Coverage Report

Created: 2022-07-16 07:03

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/StaticAnalyzer/Checkers/ObjCContainersChecker.cpp
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//== ObjCContainersChecker.cpp - Path sensitive checker for CFArray *- 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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// Performs path sensitive checks of Core Foundation static containers like
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// CFArray.
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// 1) Check for buffer overflows:
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//      In CFArrayGetArrayAtIndex( myArray, index), if the index is outside the
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//      index space of theArray (0 to N-1 inclusive (where N is the count of
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//      theArray), the behavior is undefined.
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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/ParentMap.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.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 ObjCContainersChecker : public Checker< check::PreStmt<CallExpr>,
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                                             check::PostStmt<CallExpr>,
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                                             check::PointerEscape> {
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  mutable std::unique_ptr<BugType> BT;
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  inline void initBugType() const {
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    if (!BT)
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      BT.reset(new BugType(this, "CFArray API",
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                           categories::CoreFoundationObjectiveC));
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  }
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  inline SymbolRef getArraySym(const Expr *E, CheckerContext &C) const {
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    SVal ArrayRef = C.getSVal(E);
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    SymbolRef ArraySym = ArrayRef.getAsSymbol();
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    return ArraySym;
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  }
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  void addSizeInfo(const Expr *Array, const Expr *Size,
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                   CheckerContext &C) const;
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public:
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  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
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  void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
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  ProgramStateRef checkPointerEscape(ProgramStateRef State,
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                                     const InvalidatedSymbols &Escaped,
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                                     const CallEvent *Call,
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                                     PointerEscapeKind Kind) const;
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  void printState(raw_ostream &OS, ProgramStateRef State,
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                  const char *NL, const char *Sep) const override;
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};
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} // end anonymous namespace
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// ProgramState trait - a map from array symbol to its state.
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REGISTER_MAP_WITH_PROGRAMSTATE(ArraySizeMap, SymbolRef, DefinedSVal)
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void ObjCContainersChecker::addSizeInfo(const Expr *Array, const Expr *Size,
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                                        CheckerContext &C) const {
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  ProgramStateRef State = C.getState();
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  SVal SizeV = C.getSVal(Size);
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  // Undefined is reported by another checker.
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  if (SizeV.isUnknownOrUndef())
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    return;
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  // Get the ArrayRef symbol.
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  SVal ArrayRef = C.getSVal(Array);
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  SymbolRef ArraySym = ArrayRef.getAsSymbol();
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  if (!ArraySym)
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    return;
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  C.addTransition(
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      State->set<ArraySizeMap>(ArraySym, SizeV.castAs<DefinedSVal>()));
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}
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void ObjCContainersChecker::checkPostStmt(const CallExpr *CE,
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                                          CheckerContext &C) const {
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  StringRef Name = C.getCalleeName(CE);
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  if (Name.empty() || 
CE->getNumArgs() < 1348
)
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    return;
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  // Add array size information to the state.
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  if (Name.equals("CFArrayCreate")) {
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    if (CE->getNumArgs() < 3)
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      return;
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    // Note, we can visit the Create method in the post-visit because
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    // the CFIndex parameter is passed in by value and will not be invalidated
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    // by the call.
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    addSizeInfo(CE, CE->getArg(2), C);
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    return;
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  }
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  if (Name.equals("CFArrayGetCount")) {
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    addSizeInfo(CE->getArg(0), CE, C);
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    return;
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  }
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}
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void ObjCContainersChecker::checkPreStmt(const CallExpr *CE,
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                                         CheckerContext &C) const {
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  StringRef Name = C.getCalleeName(CE);
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  if (Name.empty() || 
CE->getNumArgs() < 2351
)
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    return;
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  // Check the array access.
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  if (Name.equals("CFArrayGetValueAtIndex")) {
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    ProgramStateRef State = C.getState();
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    // Retrieve the size.
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    // Find out if we saw this array symbol before and have information about
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    // it.
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    const Expr *ArrayExpr = CE->getArg(0);
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    SymbolRef ArraySym = getArraySym(ArrayExpr, C);
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    if (!ArraySym)
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      return;
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    const DefinedSVal *Size = State->get<ArraySizeMap>(ArraySym);
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    if (!Size)
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      return;
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    // Get the index.
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    const Expr *IdxExpr = CE->getArg(1);
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    SVal IdxVal = C.getSVal(IdxExpr);
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    if (IdxVal.isUnknownOrUndef())
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      return;
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    DefinedSVal Idx = IdxVal.castAs<DefinedSVal>();
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    // Now, check if 'Idx in [0, Size-1]'.
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    const QualType T = IdxExpr->getType();
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    ProgramStateRef StInBound, StOutBound;
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    std::tie(StInBound, StOutBound) = State->assumeInBoundDual(Idx, *Size, T);
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    if (StOutBound && 
!StInBound9
) {
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      ExplodedNode *N = C.generateErrorNode(StOutBound);
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      if (!N)
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        return;
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      initBugType();
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      auto R = std::make_unique<PathSensitiveBugReport>(
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          *BT, "Index is out of bounds", N);
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      R->addRange(IdxExpr->getSourceRange());
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      bugreporter::trackExpressionValue(N, IdxExpr, *R,
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                                        {bugreporter::TrackingKind::Thorough,
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                                         /*EnableNullFPSuppression=*/false});
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      C.emitReport(std::move(R));
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      return;
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    }
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  }
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}
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ProgramStateRef
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ObjCContainersChecker::checkPointerEscape(ProgramStateRef State,
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                                          const InvalidatedSymbols &Escaped,
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                                          const CallEvent *Call,
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                                          PointerEscapeKind Kind) const {
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  for (const auto &Sym : Escaped) {
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    // When a symbol for a mutable array escapes, we can't reason precisely
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    // about its size any more -- so remove it from the map.
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    // Note that we aren't notified here when a CFMutableArrayRef escapes as a
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    // CFArrayRef. This is because CFArrayRef is typedef'd as a pointer to a
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    // const-qualified type.
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    State = State->remove<ArraySizeMap>(Sym);
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  }
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  return State;
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}
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void ObjCContainersChecker::printState(raw_ostream &OS, ProgramStateRef State,
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                                       const char *NL, const char *Sep) const {
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  ArraySizeMapTy Map = State->get<ArraySizeMap>();
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  if (Map.isEmpty())
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    return;
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  OS << Sep << "ObjC container sizes :" << NL;
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  for (auto I : Map) {
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    OS << I.first << " : " << I.second << NL;
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  }
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}
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/// Register checker.
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void ento::registerObjCContainersChecker(CheckerManager &mgr) {
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  mgr.registerChecker<ObjCContainersChecker>();
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}
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bool ento::shouldRegisterObjCContainersChecker(const CheckerManager &mgr) {
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  return true;
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}