // This EmptyAsm is required to avoid callback merge.
462  IRB.CreateCall(EmptyAsm);
463  return Call;
464}
465
466Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
467                                            Value *ShadowValue,
468                                            uint32_t TypeSize) {
469  size_t Granularity = 1 << MappingScale();
470  // Addr & (Granularity - 1)
471  Value *LastAccessedByte = IRB.CreateAnd(
472      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
473  // (Addr & (Granularity - 1)) + size - 1
474  if (TypeSize / 8 > 1)
475    LastAccessedByte = IRB.CreateAdd(
476        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
477  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
478  LastAccessedByte = IRB.CreateIntCast(
479      LastAccessedByte, ShadowValue->getType(), false);
480  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
481  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
482}
483
484void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
485                                         IRBuilder<> &IRB, Value *Addr,
486                                         uint32_t TypeSize, bool IsWrite) {
487  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
488
489  Type *ShadowTy  = IntegerType::get(
490      *C, std::max(8U, TypeSize >> MappingScale()));
491  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
492  Value *ShadowPtr = memToShadow(AddrLong, IRB);
493  Value *CmpVal = Constant::getNullValue(ShadowTy);
494  Value *ShadowValue = IRB.CreateLoad(
495      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
496
497  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
498  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
499  size_t Granularity = 1 << MappingScale();
500  TerminatorInst *CrashTerm = 0;
501
502  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
503    TerminatorInst *CheckTerm =
504        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
505    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
506    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
507    IRB.SetInsertPoint(CheckTerm);
508    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
509    BasicBlock *CrashBlock =
510        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
511    CrashTerm = new UnreachableInst(*C, CrashBlock);
512    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
513    ReplaceInstWithInst(CheckTerm, NewTerm);
514  } else {
515    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
516  }
517
518  Instruction *Crash =
519      generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
520  Crash->setDebugLoc(OrigIns->getDebugLoc());
521}
522
523void AddressSanitizerModule::createInitializerPoisonCalls(
524    Module &M, Value *FirstAddr, Value *LastAddr) {
525  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
526  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
527  // If that function is not present, this TU contains no globals, or they have
528  // all been optimized away
529  if (!GlobalInit)
530    return;
531
532  // Set up the arguments to our poison/unpoison functions.
533  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
534
535  // Declare our poisoning and unpoisoning functions.
536  Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
537      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
538  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
539  Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
540      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
541  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
542
543  // Add a call to poison all external globals before the given function starts.
544  IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
545
546  // Add calls to unpoison all globals before each return instruction.
547  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
548      I != E; ++I) {
549    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
550      CallInst::Create(AsanUnpoisonGlobals, "", RI);
551    }
552  }
553}
554
555bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
556  Type *Ty = cast<PointerType>(G->getType())->getElementType();
557  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
558
559  if (BL->isIn(*G)) return false;
560  if (!Ty->isSized()) return false;
561  if (!G->hasInitializer()) return false;
562  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
563  // Touch only those globals that will not be defined in other modules.
564  // Don't handle ODR type linkages since other modules may be built w/o asan.
565  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
566      G->getLinkage() != GlobalVariable::PrivateLinkage &&
567      G->getLinkage() != GlobalVariable::InternalLinkage)
568    return false;
569  // Two problems with thread-locals:
570  //   - The address of the main thread's copy can't be computed at link-time.
571  //   - Need to poison all copies, not just the main thread's one.
572  if (G->isThreadLocal())
573    return false;
574  // For now, just ignore this Alloca if the alignment is large.
575  if (G->getAlignment() > RedzoneSize()) return false;
576
577  // Ignore all the globals with the names starting with "\01L_OBJC_".
578  // Many of those are put into the .cstring section. The linker compresses
579  // that section by removing the spare \0s after the string terminator, so
580  // our redzones get broken.
581  if ((G->getName().find("\01L_OBJC_") == 0) ||
582      (G->getName().find("\01l_OBJC_") == 0)) {
583    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
584    return false;
585  }
586
587  if (G->hasSection()) {
588    StringRef Section(G->getSection());
589    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
590    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
591    // them.
592    if ((Section.find("__OBJC,") == 0) ||
593        (Section.find("__DATA, __objc_") == 0)) {
594      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
595      return false;
596    }
597    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
598    // Constant CFString instances are compiled in the following way:
599    //  -- the string buffer is emitted into
600    //     __TEXT,__cstring,cstring_literals
601    //  -- the constant NSConstantString structure referencing that buffer
602    //     is placed into __DATA,__cfstring
603    // Therefore there's no point in placing redzones into __DATA,__cfstring.
604    // Moreover, it causes the linker to crash on OS X 10.7
605    if (Section.find("__DATA,__cfstring") == 0) {
606      DEBUG(dbgs() << "Ignoring CFString: " << *G);
607      return false;
608    }
609  }
610
611  return true;
612}
613
614// This function replaces all global variables with new variables that have
615// trailing redzones. It also creates a function that poisons
616// redzones and inserts this function into llvm.global_ctors.
617bool AddressSanitizerModule::runOnModule(Module &M) {
618  if (!ClGlobals) return false;
619  TD = getAnalysisIfAvailable<DataLayout>();
620  if (!TD)
621    return false;
622  BL.reset(new BlackList(ClBlackListFile));
623  DynamicallyInitializedGlobals.Init(M);
624  C = &(M.getContext());
625  IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
626
627  SmallVector<GlobalVariable *, 16> GlobalsToChange;
628
629  for (Module::GlobalListType::iterator G = M.global_begin(),
630       E = M.global_end(); G != E; ++G) {
631    if (ShouldInstrumentGlobal(G))
632      GlobalsToChange.push_back(G);
633  }
634
635  size_t n = GlobalsToChange.size();
636  if (n == 0) return false;
637
638  // A global is described by a structure
639  //   size_t beg;
640  //   size_t size;
641  //   size_t size_with_redzone;
642  //   const char *name;
643  //   size_t has_dynamic_init;
644  // We initialize an array of such structures and pass it to a run-time call.
645  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
646                                               IntptrTy, IntptrTy,
647                                               IntptrTy, NULL);
648  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
649
650
651  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
652  assert(CtorFunc);
653  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
654
655  // The addresses of the first and last dynamically initialized globals in
656  // this TU.  Used in initialization order checking.
657  Value *FirstDynamic = 0, *LastDynamic = 0;
658
659  for (size_t i = 0; i < n; i++) {
660    GlobalVariable *G = GlobalsToChange[i];
661    PointerType *PtrTy = cast<PointerType>(G->getType());
662    Type *Ty = PtrTy->getElementType();
663    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
664    size_t RZ = RedzoneSize();
665    uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
666    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
667    // Determine whether this global should be poisoned in initialization.
668    bool GlobalHasDynamicInitializer =
669        DynamicallyInitializedGlobals.Contains(G);
670    // Don't check initialization order if this global is blacklisted.
671    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
672
673    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
674    Constant *NewInitializer = ConstantStruct::get(
675        NewTy, G->getInitializer(),
676        Constant::getNullValue(RightRedZoneTy), NULL);
677
678    SmallString<2048> DescriptionOfGlobal = G->getName();
679    DescriptionOfGlobal += " (";
680    DescriptionOfGlobal += M.getModuleIdentifier();
681    DescriptionOfGlobal += ")";
682    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
683
684    // Create a new global variable with enough space for a redzone.
685    GlobalVariable *NewGlobal = new GlobalVariable(
686        M, NewTy, G->isConstant(), G->getLinkage(),
687        NewInitializer, "", G, G->getThreadLocalMode());
688    NewGlobal->copyAttributesFrom(G);
689    NewGlobal->setAlignment(RZ);
690
691    Value *Indices2[2];
692    Indices2[0] = IRB.getInt32(0);
693    Indices2[1] = IRB.getInt32(0);
694
695    G->replaceAllUsesWith(
696        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
697    NewGlobal->takeName(G);
698    G->eraseFromParent();
699
700    Initializers[i] = ConstantStruct::get(
701        GlobalStructTy,
702        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
703        ConstantInt::get(IntptrTy, SizeInBytes),
704        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
705        ConstantExpr::getPointerCast(Name, IntptrTy),
706        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
707        NULL);
708
709    // Populate the first and last globals declared in this TU.
710    if (CheckInitOrder && GlobalHasDynamicInitializer) {
711      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
712      if (FirstDynamic == 0)
713        FirstDynamic = LastDynamic;
714    }
715
716    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
717  }
718
719  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
720  GlobalVariable *AllGlobals = new GlobalVariable(
721      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
722      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
723
724  // Create calls for poisoning before initializers run and unpoisoning after.
725  if (CheckInitOrder && FirstDynamic && LastDynamic)
726    createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
727
728  Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
729      kAsanRegisterGlobalsName, IRB.getVoidTy(),
730      IntptrTy, IntptrTy, NULL));
731  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
732
733  IRB.CreateCall2(AsanRegisterGlobals,
734                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
735                  ConstantInt::get(IntptrTy, n));
736
737  // We also need to unregister globals at the end, e.g. when a shared library
738  // gets closed.
739  Function *AsanDtorFunction = Function::Create(
740      FunctionType::get(Type::getVoidTy(*C), false),
741      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
742  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
743  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
744  Function *AsanUnregisterGlobals =
745      checkInterfaceFunction(M.getOrInsertFunction(
746          kAsanUnregisterGlobalsName,
747          IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
748  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
749
750  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
751                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
752                       ConstantInt::get(IntptrTy, n));
753  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
754
755  DEBUG(dbgs() << M);
756  return true;
757}
758
759void AddressSanitizer::initializeCallbacks(Module &M) {
760  IRBuilder<> IRB(*C);
761  // Create __asan_report* callbacks.
762  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
763    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
764         AccessSizeIndex++) {
765      // IsWrite and TypeSize are encoded in the function name.
766      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
767          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
768      // If we are merging crash callbacks, they have two parameters.
769      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
770          checkInterfaceFunction(M.getOrInsertFunction(
771              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
772    }
773  }
774
775  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
776      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
777  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
778      kAsanStackFreeName, IRB.getVoidTy(),
779      IntptrTy, IntptrTy, IntptrTy, NULL));
780  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
781      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
782
783  // We insert an empty inline asm after __asan_report* to avoid callback merge.
784  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
785                            StringRef(""), StringRef(""),
786                            /*hasSideEffects=*/true);
787}
788
789// virtual
790bool AddressSanitizer::doInitialization(Module &M) {
791  // Initialize the private fields. No one has accessed them before.
792  TD = getAnalysisIfAvailable<DataLayout>();
793
794  if (!TD)
795    return false;
796  BL.reset(new BlackList(ClBlackListFile));
797  DynamicallyInitializedGlobals.Init(M);
798
799  C = &(M.getContext());
800  LongSize = TD->getPointerSizeInBits();
801  IntptrTy = Type::getIntNTy(*C, LongSize);
802  IntptrPtrTy = PointerType::get(IntptrTy, 0);
803
804  AsanCtorFunction = Function::Create(
805      FunctionType::get(Type::getVoidTy(*C), false),
806      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
807  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
808  // call __asan_init in the module ctor.
809  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
810  AsanInitFunction = checkInterfaceFunction(
811      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
812  AsanInitFunction->setLinkage(Function::ExternalLinkage);
813  IRB.CreateCall(AsanInitFunction);
814
815  llvm::Triple targetTriple(M.getTargetTriple());
816  bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
817
818  MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
819    (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
820  if (ClMappingOffsetLog >= 0) {
821    if (ClMappingOffsetLog == 0) {
822      // special case
823      MappingOffset = 0;
824    } else {
825      MappingOffset = 1ULL << ClMappingOffsetLog;
826    }
827  }
828
829
830  if (ClMappingOffsetLog >= 0) {
831    // Tell the run-time the current values of mapping offset and scale.
832    GlobalValue *asan_mapping_offset =
833        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
834                       ConstantInt::get(IntptrTy, MappingOffset),
835                       kAsanMappingOffsetName);
836    // Read the global, otherwise it may be optimized away.
837    IRB.CreateLoad(asan_mapping_offset, true);
838  }
839  if (ClMappingScale) {
840    GlobalValue *asan_mapping_scale =
841        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
842                           ConstantInt::get(IntptrTy, MappingScale()),
843                           kAsanMappingScaleName);
844    // Read the global, otherwise it may be optimized away.
845    IRB.CreateLoad(asan_mapping_scale, true);
846  }
847
848  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
849
850  return true;
851}
852
853bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
854  // For each NSObject descendant having a +load method, this method is invoked
855  // by the ObjC runtime before any of the static constructors is called.
856  // Therefore we need to instrument such methods with a call to __asan_init
857  // at the beginning in order to initialize our runtime before any access to
858  // the shadow memory.
859  // We cannot just ignore these methods, because they may call other
860  // instrumented functions.
861  if (F.getName().find(" load]") != std::string::npos) {
862    IRBuilder<> IRB(F.begin()->begin());
863    IRB.CreateCall(AsanInitFunction);
864    return true;
865  }
866  return false;
867}
868
869// Check both the call and the callee for doesNotReturn().
870static bool isNoReturnCall(CallInst *CI) {
871  if (CI->doesNotReturn()) return true;
872  Function *F = CI->getCalledFunction();
873  if (F && F->doesNotReturn()) return true;
874  return false;
875}
876
877bool AddressSanitizer::runOnFunction(Function &F) {
878  if (BL->isIn(F)) return false;
879  if (&F == AsanCtorFunction) return false;
880  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
881  initializeCallbacks(*F.getParent());
882
883  // If needed, insert __asan_init before checking for AddressSafety attr.
884  maybeInsertAsanInitAtFunctionEntry(F);
885
886  if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
887    return false;
888
889  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
890    return false;
891
892  // We want to instrument every address only once per basic block (unless there
893  // are calls between uses).
894  SmallSet<Value*, 16> TempsToInstrument;
895  SmallVector<Instruction*, 16> ToInstrument;
896  SmallVector<Instruction*, 8> NoReturnCalls;
897  bool IsWrite;
898
899  // Fill the set of memory operations to instrument.
900  for (Function::iterator FI = F.begin(), FE = F.end();
901       FI != FE; ++FI) {
902    TempsToInstrument.clear();
903    int NumInsnsPerBB = 0;
904    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
905         BI != BE; ++BI) {
906      if (LooksLikeCodeInBug11395(BI)) return false;
907      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
908        if (ClOpt && ClOptSameTemp) {
909          if (!TempsToInstrument.insert(Addr))
910            continue;  // We've seen this temp in the current BB.
911        }
912      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
913        // ok, take it.
914      } else {
915        if (CallInst *CI = dyn_cast<CallInst>(BI)) {
916          // A call inside BB.
917          TempsToInstrument.clear();
918          if (isNoReturnCall(CI)) {
919            NoReturnCalls.push_back(CI);
920          }
921        }
922        continue;
923      }
924      ToInstrument.push_back(BI);
925      NumInsnsPerBB++;
926      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
927        break;
928    }
929  }
930
931  // Instrument.
932  int NumInstrumented = 0;
933  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
934    Instruction *Inst = ToInstrument[i];
935    if (ClDebugMin < 0 || ClDebugMax < 0 ||
936        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
937      if (isInterestingMemoryAccess(Inst, &IsWrite))
938        instrumentMop(Inst);
939      else
940        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
941    }
942    NumInstrumented++;
943  }
944
945  bool ChangedStack = poisonStackInFunction(F);
946
947  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
948  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
949  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
950    Instruction *CI = NoReturnCalls[i];
951    IRBuilder<> IRB(CI);
952    IRB.CreateCall(AsanHandleNoReturnFunc);
953  }
954  DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
955
956  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
957}
958
959static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
960  if (ShadowRedzoneSize == 1) return PoisonByte;
961  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
962  if (ShadowRedzoneSize == 4)
963    return (PoisonByte << 24) + (PoisonByte << 16) +
964        (PoisonByte << 8) + (PoisonByte);
965  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
966}
967
968static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
969                                            size_t Size,
970                                            size_t RZSize,
971                                            size_t ShadowGranularity,
972                                            uint8_t Magic) {
973  for (size_t i = 0; i < RZSize;
974       i+= ShadowGranularity, Shadow++) {
975    if (i + ShadowGranularity <= Size) {
976      *Shadow = 0;  // fully addressable
977    } else if (i >= Size) {
978      *Shadow = Magic;  // unaddressable
979    } else {
980      *Shadow = Size - i;  // first Size-i bytes are addressable
981    }
982  }
983}
984
985void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
986                                   IRBuilder<> IRB,
987                                   Value *ShadowBase, bool DoPoison) {
988  size_t ShadowRZSize = RedzoneSize() >> MappingScale();
989  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
990  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
991  Type *RZPtrTy = PointerType::get(RZTy, 0);
992
993  Value *PoisonLeft  = ConstantInt::get(RZTy,
994    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
995  Value *PoisonMid   = ConstantInt::get(RZTy,
996    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
997  Value *PoisonRight = ConstantInt::get(RZTy,
998    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
999
1000  // poison the first red zone.
1001  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1002
1003  // poison all other red zones.
1004  uint64_t Pos = RedzoneSize();
1005  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1006    AllocaInst *AI = AllocaVec[i];
1007    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1008    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1009    assert(AlignedSize - SizeInBytes < RedzoneSize());
1010    Value *Ptr = NULL;
1011
1012    Pos += AlignedSize;
1013
1014    assert(ShadowBase->getType() == IntptrTy);
1015    if (SizeInBytes < AlignedSize) {
1016      // Poison the partial redzone at right
1017      Ptr = IRB.CreateAdd(
1018          ShadowBase, ConstantInt::get(IntptrTy,
1019                                       (Pos >> MappingScale()) - ShadowRZSize));
1020      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1021      uint32_t Poison = 0;
1022      if (DoPoison) {
1023        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1024                                        RedzoneSize(),
1025                                        1ULL << MappingScale(),
1026                                        kAsanStackPartialRedzoneMagic);
1027      }
1028      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1029      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1030    }
1031
1032    // Poison the full redzone at right.
1033    Ptr = IRB.CreateAdd(ShadowBase,
1034                        ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1035    Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1036    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1037
1038    Pos += RedzoneSize();
1039  }
1040}
1041
1042// Workaround for bug 11395: we don't want to instrument stack in functions
1043// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1044// FIXME: remove once the bug 11395 is fixed.
1045bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1046  if (LongSize != 32) return false;
1047  CallInst *CI = dyn_cast<CallInst>(I);
1048  if (!CI || !CI->isInlineAsm()) return false;
1049  if (CI->getNumArgOperands() <= 5) return false;
1050  // We have inline assembly with quite a few arguments.
1051  return true;
1052}
1053
1054// Find all static Alloca instructions and put
1055// poisoned red zones around all of them.
1056// Then unpoison everything back before the function returns.
1057//
1058// Stack poisoning does not play well with exception handling.
1059// When an exception is thrown, we essentially bypass the code
1060// that unpoisones the stack. This is why the run-time library has
1061// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1062// stack in the interceptor. This however does not work inside the
1063// actual function which catches the exception. Most likely because the
1064// compiler hoists the load of the shadow value somewhere too high.
1065// This causes asan to report a non-existing bug on 453.povray.
1066// It sounds like an LLVM bug.
1067bool AddressSanitizer::poisonStackInFunction(Function &F) {
1068  if (!ClStack) return false;
1069  SmallVector<AllocaInst*, 16> AllocaVec;
1070  SmallVector<Instruction*, 8> RetVec;
1071  uint64_t TotalSize = 0;
1072
1073  // Filter out Alloca instructions we want (and can) handle.
1074  // Collect Ret instructions.
1075  for (Function::iterator FI = F.begin(), FE = F.end();
1076       FI != FE; ++FI) {
1077    BasicBlock &BB = *FI;
1078    for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1079         BI != BE; ++BI) {
1080      if (isa<ReturnInst>(BI)) {
1081          RetVec.push_back(BI);
1082          continue;
1083      }
1084
1085      AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1086      if (!AI) continue;
1087      if (AI->isArrayAllocation()) continue;
1088      if (!AI->isStaticAlloca()) continue;
1089      if (!AI->getAllocatedType()->isSized()) continue;
1090      if (AI->getAlignment() > RedzoneSize()) continue;
1091      AllocaVec.push_back(AI);
1092      uint64_t AlignedSize =  getAlignedAllocaSize(AI);
1093      TotalSize += AlignedSize;
1094    }
1095  }
1096
1097  if (AllocaVec.empty()) return false;
1098
1099  uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize();
1100
1101  bool DoStackMalloc = CheckUseAfterReturn
1102      && LocalStackSize <= kMaxStackMallocSize;
1103
1104  Instruction *InsBefore = AllocaVec[0];
1105  IRBuilder<> IRB(InsBefore);
1106
1107
1108  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1109  AllocaInst *MyAlloca =
1110      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1111  MyAlloca->setAlignment(RedzoneSize());
1112  assert(MyAlloca->isStaticAlloca());
1113  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1114  Value *LocalStackBase = OrigStackBase;
1115
1116  if (DoStackMalloc) {
1117    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1118        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1119  }
1120
1121  // This string will be parsed by the run-time (DescribeStackAddress).
1122  SmallString<2048> StackDescriptionStorage;
1123  raw_svector_ostream StackDescription(StackDescriptionStorage);
1124  StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1125
1126  uint64_t Pos = RedzoneSize();
1127  // Replace Alloca instructions with base+offset.
1128  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1129    AllocaInst *AI = AllocaVec[i];
1130    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1131    StringRef Name = AI->getName();
1132    StackDescription << Pos << " " << SizeInBytes << " "
1133                     << Name.size() << " " << Name << " ";
1134    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1135    assert((AlignedSize % RedzoneSize()) == 0);
1136    AI->replaceAllUsesWith(
1137        IRB.CreateIntToPtr(
1138            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1139            AI->getType()));
1140    Pos += AlignedSize + RedzoneSize();
1141  }
1142  assert(Pos == LocalStackSize);
1143
1144  // Write the Magic value and the frame description constant to the redzone.
1145  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1146  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1147                  BasePlus0);
1148  Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1149                                   ConstantInt::get(IntptrTy, LongSize/8));
1150  BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1151  GlobalVariable *StackDescriptionGlobal =
1152      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1153  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1154  IRB.CreateStore(Description, BasePlus1);
1155
1156  // Poison the stack redzones at the entry.
1157  Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1158  PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1159
1160  // Unpoison the stack before all ret instructions.
1161  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1162    Instruction *Ret = RetVec[i];
1163    IRBuilder<> IRBRet(Ret);
1164
1165    // Mark the current frame as retired.
1166    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1167                       BasePlus0);
1168    // Unpoison the stack.
1169    PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1170
1171    if (DoStackMalloc) {
1172      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1173                         ConstantInt::get(IntptrTy, LocalStackSize),
1174                         OrigStackBase);
1175    }
1176  }
1177
1178  // We are done. Remove the old unused alloca instructions.
1179  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1180    AllocaVec[i]->eraseFromParent();
1181
1182  if (ClDebugStack) {
1183    DEBUG(dbgs() << F);
1184  }
1185
1186  return true;
1187}
1188