| //== ArrayBoundChecker.cpp ------------------------------*- C++ -*--==// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines ArrayBoundChecker, which is a path-sensitive check |
| // which looks for an out-of-bound array element access. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| namespace { |
| class ArrayBoundChecker : |
| public Checker<check::Location> { |
| mutable std::unique_ptr<BuiltinBug> BT; |
| |
| public: |
| void checkLocation(SVal l, bool isLoad, const Stmt* S, |
| CheckerContext &C) const; |
| }; |
| } |
| |
| void ArrayBoundChecker::checkLocation(SVal l, bool isLoad, const Stmt* LoadS, |
| CheckerContext &C) const { |
| // Check for out of bound array element access. |
| const MemRegion *R = l.getAsRegion(); |
| if (!R) |
| return; |
| |
| const ElementRegion *ER = dyn_cast<ElementRegion>(R); |
| if (!ER) |
| return; |
| |
| // Get the index of the accessed element. |
| DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>(); |
| |
| // Zero index is always in bound, this also passes ElementRegions created for |
| // pointer casts. |
| if (Idx.isZeroConstant()) |
| return; |
| |
| ProgramStateRef state = C.getState(); |
| |
| // Get the size of the array. |
| DefinedOrUnknownSVal NumElements |
| = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(), |
| ER->getValueType()); |
| |
| ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true); |
| ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false); |
| if (StOutBound && !StInBound) { |
| ExplodedNode *N = C.generateErrorNode(StOutBound); |
| if (!N) |
| return; |
| |
| if (!BT) |
| BT.reset(new BuiltinBug( |
| this, "Out-of-bound array access", |
| "Access out-of-bound array element (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. |
| auto report = |
| std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N); |
| |
| report->addRange(LoadS->getSourceRange()); |
| C.emitReport(std::move(report)); |
| return; |
| } |
| |
| // Array bound check succeeded. From this point forward the array bound |
| // should always succeed. |
| C.addTransition(StInBound); |
| } |
| |
| void ento::registerArrayBoundChecker(CheckerManager &mgr) { |
| mgr.registerChecker<ArrayBoundChecker>(); |
| } |
| |
| bool ento::shouldRegisterArrayBoundChecker(const LangOptions &LO) { |
| return true; |
| } |