121 lines
4.0 KiB
C++
121 lines
4.0 KiB
C++
//=== UndefBranchChecker.cpp -----------------------------------*- 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 file defines UndefBranchChecker, which checks for undefined branch
|
|
// condition.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "clang/AST/StmtObjC.h"
|
|
#include "clang/AST/Type.h"
|
|
#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"
|
|
#include <utility>
|
|
|
|
using namespace clang;
|
|
using namespace ento;
|
|
|
|
namespace {
|
|
|
|
class UndefBranchChecker : public Checker<check::BranchCondition> {
|
|
mutable std::unique_ptr<BuiltinBug> BT;
|
|
|
|
struct FindUndefExpr {
|
|
ProgramStateRef St;
|
|
const LocationContext *LCtx;
|
|
|
|
FindUndefExpr(ProgramStateRef S, const LocationContext *L)
|
|
: St(std::move(S)), LCtx(L) {}
|
|
|
|
const Expr *FindExpr(const Expr *Ex) {
|
|
if (!MatchesCriteria(Ex))
|
|
return nullptr;
|
|
|
|
for (const Stmt *SubStmt : Ex->children())
|
|
if (const Expr *ExI = dyn_cast_or_null<Expr>(SubStmt))
|
|
if (const Expr *E2 = FindExpr(ExI))
|
|
return E2;
|
|
|
|
return Ex;
|
|
}
|
|
|
|
bool MatchesCriteria(const Expr *Ex) {
|
|
return St->getSVal(Ex, LCtx).isUndef();
|
|
}
|
|
};
|
|
|
|
public:
|
|
void checkBranchCondition(const Stmt *Condition, CheckerContext &Ctx) const;
|
|
};
|
|
|
|
} // namespace
|
|
|
|
void UndefBranchChecker::checkBranchCondition(const Stmt *Condition,
|
|
CheckerContext &Ctx) const {
|
|
// ObjCForCollection is a loop, but has no actual condition.
|
|
if (isa<ObjCForCollectionStmt>(Condition))
|
|
return;
|
|
SVal X = Ctx.getSVal(Condition);
|
|
if (X.isUndef()) {
|
|
// Generate a sink node, which implicitly marks both outgoing branches as
|
|
// infeasible.
|
|
ExplodedNode *N = Ctx.generateErrorNode();
|
|
if (N) {
|
|
if (!BT)
|
|
BT.reset(new BuiltinBug(
|
|
this, "Branch condition evaluates to a garbage value"));
|
|
|
|
// What's going on here: we want to highlight the subexpression of the
|
|
// condition that is the most likely source of the "uninitialized
|
|
// branch condition." We do a recursive walk of the condition's
|
|
// subexpressions and roughly look for the most nested subexpression
|
|
// that binds to Undefined. We then highlight that expression's range.
|
|
|
|
// Get the predecessor node and check if is a PostStmt with the Stmt
|
|
// being the terminator condition. We want to inspect the state
|
|
// of that node instead because it will contain main information about
|
|
// the subexpressions.
|
|
|
|
// Note: any predecessor will do. They should have identical state,
|
|
// since all the BlockEdge did was act as an error sink since the value
|
|
// had to already be undefined.
|
|
assert (!N->pred_empty());
|
|
const Expr *Ex = cast<Expr>(Condition);
|
|
ExplodedNode *PrevN = *N->pred_begin();
|
|
ProgramPoint P = PrevN->getLocation();
|
|
ProgramStateRef St = N->getState();
|
|
|
|
if (Optional<PostStmt> PS = P.getAs<PostStmt>())
|
|
if (PS->getStmt() == Ex)
|
|
St = PrevN->getState();
|
|
|
|
FindUndefExpr FindIt(St, Ctx.getLocationContext());
|
|
Ex = FindIt.FindExpr(Ex);
|
|
|
|
// Emit the bug report.
|
|
auto R = std::make_unique<PathSensitiveBugReport>(
|
|
*BT, BT->getDescription(), N);
|
|
bugreporter::trackExpressionValue(N, Ex, *R);
|
|
R->addRange(Ex->getSourceRange());
|
|
|
|
Ctx.emitReport(std::move(R));
|
|
}
|
|
}
|
|
}
|
|
|
|
void ento::registerUndefBranchChecker(CheckerManager &mgr) {
|
|
mgr.registerChecker<UndefBranchChecker>();
|
|
}
|
|
|
|
bool ento::shouldRegisterUndefBranchChecker(const CheckerManager &mgr) {
|
|
return true;
|
|
}
|