void AdjustedReturnValueChecker::PostVisitCallExpr(CheckerContext &C,
const CallExpr *CE) {
// Get the result type of the call.
QualType expectedResultTy = CE->getType();
// Fetch the signature of the called function.
const GRState *state = C.getState();
SVal V = state->getSVal(CE);
if (V.isUnknown())
return;
// Casting to void? Discard the value.
if (expectedResultTy->isVoidType()) {
C.GenerateNode(state->BindExpr(CE, UnknownVal()));
return;
}
const MemRegion *callee = state->getSVal(CE->getCallee()).getAsRegion();
if (!callee)
return;
QualType actualResultTy;
if (const FunctionTextRegion *FT = dyn_cast<FunctionTextRegion>(callee)) {
const FunctionDecl *FD = FT->getDecl();
actualResultTy = FD->getResultType();
}
else if (const BlockDataRegion *BD = dyn_cast<BlockDataRegion>(callee)) {
const BlockTextRegion *BR = BD->getCodeRegion();
const BlockPointerType *BT =
BR->getLocationType(C.getASTContext())->getAs<BlockPointerType>();
const FunctionType *FT = BT->getPointeeType()->getAs<FunctionType>();
actualResultTy = FT->getResultType();
}
// Can this happen?
if (actualResultTy.isNull())
return;
// For now, ignore references.
if (actualResultTy->getAs<ReferenceType>())
return;
// Are they the same?
if (expectedResultTy != actualResultTy) {
// FIXME: Do more checking and actual emit an error. At least performing
// the cast avoids some assertion failures elsewhere.
SValuator &SVator = C.getSValuator();
V = SVator.EvalCast(V, expectedResultTy, actualResultTy);
C.GenerateNode(state->BindExpr(CE, V));
}
}
void FixedAddressChecker::PreVisitBinaryOperator(CheckerContext &C,
const BinaryOperator *B) {
// Using a fixed address is not portable because that address will probably
// not be valid in all environments or platforms.
if (B->getOpcode() != BinaryOperator::Assign)
return;
QualType T = B->getType();
if (!T->isPointerType())
return;
const GRState *state = C.getState();
SVal RV = state->getSVal(B->getRHS());
if (!RV.isConstant() || RV.isZeroConstant())
return;
if (ExplodedNode *N = C.GenerateNode()) {
if (!BT)
BT = new BuiltinBug("Use fixed address",
"Using a fixed address is not portable because that "
"address will probably not be valid in all "
"environments or platforms.");
RangedBugReport *R = new RangedBugReport(*BT, BT->getDescription(), N);
R->addRange(B->getRHS()->getSourceRange());
C.EmitReport(R);
}
}
void ClassReleaseChecker::PreVisitObjCMessageExpr(CheckerContext &C,
const ObjCMessageExpr *ME) {
const IdentifierInfo *ClsName = ME->getClassName();
if (!ClsName)
return;
Selector S = ME->getSelector();
if (!(S == releaseS || S == retainS || S == autoreleaseS || S == drainS))
return;
if (!BT)
BT = new APIMisuse("message incorrectly sent to class instead of class "
"instance");
ExplodedNode *N = C.GenerateNode();
if (!N)
return;
llvm::SmallString<200> buf;
llvm::raw_svector_ostream os(buf);
os << "The '" << S.getAsString() << "' message should be sent to instances "
"of class '" << ClsName->getName()
<< "' and not the class directly";
RangedBugReport *report = new RangedBugReport(*BT, os.str(), N);
report->addRange(ME->getSourceRange());
C.EmitReport(report);
}
void ReturnPointerRangeChecker::PreVisitReturnStmt(CheckerContext &C,
const ReturnStmt *RS) {
const GRState *state = C.getState();
const Expr *RetE = RS->getRetValue();
if (!RetE)
return;
SVal V = state->getSVal(RetE);
const MemRegion *R = V.getAsRegion();
if (!R)
return;
R = R->StripCasts();
if (!R)
return;
const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
if (!ER)
return;
DefinedOrUnknownSVal &Idx = cast<DefinedOrUnknownSVal>(ER->getIndex());
// FIXME: All of this out-of-bounds checking should eventually be refactored
// into a common place.
DefinedOrUnknownSVal NumElements
= C.getStoreManager().getSizeInElements(state, ER->getSuperRegion());
const GRState *StInBound = state->AssumeInBound(Idx, NumElements, true);
const GRState *StOutBound = state->AssumeInBound(Idx, NumElements, false);
if (StOutBound && !StInBound) {
ExplodedNode *N = C.GenerateNode(RS, StOutBound, true);
if (!N)
return;
// FIXME: This bug correspond to CWE-466. Eventually we should have bug
// types explicitly reference such exploit categories (when applicable).
if (!BT)
BT = new BuiltinBug("Return of pointer value outside of expected range",
"Returned pointer value points outside the original object "
"(potential buffer overflow)");
// FIXME: It would be nice to eventually make this diagnostic more clear,
// e.g., by referencing the original declaration or by saying *why* this
// reference is outside the range.
// Generate a report for this bug.
RangedBugReport *report =
new RangedBugReport(*BT, BT->getDescription(), N);
report->addRange(RetE->getSourceRange());
C.EmitReport(report);
}
}
void CastToStructChecker::PreVisitCastExpr(CheckerContext &C,
const CastExpr *CE) {
const Expr *E = CE->getSubExpr();
ASTContext &Ctx = C.getASTContext();
QualType OrigTy = Ctx.getCanonicalType(E->getType());
QualType ToTy = Ctx.getCanonicalType(CE->getType());
PointerType *OrigPTy = dyn_cast<PointerType>(OrigTy.getTypePtr());
PointerType *ToPTy = dyn_cast<PointerType>(ToTy.getTypePtr());
if (!ToPTy || !OrigPTy)
return;
QualType OrigPointeeTy = OrigPTy->getPointeeType();
QualType ToPointeeTy = ToPTy->getPointeeType();
if (!ToPointeeTy->isStructureOrClassType())
return;
// We allow cast from void*.
if (OrigPointeeTy->isVoidType())
return;
// Now the cast-to-type is struct pointer, the original type is not void*.
if (!OrigPointeeTy->isRecordType()) {
if (ExplodedNode *N = C.GenerateNode()) {
if (!BT)
BT = new BuiltinBug("Cast from non-struct type to struct type",
"Casting a non-structure type to a structure type "
"and accessing a field can lead to memory access "
"errors or data corruption.");
RangedBugReport *R = new RangedBugReport(*BT,BT->getDescription(), N);
R->addRange(CE->getSourceRange());
C.EmitReport(R);
}
}
}
bool OSAtomicChecker::EvalOSAtomicCompareAndSwap(CheckerContext &C,
const CallExpr *CE) {
// Not enough arguments to match OSAtomicCompareAndSwap?
if (CE->getNumArgs() != 3)
return false;
ASTContext &Ctx = C.getASTContext();
const Expr *oldValueExpr = CE->getArg(0);
QualType oldValueType = Ctx.getCanonicalType(oldValueExpr->getType());
const Expr *newValueExpr = CE->getArg(1);
QualType newValueType = Ctx.getCanonicalType(newValueExpr->getType());
// Do the types of 'oldValue' and 'newValue' match?
if (oldValueType != newValueType)
return false;
const Expr *theValueExpr = CE->getArg(2);
const PointerType *theValueType=theValueExpr->getType()->getAs<PointerType>();
// theValueType not a pointer?
if (!theValueType)
return false;
QualType theValueTypePointee =
Ctx.getCanonicalType(theValueType->getPointeeType()).getUnqualifiedType();
// The pointee must match newValueType and oldValueType.
if (theValueTypePointee != newValueType)
return false;
static unsigned magic_load = 0;
static unsigned magic_store = 0;
const void *OSAtomicLoadTag = &magic_load;
const void *OSAtomicStoreTag = &magic_store;
// Load 'theValue'.
GRExprEngine &Engine = C.getEngine();
const GRState *state = C.getState();
ExplodedNodeSet Tmp;
SVal location = state->getSVal(theValueExpr);
// Here we should use the value type of the region as the load type, because
// we are simulating the semantics of the function, not the semantics of
// passing argument. So the type of theValue expr is not we are loading.
// But usually the type of the varregion is not the type we want either,
// we still need to do a CastRetrievedVal in store manager. So actually this
// LoadTy specifying can be omitted. But we put it here to emphasize the
// semantics.
QualType LoadTy;
if (const TypedRegion *TR =
dyn_cast_or_null<TypedRegion>(location.getAsRegion())) {
LoadTy = TR->getValueType();
}
Engine.EvalLoad(Tmp, theValueExpr, C.getPredecessor(),
state, location, OSAtomicLoadTag, LoadTy);
if (Tmp.empty()) {
// If no nodes were generated, other checkers must generated sinks. But
// since the builder state was restored, we set it manually to prevent
// auto transition.
// FIXME: there should be a better approach.
C.getNodeBuilder().BuildSinks = true;
return true;
}
for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end();
I != E; ++I) {
ExplodedNode *N = *I;
const GRState *stateLoad = N->getState();
SVal theValueVal_untested = stateLoad->getSVal(theValueExpr);
SVal oldValueVal_untested = stateLoad->getSVal(oldValueExpr);
// FIXME: Issue an error.
if (theValueVal_untested.isUndef() || oldValueVal_untested.isUndef()) {
return false;
}
DefinedOrUnknownSVal theValueVal =
cast<DefinedOrUnknownSVal>(theValueVal_untested);
DefinedOrUnknownSVal oldValueVal =
cast<DefinedOrUnknownSVal>(oldValueVal_untested);
SValuator &SVator = Engine.getSValuator();
// Perform the comparison.
DefinedOrUnknownSVal Cmp = SVator.EvalEQ(stateLoad,theValueVal,oldValueVal);
const GRState *stateEqual = stateLoad->Assume(Cmp, true);
// Were they equal?
if (stateEqual) {
// Perform the store.
ExplodedNodeSet TmpStore;
SVal val = stateEqual->getSVal(newValueExpr);
// Handle implicit value casts.
if (const TypedRegion *R =
dyn_cast_or_null<TypedRegion>(location.getAsRegion())) {
val = SVator.EvalCast(val,R->getValueType(), newValueExpr->getType());
}
Engine.EvalStore(TmpStore, NULL, theValueExpr, N,
stateEqual, location, val, OSAtomicStoreTag);
if (TmpStore.empty()) {
// If no nodes were generated, other checkers must generated sinks. But
// since the builder state was restored, we set it manually to prevent
// auto transition.
// FIXME: there should be a better approach.
C.getNodeBuilder().BuildSinks = true;
return true;
}
// Now bind the result of the comparison.
for (ExplodedNodeSet::iterator I2 = TmpStore.begin(),
E2 = TmpStore.end(); I2 != E2; ++I2) {
ExplodedNode *predNew = *I2;
const GRState *stateNew = predNew->getState();
// Check for 'void' return type if we have a bogus function prototype.
SVal Res = UnknownVal();
QualType T = CE->getType();
if (!T->isVoidType())
Res = Engine.getValueManager().makeTruthVal(true, T);
C.GenerateNode(stateNew->BindExpr(CE, Res), predNew);
}
}
// Were they not equal?
if (const GRState *stateNotEqual = stateLoad->Assume(Cmp, false)) {
// Check for 'void' return type if we have a bogus function prototype.
SVal Res = UnknownVal();
QualType T = CE->getType();
if (!T->isVoidType())
Res = Engine.getValueManager().makeTruthVal(false, CE->getType());
C.GenerateNode(stateNotEqual->BindExpr(CE, Res), N);
}
}
return true;
}
void AttrNonNullChecker::PreVisitCallExpr(CheckerContext &C,
const CallExpr *CE) {
const GRState *state = C.getState();
const GRState *originalState = state;
// Check if the callee has a 'nonnull' attribute.
SVal X = state->getSVal(CE->getCallee());
const FunctionDecl* FD = X.getAsFunctionDecl();
if (!FD)
return;
const NonNullAttr* Att = FD->getAttr<NonNullAttr>();
if (!Att)
return;
// Iterate through the arguments of CE and check them for null.
unsigned idx = 0;
for (CallExpr::const_arg_iterator I=CE->arg_begin(), E=CE->arg_end(); I!=E;
++I, ++idx) {
if (!Att->isNonNull(idx))
continue;
const SVal &V = state->getSVal(*I);
const DefinedSVal *DV = dyn_cast<DefinedSVal>(&V);
if (!DV)
continue;
ConstraintManager &CM = C.getConstraintManager();
const GRState *stateNotNull, *stateNull;
llvm::tie(stateNotNull, stateNull) = CM.AssumeDual(state, *DV);
if (stateNull && !stateNotNull) {
// Generate an error node. Check for a null node in case
// we cache out.
if (ExplodedNode *errorNode = C.GenerateNode(CE, stateNull, true)) {
// Lazily allocate the BugType object if it hasn't already been
// created. Ownership is transferred to the BugReporter object once
// the BugReport is passed to 'EmitWarning'.
if (!BT)
BT = new BugType("Argument with 'nonnull' attribute passed null",
"API");
EnhancedBugReport *R =
new EnhancedBugReport(*BT,
"Null pointer passed as an argument to a "
"'nonnull' parameter", errorNode);
// Highlight the range of the argument that was null.
const Expr *arg = *I;
R->addRange(arg->getSourceRange());
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, arg);
// Emit the bug report.
C.EmitReport(R);
}
// Always return. Either we cached out or we just emitted an error.
return;
}
// If a pointer value passed the check we should assume that it is
// indeed not null from this point forward.
assert(stateNotNull);
state = stateNotNull;
}
// If we reach here all of the arguments passed the nonnull check.
// If 'state' has been updated generated a new node.
if (state != originalState)
C.addTransition(C.GenerateNode(CE, state));
}