AddressSanitizer.cpp revision 51c7c65e32f76ec5a50cdecfe2b4c287c57da127 
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
139// Debug flags.
140static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
141                            cl::init(0));
142static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
143                                 cl::Hidden, cl::init(0));
144static cl::opt<std::string> ClDebugFunc("asan-debug-func",
145                                        cl::Hidden, cl::desc("Debug func"));
146static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
147                               cl::Hidden, cl::init(-1));
148static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
149                               cl::Hidden, cl::init(-1));
150
151namespace {
152/// A set of dynamically initialized globals extracted from metadata.
153class SetOfDynamicallyInitializedGlobals {
154 public:
155  void Init(Module& M) {
156    // Clang generates metadata identifying all dynamically initialized globals.
157    NamedMDNode *DynamicGlobals =
158        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
159    if (!DynamicGlobals)
160      return;
161    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
162      MDNode *MDN = DynamicGlobals->getOperand(i);
163      assert(MDN->getNumOperands() == 1);
164      Value *VG = MDN->getOperand(0);
165      // The optimizer may optimize away a global entirely, in which case we
166      // cannot instrument access to it.
167      if (!VG)
168        continue;
169      DynInitGlobals.insert(cast<GlobalVariable>(VG));
170    }
171  }
172  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
173 private:
174  SmallSet<GlobalValue*, 32> DynInitGlobals;
175};
176
177
178/// AddressSanitizer: instrument the code in module to find memory bugs.
179struct AddressSanitizer : public FunctionPass {
180  AddressSanitizer();
181  virtual const char *getPassName() const;
182  void instrumentMop(Instruction *I);
183  void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
184                         Value *Addr, uint32_t TypeSize, bool IsWrite);
185  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
186                           Value *ShadowValue, uint32_t TypeSize);
187  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
188                                 bool IsWrite, size_t AccessSizeIndex);
189  bool instrumentMemIntrinsic(MemIntrinsic *MI);
190  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
191                                   Value *Size,
192                                   Instruction *InsertBefore, bool IsWrite);
193  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
194  bool runOnFunction(Function &F);
195  void createInitializerPoisonCalls(Module &M,
196                                    Value *FirstAddr, Value *LastAddr);
197  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
198  bool poisonStackInFunction(Function &F);
199  virtual bool doInitialization(Module &M);
200  virtual bool doFinalization(Module &M);
201  bool insertGlobalRedzones(Module &M);
202  static char ID;  // Pass identification, replacement for typeid
203
204 private:
205  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
206    Type *Ty = AI->getAllocatedType();
207    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
208    return SizeInBytes;
209  }
210  uint64_t getAlignedSize(uint64_t SizeInBytes) {
211    return ((SizeInBytes + RedzoneSize - 1)
212            / RedzoneSize) * RedzoneSize;
213  }
214  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
215    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
216    return getAlignedSize(SizeInBytes);
217  }
218
219  Function *checkInterfaceFunction(Constant *FuncOrBitcast);
220  bool ShouldInstrumentGlobal(GlobalVariable *G);
221  void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
222                   Value *ShadowBase, bool DoPoison);
223  bool LooksLikeCodeInBug11395(Instruction *I);
224  void FindDynamicInitializers(Module &M);
225
226  LLVMContext *C;
227  DataLayout *TD;
228  uint64_t MappingOffset;
229  int MappingScale;
230  size_t RedzoneSize;
231  int LongSize;
232  Type *IntptrTy;
233  Type *IntptrPtrTy;
234  Function *AsanCtorFunction;
235  Function *AsanInitFunction;
236  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
237  Function *AsanHandleNoReturnFunc;
238  Instruction *CtorInsertBefore;
239  OwningPtr<BlackList> BL;
240  // This array is indexed by AccessIsWrite and log2(AccessSize).
241  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
242  InlineAsm *EmptyAsm;
243  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
244};
245
246}  // namespace
247
248char AddressSanitizer::ID = 0;
249INITIALIZE_PASS(AddressSanitizer, "asan",
250    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
251    false, false)
252AddressSanitizer::AddressSanitizer() : FunctionPass(ID) { }
253FunctionPass *llvm::createAddressSanitizerPass() {
254  return new AddressSanitizer();
255}
256
257const char *AddressSanitizer::getPassName() const {
258  return "AddressSanitizer";
259}
260
261static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
262  size_t Res = CountTrailingZeros_32(TypeSize / 8);
263  assert(Res < kNumberOfAccessSizes);
264  return Res;
265}
266
267// Create a constant for Str so that we can pass it to the run-time lib.
268static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
269  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
270  return new GlobalVariable(M, StrConst->getType(), true,
271                            GlobalValue::PrivateLinkage, StrConst,
272                            kAsanGenPrefix);
273}
274
275static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
276  return G->getName().find(kAsanGenPrefix) == 0;
277}
278
279Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
280  // Shadow >> scale
281  Shadow = IRB.CreateLShr(Shadow, MappingScale);
282  if (MappingOffset == 0)
283    return Shadow;
284  // (Shadow >> scale) | offset
285  return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
286                                               MappingOffset));
287}
288
289void AddressSanitizer::instrumentMemIntrinsicParam(
290    Instruction *OrigIns,
291    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
292  // Check the first byte.
293  {
294    IRBuilder<> IRB(InsertBefore);
295    instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
296  }
297  // Check the last byte.
298  {
299    IRBuilder<> IRB(InsertBefore);
300    Value *SizeMinusOne = IRB.CreateSub(
301        Size, ConstantInt::get(Size->getType(), 1));
302    SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
303    Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
304    Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
305    instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
306  }
307}
308
309// Instrument memset/memmove/memcpy
310bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
311  Value *Dst = MI->getDest();
312  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
313  Value *Src = MemTran ? MemTran->getSource() : 0;
314  Value *Length = MI->getLength();
315
316  Constant *ConstLength = dyn_cast<Constant>(Length);
317  Instruction *InsertBefore = MI;
318  if (ConstLength) {
319    if (ConstLength->isNullValue()) return false;
320  } else {
321    // The size is not a constant so it could be zero -- check at run-time.
322    IRBuilder<> IRB(InsertBefore);
323
324    Value *Cmp = IRB.CreateICmpNE(Length,
325                                  Constant::getNullValue(Length->getType()));
326    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
327  }
328
329  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
330  if (Src)
331    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
332  return true;
333}
334
335// If I is an interesting memory access, return the PointerOperand
336// and set IsWrite. Otherwise return NULL.
337static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
338  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
339    if (!ClInstrumentReads) return NULL;
340    *IsWrite = false;
341    return LI->getPointerOperand();
342  }
343  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
344    if (!ClInstrumentWrites) return NULL;
345    *IsWrite = true;
346    return SI->getPointerOperand();
347  }
348  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
349    if (!ClInstrumentAtomics) return NULL;
350    *IsWrite = true;
351    return RMW->getPointerOperand();
352  }
353  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
354    if (!ClInstrumentAtomics) return NULL;
355    *IsWrite = true;
356    return XCHG->getPointerOperand();
357  }
358  return NULL;
359}
360
361void AddressSanitizer::instrumentMop(Instruction *I) {
362  bool IsWrite = false;
363  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
364  assert(Addr);
365  if (ClOpt && ClOptGlobals) {
366    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
367      // If initialization order checking is disabled, a simple access to a
368      // dynamically initialized global is always valid.
369      if (!ClInitializers)
370        return;
371      // If a global variable does not have dynamic initialization we don't
372      // have to instrument it.  However, if a global does not have initailizer
373      // at all, we assume it has dynamic initializer (in other TU).
374      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
375        return;
376    }
377  }
378
379  Type *OrigPtrTy = Addr->getType();
380  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
381
382  assert(OrigTy->isSized());
383  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
384
385  if (TypeSize != 8  && TypeSize != 16 &&
386      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
387    // Ignore all unusual sizes.
388    return;
389  }
390
391  IRBuilder<> IRB(I);
392  instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
393}
394
395// Validate the result of Module::getOrInsertFunction called for an interface
396// function of AddressSanitizer. If the instrumented module defines a function
397// with the same name, their prototypes must match, otherwise
398// getOrInsertFunction returns a bitcast.
399Function *AddressSanitizer::checkInterfaceFunction(Constant *FuncOrBitcast) {
400  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
401  FuncOrBitcast->dump();
402  report_fatal_error("trying to redefine an AddressSanitizer "
403                     "interface function");
404}
405
406Instruction *AddressSanitizer::generateCrashCode(
407    Instruction *InsertBefore, Value *Addr,
408    bool IsWrite, size_t AccessSizeIndex) {
409  IRBuilder<> IRB(InsertBefore);
410  CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
411                                  Addr);
412  // We don't do Call->setDoesNotReturn() because the BB already has
413  // UnreachableInst at the end.
414  // This EmptyAsm is required to avoid callback merge.
415  IRB.CreateCall(EmptyAsm);
416  return Call;
417}
418
419Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
420                                            Value *ShadowValue,
421                                            uint32_t TypeSize) {
422  size_t Granularity = 1 << MappingScale;
423  // Addr & (Granularity - 1)
424  Value *LastAccessedByte = IRB.CreateAnd(
425      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
426  // (Addr & (Granularity - 1)) + size - 1
427  if (TypeSize / 8 > 1)
428    LastAccessedByte = IRB.CreateAdd(
429        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
430  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
431  LastAccessedByte = IRB.CreateIntCast(
432      LastAccessedByte, ShadowValue->getType(), false);
433  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
434  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
435}
436
437void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
438                                         IRBuilder<> &IRB, Value *Addr,
439                                         uint32_t TypeSize, bool IsWrite) {
440  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
441
442  Type *ShadowTy  = IntegerType::get(
443      *C, std::max(8U, TypeSize >> MappingScale));
444  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
445  Value *ShadowPtr = memToShadow(AddrLong, IRB);
446  Value *CmpVal = Constant::getNullValue(ShadowTy);
447  Value *ShadowValue = IRB.CreateLoad(
448      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
449
450  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
451  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
452  size_t Granularity = 1 << MappingScale;
453  TerminatorInst *CrashTerm = 0;
454
455  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
456    TerminatorInst *CheckTerm =
457        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
458    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
459    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
460    IRB.SetInsertPoint(CheckTerm);
461    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
462    BasicBlock *CrashBlock =
463        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
464    CrashTerm = new UnreachableInst(*C, CrashBlock);
465    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
466    ReplaceInstWithInst(CheckTerm, NewTerm);
467  } else {
468    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
469  }
470
471  Instruction *Crash =
472      generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
473  Crash->setDebugLoc(OrigIns->getDebugLoc());
474}
475
476void AddressSanitizer::createInitializerPoisonCalls(Module &M,
477                                                    Value *FirstAddr,
478                                                    Value *LastAddr) {
479  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
480  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
481  // If that function is not present, this TU contains no globals, or they have
482  // all been optimized away
483  if (!GlobalInit)
484    return;
485
486  // Set up the arguments to our poison/unpoison functions.
487  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
488
489  // Declare our poisoning and unpoisoning functions.
490  Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
491      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
492  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
493  Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
494      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
495  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
496
497  // Add a call to poison all external globals before the given function starts.
498  IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
499
500  // Add calls to unpoison all globals before each return instruction.
501  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
502      I != E; ++I) {
503    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
504      CallInst::Create(AsanUnpoisonGlobals, "", RI);
505    }
506  }
507}
508
509bool AddressSanitizer::ShouldInstrumentGlobal(GlobalVariable *G) {
510  Type *Ty = cast<PointerType>(G->getType())->getElementType();
511  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
512
513  if (BL->isIn(*G)) return false;
514  if (!Ty->isSized()) return false;
515  if (!G->hasInitializer()) return false;
516  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
517  // Touch only those globals that will not be defined in other modules.
518  // Don't handle ODR type linkages since other modules may be built w/o asan.
519  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
520      G->getLinkage() != GlobalVariable::PrivateLinkage &&
521      G->getLinkage() != GlobalVariable::InternalLinkage)
522    return false;
523  // Two problems with thread-locals:
524  //   - The address of the main thread's copy can't be computed at link-time.
525  //   - Need to poison all copies, not just the main thread's one.
526  if (G->isThreadLocal())
527    return false;
528  // For now, just ignore this Alloca if the alignment is large.
529  if (G->getAlignment() > RedzoneSize) return false;
530
531  // Ignore all the globals with the names starting with "\01L_OBJC_".
532  // Many of those are put into the .cstring section. The linker compresses
533  // that section by removing the spare \0s after the string terminator, so
534  // our redzones get broken.
535  if ((G->getName().find("\01L_OBJC_") == 0) ||
536      (G->getName().find("\01l_OBJC_") == 0)) {
537    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
538    return false;
539  }
540
541  if (G->hasSection()) {
542    StringRef Section(G->getSection());
543    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
544    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
545    // them.
546    if ((Section.find("__OBJC,") == 0) ||
547        (Section.find("__DATA, __objc_") == 0)) {
548      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
549      return false;
550    }
551    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
552    // Constant CFString instances are compiled in the following way:
553    //  -- the string buffer is emitted into
554    //     __TEXT,__cstring,cstring_literals
555    //  -- the constant NSConstantString structure referencing that buffer
556    //     is placed into __DATA,__cfstring
557    // Therefore there's no point in placing redzones into __DATA,__cfstring.
558    // Moreover, it causes the linker to crash on OS X 10.7
559    if (Section.find("__DATA,__cfstring") == 0) {
560      DEBUG(dbgs() << "Ignoring CFString: " << *G);
561      return false;
562    }
563  }
564
565  return true;
566}
567
568// This function replaces all global variables with new variables that have
569// trailing redzones. It also creates a function that poisons
570// redzones and inserts this function into llvm.global_ctors.
571bool AddressSanitizer::insertGlobalRedzones(Module &M) {
572  SmallVector<GlobalVariable *, 16> GlobalsToChange;
573
574  for (Module::GlobalListType::iterator G = M.global_begin(),
575       E = M.global_end(); G != E; ++G) {
576    if (ShouldInstrumentGlobal(G))
577      GlobalsToChange.push_back(G);
578  }
579
580  size_t n = GlobalsToChange.size();
581  if (n == 0) return false;
582
583  // A global is described by a structure
584  //   size_t beg;
585  //   size_t size;
586  //   size_t size_with_redzone;
587  //   const char *name;
588  //   size_t has_dynamic_init;
589  // We initialize an array of such structures and pass it to a run-time call.
590  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
591                                               IntptrTy, IntptrTy,
592                                               IntptrTy, NULL);
593  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
594
595  IRBuilder<> IRB(CtorInsertBefore);
596
597  // The addresses of the first and last dynamically initialized globals in
598  // this TU.  Used in initialization order checking.
599  Value *FirstDynamic = 0, *LastDynamic = 0;
600
601  for (size_t i = 0; i < n; i++) {
602    GlobalVariable *G = GlobalsToChange[i];
603    PointerType *PtrTy = cast<PointerType>(G->getType());
604    Type *Ty = PtrTy->getElementType();
605    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
606    uint64_t RightRedzoneSize = RedzoneSize +
607        (RedzoneSize - (SizeInBytes % RedzoneSize));
608    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
609    // Determine whether this global should be poisoned in initialization.
610    bool GlobalHasDynamicInitializer =
611        DynamicallyInitializedGlobals.Contains(G);
612    // Don't check initialization order if this global is blacklisted.
613    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
614
615    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
616    Constant *NewInitializer = ConstantStruct::get(
617        NewTy, G->getInitializer(),
618        Constant::getNullValue(RightRedZoneTy), NULL);
619
620    SmallString<2048> DescriptionOfGlobal = G->getName();
621    DescriptionOfGlobal += " (";
622    DescriptionOfGlobal += M.getModuleIdentifier();
623    DescriptionOfGlobal += ")";
624    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
625
626    // Create a new global variable with enough space for a redzone.
627    GlobalVariable *NewGlobal = new GlobalVariable(
628        M, NewTy, G->isConstant(), G->getLinkage(),
629        NewInitializer, "", G, G->getThreadLocalMode());
630    NewGlobal->copyAttributesFrom(G);
631    NewGlobal->setAlignment(RedzoneSize);
632
633    Value *Indices2[2];
634    Indices2[0] = IRB.getInt32(0);
635    Indices2[1] = IRB.getInt32(0);
636
637    G->replaceAllUsesWith(
638        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
639    NewGlobal->takeName(G);
640    G->eraseFromParent();
641
642    Initializers[i] = ConstantStruct::get(
643        GlobalStructTy,
644        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
645        ConstantInt::get(IntptrTy, SizeInBytes),
646        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
647        ConstantExpr::getPointerCast(Name, IntptrTy),
648        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
649        NULL);
650
651    // Populate the first and last globals declared in this TU.
652    if (ClInitializers && GlobalHasDynamicInitializer) {
653      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
654      if (FirstDynamic == 0)
655        FirstDynamic = LastDynamic;
656    }
657
658    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
659  }
660
661  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
662  GlobalVariable *AllGlobals = new GlobalVariable(
663      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
664      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
665
666  // Create calls for poisoning before initializers run and unpoisoning after.
667  if (ClInitializers && FirstDynamic && LastDynamic)
668    createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
669
670  Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
671      kAsanRegisterGlobalsName, IRB.getVoidTy(),
672      IntptrTy, IntptrTy, NULL));
673  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
674
675  IRB.CreateCall2(AsanRegisterGlobals,
676                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
677                  ConstantInt::get(IntptrTy, n));
678
679  // We also need to unregister globals at the end, e.g. when a shared library
680  // gets closed.
681  Function *AsanDtorFunction = Function::Create(
682      FunctionType::get(Type::getVoidTy(*C), false),
683      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
684  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
685  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
686  Function *AsanUnregisterGlobals =
687      checkInterfaceFunction(M.getOrInsertFunction(
688          kAsanUnregisterGlobalsName,
689          IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
690  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
691
692  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
693                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
694                       ConstantInt::get(IntptrTy, n));
695  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
696
697  DEBUG(dbgs() << M);
698  return true;
699}
700
701// virtual
702bool AddressSanitizer::doInitialization(Module &M) {
703  // Initialize the private fields. No one has accessed them before.
704  TD = getAnalysisIfAvailable<DataLayout>();
705
706  if (!TD)
707    return false;
708  BL.reset(new BlackList(ClBlackListFile));
709  DynamicallyInitializedGlobals.Init(M);
710
711  C = &(M.getContext());
712  LongSize = TD->getPointerSizeInBits();
713  IntptrTy = Type::getIntNTy(*C, LongSize);
714  IntptrPtrTy = PointerType::get(IntptrTy, 0);
715
716  AsanCtorFunction = Function::Create(
717      FunctionType::get(Type::getVoidTy(*C), false),
718      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
719  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
720  CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB);
721
722  // call __asan_init in the module ctor.
723  IRBuilder<> IRB(CtorInsertBefore);
724  AsanInitFunction = checkInterfaceFunction(
725      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
726  AsanInitFunction->setLinkage(Function::ExternalLinkage);
727  IRB.CreateCall(AsanInitFunction);
728
729  // Create __asan_report* callbacks.
730  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
731    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
732         AccessSizeIndex++) {
733      // IsWrite and TypeSize are encoded in the function name.
734      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
735          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
736      // If we are merging crash callbacks, they have two parameters.
737      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
738          checkInterfaceFunction(M.getOrInsertFunction(
739              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
740    }
741  }
742
743  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
744      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
745  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
746      kAsanStackFreeName, IRB.getVoidTy(),
747      IntptrTy, IntptrTy, IntptrTy, NULL));
748  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
749      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
750
751  // We insert an empty inline asm after __asan_report* to avoid callback merge.
752  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
753                            StringRef(""), StringRef(""),
754                            /*hasSideEffects=*/true);
755
756  llvm::Triple targetTriple(M.getTargetTriple());
757  bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
758
759  MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
760    (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
761  if (ClMappingOffsetLog >= 0) {
762    if (ClMappingOffsetLog == 0) {
763      // special case
764      MappingOffset = 0;
765    } else {
766      MappingOffset = 1ULL << ClMappingOffsetLog;
767    }
768  }
769  MappingScale = kDefaultShadowScale;
770  if (ClMappingScale) {
771    MappingScale = ClMappingScale;
772  }
773  // Redzone used for stack and globals is at least 32 bytes.
774  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
775  RedzoneSize = std::max(32, (int)(1 << MappingScale));
776
777
778  if (ClMappingOffsetLog >= 0) {
779    // Tell the run-time the current values of mapping offset and scale.
780    GlobalValue *asan_mapping_offset =
781        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
782                       ConstantInt::get(IntptrTy, MappingOffset),
783                       kAsanMappingOffsetName);
784    // Read the global, otherwise it may be optimized away.
785    IRB.CreateLoad(asan_mapping_offset, true);
786  }
787  if (ClMappingScale) {
788    GlobalValue *asan_mapping_scale =
789        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
790                           ConstantInt::get(IntptrTy, MappingScale),
791                           kAsanMappingScaleName);
792    // Read the global, otherwise it may be optimized away.
793    IRB.CreateLoad(asan_mapping_scale, true);
794  }
795
796  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
797
798  return true;
799}
800
801bool AddressSanitizer::doFinalization(Module &M) {
802  // We transform the globals at the very end so that the optimization analysis
803  // works on the original globals.
804  if (ClGlobals)
805    return insertGlobalRedzones(M);
806  return false;
807}
808
809
810bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
811  // For each NSObject descendant having a +load method, this method is invoked
812  // by the ObjC runtime before any of the static constructors is called.
813  // Therefore we need to instrument such methods with a call to __asan_init
814  // at the beginning in order to initialize our runtime before any access to
815  // the shadow memory.
816  // We cannot just ignore these methods, because they may call other
817  // instrumented functions.
818  if (F.getName().find(" load]") != std::string::npos) {
819    IRBuilder<> IRB(F.begin()->begin());
820    IRB.CreateCall(AsanInitFunction);
821    return true;
822  }
823  return false;
824}
825
826bool AddressSanitizer::runOnFunction(Function &F) {
827  if (BL->isIn(F)) return false;
828  if (&F == AsanCtorFunction) return false;
829  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
830
831  // If needed, insert __asan_init before checking for AddressSafety attr.
832  maybeInsertAsanInitAtFunctionEntry(F);
833
834  if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
835    return false;
836
837  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
838    return false;
839
840  // We want to instrument every address only once per basic block (unless there
841  // are calls between uses).
842  SmallSet<Value*, 16> TempsToInstrument;
843  SmallVector<Instruction*, 16> ToInstrument;
844  SmallVector<Instruction*, 8> NoReturnCalls;
845  bool IsWrite;
846
847  // Fill the set of memory operations to instrument.
848  for (Function::iterator FI = F.begin(), FE = F.end();
849       FI != FE; ++FI) {
850    TempsToInstrument.clear();
851    int NumInsnsPerBB = 0;
852    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
853         BI != BE; ++BI) {
854      if (LooksLikeCodeInBug11395(BI)) return false;
855      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
856        if (ClOpt && ClOptSameTemp) {
857          if (!TempsToInstrument.insert(Addr))
858            continue;  // We've seen this temp in the current BB.
859        }
860      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
861        // ok, take it.
862      } else {
863        if (CallInst *CI = dyn_cast<CallInst>(BI)) {
864          // A call inside BB.
865          TempsToInstrument.clear();
866          if (CI->doesNotReturn()) {
867            NoReturnCalls.push_back(CI);
868          }
869        }
870        continue;
871      }
872      ToInstrument.push_back(BI);
873      NumInsnsPerBB++;
874      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
875        break;
876    }
877  }
878
879  // Instrument.
880  int NumInstrumented = 0;
881  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
882    Instruction *Inst = ToInstrument[i];
883    if (ClDebugMin < 0 || ClDebugMax < 0 ||
884        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
885      if (isInterestingMemoryAccess(Inst, &IsWrite))
886        instrumentMop(Inst);
887      else
888        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
889    }
890    NumInstrumented++;
891  }
892
893  bool ChangedStack = poisonStackInFunction(F);
894
895  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
896  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
897  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
898    Instruction *CI = NoReturnCalls[i];
899    IRBuilder<> IRB(CI);
900    IRB.CreateCall(AsanHandleNoReturnFunc);
901  }
902  DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
903
904  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
905}
906
907static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
908  if (ShadowRedzoneSize == 1) return PoisonByte;
909  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
910  if (ShadowRedzoneSize == 4)
911    return (PoisonByte << 24) + (PoisonByte << 16) +
912        (PoisonByte << 8) + (PoisonByte);
913  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
914}
915
916static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
917                                            size_t Size,
918                                            size_t RedzoneSize,
919                                            size_t ShadowGranularity,
920                                            uint8_t Magic) {
921  for (size_t i = 0; i < RedzoneSize;
922       i+= ShadowGranularity, Shadow++) {
923    if (i + ShadowGranularity <= Size) {
924      *Shadow = 0;  // fully addressable
925    } else if (i >= Size) {
926      *Shadow = Magic;  // unaddressable
927    } else {
928      *Shadow = Size - i;  // first Size-i bytes are addressable
929    }
930  }
931}
932
933void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
934                                   IRBuilder<> IRB,
935                                   Value *ShadowBase, bool DoPoison) {
936  size_t ShadowRZSize = RedzoneSize >> MappingScale;
937  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
938  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
939  Type *RZPtrTy = PointerType::get(RZTy, 0);
940
941  Value *PoisonLeft  = ConstantInt::get(RZTy,
942    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
943  Value *PoisonMid   = ConstantInt::get(RZTy,
944    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
945  Value *PoisonRight = ConstantInt::get(RZTy,
946    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
947
948  // poison the first red zone.
949  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
950
951  // poison all other red zones.
952  uint64_t Pos = RedzoneSize;
953  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
954    AllocaInst *AI = AllocaVec[i];
955    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
956    uint64_t AlignedSize = getAlignedAllocaSize(AI);
957    assert(AlignedSize - SizeInBytes < RedzoneSize);
958    Value *Ptr = NULL;
959
960    Pos += AlignedSize;
961
962    assert(ShadowBase->getType() == IntptrTy);
963    if (SizeInBytes < AlignedSize) {
964      // Poison the partial redzone at right
965      Ptr = IRB.CreateAdd(
966          ShadowBase, ConstantInt::get(IntptrTy,
967                                       (Pos >> MappingScale) - ShadowRZSize));
968      size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes);
969      uint32_t Poison = 0;
970      if (DoPoison) {
971        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
972                                        RedzoneSize,
973                                        1ULL << MappingScale,
974                                        kAsanStackPartialRedzoneMagic);
975      }
976      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
977      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
978    }
979
980    // Poison the full redzone at right.
981    Ptr = IRB.CreateAdd(ShadowBase,
982                        ConstantInt::get(IntptrTy, Pos >> MappingScale));
983    Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
984    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
985
986    Pos += RedzoneSize;
987  }
988}
989
990// Workaround for bug 11395: we don't want to instrument stack in functions
991// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
992// FIXME: remove once the bug 11395 is fixed.
993bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
994  if (LongSize != 32) return false;
995  CallInst *CI = dyn_cast<CallInst>(I);
996  if (!CI || !CI->isInlineAsm()) return false;
997  if (CI->getNumArgOperands() <= 5) return false;
998  // We have inline assembly with quite a few arguments.
999  return true;
1000}
1001
1002// Find all static Alloca instructions and put
1003// poisoned red zones around all of them.
1004// Then unpoison everything back before the function returns.
1005//
1006// Stack poisoning does not play well with exception handling.
1007// When an exception is thrown, we essentially bypass the code
1008// that unpoisones the stack. This is why the run-time library has
1009// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1010// stack in the interceptor. This however does not work inside the
1011// actual function which catches the exception. Most likely because the
1012// compiler hoists the load of the shadow value somewhere too high.
1013// This causes asan to report a non-existing bug on 453.povray.
1014// It sounds like an LLVM bug.
1015bool AddressSanitizer::poisonStackInFunction(Function &F) {
1016  if (!ClStack) return false;
1017  SmallVector<AllocaInst*, 16> AllocaVec;
1018  SmallVector<Instruction*, 8> RetVec;
1019  uint64_t TotalSize = 0;
1020
1021  // Filter out Alloca instructions we want (and can) handle.
1022  // Collect Ret instructions.
1023  for (Function::iterator FI = F.begin(), FE = F.end();
1024       FI != FE; ++FI) {
1025    BasicBlock &BB = *FI;
1026    for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1027         BI != BE; ++BI) {
1028      if (isa<ReturnInst>(BI)) {
1029          RetVec.push_back(BI);
1030          continue;
1031      }
1032
1033      AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1034      if (!AI) continue;
1035      if (AI->isArrayAllocation()) continue;
1036      if (!AI->isStaticAlloca()) continue;
1037      if (!AI->getAllocatedType()->isSized()) continue;
1038      if (AI->getAlignment() > RedzoneSize) continue;
1039      AllocaVec.push_back(AI);
1040      uint64_t AlignedSize =  getAlignedAllocaSize(AI);
1041      TotalSize += AlignedSize;
1042    }
1043  }
1044
1045  if (AllocaVec.empty()) return false;
1046
1047  uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize;
1048
1049  bool DoStackMalloc = ClUseAfterReturn
1050      && LocalStackSize <= kMaxStackMallocSize;
1051
1052  Instruction *InsBefore = AllocaVec[0];
1053  IRBuilder<> IRB(InsBefore);
1054
1055
1056  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1057  AllocaInst *MyAlloca =
1058      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1059  MyAlloca->setAlignment(RedzoneSize);
1060  assert(MyAlloca->isStaticAlloca());
1061  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1062  Value *LocalStackBase = OrigStackBase;
1063
1064  if (DoStackMalloc) {
1065    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1066        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1067  }
1068
1069  // This string will be parsed by the run-time (DescribeStackAddress).
1070  SmallString<2048> StackDescriptionStorage;
1071  raw_svector_ostream StackDescription(StackDescriptionStorage);
1072  StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1073
1074  uint64_t Pos = RedzoneSize;
1075  // Replace Alloca instructions with base+offset.
1076  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1077    AllocaInst *AI = AllocaVec[i];
1078    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1079    StringRef Name = AI->getName();
1080    StackDescription << Pos << " " << SizeInBytes << " "
1081                     << Name.size() << " " << Name << " ";
1082    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1083    assert((AlignedSize % RedzoneSize) == 0);
1084    AI->replaceAllUsesWith(
1085        IRB.CreateIntToPtr(
1086            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1087            AI->getType()));
1088    Pos += AlignedSize + RedzoneSize;
1089  }
1090  assert(Pos == LocalStackSize);
1091
1092  // Write the Magic value and the frame description constant to the redzone.
1093  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1094  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1095                  BasePlus0);
1096  Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1097                                   ConstantInt::get(IntptrTy, LongSize/8));
1098  BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1099  GlobalVariable *StackDescriptionGlobal =
1100      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1101  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1102  IRB.CreateStore(Description, BasePlus1);
1103
1104  // Poison the stack redzones at the entry.
1105  Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1106  PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1107
1108  // Unpoison the stack before all ret instructions.
1109  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1110    Instruction *Ret = RetVec[i];
1111    IRBuilder<> IRBRet(Ret);
1112
1113    // Mark the current frame as retired.
1114    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1115                       BasePlus0);
1116    // Unpoison the stack.
1117    PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1118
1119    if (DoStackMalloc) {
1120      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1121                         ConstantInt::get(IntptrTy, LocalStackSize),
1122                         OrigStackBase);
1123    }
1124  }
1125
1126  // We are done. Remove the old unused alloca instructions.
1127  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1128    AllocaVec[i]->eraseFromParent();
1129
1130  if (ClDebugStack) {
1131    DEBUG(dbgs() << F);
1132  }
1133
1134  return true;
1135}
1136