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//=======- UncountedCallArgsChecker.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
//
//===----------------------------------------------------------------------===//
#include "ASTUtils.h"
#include "DiagOutputUtils.h"
#include "PtrTypesSemantics.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "llvm/ADT/DenseSet.h"
#include <optional>
using namespace clang;
using namespace ento;
namespace {
class UncountedCallArgsChecker
: public Checker<check::ASTDecl<TranslationUnitDecl>> {
BugType Bug{this,
"Uncounted call argument for a raw pointer/reference parameter",
"WebKit coding guidelines"};
mutable BugReporter *BR;
public:
void checkASTDecl(const TranslationUnitDecl *TUD, AnalysisManager &MGR,
BugReporter &BRArg) const {
BR = &BRArg;
// The calls to checkAST* from AnalysisConsumer don't
// visit template instantiations or lambda classes. We
// want to visit those, so we make our own RecursiveASTVisitor.
struct LocalVisitor : public RecursiveASTVisitor<LocalVisitor> {
const UncountedCallArgsChecker *Checker;
explicit LocalVisitor(const UncountedCallArgsChecker *Checker)
: Checker(Checker) {
assert(Checker);
}
bool shouldVisitTemplateInstantiations() const { return true; }
bool shouldVisitImplicitCode() const { return false; }
bool VisitCallExpr(const CallExpr *CE) {
Checker->visitCallExpr(CE);
return true;
}
};
LocalVisitor visitor(this);
visitor.TraverseDecl(const_cast<TranslationUnitDecl *>(TUD));
}
void visitCallExpr(const CallExpr *CE) const {
if (shouldSkipCall(CE))
return;
if (auto *F = CE->getDirectCallee()) {
// Skip the first argument for overloaded member operators (e. g. lambda
// or std::function call operator).
unsigned ArgIdx = isa<CXXOperatorCallExpr>(CE) && isa_and_nonnull<CXXMethodDecl>(F);
for (auto P = F->param_begin();
// FIXME: Also check variadic function parameters.
// FIXME: Also check default function arguments. Probably a different
// checker. In case there are default arguments the call can have
// fewer arguments than the callee has parameters.
P < F->param_end() && ArgIdx < CE->getNumArgs(); ++P, ++ArgIdx) {
// TODO: attributes.
// if ((*P)->hasAttr<SafeRefCntblRawPtrAttr>())
// continue;
const auto *ArgType = (*P)->getType().getTypePtrOrNull();
if (!ArgType)
continue; // FIXME? Should we bail?
// FIXME: more complex types (arrays, references to raw pointers, etc)
std::optional<bool> IsUncounted = isUncountedPtr(ArgType);
if (!IsUncounted || !(*IsUncounted))
continue;
const auto *Arg = CE->getArg(ArgIdx);
std::pair<const clang::Expr *, bool> ArgOrigin =
tryToFindPtrOrigin(Arg, true);
// Temporary ref-counted object created as part of the call argument
// would outlive the call.
if (ArgOrigin.second)
continue;
if (isa<CXXNullPtrLiteralExpr>(ArgOrigin.first)) {
// foo(nullptr)
continue;
}
if (isa<IntegerLiteral>(ArgOrigin.first)) {
// FIXME: Check the value.
// foo(NULL)
continue;
}
if (isASafeCallArg(ArgOrigin.first))
continue;
reportBug(Arg, *P);
}
}
}
bool shouldSkipCall(const CallExpr *CE) const {
if (CE->getNumArgs() == 0)
return false;
// If an assignment is problematic we should warn about the sole existence
// of object on LHS.
if (auto *MemberOp = dyn_cast<CXXOperatorCallExpr>(CE)) {
// Note: assignemnt to built-in type isn't derived from CallExpr.
if (MemberOp->isAssignmentOp())
return false;
}
const auto *Callee = CE->getDirectCallee();
if (!Callee)
return false;
auto overloadedOperatorType = Callee->getOverloadedOperator();
if (overloadedOperatorType == OO_EqualEqual ||
overloadedOperatorType == OO_ExclaimEqual ||
overloadedOperatorType == OO_LessEqual ||
overloadedOperatorType == OO_GreaterEqual ||
overloadedOperatorType == OO_Spaceship ||
overloadedOperatorType == OO_AmpAmp ||
overloadedOperatorType == OO_PipePipe)
return true;
if (isCtorOfRefCounted(Callee))
return true;
auto name = safeGetName(Callee);
if (name == "adoptRef" || name == "getPtr" || name == "WeakPtr" ||
name == "makeWeakPtr" || name == "downcast" || name == "bitwise_cast" ||
name == "is" || name == "equal" || name == "hash" ||
name == "isType"
// FIXME: Most/all of these should be implemented via attributes.
|| name == "equalIgnoringASCIICase" ||
name == "equalIgnoringASCIICaseCommon" ||
name == "equalIgnoringNullity")
return true;
return false;
}
void reportBug(const Expr *CallArg, const ParmVarDecl *Param) const {
assert(CallArg);
SmallString<100> Buf;
llvm::raw_svector_ostream Os(Buf);
const std::string paramName = safeGetName(Param);
Os << "Call argument";
if (!paramName.empty()) {
Os << " for parameter ";
printQuotedQualifiedName(Os, Param);
}
Os << " is uncounted and unsafe.";
const SourceLocation SrcLocToReport =
isa<CXXDefaultArgExpr>(CallArg) ? Param->getDefaultArg()->getExprLoc()
: CallArg->getSourceRange().getBegin();
PathDiagnosticLocation BSLoc(SrcLocToReport, BR->getSourceManager());
auto Report = std::make_unique<BasicBugReport>(Bug, Os.str(), BSLoc);
Report->addRange(CallArg->getSourceRange());
BR->emitReport(std::move(Report));
}
};
} // namespace
void ento::registerUncountedCallArgsChecker(CheckerManager &Mgr) {
Mgr.registerChecker<UncountedCallArgsChecker>();
}
bool ento::shouldRegisterUncountedCallArgsChecker(const CheckerManager &) {
return true;
}
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