| //=== UndefResultChecker.cpp ------------------------------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This defines UndefResultChecker, a builtin check in ExprEngine that |
| // performs checks for undefined results of non-assignment binary operators. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "ClangSACheckers.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" |
| #include "clang/StaticAnalyzer/Core/Checker.h" |
| #include "clang/StaticAnalyzer/Core/CheckerManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| namespace { |
| class UndefResultChecker |
| : public Checker< check::PostStmt<BinaryOperator> > { |
| |
| mutable std::unique_ptr<BugType> BT; |
| |
| public: |
| void checkPostStmt(const BinaryOperator *B, CheckerContext &C) const; |
| }; |
| } // end anonymous namespace |
| |
| static bool isArrayIndexOutOfBounds(CheckerContext &C, const Expr *Ex) { |
| ProgramStateRef state = C.getState(); |
| const LocationContext *LCtx = C.getLocationContext(); |
| |
| if (!isa<ArraySubscriptExpr>(Ex)) |
| return false; |
| |
| SVal Loc = state->getSVal(Ex, LCtx); |
| if (!Loc.isValid()) |
| return false; |
| |
| const MemRegion *MR = Loc.castAs<loc::MemRegionVal>().getRegion(); |
| const ElementRegion *ER = dyn_cast<ElementRegion>(MR); |
| if (!ER) |
| return false; |
| |
| DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>(); |
| DefinedOrUnknownSVal NumElements = C.getStoreManager().getSizeInElements( |
| state, ER->getSuperRegion(), ER->getValueType()); |
| ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true); |
| ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false); |
| return StOutBound && !StInBound; |
| } |
| |
| void UndefResultChecker::checkPostStmt(const BinaryOperator *B, |
| CheckerContext &C) const { |
| ProgramStateRef state = C.getState(); |
| const LocationContext *LCtx = C.getLocationContext(); |
| if (state->getSVal(B, LCtx).isUndef()) { |
| |
| // Do not report assignments of uninitialized values inside swap functions. |
| // This should allow to swap partially uninitialized structs |
| // (radar://14129997) |
| if (const FunctionDecl *EnclosingFunctionDecl = |
| dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl())) |
| if (C.getCalleeName(EnclosingFunctionDecl) == "swap") |
| return; |
| |
| // Generate an error node. |
| ExplodedNode *N = C.generateErrorNode(); |
| if (!N) |
| return; |
| |
| if (!BT) |
| BT.reset( |
| new BuiltinBug(this, "Result of operation is garbage or undefined")); |
| |
| SmallString<256> sbuf; |
| llvm::raw_svector_ostream OS(sbuf); |
| const Expr *Ex = nullptr; |
| bool isLeft = true; |
| |
| if (state->getSVal(B->getLHS(), LCtx).isUndef()) { |
| Ex = B->getLHS()->IgnoreParenCasts(); |
| isLeft = true; |
| } |
| else if (state->getSVal(B->getRHS(), LCtx).isUndef()) { |
| Ex = B->getRHS()->IgnoreParenCasts(); |
| isLeft = false; |
| } |
| |
| if (Ex) { |
| OS << "The " << (isLeft ? "left" : "right") |
| << " operand of '" |
| << BinaryOperator::getOpcodeStr(B->getOpcode()) |
| << "' is a garbage value"; |
| if (isArrayIndexOutOfBounds(C, Ex)) |
| OS << " due to array index out of bounds"; |
| } |
| else { |
| // Neither operand was undefined, but the result is undefined. |
| OS << "The result of the '" |
| << BinaryOperator::getOpcodeStr(B->getOpcode()) |
| << "' expression is undefined"; |
| } |
| auto report = llvm::make_unique<BugReport>(*BT, OS.str(), N); |
| if (Ex) { |
| report->addRange(Ex->getSourceRange()); |
| bugreporter::trackNullOrUndefValue(N, Ex, *report); |
| } |
| else |
| bugreporter::trackNullOrUndefValue(N, B, *report); |
| |
| C.emitReport(std::move(report)); |
| } |
| } |
| |
| void ento::registerUndefResultChecker(CheckerManager &mgr) { |
| mgr.registerChecker<UndefResultChecker>(); |
| } |