/*
* Compile LLVM bytecode to ClamAV bytecode.
*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2009-2013 Sourcefire, Inc.
*
* Authors: Török Edvin, Kevin Lin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#define DEBUG_TYPE "clambc-rtcheck"
#include "ClamBCModule.h"
#include "ClamBCDiagnostics.h"
#include "llvm30_compat.h" /* libclamav-specific */
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/Analysis/CallGraph.h"
#if LLVM_VERSION < 32
#include "llvm/Analysis/DebugInfo.h"
#elif LLVM_VERSION < 35
#include "llvm/DebugInfo.h"
#else
#include "llvm/IR/DebugInfo.h"
#endif
#if LLVM_VERSION < 35
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/Verifier.h"
#else
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Verifier.h"
#endif
#include "llvm/Analysis/ConstantFolding.h"
#if LLVM_VERSION < 29
//#include "llvm/Analysis/LiveValues.h" (unused)
#include "llvm/Analysis/PointerTracking.h"
#else
#include "llvm/Analysis/ValueTracking.h"
#include "PointerTracking.h" /* included from old LLVM source */
#endif
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Config/config.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#if LLVM_VERSION < 35
#include "llvm/Support/DataFlow.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#else
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#endif
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Support/Debug.h"
#if LLVM_VERSION < 32
#include "llvm/Target/TargetData.h"
#elif LLVM_VERSION < 33
#include "llvm/DataLayout.h"
#else
#include "llvm/IR/DataLayout.h"
#endif
#if LLVM_VERSION < 33
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Intrinsics.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#else
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#endif
#if LLVM_VERSION < 33
#include "llvm/Support/InstVisitor.h"
#elif LLVM_VERSION < 35
#include "llvm/InstVisitor.h"
#else
#include "llvm/IR/InstVisitor.h"
#endif
#define DEFINEPASS(passname) passname() : FunctionPass(ID)
using namespace llvm;
#if LLVM_VERSION < 29
/* function is succeeded in later LLVM with LLVM corresponding standalone */
static Value *GetUnderlyingObject(Value *P, TargetData *TD)
{
return P->getUnderlyingObject();
}
#endif
namespace llvm {
class PtrVerifier;
#if LLVM_VERSION >= 29
void initializePtrVerifierPass(PassRegistry&);
#endif
class PtrVerifier : public FunctionPass {
private:
DenseSet<Function*> badFunctions;
std::vector<Instruction*> delInst;
#if LLVM_VERSION < 35
CallGraphNode *rootNode;
#else
CallGraph *CG;
#endif
public:
static char ID;
#if LLVM_VERSION < 35
DEFINEPASS(PtrVerifier), rootNode(0), PT(), TD(), SE(), expander(),
#else
DEFINEPASS(PtrVerifier), CG(0), PT(), TD(), SE(), expander(),
#endif
DT(), AbrtBB(), Changed(false), valid(false), EP() {
#if LLVM_VERSION >= 29
initializePtrVerifierPass(*PassRegistry::getPassRegistry());
#endif
}
virtual bool runOnFunction(Function &F) {
/*
#ifndef CLAMBC_COMPILER
// Bytecode was already verified and had stack protector applied.
// We get called again because ALL bytecode functions loaded are part of
// the same module.
if (F.hasFnAttr(Attribute::StackProtectReq))
return false;
#endif
*/
DEBUG(errs() << "Running on " << F.getName() << "\n");
DEBUG(F.dump());
Changed = false;
BaseMap.clear();
BoundsMap.clear();
delInst.clear();
AbrtBB = 0;
valid = true;
#if LLVM_VERSION < 35
if (!rootNode) {
rootNode = getAnalysis<CallGraph>().getRoot();
#else
if (!CG) {
CG = &getAnalysis<CallGraphWrapperPass>().getCallGraph();
#endif
// No recursive functions for now.
// In the future we may insert runtime checks for stack depth.
#if LLVM_VERSION < 35
for (scc_iterator<CallGraphNode*> SCCI = scc_begin(rootNode),
E = scc_end(rootNode); SCCI != E; ++SCCI) {
#else
for (scc_iterator<CallGraph*> SCCI = scc_begin(CG); !SCCI.isAtEnd(); ++SCCI) {
#endif
const std::vector<CallGraphNode*> &nextSCC = *SCCI;
if (nextSCC.size() > 1 || SCCI.hasLoop()) {
errs() << "INVALID: Recursion detected, callgraph SCC components: ";
for (std::vector<CallGraphNode*>::const_iterator I = nextSCC.begin(),
E = nextSCC.end(); I != E; ++I) {
Function *FF = (*I)->getFunction();
if (FF) {
errs() << FF->getName() << ", ";
badFunctions.insert(FF);
}
}
if (SCCI.hasLoop())
errs() << "(self-loop)";
errs() << "\n";
}
// we could also have recursion via function pointers, but we don't
// allow calls to unknown functions, see runOnFunction() below
}
}
BasicBlock::iterator It = F.getEntryBlock().begin();
while (isa<AllocaInst>(It) || isa<PHINode>(It)) ++It;
EP = &*It;
#if LLVM_VERSION < 32
TD = &getAnalysis<TargetData>();
#elif LLVM_VERSION < 35
TD = &getAnalysis<DataLayout>();
#else
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
TD = DLP ? &DLP->getDataLayout() : 0;
#endif
SE = &getAnalysis<ScalarEvolution>();
PT = &getAnalysis<PointerTracking>();
#if LLVM_VERSION < 35
DT = &getAnalysis<DominatorTree>();
#else
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
#endif
expander = new SCEVExpander(*SE OPT("SCEVexpander"));
std::vector<Instruction*> insns;
BasicBlock *LastBB = 0;
for (inst_iterator I=inst_begin(F),E=inst_end(F); I != E;++I) {
Instruction *II = &*I;
/* only appears in the libclamav version */
if (II->getParent() != LastBB) {
LastBB = II->getParent();
if (DT->getNode(LastBB) == 0)
continue;
}
/* end-block */
if (isa<LoadInst>(II) || isa<StoreInst>(II) || isa<MemIntrinsic>(II))
insns.push_back(II);
else if (CallInst *CI = dyn_cast<CallInst>(II)) {
Value *V = CI->getCalledValue()->stripPointerCasts();
Function *F = dyn_cast<Function>(V);
if (!F) {
printLocation(CI, true);
errs() << "Could not determine call target\n";
valid = 0;
continue;
}
// this statement disable checks on user-defined CallInst
//if (!F->isDeclaration())
//continue;
insns.push_back(CI);
}
}
for (unsigned Idx = 0; Idx < insns.size(); ++Idx) {
Instruction *II = insns[Idx];
DEBUG(dbgs() << "checking " << *II << "\n");
if (LoadInst *LI = dyn_cast<LoadInst>(II)) {
constType *Ty = LI->getType();
valid &= validateAccess(LI->getPointerOperand(),
TD->getTypeAllocSize(Ty), LI);
} else if (StoreInst *SI = dyn_cast<StoreInst>(II)) {
constType *Ty = SI->getOperand(0)->getType();
valid &= validateAccess(SI->getPointerOperand(),
TD->getTypeAllocSize(Ty), SI);
} else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
valid &= validateAccess(MI->getDest(), MI->getLength(), MI);
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
valid &= validateAccess(MTI->getSource(), MI->getLength(), MI);
}
} else if (CallInst *CI = dyn_cast<CallInst>(II)) {
Value *V = CI->getCalledValue()->stripPointerCasts();
Function *F = cast<Function>(V);
constFunctionType *FTy = F->getFunctionType();
CallSite CS(CI);
if (F->getName().equals("memcmp") && FTy->getNumParams() == 3) {
valid &= validateAccess(CS.getArgument(0), CS.getArgument(2), CI);
valid &= validateAccess(CS.getArgument(1), CS.getArgument(2), CI);
continue;
}
unsigned i;
#ifdef CLAMBC_COMPILER
i = 0;
#else
i = 1;// skip hidden ctx*
#endif
for (;i<FTy->getNumParams();i++) {
if (isa<PointerType>(FTy->getParamType(i))) {
Value *Ptr = CS.getArgument(i);
if (i+1 >= FTy->getNumParams()) {
printLocation(CI, false);
errs() << "Call to external function with pointer parameter last"
" cannot be analyzed\n";
errs() << *CI << "\n";
valid = 0;
break;
}
Value *Size = CS.getArgument(i+1);
if (!Size->getType()->isIntegerTy()) {
printLocation(CI, false);
errs() << "Pointer argument must be followed by integer argument"
" representing its size\n";
errs() << *CI << "\n";
valid = 0;
break;
}
valid &= validateAccess(Ptr, Size, CI);
}
}
}
}
if (badFunctions.count(&F))
valid = 0;
if (!valid) {
DEBUG(F.dump());
ClamBCModule::stop("Verification found errors!", &F);
// replace function with call to abort
std::vector<constType*>args;
FunctionType* abrtTy = FunctionType::get(Type::getVoidTy(F.getContext()),args,false);
Constant *func_abort = F.getParent()->getOrInsertFunction("abort", abrtTy);
BasicBlock *BB = &F.getEntryBlock();
Instruction *I = &*BB->begin();
Instruction *UI = new UnreachableInst(F.getContext(), I);
CallInst *AbrtC = CallInst::Create(func_abort, "", UI);
AbrtC->setCallingConv(CallingConv::C);
AbrtC->setTailCall(true);
#if LLVM_VERSION < 32
AbrtC->setDoesNotReturn(true);
AbrtC->setDoesNotThrow(true);
#else
AbrtC->setDoesNotReturn();
AbrtC->setDoesNotThrow();
#endif
// remove all instructions from entry
BasicBlock::iterator BBI = I, BBE=BB->end();
while (BBI != BBE) {
if (!BBI->use_empty())
BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
BB->getInstList().erase(BBI++);
}
}
// bb#9967 - deleting obsolete termination instructions
for (unsigned i = 0; i < delInst.size(); ++i)
delInst[i]->eraseFromParent();
delete expander;
return Changed;
}
virtual void releaseMemory() {
badFunctions.clear();
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
#if LLVM_VERSION < 32
AU.addRequired<TargetData>();
#elif LLVM_VERSION < 35
AU.addRequired<DataLayout>();
#else
AU.addRequired<DataLayoutPass>();
#endif
#if LLVM_VERSION < 35
AU.addRequired<DominatorTree>();
#else
AU.addRequired<DominatorTreeWrapperPass>();
#endif
AU.addRequired<ScalarEvolution>();
AU.addRequired<PointerTracking>();
#if LLVM_VERSION < 35
AU.addRequired<CallGraph>();
#else
AU.addRequired<CallGraphWrapperPass>();
#endif
}
bool isValid() const { return valid; }
private:
PointerTracking *PT;
#if LLVM_VERSION < 32
TargetData *TD;
#elif LLVM_VERSION < 35
DataLayout *TD;
#else
const DataLayout *TD;
#endif
ScalarEvolution *SE;
SCEVExpander *expander;
DominatorTree *DT;
DenseMap<Value*, Value*> BaseMap;
DenseMap<Value*, Value*> BoundsMap;
BasicBlock *AbrtBB;
bool Changed;
bool valid;
Instruction *EP;
Instruction *getInsertPoint(Value *V)
{
BasicBlock::iterator It = EP;
if (Instruction *I = dyn_cast<Instruction>(V)) {
It = I;
++It;
}
return &*It;
}
Value *getPointerBase(Value *Ptr)
{
if (BaseMap.count(Ptr))
return BaseMap[Ptr];
Value *P = Ptr->stripPointerCasts();
if (BaseMap.count(P)) {
return BaseMap[Ptr] = BaseMap[P];
}
Value *P2 = GetUnderlyingObject(P, TD);
if (P2 != P) {
Value *V = getPointerBase(P2);
return BaseMap[Ptr] = V;
}
constType *P8Ty =
PointerType::getUnqual(Type::getInt8Ty(Ptr->getContext()));
if (PHINode *PN = dyn_cast<PHINode>(Ptr)) {
BasicBlock::iterator It = PN;
++It;
PHINode *newPN = PHINode::Create(P8Ty, HINT(PN->getNumIncomingValues()) ".verif.base", &*It);
Changed = true;
BaseMap[Ptr] = newPN;
for (unsigned i=0;i<PN->getNumIncomingValues();i++) {
Value *Inc = PN->getIncomingValue(i);
Value *V = getPointerBase(Inc);
newPN->addIncoming(V, PN->getIncomingBlock(i));
}
return newPN;
}
if (SelectInst *SI = dyn_cast<SelectInst>(Ptr)) {
BasicBlock::iterator It = SI;
++It;
Value *TrueB = getPointerBase(SI->getTrueValue());
Value *FalseB = getPointerBase(SI->getFalseValue());
if (TrueB && FalseB) {
SelectInst *NewSI = SelectInst::Create(SI->getCondition(), TrueB,
FalseB, ".select.base", &*It);
Changed = true;
return BaseMap[Ptr] = NewSI;
}
}
if (Ptr->getType() != P8Ty) {
if (Constant *C = dyn_cast<Constant>(Ptr))
Ptr = ConstantExpr::getPointerCast(C, P8Ty);
else {
Instruction *I = getInsertPoint(Ptr);
Ptr = new BitCastInst(Ptr, P8Ty, "", I);
}
}
return BaseMap[Ptr] = Ptr;
}
Value* getValAtIdx(Function *F, unsigned Idx) {
Value *Val= NULL;
// check if accessed Idx is within function parameter list
if (Idx < F->arg_size()) {
Function::arg_iterator It = F->arg_begin();
Function::arg_iterator ItEnd = F->arg_end();
for (unsigned i = 0; i < Idx; ++i, ++It) {
// redundant check, should not be possible
if (It == ItEnd) {
// Houston, the impossible has become possible
//printDiagnostic("Idx is outside of Function parameters", F);
errs() << "Idx is outside of Function parameters\n";
errs() << *F << "\n";
//valid = 0;
break;
}
}
// retrieve value ptr of argument of F at Idx
Val = &(*It);
}
else {
// Idx is outside function parameter list
//printDiagnostic("Idx is outside of Function parameters", F);
errs() << "Idx is outside of Function parameters\n";
errs() << *F << "\n";
//valid = 0;
}
return Val;
}
Value* getPointerBounds(Value *Base) {
if (BoundsMap.count(Base))
return BoundsMap[Base];
constType *I64Ty =
Type::getInt64Ty(Base->getContext());
#ifndef CLAMBC_COMPILER
// first arg is hidden ctx
if (Argument *A = dyn_cast<Argument>(Base)) {
if (A->getArgNo() == 0) {
constType *Ty = cast<PointerType>(A->getType())->getElementType();
return ConstantInt::get(I64Ty, TD->getTypeAllocSize(Ty));
} else if (Base->getType()->isPointerTy()) {
Function *F = A->getParent();
const FunctionType *FT = F->getFunctionType();
bool checks = true;
// last argument check
if (A->getArgNo() == (FT->getNumParams()-1)) {
//printDiagnostic("pointer argument cannot be last argument", F);
errs() << "pointer argument cannot be last argument\n";
errs() << *F << "\n";
checks = false;
}
// argument after pointer MUST be a integer (unsigned probably too)
if (checks && !FT->getParamType(A->getArgNo()+1)->isIntegerTy()) {
//printDiagnostic("argument following pointer argument is not an integer", F);
errs() << "argument following pointer argument is not an integer\n";
errs() << *F << "\n";
checks = false;
}
if (checks)
return BoundsMap[Base] = getValAtIdx(F, A->getArgNo()+1);
}
}
if (LoadInst *LI = dyn_cast<LoadInst>(Base)) {
Value *V = GetUnderlyingObject(LI->getPointerOperand()->stripPointerCasts(), TD);
if (Argument *A = dyn_cast<Argument>(V)) {
if (A->getArgNo() == 0) {
// pointers from hidden ctx are trusted to be at least the
// size they say they are
constType *Ty = cast<PointerType>(LI->getType())->getElementType();
return ConstantInt::get(I64Ty, TD->getTypeAllocSize(Ty));
}
}
}
#else
if (Base->getType()->isPointerTy()) {
if (Argument *A = dyn_cast<Argument>(Base)) {
Function *F = A->getParent();
const FunctionType *FT = F->getFunctionType();
bool checks = true;
// last argument check
if (A->getArgNo() == (FT->getNumParams()-1)) {
//printDiagnostic("pointer argument cannot be last argument", F);
errs() << "pointer argument cannot be last argument\n";
errs() << *F << "\n";
checks = false;
}
// argument after pointer MUST be a integer (unsigned probably too)
if (checks && !FT->getParamType(A->getArgNo()+1)->isIntegerTy()) {
//printDiagnostic("argument following pointer argument is not an integer", F);
errs() << "argument following pointer argument is not an integer\n";
errs() << *F << "\n";
checks = false;
}
if (checks)
return BoundsMap[Base] = getValAtIdx(F, A->getArgNo()+1);
}
}
#endif
if (PHINode *PN = dyn_cast<PHINode>(Base)) {
BasicBlock::iterator It = PN;
++It;
PHINode *newPN = PHINode::Create(I64Ty, HINT(PN->getNumIncomingValues()) ".verif.bounds", &*It);
Changed = true;
BoundsMap[Base] = newPN;
bool good = true;
for (unsigned i=0;i<PN->getNumIncomingValues();i++) {
Value *Inc = PN->getIncomingValue(i);
Value *B = getPointerBounds(Inc);
if (!B) {
good = false;
B = ConstantInt::get(newPN->getType(), 0);
DEBUG(dbgs() << "bounds not found while solving phi node: " << *Inc
<< "\n");
}
newPN->addIncoming(B, PN->getIncomingBlock(i));
}
if (!good)
newPN = 0;
return BoundsMap[Base] = newPN;
}
if (SelectInst *SI = dyn_cast<SelectInst>(Base)) {
BasicBlock::iterator It = SI;
++It;
Value *TrueB = getPointerBounds(SI->getTrueValue());
Value *FalseB = getPointerBounds(SI->getFalseValue());
if (TrueB && FalseB) {
SelectInst *NewSI = SelectInst::Create(SI->getCondition(), TrueB,
FalseB, ".select.bounds", &*It);
Changed = true;
return BoundsMap[Base] = NewSI;
}
}
constType *Ty;
Value *V = PT->computeAllocationCountValue(Base, Ty);
if (!V) {
Base = Base->stripPointerCasts();
if (CallInst *CI = dyn_cast<CallInst>(Base)) {
Function *F = CI->getCalledFunction();
constFunctionType *FTy = F->getFunctionType();
// last operand is always size for this API call kind
if (F->isDeclaration() && FTy->getNumParams() > 0) {
CallSite CS(CI);
if (FTy->getParamType(FTy->getNumParams()-1)->isIntegerTy())
V = CS.getArgument(FTy->getNumParams()-1);
}
}
if (!V)
return BoundsMap[Base] = 0;
} else {
unsigned size = TD->getTypeAllocSize(Ty);
if (size > 1) {
Constant *C = cast<Constant>(V);
C = ConstantExpr::getMul(C,
ConstantInt::get(Type::getInt32Ty(C->getContext()),
size));
V = C;
}
}
if (V->getType() != I64Ty) {
if (Constant *C = dyn_cast<Constant>(V))
V = ConstantExpr::getZExt(C, I64Ty);
else {
Instruction *I = getInsertPoint(V);
V = new ZExtInst(V, I64Ty, "", I);
}
}
return BoundsMap[Base] = V;
}
MDNode *getLocation(Instruction *I, bool &Approximate, unsigned MDDbgKind)
{
Approximate = false;
if (MDNode *Dbg = I->getMetadata(MDDbgKind))
return Dbg;
if (!MDDbgKind)
return 0;
Approximate = true;
BasicBlock::iterator It = I;
while (It != I->getParent()->begin()) {
--It;
if (MDNode *Dbg = It->getMetadata(MDDbgKind))
return Dbg;
}
BasicBlock *BB = I->getParent();
while ((BB = BB->getUniquePredecessor())) {
It = BB->end();
while (It != BB->begin()) {
--It;
if (MDNode *Dbg = It->getMetadata(MDDbgKind))
return Dbg;
}
}
return 0;
}
bool insertCheck(const SCEV *Idx, const SCEV *Limit, Instruction *I,
bool strict)
{
if (isa<SCEVCouldNotCompute>(Idx) && isa<SCEVCouldNotCompute>(Limit)) {
errs() << "Could not compute the index and the limit!: \n" << *I << "\n";
return false;
}
if (isa<SCEVCouldNotCompute>(Idx)) {
errs() << "Could not compute index: \n" << *I << "\n";
return false;
}
if (isa<SCEVCouldNotCompute>(Limit)) {
errs() << "Could not compute limit: " << *I << "\n";
return false;
}
BasicBlock *BB = I->getParent();
BasicBlock::iterator It = I;
BasicBlock *newBB = SplitBlock(BB, &*It, this);
PHINode *PN;
unsigned MDDbgKind = I->getContext().getMDKindID("dbg");
//verifyFunction(*BB->getParent());
if (!AbrtBB) {
std::vector<constType*>args;
FunctionType* abrtTy = FunctionType::get(Type::getVoidTy(BB->getContext()),args,false);
args.push_back(Type::getInt32Ty(BB->getContext()));
FunctionType* rterrTy = FunctionType::get(Type::getInt32Ty(BB->getContext()),args,false);
Constant *func_abort = BB->getParent()->getParent()->getOrInsertFunction("abort", abrtTy);
Constant *func_rterr = BB->getParent()->getParent()->getOrInsertFunction("bytecode_rt_error",
rterrTy);
AbrtBB = BasicBlock::Create(BB->getContext(), "rterr.trig", BB->getParent());
PN = PHINode::Create(Type::getInt32Ty(BB->getContext()),HINT(1) "",
AbrtBB);
if (MDDbgKind) {
CallInst *RtErrCall = CallInst::Create(func_rterr, PN, "", AbrtBB);
RtErrCall->setCallingConv(CallingConv::C);
RtErrCall->setTailCall(true);
#if LLVM_VERSION < 32
RtErrCall->setDoesNotThrow(true);
#else
RtErrCall->setDoesNotThrow();
#endif
}
CallInst* AbrtC = CallInst::Create(func_abort, "", AbrtBB);
AbrtC->setCallingConv(CallingConv::C);
AbrtC->setTailCall(true);
#if LLVM_VERSION < 32
AbrtC->setDoesNotReturn(true);
AbrtC->setDoesNotThrow(true);
#else
AbrtC->setDoesNotReturn();
AbrtC->setDoesNotThrow();
#endif
new UnreachableInst(BB->getContext(), AbrtBB);
DT->addNewBlock(AbrtBB, BB);
//verifyFunction(*BB->getParent());
} else {
PN = cast<PHINode>(AbrtBB->begin());
}
unsigned locationid = 0;
bool Approximate;
if (MDNode *Dbg = getLocation(I, Approximate, MDDbgKind)) {
DILocation Loc(Dbg);
locationid = Loc.getLineNumber() << 8;
unsigned col = Loc.getColumnNumber();
if (col > 254)
col = 254;
if (Approximate)
col = 255;
locationid |= col;
}
PN->addIncoming(ConstantInt::get(Type::getInt32Ty(BB->getContext()),
locationid), BB);
TerminatorInst *TI = BB->getTerminator();
Value *IdxV = expander->expandCodeFor(Idx, Limit->getType(), TI);
Value *LimitV = expander->expandCodeFor(Limit, Limit->getType(), TI);
if (isa<Instruction>(IdxV) &&
!DT->dominates(cast<Instruction>(IdxV)->getParent(),I->getParent())) {
printLocation(I, true);
errs() << "basic block with value [ " << IdxV->getName();
errs() << " ] with limit [ " << LimitV->getName();
errs() << " ] does not dominate" << *I << "\n";
return false;
}
if (isa<Instruction>(LimitV) &&
!DT->dominates(cast<Instruction>(LimitV)->getParent(),I->getParent())) {
printLocation(I, true);
errs() << "basic block with limit [" << LimitV->getName();
errs() << " ] on value [ " << IdxV->getName();
errs() << " ] does not dominate" << *I << "\n";
return false;
}
Value *Cond = new ICmpInst(TI, strict ?
ICmpInst::ICMP_ULT :
ICmpInst::ICMP_ULE, IdxV, LimitV);
BranchInst::Create(newBB, AbrtBB, Cond, TI);
//TI->eraseFromParent();
delInst.push_back(TI);
// Update dominator info
BasicBlock *DomBB =
DT->findNearestCommonDominator(BB, DT->getNode(AbrtBB)->getIDom()->getBlock());
DT->changeImmediateDominator(AbrtBB, DomBB);
return true;
}
static void MakeCompatible(ScalarEvolution *SE, const SCEV*& LHS, const SCEV*& RHS)
{
if (const SCEVZeroExtendExpr *ZL = dyn_cast<SCEVZeroExtendExpr>(LHS))
LHS = ZL->getOperand();
if (const SCEVZeroExtendExpr *ZR = dyn_cast<SCEVZeroExtendExpr>(RHS))
RHS = ZR->getOperand();
constType* LTy = SE->getEffectiveSCEVType(LHS->getType());
constType *RTy = SE->getEffectiveSCEVType(RHS->getType());
if (SE->getTypeSizeInBits(RTy) > SE->getTypeSizeInBits(LTy))
LTy = RTy;
LHS = SE->getNoopOrZeroExtend(LHS, LTy);
RHS = SE->getNoopOrZeroExtend(RHS, LTy);
}
bool checkCond(Instruction *ICI, Instruction *I, bool equal)
{
for (Value::use_iterator JU=ICI->use_begin(),JUE=ICI->use_end();
JU != JUE; ++JU) {
Value *JU_V = *JU;
if (BranchInst *BI = dyn_cast<BranchInst>(JU_V)) {
if (!BI->isConditional())
continue;
BasicBlock *S = BI->getSuccessor(equal);
if (DT->dominates(S, I->getParent()))
return true;
}
if (BinaryOperator *BI = dyn_cast<BinaryOperator>(JU_V)) {
if (BI->getOpcode() == Instruction::Or &&
checkCond(BI, I, equal))
return true;
if (BI->getOpcode() == Instruction::And &&
checkCond(BI, I, !equal))
return true;
}
}
return false;
}
bool checkCondition(Instruction *CI, Instruction *I)
{
for (Value::use_iterator U=CI->use_begin(),UE=CI->use_end();
U != UE; ++U) {
Value *U_V = *U;
if (ICmpInst *ICI = dyn_cast<ICmpInst>(U_V)) {
if (ICI->getOperand(0)->stripPointerCasts() == CI &&
isa<ConstantPointerNull>(ICI->getOperand(1))) {
if (checkCond(ICI, I, ICI->getPredicate() == ICmpInst::ICMP_EQ))
return true;
}
}
}
return false;
}
bool validateAccess(Value *Pointer, Value *Length, Instruction *I)
{
// get base
Value *Base = getPointerBase(Pointer);
Value *SBase = Base->stripPointerCasts();
// get bounds
Value *Bounds = getPointerBounds(SBase);
if (!Bounds) {
printLocation(I, true);
errs() << "no bounds for base ";
printValue(SBase);
errs() << " while checking access to ";
printValue(Pointer);
errs() << " of length ";
printValue(Length);
errs() << "\n";
return false;
}
// checks if a NULL pointer check (returned from function) is made:
if (CallInst *CI = dyn_cast<CallInst>(Base->stripPointerCasts())) {
// by checking if use is in the same block (i.e. no branching decisions)
if (I->getParent() == CI->getParent()) {
printLocation(I, true);
errs() << "no null pointer check of pointer ";
printValue(Base, false, true);
errs() << " obtained by function call";
errs() << " before use in same block\n";
return false;
}
// by checking if a conditional contains the values in question somewhere
// between their usage
if (!checkCondition(CI, I)) {
printLocation(I, true);
errs() << "no null pointer check of pointer ";
printValue(Base, false, true);
errs() << " obtained by function call";
errs() << " before use\n";
return false;
}
}
constType *I64Ty =
Type::getInt64Ty(Base->getContext());
const SCEV *SLen = SE->getSCEV(Length);
const SCEV *OffsetP = SE->getMinusSCEV(SE->getSCEV(Pointer),
SE->getSCEV(Base));
SLen = SE->getNoopOrZeroExtend(SLen, I64Ty);
OffsetP = SE->getNoopOrZeroExtend(OffsetP, I64Ty);
const SCEV *Limit = SE->getSCEV(Bounds);
Limit = SE->getNoopOrZeroExtend(Limit, I64Ty);
DEBUG(dbgs() << "Checking access to " << *Pointer << " of length " <<
*Length << "\n");
if (OffsetP == Limit) {
printLocation(I, true);
errs() << "OffsetP == Limit: " << *OffsetP << "\n";
errs() << " while checking access to ";
printValue(Pointer);
errs() << " of length ";
printValue(Length);
errs() << "\n";
return false;
}
if (SLen == Limit) {
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(OffsetP)) {
if (SC->isZero())
return true;
}
errs() << "SLen == Limit: " << *SLen << "\n";
errs() << " while checking access to " << *Pointer << " of length "
<< *Length << " at " << *I << "\n";
return false;
}
bool valid = true;
SLen = SE->getAddExpr(OffsetP, SLen);
// check that offset + slen <= limit;
// umax(offset+slen, limit) == limit is a sufficient (but not necessary
// condition)
const SCEV *MaxL = SE->getUMaxExpr(SLen, Limit);
if (MaxL != Limit) {
DEBUG(dbgs() << "MaxL != Limit: " << *MaxL << ", " << *Limit << "\n");
valid &= insertCheck(SLen, Limit, I, false);
}
//TODO: nullpointer check
const SCEV *Max = SE->getUMaxExpr(OffsetP, Limit);
if (Max == Limit)
return valid;
DEBUG(dbgs() << "Max != Limit: " << *Max << ", " << *Limit << "\n");
// check that offset < limit
valid &= insertCheck(OffsetP, Limit, I, true);
return valid;
}
bool validateAccess(Value *Pointer, unsigned size, Instruction *I)
{
return validateAccess(Pointer,
ConstantInt::get(Type::getInt32Ty(Pointer->getContext()),
size), I);
}
};
char PtrVerifier::ID;
} /* end namespace llvm */
#if LLVM_VERSION >= 29
INITIALIZE_PASS_BEGIN(PtrVerifier, "", "", false, false)
#if LLVM_VERSION < 32
INITIALIZE_PASS_DEPENDENCY(TargetData)
#elif LLVM_VERSION < 35
INITIALIZE_PASS_DEPENDENCY(DataLayout)
#else
INITIALIZE_PASS_DEPENDENCY(DataLayoutPass)
#endif
#if LLVM_VERSION < 35
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
#else
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
#endif
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
#if LLVM_VERSION < 34
INITIALIZE_AG_DEPENDENCY(CallGraph)
#elif LLVM_VERSION < 35
INITIALIZE_PASS_DEPENDENCY(CallGraph)
#else
INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
#endif
INITIALIZE_PASS_DEPENDENCY(PointerTracking)
INITIALIZE_PASS_END(PtrVerifier, "clambc-rtchecks", "ClamBC RTchecks", false, false)
#endif
llvm::Pass *createClamBCRTChecks()
{
return new PtrVerifier();
}