C++ ProgramStateRef::assumeInBound方法代码示例

void ArrayBoundChecker::checkLocation(SVal l, bool isLoad, const Stmt* LoadS,
                                      CheckerContext &C) const {
  // Check for out of bound array element access.
  const MemRegion *R = l.getAsRegion();
  if (!R)
    return;

  const ElementRegion *ER = dyn_cast<ElementRegion>(R);
  if (!ER)
    return;

  // Get the index of the accessed element.
  DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();

  // Zero index is always in bound, this also passes ElementRegions created for
  // pointer casts.
  if (Idx.isZeroConstant())
    return;

  ProgramStateRef state = C.getState();

  // Get the size of the array.
  DefinedOrUnknownSVal NumElements
    = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
                                            ER->getValueType());

  ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
  ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
  if (StOutBound && !StInBound) {
    ExplodedNode *N = C.generateErrorNode(StOutBound);
    if (!N)
      return;

    if (!BT)
      BT.reset(new BuiltinBug(
          this, "Out-of-bound array access",
          "Access out-of-bound array element (buffer overflow)"));

    // FIXME: It would be nice to eventually make this diagnostic more clear,
    // e.g., by referencing the original declaration or by saying *why* this
    // reference is outside the range.

    // Generate a report for this bug.
    auto report = llvm::make_unique<BugReport>(*BT, BT->getDescription(), N);

    report->addRange(LoadS->getSourceRange());
    C.emitReport(std::move(report));
    return;
  }

  // Array bound check succeeded.  From this point forward the array bound
  // should always succeed.
  C.addTransition(StInBound);
}

void ReturnPointerRangeChecker::checkPreStmt(const ReturnStmt *RS,
                                             CheckerContext &C) const {
  ProgramStateRef state = C.getState();

  const Expr *RetE = RS->getRetValue();
  if (!RetE)
    return;

  SVal V = state->getSVal(RetE, C.getLocationContext());
  const MemRegion *R = V.getAsRegion();

  const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
  if (!ER)
    return;

  DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
  // Zero index is always in bound, this also passes ElementRegions created for
  // pointer casts.
  if (Idx.isZeroConstant())
    return;
  // FIXME: All of this out-of-bounds checking should eventually be refactored
  // into a common place.

  DefinedOrUnknownSVal NumElements
    = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
                                           ER->getValueType());

  ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
  ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
  if (StOutBound && !StInBound) {
    ExplodedNode *N = C.generateSink(StOutBound);

    if (!N)
      return;

    // FIXME: This bug correspond to CWE-466.  Eventually we should have bug
    // types explicitly reference such exploit categories (when applicable).
    if (!BT)
      BT.reset(new BuiltinBug(
          this, "Return of pointer value outside of expected range",
          "Returned pointer value points outside the original object "
          "(potential buffer overflow)"));

    // FIXME: It would be nice to eventually make this diagnostic more clear,
    // e.g., by referencing the original declaration or by saying *why* this
    // reference is outside the range.

    // Generate a report for this bug.
    auto report = llvm::make_unique<BugReport>(*BT, BT->getDescription(), N);

    report->addRange(RetE->getSourceRange());
    C.emitReport(std::move(report));
  }
}

void ObjCContainersChecker::checkPreStmt(const CallExpr *CE,
                                         CheckerContext &C) const {
  StringRef Name = C.getCalleeName(CE);
  if (Name.empty() || CE->getNumArgs() < 2)
    return;

  // Check the array access.
  if (Name.equals("CFArrayGetValueAtIndex")) {
    ProgramStateRef State = C.getState();
    // Retrieve the size.
    // Find out if we saw this array symbol before and have information about
    // it.
    const Expr *ArrayExpr = CE->getArg(0);
    SymbolRef ArraySym = getArraySym(ArrayExpr, C);
    if (!ArraySym)
      return;

    const DefinedSVal *Size = State->get<ArraySizeMap>(ArraySym);

    if (!Size)
      return;

    // Get the index.
    const Expr *IdxExpr = CE->getArg(1);
    SVal IdxVal = State->getSVal(IdxExpr, C.getLocationContext());
    if (IdxVal.isUnknownOrUndef())
      return;
    DefinedSVal Idx = IdxVal.castAs<DefinedSVal>();

    // Now, check if 'Idx in [0, Size-1]'.
    const QualType T = IdxExpr->getType();
    ProgramStateRef StInBound = State->assumeInBound(Idx, *Size, true, T);
    ProgramStateRef StOutBound = State->assumeInBound(Idx, *Size, false, T);
    if (StOutBound && !StInBound) {
      ExplodedNode *N = C.generateSink(StOutBound);
      if (!N)
        return;
      initBugType();
      auto R = llvm::make_unique<BugReport>(*BT, "Index is out of bounds", N);
      R->addRange(IdxExpr->getSourceRange());
      C.emitReport(std::move(R));
      return;
    }
  }
}