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-rw-r--r--gnu/llvm/tools/clang/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp306
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diff --git a/gnu/llvm/tools/clang/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp b/gnu/llvm/tools/clang/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
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index d01a889d256..00000000000
--- a/gnu/llvm/tools/clang/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
+++ /dev/null
@@ -1,306 +0,0 @@
-//== NullDerefChecker.cpp - Null dereference checker ------------*- C++ -*--==//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This defines NullDerefChecker, a builtin check in ExprEngine that performs
-// checks for null pointers at loads and stores.
-//
-//===----------------------------------------------------------------------===//
-
-#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
-#include "clang/AST/ExprObjC.h"
-#include "clang/AST/ExprOpenMP.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 "clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/Support/raw_ostream.h"
-
-using namespace clang;
-using namespace ento;
-
-namespace {
-class DereferenceChecker
- : public Checker< check::Location,
- check::Bind,
- EventDispatcher<ImplicitNullDerefEvent> > {
- mutable std::unique_ptr<BuiltinBug> BT_null;
- mutable std::unique_ptr<BuiltinBug> BT_undef;
-
- void reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C) const;
-
-public:
- void checkLocation(SVal location, bool isLoad, const Stmt* S,
- CheckerContext &C) const;
- void checkBind(SVal L, SVal V, const Stmt *S, CheckerContext &C) const;
-
- static void AddDerefSource(raw_ostream &os,
- SmallVectorImpl<SourceRange> &Ranges,
- const Expr *Ex, const ProgramState *state,
- const LocationContext *LCtx,
- bool loadedFrom = false);
-};
-} // end anonymous namespace
-
-void
-DereferenceChecker::AddDerefSource(raw_ostream &os,
- SmallVectorImpl<SourceRange> &Ranges,
- const Expr *Ex,
- const ProgramState *state,
- const LocationContext *LCtx,
- bool loadedFrom) {
- Ex = Ex->IgnoreParenLValueCasts();
- switch (Ex->getStmtClass()) {
- default:
- break;
- case Stmt::DeclRefExprClass: {
- const DeclRefExpr *DR = cast<DeclRefExpr>(Ex);
- if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
- os << " (" << (loadedFrom ? "loaded from" : "from")
- << " variable '" << VD->getName() << "')";
- Ranges.push_back(DR->getSourceRange());
- }
- break;
- }
- case Stmt::MemberExprClass: {
- const MemberExpr *ME = cast<MemberExpr>(Ex);
- os << " (" << (loadedFrom ? "loaded from" : "via")
- << " field '" << ME->getMemberNameInfo() << "')";
- SourceLocation L = ME->getMemberLoc();
- Ranges.push_back(SourceRange(L, L));
- break;
- }
- case Stmt::ObjCIvarRefExprClass: {
- const ObjCIvarRefExpr *IV = cast<ObjCIvarRefExpr>(Ex);
- os << " (" << (loadedFrom ? "loaded from" : "via")
- << " ivar '" << IV->getDecl()->getName() << "')";
- SourceLocation L = IV->getLocation();
- Ranges.push_back(SourceRange(L, L));
- break;
- }
- }
-}
-
-static const Expr *getDereferenceExpr(const Stmt *S, bool IsBind=false){
- const Expr *E = nullptr;
-
- // Walk through lvalue casts to get the original expression
- // that syntactically caused the load.
- if (const Expr *expr = dyn_cast<Expr>(S))
- E = expr->IgnoreParenLValueCasts();
-
- if (IsBind) {
- const VarDecl *VD;
- const Expr *Init;
- std::tie(VD, Init) = parseAssignment(S);
- if (VD && Init)
- E = Init;
- }
- return E;
-}
-
-static bool suppressReport(const Expr *E) {
- // Do not report dereferences on memory in non-default address spaces.
- return E->getType().getQualifiers().hasAddressSpace();
-}
-
-static bool isDeclRefExprToReference(const Expr *E) {
- if (const auto *DRE = dyn_cast<DeclRefExpr>(E))
- return DRE->getDecl()->getType()->isReferenceType();
- return false;
-}
-
-void DereferenceChecker::reportBug(ProgramStateRef State, const Stmt *S,
- CheckerContext &C) const {
- // Generate an error node.
- ExplodedNode *N = C.generateErrorNode(State);
- if (!N)
- return;
-
- // We know that 'location' cannot be non-null. This is what
- // we call an "explicit" null dereference.
- if (!BT_null)
- BT_null.reset(new BuiltinBug(this, "Dereference of null pointer"));
-
- SmallString<100> buf;
- llvm::raw_svector_ostream os(buf);
-
- SmallVector<SourceRange, 2> Ranges;
-
- switch (S->getStmtClass()) {
- case Stmt::ArraySubscriptExprClass: {
- os << "Array access";
- const ArraySubscriptExpr *AE = cast<ArraySubscriptExpr>(S);
- AddDerefSource(os, Ranges, AE->getBase()->IgnoreParenCasts(),
- State.get(), N->getLocationContext());
- os << " results in a null pointer dereference";
- break;
- }
- case Stmt::OMPArraySectionExprClass: {
- os << "Array access";
- const OMPArraySectionExpr *AE = cast<OMPArraySectionExpr>(S);
- AddDerefSource(os, Ranges, AE->getBase()->IgnoreParenCasts(),
- State.get(), N->getLocationContext());
- os << " results in a null pointer dereference";
- break;
- }
- case Stmt::UnaryOperatorClass: {
- os << "Dereference of null pointer";
- const UnaryOperator *U = cast<UnaryOperator>(S);
- AddDerefSource(os, Ranges, U->getSubExpr()->IgnoreParens(),
- State.get(), N->getLocationContext(), true);
- break;
- }
- case Stmt::MemberExprClass: {
- const MemberExpr *M = cast<MemberExpr>(S);
- if (M->isArrow() || isDeclRefExprToReference(M->getBase())) {
- os << "Access to field '" << M->getMemberNameInfo()
- << "' results in a dereference of a null pointer";
- AddDerefSource(os, Ranges, M->getBase()->IgnoreParenCasts(),
- State.get(), N->getLocationContext(), true);
- }
- break;
- }
- case Stmt::ObjCIvarRefExprClass: {
- const ObjCIvarRefExpr *IV = cast<ObjCIvarRefExpr>(S);
- os << "Access to instance variable '" << *IV->getDecl()
- << "' results in a dereference of a null pointer";
- AddDerefSource(os, Ranges, IV->getBase()->IgnoreParenCasts(),
- State.get(), N->getLocationContext(), true);
- break;
- }
- default:
- break;
- }
-
- auto report = llvm::make_unique<BugReport>(
- *BT_null, buf.empty() ? BT_null->getDescription() : StringRef(buf), N);
-
- bugreporter::trackExpressionValue(N, bugreporter::getDerefExpr(S), *report);
-
- for (SmallVectorImpl<SourceRange>::iterator
- I = Ranges.begin(), E = Ranges.end(); I!=E; ++I)
- report->addRange(*I);
-
- C.emitReport(std::move(report));
-}
-
-void DereferenceChecker::checkLocation(SVal l, bool isLoad, const Stmt* S,
- CheckerContext &C) const {
- // Check for dereference of an undefined value.
- if (l.isUndef()) {
- if (ExplodedNode *N = C.generateErrorNode()) {
- if (!BT_undef)
- BT_undef.reset(
- new BuiltinBug(this, "Dereference of undefined pointer value"));
-
- auto report =
- llvm::make_unique<BugReport>(*BT_undef, BT_undef->getDescription(), N);
- bugreporter::trackExpressionValue(N, bugreporter::getDerefExpr(S), *report);
- C.emitReport(std::move(report));
- }
- return;
- }
-
- DefinedOrUnknownSVal location = l.castAs<DefinedOrUnknownSVal>();
-
- // Check for null dereferences.
- if (!location.getAs<Loc>())
- return;
-
- ProgramStateRef state = C.getState();
-
- ProgramStateRef notNullState, nullState;
- std::tie(notNullState, nullState) = state->assume(location);
-
- // The explicit NULL case.
- if (nullState) {
- if (!notNullState) {
- const Expr *expr = getDereferenceExpr(S);
- if (!suppressReport(expr)) {
- reportBug(nullState, expr, C);
- return;
- }
- }
-
- // Otherwise, we have the case where the location could either be
- // null or not-null. Record the error node as an "implicit" null
- // dereference.
- if (ExplodedNode *N = C.generateSink(nullState, C.getPredecessor())) {
- ImplicitNullDerefEvent event = {l, isLoad, N, &C.getBugReporter(),
- /*IsDirectDereference=*/true};
- dispatchEvent(event);
- }
- }
-
- // From this point forward, we know that the location is not null.
- C.addTransition(notNullState);
-}
-
-void DereferenceChecker::checkBind(SVal L, SVal V, const Stmt *S,
- CheckerContext &C) const {
- // If we're binding to a reference, check if the value is known to be null.
- if (V.isUndef())
- return;
-
- const MemRegion *MR = L.getAsRegion();
- const TypedValueRegion *TVR = dyn_cast_or_null<TypedValueRegion>(MR);
- if (!TVR)
- return;
-
- if (!TVR->getValueType()->isReferenceType())
- return;
-
- ProgramStateRef State = C.getState();
-
- ProgramStateRef StNonNull, StNull;
- std::tie(StNonNull, StNull) = State->assume(V.castAs<DefinedOrUnknownSVal>());
-
- if (StNull) {
- if (!StNonNull) {
- const Expr *expr = getDereferenceExpr(S, /*IsBind=*/true);
- if (!suppressReport(expr)) {
- reportBug(StNull, expr, C);
- return;
- }
- }
-
- // At this point the value could be either null or non-null.
- // Record this as an "implicit" null dereference.
- if (ExplodedNode *N = C.generateSink(StNull, C.getPredecessor())) {
- ImplicitNullDerefEvent event = {V, /*isLoad=*/true, N,
- &C.getBugReporter(),
- /*IsDirectDereference=*/true};
- dispatchEvent(event);
- }
- }
-
- // Unlike a regular null dereference, initializing a reference with a
- // dereferenced null pointer does not actually cause a runtime exception in
- // Clang's implementation of references.
- //
- // int &r = *p; // safe??
- // if (p != NULL) return; // uh-oh
- // r = 5; // trap here
- //
- // The standard says this is invalid as soon as we try to create a "null
- // reference" (there is no such thing), but turning this into an assumption
- // that 'p' is never null will not match our actual runtime behavior.
- // So we do not record this assumption, allowing us to warn on the last line
- // of this example.
- //
- // We do need to add a transition because we may have generated a sink for
- // the "implicit" null dereference.
- C.addTransition(State, this);
-}
-
-void ento::registerDereferenceChecker(CheckerManager &mgr) {
- mgr.registerChecker<DereferenceChecker>();
-}
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