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//==- CheckSizeofPointer.cpp - Check for sizeof on pointers ------*- 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 a check for unintended use of sizeof() on pointer
// expressions.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
using namespace clang;
using namespace ento;
namespace {
class WalkAST : public StmtVisitor<WalkAST> {
BugReporter &BR;
const CheckerBase *Checker;
AnalysisDeclContext* AC;
public:
WalkAST(BugReporter &br, const CheckerBase *checker, AnalysisDeclContext *ac)
: BR(br), Checker(checker), AC(ac) {}
void VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E);
void VisitStmt(Stmt *S) { VisitChildren(S); }
void VisitChildren(Stmt *S);
};
}
void WalkAST::VisitChildren(Stmt *S) {
for (Stmt *Child : S->children())
if (Child)
Visit(Child);
}
// CWE-467: Use of sizeof() on a Pointer Type
void WalkAST::VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E) {
if (E->getKind() != UETT_SizeOf)
return;
// If an explicit type is used in the code, usually the coder knows what they are
// doing.
if (E->isArgumentType())
return;
QualType T = E->getTypeOfArgument();
if (T->isPointerType()) {
// Many false positives have the form 'sizeof *p'. This is reasonable
// because people know what they are doing when they intentionally
// dereference the pointer.
Expr *ArgEx = E->getArgumentExpr();
if (!isa<DeclRefExpr>(ArgEx->IgnoreParens()))
return;
PathDiagnosticLocation ELoc =
PathDiagnosticLocation::createBegin(E, BR.getSourceManager(), AC);
BR.EmitBasicReport(AC->getDecl(), Checker,
"Potential unintended use of sizeof() on pointer type",
categories::LogicError,
"The code calls sizeof() on a pointer type. "
"This can produce an unexpected result.",
ELoc, ArgEx->getSourceRange());
}
}
//===----------------------------------------------------------------------===//
// SizeofPointerChecker
//===----------------------------------------------------------------------===//
namespace {
class SizeofPointerChecker : public Checker<check::ASTCodeBody> {
public:
void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
BugReporter &BR) const {
WalkAST walker(BR, this, mgr.getAnalysisDeclContext(D));
walker.Visit(D->getBody());
}
};
}
void ento::registerSizeofPointerChecker(CheckerManager &mgr) {
mgr.registerChecker<SizeofPointerChecker>();
}
bool ento::shouldRegisterSizeofPointerChecker(const CheckerManager &mgr) {
return true;
}
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