UndefinedAssignmentChecker.cpp
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//===--- UndefinedAssignmentChecker.h ---------------------------*- C++ -*--==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This defines UndefinedAssignmentChecker, a builtin check in ExprEngine that
// checks for assigning undefined values.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
using namespace clang;
using namespace ento;
namespace {
class UndefinedAssignmentChecker
: public Checker<check::Bind> {
mutable std::unique_ptr<BugType> BT;
public:
void checkBind(SVal location, SVal val, const Stmt *S,
CheckerContext &C) const;
};
}
void UndefinedAssignmentChecker::checkBind(SVal location, SVal val,
const Stmt *StoreE,
CheckerContext &C) const {
if (!val.isUndef())
return;
// Do not report assignments of uninitialized values inside swap functions.
// This should allow to swap partially uninitialized structs
// (radar://14129997)
if (const FunctionDecl *EnclosingFunctionDecl =
dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
if (C.getCalleeName(EnclosingFunctionDecl) == "swap")
return;
ExplodedNode *N = C.generateErrorNode();
if (!N)
return;
static const char *const DefaultMsg =
"Assigned value is garbage or undefined";
if (!BT)
BT.reset(new BuiltinBug(this, DefaultMsg));
// Generate a report for this bug.
llvm::SmallString<128> Str;
llvm::raw_svector_ostream OS(Str);
const Expr *ex = nullptr;
while (StoreE) {
if (const UnaryOperator *U = dyn_cast<UnaryOperator>(StoreE)) {
OS << "The expression is an uninitialized value. "
"The computed value will also be garbage";
ex = U->getSubExpr();
break;
}
if (const BinaryOperator *B = dyn_cast<BinaryOperator>(StoreE)) {
if (B->isCompoundAssignmentOp()) {
if (C.getSVal(B->getLHS()).isUndef()) {
OS << "The left expression of the compound assignment is an "
"uninitialized value. The computed value will also be garbage";
ex = B->getLHS();
break;
}
}
ex = B->getRHS();
break;
}
if (const DeclStmt *DS = dyn_cast<DeclStmt>(StoreE)) {
const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
ex = VD->getInit();
}
if (const auto *CD =
dyn_cast<CXXConstructorDecl>(C.getStackFrame()->getDecl())) {
if (CD->isImplicit()) {
for (auto I : CD->inits()) {
if (I->getInit()->IgnoreImpCasts() == StoreE) {
OS << "Value assigned to field '" << I->getMember()->getName()
<< "' in implicit constructor is garbage or undefined";
break;
}
}
}
}
break;
}
if (OS.str().empty())
OS << DefaultMsg;
auto R = std::make_unique<PathSensitiveBugReport>(*BT, OS.str(), N);
if (ex) {
R->addRange(ex->getSourceRange());
bugreporter::trackExpressionValue(N, ex, *R);
}
C.emitReport(std::move(R));
}
void ento::registerUndefinedAssignmentChecker(CheckerManager &mgr) {
mgr.registerChecker<UndefinedAssignmentChecker>();
}
bool ento::shouldRegisterUndefinedAssignmentChecker(const LangOptions &LO) {
return true;
}