From 42d241fc0b25d71c4c048019a25e286b8bd4bb6f Mon Sep 17 00:00:00 2001 From: Adam Balogh Date: Tue, 4 Dec 2018 10:22:28 +0000 Subject: [PATCH] [Analyzer] Iterator Checkers - Use the region of the topmost base class for iterators stored in a region If an iterator is represented by a derived C++ class but its comparison operator is for its base the iterator checkers cannot recognize the iterators compared. This results in false positives in very straightforward cases (range error when dereferencing an iterator after disclosing that it is equal to the past-the-end iterator). To overcome this problem we always use the region of the topmost base class for iterators stored in a region. A new method called getMostDerivedObjectRegion() was added to the MemRegion class to get this region. Differential Revision: https://reviews.llvm.org/D54466 llvm-svn: 348244 --- .../StaticAnalyzer/Core/PathSensitive/MemRegion.h | 4 ++ .../StaticAnalyzer/Checkers/IteratorChecker.cpp | 60 ++++++++-------------- clang/lib/StaticAnalyzer/Core/MemRegion.cpp | 9 ++++ clang/test/Analysis/iterator-range.cpp | 37 +++++++++++++ 4 files changed, 71 insertions(+), 39 deletions(-) diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h index 0b0e32b..a4ddb58 100644 --- a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h +++ b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h @@ -118,6 +118,10 @@ public: const MemRegion *getBaseRegion() const; + /// Recursively retrieve the region of the most derived class instance of + /// regions of C++ base class instances. + const MemRegion *getMostDerivedObjectRegion() const; + /// Check if the region is a subregion of the given region. /// Each region is a subregion of itself. virtual bool isSubRegionOf(const MemRegion *R) const; diff --git a/clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp index 7a71751..e221252 100644 --- a/clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp +++ b/clang/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp @@ -1089,9 +1089,7 @@ void IteratorChecker::verifyRandomIncrOrDecr(CheckerContext &C, void IteratorChecker::verifyMatch(CheckerContext &C, const SVal &Iter, const MemRegion *Cont) const { // Verify match between a container and the container of an iterator - while (const auto *CBOR = Cont->getAs()) { - Cont = CBOR->getSuperRegion(); - } + Cont = Cont->getMostDerivedObjectRegion(); auto State = C.getState(); const auto *Pos = getIteratorPosition(State, Iter); @@ -1125,9 +1123,7 @@ void IteratorChecker::handleBegin(CheckerContext &C, const Expr *CE, if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); // If the container already has a begin symbol then use it. Otherwise first // create a new one. @@ -1151,9 +1147,7 @@ void IteratorChecker::handleEnd(CheckerContext &C, const Expr *CE, if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); // If the container already has an end symbol then use it. Otherwise first // create a new one. @@ -1174,9 +1168,7 @@ void IteratorChecker::handleEnd(CheckerContext &C, const Expr *CE, void IteratorChecker::assignToContainer(CheckerContext &C, const Expr *CE, const SVal &RetVal, const MemRegion *Cont) const { - while (const auto *CBOR = Cont->getAs()) { - Cont = CBOR->getSuperRegion(); - } + Cont = Cont->getMostDerivedObjectRegion(); auto State = C.getState(); auto &SymMgr = C.getSymbolManager(); @@ -1194,9 +1186,7 @@ void IteratorChecker::handleAssign(CheckerContext &C, const SVal &Cont, if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); // Assignment of a new value to a container always invalidates all its // iterators @@ -1211,9 +1201,7 @@ void IteratorChecker::handleAssign(CheckerContext &C, const SVal &Cont, if (!OldCont.isUndef()) { const auto *OldContReg = OldCont.getAsRegion(); if (OldContReg) { - while (const auto *CBOR = OldContReg->getAs()) { - OldContReg = CBOR->getSuperRegion(); - } + OldContReg = OldContReg->getMostDerivedObjectRegion(); const auto OldCData = getContainerData(State, OldContReg); if (OldCData) { if (const auto OldEndSym = OldCData->getEnd()) { @@ -1273,9 +1261,7 @@ void IteratorChecker::handleClear(CheckerContext &C, const SVal &Cont) const { if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); // The clear() operation invalidates all the iterators, except the past-end // iterators of list-like containers @@ -1302,9 +1288,7 @@ void IteratorChecker::handlePushBack(CheckerContext &C, if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); // For deque-like containers invalidate all iterator positions auto State = C.getState(); @@ -1341,9 +1325,7 @@ void IteratorChecker::handlePopBack(CheckerContext &C, const SVal &Cont) const { if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); auto State = C.getState(); const auto CData = getContainerData(State, ContReg); @@ -1381,9 +1363,7 @@ void IteratorChecker::handlePushFront(CheckerContext &C, if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); // For deque-like containers invalidate all iterator positions auto State = C.getState(); @@ -1416,9 +1396,7 @@ void IteratorChecker::handlePopFront(CheckerContext &C, if (!ContReg) return; - while (const auto *CBOR = ContReg->getAs()) { - ContReg = CBOR->getSuperRegion(); - } + ContReg = ContReg->getMostDerivedObjectRegion(); auto State = C.getState(); const auto CData = getContainerData(State, ContReg); @@ -2015,7 +1993,8 @@ ProgramStateRef setContainerData(ProgramStateRef State, const MemRegion *Cont, const IteratorPosition *getIteratorPosition(ProgramStateRef State, const SVal &Val) { - if (const auto Reg = Val.getAsRegion()) { + if (auto Reg = Val.getAsRegion()) { + Reg = Reg->getMostDerivedObjectRegion(); return State->get(Reg); } else if (const auto Sym = Val.getAsSymbol()) { return State->get(Sym); @@ -2028,7 +2007,8 @@ const IteratorPosition *getIteratorPosition(ProgramStateRef State, const IteratorPosition *getIteratorPosition(ProgramStateRef State, RegionOrSymbol RegOrSym) { if (RegOrSym.is()) { - return State->get(RegOrSym.get()); + auto Reg = RegOrSym.get()->getMostDerivedObjectRegion(); + return State->get(Reg); } else if (RegOrSym.is()) { return State->get(RegOrSym.get()); } @@ -2037,7 +2017,8 @@ const IteratorPosition *getIteratorPosition(ProgramStateRef State, ProgramStateRef setIteratorPosition(ProgramStateRef State, const SVal &Val, const IteratorPosition &Pos) { - if (const auto Reg = Val.getAsRegion()) { + if (auto Reg = Val.getAsRegion()) { + Reg = Reg->getMostDerivedObjectRegion(); return State->set(Reg, Pos); } else if (const auto Sym = Val.getAsSymbol()) { return State->set(Sym, Pos); @@ -2051,8 +2032,8 @@ ProgramStateRef setIteratorPosition(ProgramStateRef State, RegionOrSymbol RegOrSym, const IteratorPosition &Pos) { if (RegOrSym.is()) { - return State->set(RegOrSym.get(), - Pos); + auto Reg = RegOrSym.get()->getMostDerivedObjectRegion(); + return State->set(Reg, Pos); } else if (RegOrSym.is()) { return State->set(RegOrSym.get(), Pos); } @@ -2060,7 +2041,8 @@ ProgramStateRef setIteratorPosition(ProgramStateRef State, } ProgramStateRef removeIteratorPosition(ProgramStateRef State, const SVal &Val) { - if (const auto Reg = Val.getAsRegion()) { + if (auto Reg = Val.getAsRegion()) { + Reg = Reg->getMostDerivedObjectRegion(); return State->remove(Reg); } else if (const auto Sym = Val.getAsSymbol()) { return State->remove(Sym); diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp index 221b917..da368de 100644 --- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp +++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp @@ -1175,6 +1175,15 @@ const MemRegion *MemRegion::getBaseRegion() const { return R; } +// getgetMostDerivedObjectRegion gets the region of the root class of a C++ +// class hierarchy. +const MemRegion *MemRegion::getMostDerivedObjectRegion() const { + const MemRegion *R = this; + while (const auto *BR = dyn_cast(R)) + R = BR->getSuperRegion(); + return R; +} + bool MemRegion::isSubRegionOf(const MemRegion *) const { return false; } diff --git a/clang/test/Analysis/iterator-range.cpp b/clang/test/Analysis/iterator-range.cpp index 78cdb09..1a32073 100644 --- a/clang/test/Analysis/iterator-range.cpp +++ b/clang/test/Analysis/iterator-range.cpp @@ -200,3 +200,40 @@ void bad_move_push_back(std::list &L1, std::list &L2, int n) { ++i0; *++i0; // expected-warning{{Iterator accessed outside of its range}} } + +struct simple_iterator_base { + simple_iterator_base(); + simple_iterator_base(const simple_iterator_base& rhs); + simple_iterator_base &operator=(const simple_iterator_base& rhs); + virtual ~simple_iterator_base(); + bool friend operator==(const simple_iterator_base &lhs, + const simple_iterator_base &rhs); + bool friend operator!=(const simple_iterator_base &lhs, + const simple_iterator_base &rhs); +private: + int *ptr; +}; + +struct simple_derived_iterator: public simple_iterator_base { + int& operator*(); + int* operator->(); + simple_iterator_base &operator++(); + simple_iterator_base operator++(int); + simple_iterator_base &operator--(); + simple_iterator_base operator--(int); +}; + +struct simple_container { + typedef simple_derived_iterator iterator; + + iterator begin(); + iterator end(); +}; + +void good_derived(simple_container c) { + auto i0 = c.end(); + if (i0 != c.end()) { + clang_analyzer_warnIfReached(); + *i0; // no-warning + } +} -- 2.7.4