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