Coverage Report

Created: 2022-01-18 06:27

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/StaticAnalyzer/Checkers/CheckSizeofPointer.cpp
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//==- CheckSizeofPointer.cpp - Check for sizeof on pointers ------*- C++ -*-==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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 "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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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bool ento::shouldRegisterSizeofPointerChecker(const CheckerManager &mgr) {
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  return true;
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}