head 1.1; branch 1.1.1; access; symbols netbsd-9-5-RELEASE:1.1.1.6 netbsd-11-0-RELEASE:1.1.1.7 netbsd-11-0-RC7:1.1.1.7 netbsd-11-0-RC6:1.1.1.7 netbsd-11-0-RC5:1.1.1.7 netbsd-11-0-RC4:1.1.1.7 netbsd-11-0-RC3:1.1.1.7 netbsd-11-0-RC2:1.1.1.7 netbsd-11-0-RC1:1.1.1.7 perseant-exfatfs-base-20250801:1.1.1.7 netbsd-11:1.1.1.7.0.10 netbsd-11-base:1.1.1.7 netbsd-10-1-RELEASE:1.1.1.7 perseant-exfatfs-base-20240630:1.1.1.7 perseant-exfatfs:1.1.1.7.0.8 perseant-exfatfs-base:1.1.1.7 netbsd-8-3-RELEASE:1.1.1.6 netbsd-9-4-RELEASE:1.1.1.6 netbsd-10-0-RELEASE:1.1.1.7 netbsd-10-0-RC6:1.1.1.7 netbsd-10-0-RC5:1.1.1.7 netbsd-10-0-RC4:1.1.1.7 netbsd-10-0-RC3:1.1.1.7 netbsd-10-0-RC2:1.1.1.7 netbsd-10-0-RC1:1.1.1.7 netbsd-10:1.1.1.7.0.6 netbsd-10-base:1.1.1.7 netbsd-9-3-RELEASE:1.1.1.6 cjep_sun2x:1.1.1.7.0.4 cjep_sun2x-base:1.1.1.7 cjep_staticlib_x-base1:1.1.1.7 netbsd-9-2-RELEASE:1.1.1.6 cjep_staticlib_x:1.1.1.7.0.2 cjep_staticlib_x-base:1.1.1.7 netbsd-9-1-RELEASE:1.1.1.6 phil-wifi-20200421:1.1.1.7 phil-wifi-20200411:1.1.1.7 phil-wifi-20200406:1.1.1.7 netbsd-8-2-RELEASE:1.1.1.6 netbsd-9-0-RELEASE:1.1.1.6 netbsd-9-0-RC2:1.1.1.6 netbsd-9-0-RC1:1.1.1.6 netbsd-9:1.1.1.6.0.16 netbsd-9-base:1.1.1.6 phil-wifi-20190609:1.1.1.6 netbsd-8-1-RELEASE:1.1.1.6 netbsd-8-1-RC1:1.1.1.6 pgoyette-compat-merge-20190127:1.1.1.6 pgoyette-compat-20190127:1.1.1.6 pgoyette-compat-20190118:1.1.1.6 pgoyette-compat-1226:1.1.1.6 pgoyette-compat-1126:1.1.1.6 pgoyette-compat-1020:1.1.1.6 pgoyette-compat-0930:1.1.1.6 pgoyette-compat-0906:1.1.1.6 netbsd-7-2-RELEASE:1.1.1.4 pgoyette-compat-0728:1.1.1.6 clang-337282:1.1.1.6 netbsd-8-0-RELEASE:1.1.1.6 phil-wifi:1.1.1.6.0.14 phil-wifi-base:1.1.1.6 pgoyette-compat-0625:1.1.1.6 netbsd-8-0-RC2:1.1.1.6 pgoyette-compat-0521:1.1.1.6 pgoyette-compat-0502:1.1.1.6 pgoyette-compat-0422:1.1.1.6 netbsd-8-0-RC1:1.1.1.6 pgoyette-compat-0415:1.1.1.6 pgoyette-compat-0407:1.1.1.6 pgoyette-compat-0330:1.1.1.6 pgoyette-compat-0322:1.1.1.6 pgoyette-compat-0315:1.1.1.6 netbsd-7-1-2-RELEASE:1.1.1.4 pgoyette-compat:1.1.1.6.0.12 pgoyette-compat-base:1.1.1.6 netbsd-7-1-1-RELEASE:1.1.1.4 clang-319952:1.1.1.6 matt-nb8-mediatek:1.1.1.6.0.10 matt-nb8-mediatek-base:1.1.1.6 clang-309604:1.1.1.6 perseant-stdc-iso10646:1.1.1.6.0.8 perseant-stdc-iso10646-base:1.1.1.6 netbsd-8:1.1.1.6.0.6 netbsd-8-base:1.1.1.6 prg-localcount2-base3:1.1.1.6 prg-localcount2-base2:1.1.1.6 prg-localcount2-base1:1.1.1.6 prg-localcount2:1.1.1.6.0.4 prg-localcount2-base:1.1.1.6 pgoyette-localcount-20170426:1.1.1.6 bouyer-socketcan-base1:1.1.1.6 pgoyette-localcount-20170320:1.1.1.6 netbsd-7-1:1.1.1.4.0.10 netbsd-7-1-RELEASE:1.1.1.4 netbsd-7-1-RC2:1.1.1.4 clang-294123:1.1.1.6 netbsd-7-nhusb-base-20170116:1.1.1.4 bouyer-socketcan:1.1.1.6.0.2 bouyer-socketcan-base:1.1.1.6 clang-291444:1.1.1.6 pgoyette-localcount-20170107:1.1.1.5 netbsd-7-1-RC1:1.1.1.4 pgoyette-localcount-20161104:1.1.1.5 netbsd-7-0-2-RELEASE:1.1.1.4 localcount-20160914:1.1.1.5 netbsd-7-nhusb:1.1.1.4.0.8 netbsd-7-nhusb-base:1.1.1.4 clang-280599:1.1.1.5 pgoyette-localcount-20160806:1.1.1.5 pgoyette-localcount-20160726:1.1.1.5 pgoyette-localcount:1.1.1.5.0.2 pgoyette-localcount-base:1.1.1.5 netbsd-7-0-1-RELEASE:1.1.1.4 clang-261930:1.1.1.5 netbsd-7-0:1.1.1.4.0.6 netbsd-7-0-RELEASE:1.1.1.4 netbsd-7-0-RC3:1.1.1.4 netbsd-7-0-RC2:1.1.1.4 netbsd-7-0-RC1:1.1.1.4 clang-237755:1.1.1.4 clang-232565:1.1.1.4 clang-227398:1.1.1.4 tls-maxphys-base:1.1.1.4 tls-maxphys:1.1.1.4.0.4 netbsd-7:1.1.1.4.0.2 netbsd-7-base:1.1.1.4 clang-215315:1.1.1.4 clang-209886:1.1.1.3 yamt-pagecache:1.1.1.2.0.4 yamt-pagecache-base9:1.1.1.2 tls-earlyentropy:1.1.1.2.0.2 tls-earlyentropy-base:1.1.1.3 riastradh-xf86-video-intel-2-7-1-pre-2-21-15:1.1.1.2 riastradh-drm2-base3:1.1.1.2 clang-202566:1.1.1.2 clang-201163:1.1.1.1 clang-199312:1.1.1.1 clang-198450:1.1.1.1 clang-196603:1.1.1.1 clang-195771:1.1.1.1 LLVM:1.1.1; locks; strict; comment @// @; 1.1 date 2013.11.28.14.14.52; author joerg; state Exp; branches 1.1.1.1; next ; commitid ow8OybrawrB1f3fx; 1.1.1.1 date 2013.11.28.14.14.52; author joerg; state Exp; branches; next 1.1.1.2; commitid ow8OybrawrB1f3fx; 1.1.1.2 date 2014.03.04.19.55.00; author joerg; state Exp; branches 1.1.1.2.2.1 1.1.1.2.4.1; next 1.1.1.3; commitid 29z1hJonZISIXprx; 1.1.1.3 date 2014.05.30.18.14.44; author joerg; state Exp; branches; next 1.1.1.4; commitid 8q0kdlBlCn09GACx; 1.1.1.4 date 2014.08.10.17.08.34; author joerg; state Exp; branches 1.1.1.4.4.1; next 1.1.1.5; commitid N85tXAN6Ex9VZPLx; 1.1.1.5 date 2016.02.27.22.12.06; author joerg; state Exp; branches 1.1.1.5.2.1; next 1.1.1.6; commitid tIimz3oDlh1NpBWy; 1.1.1.6 date 2017.01.11.10.35.39; author joerg; state Exp; branches 1.1.1.6.14.1; next 1.1.1.7; commitid CNnUNfII1jgNmxBz; 1.1.1.7 date 2019.11.13.22.19.28; author joerg; state dead; branches; next ; commitid QD8YATxuNG34YJKB; 1.1.1.2.2.1 date 2014.08.10.07.08.10; author tls; state Exp; branches; next ; commitid t01A1TLTYxkpGMLx; 1.1.1.2.4.1 date 2014.03.04.19.55.00; author yamt; state dead; branches; next 1.1.1.2.4.2; commitid WSrDtL5nYAUyiyBx; 1.1.1.2.4.2 date 2014.05.22.16.18.31; author yamt; state Exp; branches; next ; commitid WSrDtL5nYAUyiyBx; 1.1.1.4.4.1 date 2014.08.10.17.08.34; author tls; state dead; branches; next 1.1.1.4.4.2; commitid jTnpym9Qu0o4R1Nx; 1.1.1.4.4.2 date 2014.08.19.23.47.31; author tls; state Exp; branches; next ; commitid jTnpym9Qu0o4R1Nx; 1.1.1.5.2.1 date 2017.03.20.06.52.42; author pgoyette; state Exp; branches; next ; commitid jjw7cAwgyKq7RfKz; 1.1.1.6.14.1 date 2020.04.13.07.46.38; author martin; state dead; branches; next ; commitid X01YhRUPVUDaec4C; desc @@ 1.1 log @Initial revision @ text @//== 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 "ClangSACheckers.h" #include "clang/AST/ExprObjC.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 "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 > { mutable OwningPtr BT_null; mutable OwningPtr BT_undef; void reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C, bool IsBind = false) 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 &Ranges, const Expr *Ex, const ProgramState *state, const LocationContext *LCtx, bool loadedFrom = false); }; } // end anonymous namespace void DereferenceChecker::AddDerefSource(raw_ostream &os, SmallVectorImpl &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(Ex); if (const VarDecl *VD = dyn_cast(DR->getDecl())) { os << " (" << (loadedFrom ? "loaded from" : "from") << " variable '" << VD->getName() << "')"; Ranges.push_back(DR->getSourceRange()); } break; } case Stmt::MemberExprClass: { const MemberExpr *ME = cast(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(Ex); os << " (" << (loadedFrom ? "loaded from" : "via") << " ivar '" << IV->getDecl()->getName() << "')"; SourceLocation L = IV->getLocation(); Ranges.push_back(SourceRange(L, L)); break; } } } void DereferenceChecker::reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C, bool IsBind) const { // Generate an error node. ExplodedNode *N = C.generateSink(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("Dereference of null pointer")); SmallString<100> buf; llvm::raw_svector_ostream os(buf); SmallVector Ranges; // Walk through lvalue casts to get the original expression // that syntactically caused the load. if (const Expr *expr = dyn_cast(S)) S = expr->IgnoreParenLValueCasts(); if (IsBind) { if (const BinaryOperator *BO = dyn_cast(S)) { if (BO->isAssignmentOp()) S = BO->getRHS(); } else if (const DeclStmt *DS = dyn_cast(S)) { assert(DS->isSingleDecl() && "We process decls one by one"); if (const VarDecl *VD = dyn_cast(DS->getSingleDecl())) if (const Expr *Init = VD->getAnyInitializer()) S = Init; } } switch (S->getStmtClass()) { case Stmt::ArraySubscriptExprClass: { os << "Array access"; const ArraySubscriptExpr *AE = cast(S); AddDerefSource(os, Ranges, AE->getBase()->IgnoreParenCasts(), State.getPtr(), N->getLocationContext()); os << " results in a null pointer dereference"; break; } case Stmt::UnaryOperatorClass: { os << "Dereference of null pointer"; const UnaryOperator *U = cast(S); AddDerefSource(os, Ranges, U->getSubExpr()->IgnoreParens(), State.getPtr(), N->getLocationContext(), true); break; } case Stmt::MemberExprClass: { const MemberExpr *M = cast(S); if (M->isArrow() || bugreporter::isDeclRefExprToReference(M->getBase())) { os << "Access to field '" << M->getMemberNameInfo() << "' results in a dereference of a null pointer"; AddDerefSource(os, Ranges, M->getBase()->IgnoreParenCasts(), State.getPtr(), N->getLocationContext(), true); } break; } case Stmt::ObjCIvarRefExprClass: { const ObjCIvarRefExpr *IV = cast(S); os << "Access to instance variable '" << *IV->getDecl() << "' results in a dereference of a null pointer"; AddDerefSource(os, Ranges, IV->getBase()->IgnoreParenCasts(), State.getPtr(), N->getLocationContext(), true); break; } default: break; } os.flush(); BugReport *report = new BugReport(*BT_null, buf.empty() ? BT_null->getDescription() : buf.str(), N); bugreporter::trackNullOrUndefValue(N, bugreporter::getDerefExpr(S), *report); for (SmallVectorImpl::iterator I = Ranges.begin(), E = Ranges.end(); I!=E; ++I) report->addRange(*I); C.emitReport(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.generateSink()) { if (!BT_undef) BT_undef.reset(new BuiltinBug("Dereference of undefined pointer value")); BugReport *report = new BugReport(*BT_undef, BT_undef->getDescription(), N); bugreporter::trackNullOrUndefValue(N, bugreporter::getDerefExpr(S), *report); C.emitReport(report); } return; } DefinedOrUnknownSVal location = l.castAs(); // Check for null dereferences. if (!location.getAs()) return; ProgramStateRef state = C.getState(); ProgramStateRef notNullState, nullState; llvm::tie(notNullState, nullState) = state->assume(location); // The explicit NULL case. if (nullState) { if (!notNullState) { reportBug(nullState, S, 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)) { ImplicitNullDerefEvent event = { l, isLoad, N, &C.getBugReporter() }; 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(MR); if (!TVR) return; if (!TVR->getValueType()->isReferenceType()) return; ProgramStateRef State = C.getState(); ProgramStateRef StNonNull, StNull; llvm::tie(StNonNull, StNull) = State->assume(V.castAs()); if (StNull) { if (!StNonNull) { reportBug(StNull, S, C, /*isBind=*/true); 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)) { ImplicitNullDerefEvent event = { V, /*isLoad=*/true, N, &C.getBugReporter() }; 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(); } @ 1.1.1.1 log @Import Clang 3.4rc1 r195771. @ text @@ 1.1.1.2 log @Import Clang 3.5svn r202566. @ text @d100 1 a100 1 BT_null.reset(new BuiltinBug(this, "Dereference of null pointer")); d183 1 a183 2 BT_undef.reset( new BuiltinBug(this, "Dereference of undefined pointer value")); @ 1.1.1.2.2.1 log @Rebase. @ text @d32 2 a33 2 mutable std::unique_ptr BT_null; mutable std::unique_ptr BT_undef; d204 1 a204 1 std::tie(notNullState, nullState) = state->assume(location); d243 2 a244 1 std::tie(StNonNull, StNull) = State->assume(V.castAs()); @ 1.1.1.3 log @Import Clang 3.5svn r209886. @ text @d32 2 a33 2 mutable std::unique_ptr BT_null; mutable std::unique_ptr BT_undef; d204 1 a204 1 std::tie(notNullState, nullState) = state->assume(location); d243 2 a244 1 std::tie(StNonNull, StNull) = State->assume(V.castAs()); @ 1.1.1.4 log @Import clang 3.6svn r215315. @ text @d129 1 a129 1 State.get(), N->getLocationContext()); d137 1 a137 1 State.get(), N->getLocationContext(), true); d146 1 a146 1 State.get(), N->getLocationContext(), true); d155 1 a155 1 State.get(), N->getLocationContext(), true); @ 1.1.1.5 log @Import Clang 3.8.0rc3 r261930. @ text @a16 1 #include "clang/AST/ExprOpenMP.h" a20 1 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h" d35 2 a36 1 void reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C) const; d86 1 a86 1 } a89 23 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(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(); } d91 1 a91 1 CheckerContext &C) const { d93 1 a93 1 ExplodedNode *N = C.generateErrorNode(State); d107 17 a132 8 case Stmt::OMPArraySectionExprClass: { os << "Array access"; const OMPArraySectionExpr *AE = cast(S); AddDerefSource(os, Ranges, AE->getBase()->IgnoreParenCasts(), State.get(), N->getLocationContext()); os << " results in a null pointer dereference"; break; } d162 5 a166 2 auto report = llvm::make_unique( *BT_null, buf.empty() ? BT_null->getDescription() : StringRef(buf), N); d174 1 a174 1 C.emitReport(std::move(report)); d181 1 a181 1 if (ExplodedNode *N = C.generateErrorNode()) { d186 2 a187 2 auto report = llvm::make_unique(*BT_undef, BT_undef->getDescription(), N); d190 1 a190 1 C.emitReport(std::move(report)); d209 2 a210 5 const Expr *expr = getDereferenceExpr(S); if (!suppressReport(expr)) { reportBug(nullState, expr, C); return; } d216 2 a217 3 if (ExplodedNode *N = C.generateSink(nullState, C.getPredecessor())) { ImplicitNullDerefEvent event = {l, isLoad, N, &C.getBugReporter(), /*IsDirectDereference=*/false}; d247 2 a248 5 const Expr *expr = getDereferenceExpr(S, /*IsBind=*/true); if (!suppressReport(expr)) { reportBug(StNull, expr, C); return; } d253 3 a255 4 if (ExplodedNode *N = C.generateSink(StNull, C.getPredecessor())) { ImplicitNullDerefEvent event = {V, /*isLoad=*/true, N, &C.getBugReporter(), /*IsDirectDereference=*/false}; @ 1.1.1.5.2.1 log @Sync with HEAD @ text @d233 1 a233 1 /*IsDirectDereference=*/true}; d275 1 a275 1 /*IsDirectDereference=*/true}; @ 1.1.1.6 log @Import Clang pre-4.0.0 r291444. @ text @d233 1 a233 1 /*IsDirectDereference=*/true}; d275 1 a275 1 /*IsDirectDereference=*/true}; @ 1.1.1.6.14.1 log @Mostly merge changes from HEAD upto 20200411 @ text @@ 1.1.1.7 log @Mark old LLVM instance as dead. @ text @@ 1.1.1.4.4.1 log @file DereferenceChecker.cpp was added on branch tls-maxphys on 2014-08-19 23:47:31 +0000 @ text @d1 281 @ 1.1.1.4.4.2 log @Rebase to HEAD as of a few days ago. @ text @a0 281 //== 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 "ClangSACheckers.h" #include "clang/AST/ExprObjC.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 "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 > { mutable std::unique_ptr BT_null; mutable std::unique_ptr BT_undef; void reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C, bool IsBind = false) 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 &Ranges, const Expr *Ex, const ProgramState *state, const LocationContext *LCtx, bool loadedFrom = false); }; } // end anonymous namespace void DereferenceChecker::AddDerefSource(raw_ostream &os, SmallVectorImpl &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(Ex); if (const VarDecl *VD = dyn_cast(DR->getDecl())) { os << " (" << (loadedFrom ? "loaded from" : "from") << " variable '" << VD->getName() << "')"; Ranges.push_back(DR->getSourceRange()); } break; } case Stmt::MemberExprClass: { const MemberExpr *ME = cast(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(Ex); os << " (" << (loadedFrom ? "loaded from" : "via") << " ivar '" << IV->getDecl()->getName() << "')"; SourceLocation L = IV->getLocation(); Ranges.push_back(SourceRange(L, L)); break; } } } void DereferenceChecker::reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C, bool IsBind) const { // Generate an error node. ExplodedNode *N = C.generateSink(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 Ranges; // Walk through lvalue casts to get the original expression // that syntactically caused the load. if (const Expr *expr = dyn_cast(S)) S = expr->IgnoreParenLValueCasts(); if (IsBind) { if (const BinaryOperator *BO = dyn_cast(S)) { if (BO->isAssignmentOp()) S = BO->getRHS(); } else if (const DeclStmt *DS = dyn_cast(S)) { assert(DS->isSingleDecl() && "We process decls one by one"); if (const VarDecl *VD = dyn_cast(DS->getSingleDecl())) if (const Expr *Init = VD->getAnyInitializer()) S = Init; } } switch (S->getStmtClass()) { case Stmt::ArraySubscriptExprClass: { os << "Array access"; const ArraySubscriptExpr *AE = cast(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(S); AddDerefSource(os, Ranges, U->getSubExpr()->IgnoreParens(), State.get(), N->getLocationContext(), true); break; } case Stmt::MemberExprClass: { const MemberExpr *M = cast(S); if (M->isArrow() || bugreporter::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(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; } os.flush(); BugReport *report = new BugReport(*BT_null, buf.empty() ? BT_null->getDescription() : buf.str(), N); bugreporter::trackNullOrUndefValue(N, bugreporter::getDerefExpr(S), *report); for (SmallVectorImpl::iterator I = Ranges.begin(), E = Ranges.end(); I!=E; ++I) report->addRange(*I); C.emitReport(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.generateSink()) { if (!BT_undef) BT_undef.reset( new BuiltinBug(this, "Dereference of undefined pointer value")); BugReport *report = new BugReport(*BT_undef, BT_undef->getDescription(), N); bugreporter::trackNullOrUndefValue(N, bugreporter::getDerefExpr(S), *report); C.emitReport(report); } return; } DefinedOrUnknownSVal location = l.castAs(); // Check for null dereferences. if (!location.getAs()) return; ProgramStateRef state = C.getState(); ProgramStateRef notNullState, nullState; std::tie(notNullState, nullState) = state->assume(location); // The explicit NULL case. if (nullState) { if (!notNullState) { reportBug(nullState, S, 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)) { ImplicitNullDerefEvent event = { l, isLoad, N, &C.getBugReporter() }; 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(MR); if (!TVR) return; if (!TVR->getValueType()->isReferenceType()) return; ProgramStateRef State = C.getState(); ProgramStateRef StNonNull, StNull; std::tie(StNonNull, StNull) = State->assume(V.castAs()); if (StNull) { if (!StNonNull) { reportBug(StNull, S, C, /*isBind=*/true); 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)) { ImplicitNullDerefEvent event = { V, /*isLoad=*/true, N, &C.getBugReporter() }; 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(); } @ 1.1.1.2.4.1 log @file DereferenceChecker.cpp was added on branch yamt-pagecache on 2014-05-22 16:18:31 +0000 @ text @d1 282 @ 1.1.1.2.4.2 log @sync with head. for a reference, the tree before this commit was tagged as yamt-pagecache-tag8. this commit was splitted into small chunks to avoid a limitation of cvs. ("Protocol error: too many arguments") @ text @a0 282 //== 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 "ClangSACheckers.h" #include "clang/AST/ExprObjC.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 "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 > { mutable OwningPtr BT_null; mutable OwningPtr BT_undef; void reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C, bool IsBind = false) 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 &Ranges, const Expr *Ex, const ProgramState *state, const LocationContext *LCtx, bool loadedFrom = false); }; } // end anonymous namespace void DereferenceChecker::AddDerefSource(raw_ostream &os, SmallVectorImpl &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(Ex); if (const VarDecl *VD = dyn_cast(DR->getDecl())) { os << " (" << (loadedFrom ? "loaded from" : "from") << " variable '" << VD->getName() << "')"; Ranges.push_back(DR->getSourceRange()); } break; } case Stmt::MemberExprClass: { const MemberExpr *ME = cast(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(Ex); os << " (" << (loadedFrom ? "loaded from" : "via") << " ivar '" << IV->getDecl()->getName() << "')"; SourceLocation L = IV->getLocation(); Ranges.push_back(SourceRange(L, L)); break; } } } void DereferenceChecker::reportBug(ProgramStateRef State, const Stmt *S, CheckerContext &C, bool IsBind) const { // Generate an error node. ExplodedNode *N = C.generateSink(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 Ranges; // Walk through lvalue casts to get the original expression // that syntactically caused the load. if (const Expr *expr = dyn_cast(S)) S = expr->IgnoreParenLValueCasts(); if (IsBind) { if (const BinaryOperator *BO = dyn_cast(S)) { if (BO->isAssignmentOp()) S = BO->getRHS(); } else if (const DeclStmt *DS = dyn_cast(S)) { assert(DS->isSingleDecl() && "We process decls one by one"); if (const VarDecl *VD = dyn_cast(DS->getSingleDecl())) if (const Expr *Init = VD->getAnyInitializer()) S = Init; } } switch (S->getStmtClass()) { case Stmt::ArraySubscriptExprClass: { os << "Array access"; const ArraySubscriptExpr *AE = cast(S); AddDerefSource(os, Ranges, AE->getBase()->IgnoreParenCasts(), State.getPtr(), N->getLocationContext()); os << " results in a null pointer dereference"; break; } case Stmt::UnaryOperatorClass: { os << "Dereference of null pointer"; const UnaryOperator *U = cast(S); AddDerefSource(os, Ranges, U->getSubExpr()->IgnoreParens(), State.getPtr(), N->getLocationContext(), true); break; } case Stmt::MemberExprClass: { const MemberExpr *M = cast(S); if (M->isArrow() || bugreporter::isDeclRefExprToReference(M->getBase())) { os << "Access to field '" << M->getMemberNameInfo() << "' results in a dereference of a null pointer"; AddDerefSource(os, Ranges, M->getBase()->IgnoreParenCasts(), State.getPtr(), N->getLocationContext(), true); } break; } case Stmt::ObjCIvarRefExprClass: { const ObjCIvarRefExpr *IV = cast(S); os << "Access to instance variable '" << *IV->getDecl() << "' results in a dereference of a null pointer"; AddDerefSource(os, Ranges, IV->getBase()->IgnoreParenCasts(), State.getPtr(), N->getLocationContext(), true); break; } default: break; } os.flush(); BugReport *report = new BugReport(*BT_null, buf.empty() ? BT_null->getDescription() : buf.str(), N); bugreporter::trackNullOrUndefValue(N, bugreporter::getDerefExpr(S), *report); for (SmallVectorImpl::iterator I = Ranges.begin(), E = Ranges.end(); I!=E; ++I) report->addRange(*I); C.emitReport(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.generateSink()) { if (!BT_undef) BT_undef.reset( new BuiltinBug(this, "Dereference of undefined pointer value")); BugReport *report = new BugReport(*BT_undef, BT_undef->getDescription(), N); bugreporter::trackNullOrUndefValue(N, bugreporter::getDerefExpr(S), *report); C.emitReport(report); } return; } DefinedOrUnknownSVal location = l.castAs(); // Check for null dereferences. if (!location.getAs()) return; ProgramStateRef state = C.getState(); ProgramStateRef notNullState, nullState; llvm::tie(notNullState, nullState) = state->assume(location); // The explicit NULL case. if (nullState) { if (!notNullState) { reportBug(nullState, S, 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)) { ImplicitNullDerefEvent event = { l, isLoad, N, &C.getBugReporter() }; 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(MR); if (!TVR) return; if (!TVR->getValueType()->isReferenceType()) return; ProgramStateRef State = C.getState(); ProgramStateRef StNonNull, StNull; llvm::tie(StNonNull, StNull) = State->assume(V.castAs()); if (StNull) { if (!StNonNull) { reportBug(StNull, S, C, /*isBind=*/true); 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)) { ImplicitNullDerefEvent event = { V, /*isLoad=*/true, N, &C.getBugReporter() }; 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(); } @