clang/lib/StaticAnalyzer/Checkers/FixedAddressChecker.cpp

   1 //=== FixedAddressChecker.cpp - Fixed address usage checker ----*- C++ -*--===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This files defines FixedAddressChecker, a builtin checker that checks for
  10 // assignment of a fixed address to a pointer.
  11 // This check corresponds to CWE-587.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
  16 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
  17 #include "clang/StaticAnalyzer/Core/Checker.h"
  18 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
  19 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
  20
  21 using namespace clang;
  22 using namespace ento;
  23
  24 namespace {
  25 class FixedAddressChecker
  26   : public Checker< check::PreStmt<BinaryOperator> > {
  27   const BugType BT{this, "Use fixed address"};
  28
  29 public:
  30   void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
  31 };
  32 }
  33
  34 void FixedAddressChecker::checkPreStmt(const BinaryOperator *B,
  35                                        CheckerContext &C) const {
  36   // Using a fixed address is not portable because that address will probably
  37   // not be valid in all environments or platforms.
  38
  39   if (B->getOpcode() != BO_Assign)
  40     return;
  41
  42   QualType T = B->getType();
  43   if (!T->isPointerType())
  44     return;
  45
  46   // Omit warning if the RHS has already pointer type. Without this passing
  47   // around one fixed value in several pointer variables would produce several
  48   // redundant warnings.
  49   if (B->getRHS()->IgnoreParenCasts()->getType()->isPointerType())
  50     return;
  51
  52   SVal RV = C.getSVal(B->getRHS());
  53
  54   if (!RV.isConstant() || RV.isZeroConstant())
  55     return;
  56
  57   if (C.getSourceManager().isInSystemMacro(B->getRHS()->getBeginLoc()))
  58     return;
  59
  60   if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
  61     // FIXME: improve grammar in the following strings:
  62     constexpr llvm::StringLiteral Msg =
  63         "Using a fixed address is not portable because that address will "
  64         "probably not be valid in all environments or platforms.";
  65     auto R = std::make_unique<PathSensitiveBugReport>(BT, Msg, N);
  66     R->addRange(B->getRHS()->getSourceRange());
  67     C.emitReport(std::move(R));
  68   }
  69 }
  70
  71 void ento::registerFixedAddressChecker(CheckerManager &mgr) {
  72   mgr.registerChecker<FixedAddressChecker>();
  73 }
  74
  75 bool ento::shouldRegisterFixedAddressChecker(const CheckerManager &mgr) {
  76   return true;
  77 }