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IteratorChecker.cpp
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IteratorChecker.cpp
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//===-- IteratorChecker.cpp ---------------------------------------*- C++ -*--//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Defines a checker for using iterators outside their range (past end). Usage
// means here dereferencing, incrementing etc.
//
//===----------------------------------------------------------------------===//
//
// In the code, iterator can be represented as a:
// * type-I: typedef-ed pointer. Operations over such iterator, such as
// comparisons or increments, are modeled straightforwardly by the
// analyzer.
// * type-II: structure with its method bodies available. Operations over such
// iterator are inlined by the analyzer, and results of modeling
// these operations are exposing implementation details of the
// iterators, which is not necessarily helping.
// * type-III: completely opaque structure. Operations over such iterator are
// modeled conservatively, producing conjured symbols everywhere.
//
// To handle all these types in a common way we introduce a structure called
// IteratorPosition which is an abstraction of the position the iterator
// represents using symbolic expressions. The checker handles all the
// operations on this structure.
//
// Additionally, depending on the circumstances, operators of types II and III
// can be represented as:
// * type-IIa, type-IIIa: conjured structure symbols - when returned by value
// from conservatively evaluated methods such as
// `.begin()`.
// * type-IIb, type-IIIb: memory regions of iterator-typed objects, such as
// variables or temporaries, when the iterator object is
// currently treated as an lvalue.
// * type-IIc, type-IIIc: compound values of iterator-typed objects, when the
// iterator object is treated as an rvalue taken of a
// particular lvalue, eg. a copy of "type-a" iterator
// object, or an iterator that existed before the
// analysis has started.
//
// To handle any of these three different representations stored in an SVal we
// use setter and getters functions which separate the three cases. To store
// them we use a pointer union of symbol and memory region.
//
// The checker works the following way: We record the begin and the
// past-end iterator for all containers whenever their `.begin()` and `.end()`
// are called. Since the Constraint Manager cannot handle such SVals we need
// to take over its role. We post-check equality and non-equality comparisons
// and record that the two sides are equal if we are in the 'equal' branch
// (true-branch for `==` and false-branch for `!=`).
//
// In case of type-I or type-II iterators we get a concrete integer as a result
// of the comparison (1 or 0) but in case of type-III we only get a Symbol. In
// this latter case we record the symbol and reload it in evalAssume() and do
// the propagation there. We also handle (maybe double) negated comparisons
// which are represented in the form of (x == 0 or x != 0) where x is the
// comparison itself.
//
// Since `SimpleConstraintManager` cannot handle complex symbolic expressions
// we only use expressions of the format S, S+n or S-n for iterator positions
// where S is a conjured symbol and n is an unsigned concrete integer. When
// making an assumption e.g. `S1 + n == S2 + m` we store `S1 - S2 == m - n` as
// a constraint which we later retrieve when doing an actual comparison.
#include "ClangSACheckers.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicTypeMap.h"
#include <utility>
using namespace clang;
using namespace ento;
namespace {
// Abstract position of an iterator. This helps to handle all three kinds
// of operators in a common way by using a symbolic position.
struct IteratorPosition {
private:
// Container the iterator belongs to
const MemRegion *Cont;
// Whether iterator is valid
const bool Valid;
// Abstract offset
const SymbolRef Offset;
IteratorPosition(const MemRegion *C, bool V, SymbolRef Of)
: Cont(C), Valid(V), Offset(Of) {}
public:
const MemRegion *getContainer() const { return Cont; }
bool isValid() const { return Valid; }
SymbolRef getOffset() const { return Offset; }
IteratorPosition invalidate() const {
return IteratorPosition(Cont, false, Offset);
}
static IteratorPosition getPosition(const MemRegion *C, SymbolRef Of) {
return IteratorPosition(C, true, Of);
}
IteratorPosition setTo(SymbolRef NewOf) const {
return IteratorPosition(Cont, Valid, NewOf);
}
IteratorPosition reAssign(const MemRegion *NewCont) const {
return IteratorPosition(NewCont, Valid, Offset);
}
bool operator==(const IteratorPosition &X) const {
return Cont == X.Cont && Valid == X.Valid && Offset == X.Offset;
}
bool operator!=(const IteratorPosition &X) const {
return Cont != X.Cont || Valid != X.Valid || Offset != X.Offset;
}
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.AddPointer(Cont);
ID.AddInteger(Valid);
ID.Add(Offset);
}
};
typedef llvm::PointerUnion<const MemRegion *, SymbolRef> RegionOrSymbol;
// Structure to record the symbolic begin and end position of a container
struct ContainerData {
private:
const SymbolRef Begin, End;
ContainerData(SymbolRef B, SymbolRef E) : Begin(B), End(E) {}
public:
static ContainerData fromBegin(SymbolRef B) {
return ContainerData(B, nullptr);
}
static ContainerData fromEnd(SymbolRef E) {
return ContainerData(nullptr, E);
}
SymbolRef getBegin() const { return Begin; }
SymbolRef getEnd() const { return End; }
ContainerData newBegin(SymbolRef B) const { return ContainerData(B, End); }
ContainerData newEnd(SymbolRef E) const { return ContainerData(Begin, E); }
bool operator==(const ContainerData &X) const {
return Begin == X.Begin && End == X.End;
}
bool operator!=(const ContainerData &X) const {
return Begin != X.Begin || End != X.End;
}
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.Add(Begin);
ID.Add(End);
}
};
// Structure fo recording iterator comparisons. We needed to retrieve the
// original comparison expression in assumptions.
struct IteratorComparison {
private:
RegionOrSymbol Left, Right;
bool Equality;
public:
IteratorComparison(RegionOrSymbol L, RegionOrSymbol R, bool Eq)
: Left(L), Right(R), Equality(Eq) {}
RegionOrSymbol getLeft() const { return Left; }
RegionOrSymbol getRight() const { return Right; }
bool isEquality() const { return Equality; }
bool operator==(const IteratorComparison &X) const {
return Left == X.Left && Right == X.Right && Equality == X.Equality;
}
bool operator!=(const IteratorComparison &X) const {
return Left != X.Left || Right != X.Right || Equality != X.Equality;
}
void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddInteger(Equality); }
};
class IteratorChecker
: public Checker<check::PreCall, check::PostCall,
check::PostStmt<MaterializeTemporaryExpr>, check::Bind,
check::LiveSymbols, check::DeadSymbols,
eval::Assume> {
std::unique_ptr<BugType> OutOfRangeBugType;
std::unique_ptr<BugType> MismatchedBugType;
std::unique_ptr<BugType> InvalidatedBugType;
void handleComparison(CheckerContext &C, const SVal &RetVal, const SVal &LVal,
const SVal &RVal, OverloadedOperatorKind Op) const;
void verifyAccess(CheckerContext &C, const SVal &Val) const;
void verifyDereference(CheckerContext &C, const SVal &Val) const;
void handleIncrement(CheckerContext &C, const SVal &RetVal, const SVal &Iter,
bool Postfix) const;
void handleDecrement(CheckerContext &C, const SVal &RetVal, const SVal &Iter,
bool Postfix) const;
void handleRandomIncrOrDecr(CheckerContext &C, OverloadedOperatorKind Op,
const SVal &RetVal, const SVal &LHS,
const SVal &RHS) const;
void handleBegin(CheckerContext &C, const Expr *CE, const SVal &RetVal,
const SVal &Cont) const;
void handleEnd(CheckerContext &C, const Expr *CE, const SVal &RetVal,
const SVal &Cont) const;
void assignToContainer(CheckerContext &C, const Expr *CE, const SVal &RetVal,
const MemRegion *Cont) const;
void handleAssign(CheckerContext &C, const SVal &Cont,
const Expr *CE = nullptr,
const SVal &OldCont = UndefinedVal()) const;
void handleClear(CheckerContext &C, const SVal &Cont) const;
void handlePushBack(CheckerContext &C, const SVal &Cont) const;
void handlePopBack(CheckerContext &C, const SVal &Cont) const;
void handlePushFront(CheckerContext &C, const SVal &Cont) const;
void handlePopFront(CheckerContext &C, const SVal &Cont) const;
void handleInsert(CheckerContext &C, const SVal &Iter) const;
void handleErase(CheckerContext &C, const SVal &Iter) const;
void handleErase(CheckerContext &C, const SVal &Iter1,
const SVal &Iter2) const;
void handleEraseAfter(CheckerContext &C, const SVal &Iter) const;
void handleEraseAfter(CheckerContext &C, const SVal &Iter1,
const SVal &Iter2) const;
void verifyIncrement(CheckerContext &C, const SVal &Iter) const;
void verifyDecrement(CheckerContext &C, const SVal &Iter) const;
void verifyRandomIncrOrDecr(CheckerContext &C, OverloadedOperatorKind Op,
const SVal &LHS, const SVal &RHS) const;
void verifyMatch(CheckerContext &C, const SVal &Iter,
const MemRegion *Cont) const;
void verifyMatch(CheckerContext &C, const SVal &Iter1,
const SVal &Iter2) const;
IteratorPosition advancePosition(CheckerContext &C, OverloadedOperatorKind Op,
const IteratorPosition &Pos,
const SVal &Distance) const;
void reportOutOfRangeBug(const StringRef &Message, const SVal &Val,
CheckerContext &C, ExplodedNode *ErrNode) const;
void reportMismatchedBug(const StringRef &Message, const SVal &Val1,
const SVal &Val2, CheckerContext &C,
ExplodedNode *ErrNode) const;
void reportMismatchedBug(const StringRef &Message, const SVal &Val,
const MemRegion *Reg, CheckerContext &C,
ExplodedNode *ErrNode) const;
void reportInvalidatedBug(const StringRef &Message, const SVal &Val,
CheckerContext &C, ExplodedNode *ErrNode) const;
public:
IteratorChecker();
enum CheckKind {
CK_IteratorRangeChecker,
CK_MismatchedIteratorChecker,
CK_InvalidatedIteratorChecker,
CK_NumCheckKinds
};
DefaultBool ChecksEnabled[CK_NumCheckKinds];
CheckName CheckNames[CK_NumCheckKinds];
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &C) const;
void checkPostStmt(const CXXConstructExpr *CCE, CheckerContext &C) const;
void checkPostStmt(const DeclStmt *DS, CheckerContext &C) const;
void checkPostStmt(const MaterializeTemporaryExpr *MTE,
CheckerContext &C) const;
void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const;
void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
ProgramStateRef evalAssume(ProgramStateRef State, SVal Cond,
bool Assumption) const;
};
} // namespace
REGISTER_MAP_WITH_PROGRAMSTATE(IteratorSymbolMap, SymbolRef, IteratorPosition)
REGISTER_MAP_WITH_PROGRAMSTATE(IteratorRegionMap, const MemRegion *,
IteratorPosition)
REGISTER_MAP_WITH_PROGRAMSTATE(ContainerMap, const MemRegion *, ContainerData)
REGISTER_MAP_WITH_PROGRAMSTATE(IteratorComparisonMap, const SymExpr *,
IteratorComparison)
namespace {
bool isIteratorType(const QualType &Type);
bool isIterator(const CXXRecordDecl *CRD);
bool isComparisonOperator(OverloadedOperatorKind OK);
bool isBeginCall(const FunctionDecl *Func);
bool isEndCall(const FunctionDecl *Func);
bool isAssignCall(const FunctionDecl *Func);
bool isClearCall(const FunctionDecl *Func);
bool isPushBackCall(const FunctionDecl *Func);
bool isEmplaceBackCall(const FunctionDecl *Func);
bool isPopBackCall(const FunctionDecl *Func);
bool isPushFrontCall(const FunctionDecl *Func);
bool isEmplaceFrontCall(const FunctionDecl *Func);
bool isPopFrontCall(const FunctionDecl *Func);
bool isInsertCall(const FunctionDecl *Func);
bool isEraseCall(const FunctionDecl *Func);
bool isEraseAfterCall(const FunctionDecl *Func);
bool isEmplaceCall(const FunctionDecl *Func);
bool isAssignmentOperator(OverloadedOperatorKind OK);
bool isSimpleComparisonOperator(OverloadedOperatorKind OK);
bool isAccessOperator(OverloadedOperatorKind OK);
bool isDereferenceOperator(OverloadedOperatorKind OK);
bool isIncrementOperator(OverloadedOperatorKind OK);
bool isDecrementOperator(OverloadedOperatorKind OK);
bool isRandomIncrOrDecrOperator(OverloadedOperatorKind OK);
bool hasSubscriptOperator(ProgramStateRef State, const MemRegion *Reg);
bool frontModifiable(ProgramStateRef State, const MemRegion *Reg);
bool backModifiable(ProgramStateRef State, const MemRegion *Reg);
BinaryOperator::Opcode getOpcode(const SymExpr *SE);
const RegionOrSymbol getRegionOrSymbol(const SVal &Val);
const ProgramStateRef processComparison(ProgramStateRef State,
RegionOrSymbol LVal,
RegionOrSymbol RVal, bool Equal);
const ProgramStateRef saveComparison(ProgramStateRef State,
const SymExpr *Condition, const SVal &LVal,
const SVal &RVal, bool Eq);
const IteratorComparison *loadComparison(ProgramStateRef State,
const SymExpr *Condition);
SymbolRef getContainerBegin(ProgramStateRef State, const MemRegion *Cont);
SymbolRef getContainerEnd(ProgramStateRef State, const MemRegion *Cont);
ProgramStateRef createContainerBegin(ProgramStateRef State,
const MemRegion *Cont,
const SymbolRef Sym);
ProgramStateRef createContainerEnd(ProgramStateRef State, const MemRegion *Cont,
const SymbolRef Sym);
const IteratorPosition *getIteratorPosition(ProgramStateRef State,
const SVal &Val);
const IteratorPosition *getIteratorPosition(ProgramStateRef State,
RegionOrSymbol RegOrSym);
ProgramStateRef setIteratorPosition(ProgramStateRef State, const SVal &Val,
const IteratorPosition &Pos);
ProgramStateRef setIteratorPosition(ProgramStateRef State,
RegionOrSymbol RegOrSym,
const IteratorPosition &Pos);
ProgramStateRef removeIteratorPosition(ProgramStateRef State, const SVal &Val);
ProgramStateRef adjustIteratorPosition(ProgramStateRef State,
RegionOrSymbol RegOrSym,
const IteratorPosition &Pos, bool Equal);
ProgramStateRef relateIteratorPositions(ProgramStateRef State,
const IteratorPosition &Pos1,
const IteratorPosition &Pos2,
bool Equal);
ProgramStateRef invalidateAllIteratorPositions(ProgramStateRef State,
const MemRegion *Cont);
ProgramStateRef
invalidateAllIteratorPositionsExcept(ProgramStateRef State,
const MemRegion *Cont, SymbolRef Offset,
BinaryOperator::Opcode Opc);
ProgramStateRef invalidateIteratorPositions(ProgramStateRef State,
SymbolRef Offset,
BinaryOperator::Opcode Opc);
ProgramStateRef invalidateIteratorPositions(ProgramStateRef State,
SymbolRef Offset1,
BinaryOperator::Opcode Opc1,
SymbolRef Offset2,
BinaryOperator::Opcode Opc2);
ProgramStateRef reassignAllIteratorPositions(ProgramStateRef State,
const MemRegion *Cont,
const MemRegion *NewCont);
ProgramStateRef reassignAllIteratorPositionsUnless(ProgramStateRef State,
const MemRegion *Cont,
const MemRegion *NewCont,
SymbolRef Offset,
BinaryOperator::Opcode Opc);
ProgramStateRef rebaseSymbolInIteratorPositionsIf(
ProgramStateRef State, SValBuilder &SVB, SymbolRef OldSym,
SymbolRef NewSym, SymbolRef CondSym, BinaryOperator::Opcode Opc);
const ContainerData *getContainerData(ProgramStateRef State,
const MemRegion *Cont);
ProgramStateRef setContainerData(ProgramStateRef State, const MemRegion *Cont,
const ContainerData &CData);
bool hasLiveIterators(ProgramStateRef State, const MemRegion *Cont);
bool isBoundThroughLazyCompoundVal(const Environment &Env,
const MemRegion *Reg);
bool isPastTheEnd(ProgramStateRef State, const IteratorPosition &Pos);
bool isAheadOfRange(ProgramStateRef State, const IteratorPosition &Pos);
bool isBehindPastTheEnd(ProgramStateRef State, const IteratorPosition &Pos);
bool isZero(ProgramStateRef State, const NonLoc &Val);
} // namespace
IteratorChecker::IteratorChecker() {
OutOfRangeBugType.reset(
new BugType(this, "Iterator out of range", "Misuse of STL APIs"));
OutOfRangeBugType->setSuppressOnSink(true);
MismatchedBugType.reset(
new BugType(this, "Iterator(s) mismatched", "Misuse of STL APIs"));
MismatchedBugType->setSuppressOnSink(true);
InvalidatedBugType.reset(
new BugType(this, "Iterator invalidated", "Misuse of STL APIs"));
InvalidatedBugType->setSuppressOnSink(true);
}
void IteratorChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
// Check for out of range access or access of invalidated position and
// iterator mismatches
const auto *Func = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
if (!Func)
return;
if (Func->isOverloadedOperator()) {
if (ChecksEnabled[CK_InvalidatedIteratorChecker] &&
isAccessOperator(Func->getOverloadedOperator())) {
// Check for any kind of access of invalidated iterator positions
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
verifyAccess(C, InstCall->getCXXThisVal());
} else {
verifyAccess(C, Call.getArgSVal(0));
}
}
if (ChecksEnabled[CK_IteratorRangeChecker]) {
if (isIncrementOperator(Func->getOverloadedOperator())) {
// Check for out-of-range incrementions
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
verifyIncrement(C, InstCall->getCXXThisVal());
} else {
if (Call.getNumArgs() >= 1) {
verifyIncrement(C, Call.getArgSVal(0));
}
}
} else if (isDecrementOperator(Func->getOverloadedOperator())) {
// Check for out-of-range decrementions
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
verifyDecrement(C, InstCall->getCXXThisVal());
} else {
if (Call.getNumArgs() >= 1) {
verifyDecrement(C, Call.getArgSVal(0));
}
}
} else if (isRandomIncrOrDecrOperator(Func->getOverloadedOperator())) {
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
// Check for out-of-range incrementions and decrementions
if (Call.getNumArgs() >= 1) {
verifyRandomIncrOrDecr(C, Func->getOverloadedOperator(),
InstCall->getCXXThisVal(),
Call.getArgSVal(0));
}
} else {
if (Call.getNumArgs() >= 2) {
verifyRandomIncrOrDecr(C, Func->getOverloadedOperator(),
Call.getArgSVal(0), Call.getArgSVal(1));
}
}
} else if (isDereferenceOperator(Func->getOverloadedOperator())) {
// Check for dereference of out-of-range iterators
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
verifyDereference(C, InstCall->getCXXThisVal());
} else {
verifyDereference(C, Call.getArgSVal(0));
}
}
} else if (ChecksEnabled[CK_MismatchedIteratorChecker] &&
isComparisonOperator(Func->getOverloadedOperator())) {
// Check for comparisons of iterators of different containers
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
if (Call.getNumArgs() < 1)
return;
if (!isIteratorType(InstCall->getCXXThisExpr()->getType()) ||
!isIteratorType(Call.getArgExpr(0)->getType()))
return;
verifyMatch(C, InstCall->getCXXThisVal(), Call.getArgSVal(0));
} else {
if (Call.getNumArgs() < 2)
return;
if (!isIteratorType(Call.getArgExpr(0)->getType()) ||
!isIteratorType(Call.getArgExpr(1)->getType()))
return;
verifyMatch(C, Call.getArgSVal(0), Call.getArgSVal(1));
}
}
} else if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
if (!ChecksEnabled[CK_MismatchedIteratorChecker])
return;
const auto *ContReg = InstCall->getCXXThisVal().getAsRegion();
if (!ContReg)
return;
// Check for erase, insert and emplace using iterator of another container
if (isEraseCall(Func) || isEraseAfterCall(Func)) {
verifyMatch(C, Call.getArgSVal(0),
InstCall->getCXXThisVal().getAsRegion());
if (Call.getNumArgs() == 2) {
verifyMatch(C, Call.getArgSVal(1),
InstCall->getCXXThisVal().getAsRegion());
}
} else if (isInsertCall(Func)) {
verifyMatch(C, Call.getArgSVal(0),
InstCall->getCXXThisVal().getAsRegion());
if (Call.getNumArgs() == 3 &&
isIteratorType(Call.getArgExpr(1)->getType()) &&
isIteratorType(Call.getArgExpr(2)->getType())) {
verifyMatch(C, Call.getArgSVal(1), Call.getArgSVal(2));
}
} else if (isEmplaceCall(Func)) {
verifyMatch(C, Call.getArgSVal(0),
InstCall->getCXXThisVal().getAsRegion());
}
} else if (isa<CXXConstructorCall>(&Call)) {
// Check match of first-last iterator pair in a constructor of a container
if (Call.getNumArgs() < 2)
return;
const auto *Ctr = cast<CXXConstructorDecl>(Call.getDecl());
if (Ctr->getNumParams() < 2)
return;
if (Ctr->getParamDecl(0)->getName() != "first" ||
Ctr->getParamDecl(1)->getName() != "last")
return;
if (!isIteratorType(Call.getArgExpr(0)->getType()) ||
!isIteratorType(Call.getArgExpr(1)->getType()))
return;
verifyMatch(C, Call.getArgSVal(0), Call.getArgSVal(1));
} else {
// The main purpose of iterators is to abstract away from different
// containers and provide a (maybe limited) uniform access to them.
// This implies that any correctly written template function that
// works on multiple containers using iterators takes different
// template parameters for different containers. So we can safely
// assume that passing iterators of different containers as arguments
// whose type replaces the same template parameter is a bug.
//
// Example:
// template<typename I1, typename I2>
// void f(I1 first1, I1 last1, I2 first2, I2 last2);
//
// In this case the first two arguments to f() must be iterators must belong
// to the same container and the last to also to the same container but
// not neccessarily to the same as the first two.
if (!ChecksEnabled[CK_MismatchedIteratorChecker])
return;
const auto *Templ = Func->getPrimaryTemplate();
if (!Templ)
return;
const auto *TParams = Templ->getTemplateParameters();
const auto *TArgs = Func->getTemplateSpecializationArgs();
// Iterate over all the template parameters
for (size_t I = 0; I < TParams->size(); ++I) {
const auto *TPDecl = dyn_cast<TemplateTypeParmDecl>(TParams->getParam(I));
if (!TPDecl)
continue;
if (TPDecl->isParameterPack())
continue;
const auto TAType = TArgs->get(I).getAsType();
if (!isIteratorType(TAType))
continue;
SVal LHS = UndefinedVal();
// For every template parameter which is an iterator type in the
// instantiation look for all functions' parameters' type by it and
// check whether they belong to the same container
for (auto J = 0U; J < Func->getNumParams(); ++J) {
const auto *Param = Func->getParamDecl(J);
const auto *ParamType =
Param->getType()->getAs<SubstTemplateTypeParmType>();
if (!ParamType ||
ParamType->getReplacedParameter()->getDecl() != TPDecl)
continue;
if (LHS.isUndef()) {
LHS = Call.getArgSVal(J);
} else {
verifyMatch(C, LHS, Call.getArgSVal(J));
}
}
}
}
}
void IteratorChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
// Record new iterator positions and iterator position changes
const auto *Func = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
if (!Func)
return;
if (Func->isOverloadedOperator()) {
const auto Op = Func->getOverloadedOperator();
if (isAssignmentOperator(Op)) {
const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call);
if (Func->getParamDecl(0)->getType()->isRValueReferenceType()) {
handleAssign(C, InstCall->getCXXThisVal(), Call.getOriginExpr(),
Call.getArgSVal(0));
} else {
handleAssign(C, InstCall->getCXXThisVal());
}
} else if (isSimpleComparisonOperator(Op)) {
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
handleComparison(C, Call.getReturnValue(), InstCall->getCXXThisVal(),
Call.getArgSVal(0), Op);
} else {
handleComparison(C, Call.getReturnValue(), Call.getArgSVal(0),
Call.getArgSVal(1), Op);
}
} else if (isRandomIncrOrDecrOperator(Func->getOverloadedOperator())) {
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
if (Call.getNumArgs() >= 1) {
handleRandomIncrOrDecr(C, Func->getOverloadedOperator(),
Call.getReturnValue(),
InstCall->getCXXThisVal(), Call.getArgSVal(0));
}
} else {
if (Call.getNumArgs() >= 2) {
handleRandomIncrOrDecr(C, Func->getOverloadedOperator(),
Call.getReturnValue(), Call.getArgSVal(0),
Call.getArgSVal(1));
}
}
} else if (isIncrementOperator(Func->getOverloadedOperator())) {
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
handleIncrement(C, Call.getReturnValue(), InstCall->getCXXThisVal(),
Call.getNumArgs());
} else {
handleIncrement(C, Call.getReturnValue(), Call.getArgSVal(0),
Call.getNumArgs());
}
} else if (isDecrementOperator(Func->getOverloadedOperator())) {
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
handleDecrement(C, Call.getReturnValue(), InstCall->getCXXThisVal(),
Call.getNumArgs());
} else {
handleDecrement(C, Call.getReturnValue(), Call.getArgSVal(0),
Call.getNumArgs());
}
}
} else {
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
if (isAssignCall(Func)) {
handleAssign(C, InstCall->getCXXThisVal());
} else if (isClearCall(Func)) {
handleClear(C, InstCall->getCXXThisVal());
} else if (isPushBackCall(Func) || isEmplaceBackCall(Func)) {
handlePushBack(C, InstCall->getCXXThisVal());
} else if (isPopBackCall(Func)) {
handlePopBack(C, InstCall->getCXXThisVal());
} else if (isPushFrontCall(Func) || isEmplaceFrontCall(Func)) {
handlePushFront(C, InstCall->getCXXThisVal());
} else if (isPopFrontCall(Func)) {
handlePopFront(C, InstCall->getCXXThisVal());
} else if (isInsertCall(Func) || isEmplaceCall(Func)) {
handleInsert(C, Call.getArgSVal(0));
} else if (isEraseCall(Func)) {
if (Call.getNumArgs() == 1) {
handleErase(C, Call.getArgSVal(0));
} else if (Call.getNumArgs() == 2) {
handleErase(C, Call.getArgSVal(0), Call.getArgSVal(1));
}
} else if (isEraseAfterCall(Func)) {
if (Call.getNumArgs() == 1) {
handleEraseAfter(C, Call.getArgSVal(0));
} else if (Call.getNumArgs() == 2) {
handleEraseAfter(C, Call.getArgSVal(0), Call.getArgSVal(1));
}
}
}
const auto *OrigExpr = Call.getOriginExpr();
if (!OrigExpr)
return;
if (!isIteratorType(Call.getResultType()))
return;
auto State = C.getState();
if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
if (isBeginCall(Func)) {
handleBegin(C, OrigExpr, Call.getReturnValue(),
InstCall->getCXXThisVal());
return;
}
if (isEndCall(Func)) {
handleEnd(C, OrigExpr, Call.getReturnValue(),
InstCall->getCXXThisVal());
return;
}
}
// Already bound to container?
if (getIteratorPosition(State, Call.getReturnValue()))
return;
// Copy-like and move constructors
if (isa<CXXConstructorCall>(&Call) && Call.getNumArgs() == 1) {
if (const auto *Pos = getIteratorPosition(State, Call.getArgSVal(0))) {
State = setIteratorPosition(State, Call.getReturnValue(), *Pos);
if (cast<CXXConstructorDecl>(Func)->isMoveConstructor()) {
State = removeIteratorPosition(State, Call.getArgSVal(0));
}
C.addTransition(State);
return;
}
}
// Assumption: if return value is an iterator which is not yet bound to a
// container, then look for the first iterator argument, and
// bind the return value to the same container. This approach
// works for STL algorithms.
// FIXME: Add a more conservative mode
for (unsigned i = 0; i < Call.getNumArgs(); ++i) {
if (isIteratorType(Call.getArgExpr(i)->getType())) {
if (const auto *Pos = getIteratorPosition(State, Call.getArgSVal(i))) {
assignToContainer(C, OrigExpr, Call.getReturnValue(),
Pos->getContainer());
return;
}
}
}
}
}
void IteratorChecker::checkBind(SVal Loc, SVal Val, const Stmt *S,
CheckerContext &C) const {
auto State = C.getState();
const auto *Pos = getIteratorPosition(State, Val);
if (Pos) {
State = setIteratorPosition(State, Loc, *Pos);
C.addTransition(State);
} else {
const auto *OldPos = getIteratorPosition(State, Loc);
if (OldPos) {
State = removeIteratorPosition(State, Loc);
C.addTransition(State);
}
}
}
void IteratorChecker::checkPostStmt(const MaterializeTemporaryExpr *MTE,
CheckerContext &C) const {
/* Transfer iterator state to temporary objects */
auto State = C.getState();
const auto *Pos =
getIteratorPosition(State, C.getSVal(MTE->GetTemporaryExpr()));
if (!Pos)
return;
State = setIteratorPosition(State, C.getSVal(MTE), *Pos);
C.addTransition(State);
}
void IteratorChecker::checkLiveSymbols(ProgramStateRef State,
SymbolReaper &SR) const {
// Keep symbolic expressions of iterator positions, container begins and ends
// alive
auto RegionMap = State->get<IteratorRegionMap>();
for (const auto Reg : RegionMap) {
const auto Offset = Reg.second.getOffset();
for (auto i = Offset->symbol_begin(); i != Offset->symbol_end(); ++i)
if (isa<SymbolData>(*i))
SR.markLive(*i);
}
auto SymbolMap = State->get<IteratorSymbolMap>();
for (const auto Sym : SymbolMap) {
const auto Offset = Sym.second.getOffset();
for (auto i = Offset->symbol_begin(); i != Offset->symbol_end(); ++i)
if (isa<SymbolData>(*i))
SR.markLive(*i);
}
auto ContMap = State->get<ContainerMap>();
for (const auto Cont : ContMap) {
const auto CData = Cont.second;
if (CData.getBegin()) {
SR.markLive(CData.getBegin());
if(const auto *SIE = dyn_cast<SymIntExpr>(CData.getBegin()))
SR.markLive(SIE->getLHS());
}
if (CData.getEnd()) {
SR.markLive(CData.getEnd());
if(const auto *SIE = dyn_cast<SymIntExpr>(CData.getEnd()))
SR.markLive(SIE->getLHS());
}
}
}
void IteratorChecker::checkDeadSymbols(SymbolReaper &SR,
CheckerContext &C) const {
// Cleanup
auto State = C.getState();
auto RegionMap = State->get<IteratorRegionMap>();
for (const auto Reg : RegionMap) {
if (!SR.isLiveRegion(Reg.first)) {
// The region behind the `LazyCompoundVal` is often cleaned up before
// the `LazyCompoundVal` itself. If there are iterator positions keyed
// by these regions their cleanup must be deferred.
if (!isBoundThroughLazyCompoundVal(State->getEnvironment(), Reg.first)) {
State = State->remove<IteratorRegionMap>(Reg.first);
}
}
}
auto SymbolMap = State->get<IteratorSymbolMap>();
for (const auto Sym : SymbolMap) {
if (!SR.isLive(Sym.first)) {
State = State->remove<IteratorSymbolMap>(Sym.first);
}
}
auto ContMap = State->get<ContainerMap>();
for (const auto Cont : ContMap) {
if (!SR.isLiveRegion(Cont.first)) {
// We must keep the container data while it has live iterators to be able
// to compare them to the begin and the end of the container.
if (!hasLiveIterators(State, Cont.first)) {
State = State->remove<ContainerMap>(Cont.first);
}
}
}
auto ComparisonMap = State->get<IteratorComparisonMap>();
for (const auto Comp : ComparisonMap) {
if (!SR.isLive(Comp.first)) {
State = State->remove<IteratorComparisonMap>(Comp.first);
}
}
C.addTransition(State);
}
ProgramStateRef IteratorChecker::evalAssume(ProgramStateRef State, SVal Cond,
bool Assumption) const {
// Load recorded comparison and transfer iterator state between sides
// according to comparison operator and assumption
const auto *SE = Cond.getAsSymExpr();
if (!SE)
return State;
auto Opc = getOpcode(SE);
if (Opc != BO_EQ && Opc != BO_NE)
return State;
bool Negated = false;
const auto *Comp = loadComparison(State, SE);
if (!Comp) {
// Try negated comparison, which is a SymExpr to 0 integer comparison
const auto *SIE = dyn_cast<SymIntExpr>(SE);
if (!SIE)
return State;
if (SIE->getRHS() != 0)
return State;
SE = SIE->getLHS();
Negated = SIE->getOpcode() == BO_EQ; // Equal to zero means negation
Opc = getOpcode(SE);
if (Opc != BO_EQ && Opc != BO_NE)
return State;
Comp = loadComparison(State, SE);
if (!Comp)
return State;
}
return processComparison(State, Comp->getLeft(), Comp->getRight(),
(Comp->isEquality() == Assumption) != Negated);
}
void IteratorChecker::handleComparison(CheckerContext &C, const SVal &RetVal,
const SVal &LVal, const SVal &RVal,
OverloadedOperatorKind Op) const {
// Record the operands and the operator of the comparison for the next
// evalAssume, if the result is a symbolic expression. If it is a concrete
// value (only one branch is possible), then transfer the state between
// the operands according to the operator and the result
auto State = C.getState();
if (const auto *Condition = RetVal.getAsSymbolicExpression()) {
const auto *LPos = getIteratorPosition(State, LVal);
const auto *RPos = getIteratorPosition(State, RVal);
if (!LPos && !RPos)
return;
State = saveComparison(State, Condition, LVal, RVal, Op == OO_EqualEqual);
C.addTransition(State);
} else if (const auto TruthVal = RetVal.getAs<nonloc::ConcreteInt>()) {
if ((State = processComparison(
State, getRegionOrSymbol(LVal), getRegionOrSymbol(RVal),
(Op == OO_EqualEqual) == (TruthVal->getValue() != 0)))) {
C.addTransition(State);
} else {
C.generateSink(State, C.getPredecessor());
}
}
}
void IteratorChecker::verifyDereference(CheckerContext &C,
const SVal &Val) const {
auto State = C.getState();
const auto *Pos = getIteratorPosition(State, Val);
if (Pos && isPastTheEnd(State, *Pos)) {
auto *N = C.generateNonFatalErrorNode(State);
if (!N)
return;
reportOutOfRangeBug("Past-the-end iterator dereferenced.", Val, C, N);
return;
}
}
void IteratorChecker::verifyAccess(CheckerContext &C, const SVal &Val) const {
auto State = C.getState();
const auto *Pos = getIteratorPosition(State, Val);
if (Pos && !Pos->isValid()) {
auto *N = C.generateNonFatalErrorNode(State);
if (!N) {
return;
}
reportInvalidatedBug("Invalidated iterator accessed.", Val, C, N);
}
}
void IteratorChecker::handleIncrement(CheckerContext &C, const SVal &RetVal,
const SVal &Iter, bool Postfix) const {
// Increment the symbolic expressions which represents the position of the
// iterator
auto State = C.getState();
const auto *Pos = getIteratorPosition(State, Iter);
if (Pos) {
auto &SymMgr = C.getSymbolManager();
auto &BVF = SymMgr.getBasicVals();
const auto NewPos =
advancePosition(C, OO_Plus, *Pos,
nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))));
State = setIteratorPosition(State, Iter, NewPos);
State = setIteratorPosition(State, RetVal, Postfix ? *Pos : NewPos);
C.addTransition(State);
}
}
void IteratorChecker::handleDecrement(CheckerContext &C, const SVal &RetVal,
const SVal &Iter, bool Postfix) const {
// Decrement the symbolic expressions which represents the position of the
// iterator
auto State = C.getState();
const auto *Pos = getIteratorPosition(State, Iter);
if (Pos) {
auto &SymMgr = C.getSymbolManager();
auto &BVF = SymMgr.getBasicVals();
const auto NewPos =
advancePosition(C, OO_Minus, *Pos,
nonloc::ConcreteInt(BVF.getValue(llvm::APSInt::get(1))));
State = setIteratorPosition(State, Iter, NewPos);
State = setIteratorPosition(State, RetVal, Postfix ? *Pos : NewPos);
C.addTransition(State);
}
}
// This function tells the analyzer's engine that symbols produced by our
// checker, most notably iterator positions, are relatively small.
// A distance between items in the container should not be very large.
// By assuming that it is within around 1/8 of the address space,
// we can help the analyzer perform operations on these symbols
// without being afraid of integer overflows.
// FIXME: Should we provide it as an API, so that all checkers could use it?
static ProgramStateRef assumeNoOverflow(ProgramStateRef State, SymbolRef Sym,
long Scale) {
SValBuilder &SVB = State->getStateManager().getSValBuilder();
BasicValueFactory &BV = SVB.getBasicValueFactory();
QualType T = Sym->getType();
assert(T->isSignedIntegerOrEnumerationType());
APSIntType AT = BV.getAPSIntType(T);
ProgramStateRef NewState = State;
llvm::APSInt Max = AT.getMaxValue() / AT.getValue(Scale);
SVal IsCappedFromAbove =
SVB.evalBinOpNN(State, BO_LE, nonloc::SymbolVal(Sym),
nonloc::ConcreteInt(Max), SVB.getConditionType());
if (auto DV = IsCappedFromAbove.getAs<DefinedSVal>()) {
NewState = NewState->assume(*DV, true);