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llvm-project/clang/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp

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//== BasicObjCFoundationChecks.cpp - Simple Apple-Foundation checks -*- C++ -*--
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines BasicObjCFoundationChecks, a class that encapsulates
// a set of simple checks to run on Objective-C code using Apple's Foundation
// classes.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "SelectorExtras.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/StmtObjC.h"
#include "clang/Analysis/DomainSpecific/CocoaConventions.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/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace ento;
namespace {
class APIMisuse : public BugType {
public:
APIMisuse(const CheckerBase *checker, const char *name)
: BugType(checker, name, "API Misuse (Apple)") {}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// Utility functions.
//===----------------------------------------------------------------------===//
static StringRef GetReceiverInterfaceName(const ObjCMethodCall &msg) {
if (const ObjCInterfaceDecl *ID = msg.getReceiverInterface())
return ID->getIdentifier()->getName();
return StringRef();
}
enum FoundationClass {
FC_None,
FC_NSArray,
FC_NSDictionary,
FC_NSEnumerator,
FC_NSNull,
FC_NSOrderedSet,
FC_NSSet,
FC_NSString
};
static FoundationClass findKnownClass(const ObjCInterfaceDecl *ID,
bool IncludeSuperclasses = true) {
static llvm::StringMap<FoundationClass> Classes;
if (Classes.empty()) {
Classes["NSArray"] = FC_NSArray;
Classes["NSDictionary"] = FC_NSDictionary;
Classes["NSEnumerator"] = FC_NSEnumerator;
Classes["NSNull"] = FC_NSNull;
Classes["NSOrderedSet"] = FC_NSOrderedSet;
Classes["NSSet"] = FC_NSSet;
Classes["NSString"] = FC_NSString;
}
// FIXME: Should we cache this at all?
FoundationClass result = Classes.lookup(ID->getIdentifier()->getName());
if (result == FC_None && IncludeSuperclasses)
if (const ObjCInterfaceDecl *Super = ID->getSuperClass())
return findKnownClass(Super);
return result;
}
//===----------------------------------------------------------------------===//
// NilArgChecker - Check for prohibited nil arguments to ObjC method calls.
//===----------------------------------------------------------------------===//
namespace {
class NilArgChecker : public Checker<check::PreObjCMessage,
check::PostStmt<ObjCDictionaryLiteral>,
check::PostStmt<ObjCArrayLiteral> > {
mutable std::unique_ptr<APIMisuse> BT;
mutable llvm::SmallDenseMap<Selector, unsigned, 16> StringSelectors;
mutable Selector ArrayWithObjectSel;
mutable Selector AddObjectSel;
mutable Selector InsertObjectAtIndexSel;
mutable Selector ReplaceObjectAtIndexWithObjectSel;
mutable Selector SetObjectAtIndexedSubscriptSel;
mutable Selector ArrayByAddingObjectSel;
mutable Selector DictionaryWithObjectForKeySel;
mutable Selector SetObjectForKeySel;
mutable Selector SetObjectForKeyedSubscriptSel;
mutable Selector RemoveObjectForKeySel;
void warnIfNilExpr(const Expr *E,
const char *Msg,
CheckerContext &C) const;
void warnIfNilArg(CheckerContext &C,
const ObjCMethodCall &msg, unsigned Arg,
FoundationClass Class,
bool CanBeSubscript = false) const;
void generateBugReport(ExplodedNode *N,
StringRef Msg,
SourceRange Range,
const Expr *Expr,
CheckerContext &C) const;
public:
void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
void checkPostStmt(const ObjCDictionaryLiteral *DL,
CheckerContext &C) const;
void checkPostStmt(const ObjCArrayLiteral *AL,
CheckerContext &C) const;
};
} // end anonymous namespace
void NilArgChecker::warnIfNilExpr(const Expr *E,
const char *Msg,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
if (State->isNull(C.getSVal(E)).isConstrainedTrue()) {
if (ExplodedNode *N = C.generateErrorNode()) {
generateBugReport(N, Msg, E->getSourceRange(), E, C);
}
}
}
void NilArgChecker::warnIfNilArg(CheckerContext &C,
const ObjCMethodCall &msg,
unsigned int Arg,
FoundationClass Class,
bool CanBeSubscript) const {
// Check if the argument is nil.
ProgramStateRef State = C.getState();
if (!State->isNull(msg.getArgSVal(Arg)).isConstrainedTrue())
return;
if (ExplodedNode *N = C.generateErrorNode()) {
SmallString<128> sbuf;
llvm::raw_svector_ostream os(sbuf);
if (CanBeSubscript && msg.getMessageKind() == OCM_Subscript) {
if (Class == FC_NSArray) {
os << "Array element cannot be nil";
} else if (Class == FC_NSDictionary) {
if (Arg == 0) {
os << "Value stored into '";
os << GetReceiverInterfaceName(msg) << "' cannot be nil";
} else {
assert(Arg == 1);
os << "'"<< GetReceiverInterfaceName(msg) << "' key cannot be nil";
}
} else
llvm_unreachable("Missing foundation class for the subscript expr");
} else {
if (Class == FC_NSDictionary) {
if (Arg == 0)
os << "Value argument ";
else {
assert(Arg == 1);
os << "Key argument ";
}
os << "to '";
msg.getSelector().print(os);
os << "' cannot be nil";
} else {
os << "Argument to '" << GetReceiverInterfaceName(msg) << "' method '";
msg.getSelector().print(os);
os << "' cannot be nil";
}
}
generateBugReport(N, os.str(), msg.getArgSourceRange(Arg),
msg.getArgExpr(Arg), C);
}
}
void NilArgChecker::generateBugReport(ExplodedNode *N,
StringRef Msg,
SourceRange Range,
const Expr *E,
CheckerContext &C) const {
if (!BT)
BT.reset(new APIMisuse(this, "nil argument"));
auto R = llvm::make_unique<BugReport>(*BT, Msg, N);
R->addRange(Range);
bugreporter::trackNullOrUndefValue(N, E, *R);
C.emitReport(std::move(R));
}
void NilArgChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
CheckerContext &C) const {
const ObjCInterfaceDecl *ID = msg.getReceiverInterface();
if (!ID)
return;
FoundationClass Class = findKnownClass(ID);
static const unsigned InvalidArgIndex = UINT_MAX;
unsigned Arg = InvalidArgIndex;
bool CanBeSubscript = false;
if (Class == FC_NSString) {
Selector S = msg.getSelector();
if (S.isUnarySelector())
return;
if (StringSelectors.empty()) {
ASTContext &Ctx = C.getASTContext();
Selector Sels[] = {
getKeywordSelector(Ctx, "caseInsensitiveCompare", nullptr),
getKeywordSelector(Ctx, "compare", nullptr),
getKeywordSelector(Ctx, "compare", "options", nullptr),
getKeywordSelector(Ctx, "compare", "options", "range", nullptr),
getKeywordSelector(Ctx, "compare", "options", "range", "locale",
nullptr),
getKeywordSelector(Ctx, "componentsSeparatedByCharactersInSet",
nullptr),
getKeywordSelector(Ctx, "initWithFormat",
nullptr),
getKeywordSelector(Ctx, "localizedCaseInsensitiveCompare", nullptr),
getKeywordSelector(Ctx, "localizedCompare", nullptr),
getKeywordSelector(Ctx, "localizedStandardCompare", nullptr),
};
for (Selector KnownSel : Sels)
StringSelectors[KnownSel] = 0;
}
auto I = StringSelectors.find(S);
if (I == StringSelectors.end())
return;
Arg = I->second;
} else if (Class == FC_NSArray) {
Selector S = msg.getSelector();
if (S.isUnarySelector())
return;
if (ArrayWithObjectSel.isNull()) {
ASTContext &Ctx = C.getASTContext();
ArrayWithObjectSel = getKeywordSelector(Ctx, "arrayWithObject", nullptr);
AddObjectSel = getKeywordSelector(Ctx, "addObject", nullptr);
InsertObjectAtIndexSel =
getKeywordSelector(Ctx, "insertObject", "atIndex", nullptr);
ReplaceObjectAtIndexWithObjectSel =
getKeywordSelector(Ctx, "replaceObjectAtIndex", "withObject", nullptr);
SetObjectAtIndexedSubscriptSel =
getKeywordSelector(Ctx, "setObject", "atIndexedSubscript", nullptr);
ArrayByAddingObjectSel =
getKeywordSelector(Ctx, "arrayByAddingObject", nullptr);
}
if (S == ArrayWithObjectSel || S == AddObjectSel ||
S == InsertObjectAtIndexSel || S == ArrayByAddingObjectSel) {
Arg = 0;
} else if (S == SetObjectAtIndexedSubscriptSel) {
Arg = 0;
CanBeSubscript = true;
} else if (S == ReplaceObjectAtIndexWithObjectSel) {
Arg = 1;
}
} else if (Class == FC_NSDictionary) {
Selector S = msg.getSelector();
if (S.isUnarySelector())
return;
if (DictionaryWithObjectForKeySel.isNull()) {
ASTContext &Ctx = C.getASTContext();
DictionaryWithObjectForKeySel =
getKeywordSelector(Ctx, "dictionaryWithObject", "forKey", nullptr);
SetObjectForKeySel =
getKeywordSelector(Ctx, "setObject", "forKey", nullptr);
SetObjectForKeyedSubscriptSel =
getKeywordSelector(Ctx, "setObject", "forKeyedSubscript", nullptr);
RemoveObjectForKeySel =
getKeywordSelector(Ctx, "removeObjectForKey", nullptr);
}
if (S == DictionaryWithObjectForKeySel || S == SetObjectForKeySel) {
Arg = 0;
warnIfNilArg(C, msg, /* Arg */1, Class);
} else if (S == SetObjectForKeyedSubscriptSel) {
CanBeSubscript = true;
Arg = 1;
} else if (S == RemoveObjectForKeySel) {
Arg = 0;
}
}
// If argument is '0', report a warning.
if ((Arg != InvalidArgIndex))
warnIfNilArg(C, msg, Arg, Class, CanBeSubscript);
}
void NilArgChecker::checkPostStmt(const ObjCArrayLiteral *AL,
CheckerContext &C) const {
unsigned NumOfElements = AL->getNumElements();
for (unsigned i = 0; i < NumOfElements; ++i) {
warnIfNilExpr(AL->getElement(i), "Array element cannot be nil", C);
}
}
void NilArgChecker::checkPostStmt(const ObjCDictionaryLiteral *DL,
CheckerContext &C) const {
unsigned NumOfElements = DL->getNumElements();
for (unsigned i = 0; i < NumOfElements; ++i) {
ObjCDictionaryElement Element = DL->getKeyValueElement(i);
warnIfNilExpr(Element.Key, "Dictionary key cannot be nil", C);
warnIfNilExpr(Element.Value, "Dictionary value cannot be nil", C);
}
}
//===----------------------------------------------------------------------===//
// Checking for mismatched types passed to CFNumberCreate/CFNumberGetValue.
//===----------------------------------------------------------------------===//
namespace {
class CFNumberChecker : public Checker< check::PreStmt<CallExpr> > {
mutable std::unique_ptr<APIMisuse> BT;
mutable IdentifierInfo *ICreate, *IGetValue;
public:
CFNumberChecker() : ICreate(nullptr), IGetValue(nullptr) {}
void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
private:
void EmitError(const TypedRegion* R, const Expr *Ex,
uint64_t SourceSize, uint64_t TargetSize, uint64_t NumberKind);
};
} // end anonymous namespace
enum CFNumberType {
kCFNumberSInt8Type = 1,
kCFNumberSInt16Type = 2,
kCFNumberSInt32Type = 3,
kCFNumberSInt64Type = 4,
kCFNumberFloat32Type = 5,
kCFNumberFloat64Type = 6,
kCFNumberCharType = 7,
kCFNumberShortType = 8,
kCFNumberIntType = 9,
kCFNumberLongType = 10,
kCFNumberLongLongType = 11,
kCFNumberFloatType = 12,
kCFNumberDoubleType = 13,
kCFNumberCFIndexType = 14,
kCFNumberNSIntegerType = 15,
kCFNumberCGFloatType = 16
};
static Optional<uint64_t> GetCFNumberSize(ASTContext &Ctx, uint64_t i) {
static const unsigned char FixedSize[] = { 8, 16, 32, 64, 32, 64 };
if (i < kCFNumberCharType)
return FixedSize[i-1];
QualType T;
switch (i) {
case kCFNumberCharType: T = Ctx.CharTy; break;
case kCFNumberShortType: T = Ctx.ShortTy; break;
case kCFNumberIntType: T = Ctx.IntTy; break;
case kCFNumberLongType: T = Ctx.LongTy; break;
case kCFNumberLongLongType: T = Ctx.LongLongTy; break;
case kCFNumberFloatType: T = Ctx.FloatTy; break;
case kCFNumberDoubleType: T = Ctx.DoubleTy; break;
case kCFNumberCFIndexType:
case kCFNumberNSIntegerType:
case kCFNumberCGFloatType:
// FIXME: We need a way to map from names to Type*.
default:
return None;
}
return Ctx.getTypeSize(T);
}
#if 0
static const char* GetCFNumberTypeStr(uint64_t i) {
static const char* Names[] = {
"kCFNumberSInt8Type",
"kCFNumberSInt16Type",
"kCFNumberSInt32Type",
"kCFNumberSInt64Type",
"kCFNumberFloat32Type",
"kCFNumberFloat64Type",
"kCFNumberCharType",
"kCFNumberShortType",
"kCFNumberIntType",
"kCFNumberLongType",
"kCFNumberLongLongType",
"kCFNumberFloatType",
"kCFNumberDoubleType",
"kCFNumberCFIndexType",
"kCFNumberNSIntegerType",
"kCFNumberCGFloatType"
};
return i <= kCFNumberCGFloatType ? Names[i-1] : "Invalid CFNumberType";
}
#endif
void CFNumberChecker::checkPreStmt(const CallExpr *CE,
CheckerContext &C) const {
ProgramStateRef state = C.getState();
const FunctionDecl *FD = C.getCalleeDecl(CE);
if (!FD)
return;
ASTContext &Ctx = C.getASTContext();
if (!ICreate) {
ICreate = &Ctx.Idents.get("CFNumberCreate");
IGetValue = &Ctx.Idents.get("CFNumberGetValue");
}
if (!(FD->getIdentifier() == ICreate || FD->getIdentifier() == IGetValue) ||
CE->getNumArgs() != 3)
return;
// Get the value of the "theType" argument.
const LocationContext *LCtx = C.getLocationContext();
SVal TheTypeVal = state->getSVal(CE->getArg(1), LCtx);
// FIXME: We really should allow ranges of valid theType values, and
// bifurcate the state appropriately.
Optional<nonloc::ConcreteInt> V = TheTypeVal.getAs<nonloc::ConcreteInt>();
if (!V)
return;
uint64_t NumberKind = V->getValue().getLimitedValue();
Optional<uint64_t> OptCFNumberSize = GetCFNumberSize(Ctx, NumberKind);
// FIXME: In some cases we can emit an error.
if (!OptCFNumberSize)
return;
uint64_t CFNumberSize = *OptCFNumberSize;
// Look at the value of the integer being passed by reference. Essentially
// we want to catch cases where the value passed in is not equal to the
// size of the type being created.
SVal TheValueExpr = state->getSVal(CE->getArg(2), LCtx);
// FIXME: Eventually we should handle arbitrary locations. We can do this
// by having an enhanced memory model that does low-level typing.
Optional<loc::MemRegionVal> LV = TheValueExpr.getAs<loc::MemRegionVal>();
if (!LV)
return;
const TypedValueRegion* R = dyn_cast<TypedValueRegion>(LV->stripCasts());
if (!R)
return;
QualType T = Ctx.getCanonicalType(R->getValueType());
// FIXME: If the pointee isn't an integer type, should we flag a warning?
// People can do weird stuff with pointers.
if (!T->isIntegralOrEnumerationType())
return;
uint64_t PrimitiveTypeSize = Ctx.getTypeSize(T);
if (PrimitiveTypeSize == CFNumberSize)
return;
// FIXME: We can actually create an abstract "CFNumber" object that has
// the bits initialized to the provided values.
ExplodedNode *N = C.generateNonFatalErrorNode();
if (N) {
SmallString<128> sbuf;
llvm::raw_svector_ostream os(sbuf);
bool isCreate = (FD->getIdentifier() == ICreate);
if (isCreate) {
os << (PrimitiveTypeSize == 8 ? "An " : "A ")
<< PrimitiveTypeSize << "-bit integer is used to initialize a "
<< "CFNumber object that represents "
<< (CFNumberSize == 8 ? "an " : "a ")
<< CFNumberSize << "-bit integer; ";
} else {
os << "A CFNumber object that represents "
<< (CFNumberSize == 8 ? "an " : "a ")
<< CFNumberSize << "-bit integer is used to initialize "
<< (PrimitiveTypeSize == 8 ? "an " : "a ")
<< PrimitiveTypeSize << "-bit integer; ";
}
if (PrimitiveTypeSize < CFNumberSize)
os << (CFNumberSize - PrimitiveTypeSize)
<< " bits of the CFNumber value will "
<< (isCreate ? "be garbage." : "overwrite adjacent storage.");
else
os << (PrimitiveTypeSize - CFNumberSize)
<< " bits of the integer value will be "
<< (isCreate ? "lost." : "garbage.");
if (!BT)
BT.reset(new APIMisuse(this, "Bad use of CFNumber APIs"));
auto report = llvm::make_unique<BugReport>(*BT, os.str(), N);
report->addRange(CE->getArg(2)->getSourceRange());
C.emitReport(std::move(report));
}
}
//===----------------------------------------------------------------------===//
// CFRetain/CFRelease/CFMakeCollectable/CFAutorelease checking for null arguments.
//===----------------------------------------------------------------------===//
namespace {
class CFRetainReleaseChecker : public Checker< check::PreStmt<CallExpr> > {
mutable std::unique_ptr<APIMisuse> BT;
mutable IdentifierInfo *Retain, *Release, *MakeCollectable, *Autorelease;
public:
CFRetainReleaseChecker()
: Retain(nullptr), Release(nullptr), MakeCollectable(nullptr),
Autorelease(nullptr) {}
void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
};
} // end anonymous namespace
void CFRetainReleaseChecker::checkPreStmt(const CallExpr *CE,
CheckerContext &C) const {
// If the CallExpr doesn't have exactly 1 argument just give up checking.
if (CE->getNumArgs() != 1)
return;
ProgramStateRef state = C.getState();
const FunctionDecl *FD = C.getCalleeDecl(CE);
if (!FD)
return;
if (!BT) {
ASTContext &Ctx = C.getASTContext();
Retain = &Ctx.Idents.get("CFRetain");
Release = &Ctx.Idents.get("CFRelease");
MakeCollectable = &Ctx.Idents.get("CFMakeCollectable");
Autorelease = &Ctx.Idents.get("CFAutorelease");
BT.reset(new APIMisuse(
this, "null passed to CF memory management function"));
}
// Check if we called CFRetain/CFRelease/CFMakeCollectable/CFAutorelease.
const IdentifierInfo *FuncII = FD->getIdentifier();
if (!(FuncII == Retain || FuncII == Release || FuncII == MakeCollectable ||
FuncII == Autorelease))
return;
// FIXME: The rest of this just checks that the argument is non-null.
// It should probably be refactored and combined with NonNullParamChecker.
// Get the argument's value.
const Expr *Arg = CE->getArg(0);
SVal ArgVal = state->getSVal(Arg, C.getLocationContext());
Optional<DefinedSVal> DefArgVal = ArgVal.getAs<DefinedSVal>();
if (!DefArgVal)
return;
// Get a NULL value.
SValBuilder &svalBuilder = C.getSValBuilder();
DefinedSVal zero =
svalBuilder.makeZeroVal(Arg->getType()).castAs<DefinedSVal>();
// Make an expression asserting that they're equal.
DefinedOrUnknownSVal ArgIsNull = svalBuilder.evalEQ(state, zero, *DefArgVal);
// Are they equal?
ProgramStateRef stateTrue, stateFalse;
std::tie(stateTrue, stateFalse) = state->assume(ArgIsNull);
if (stateTrue && !stateFalse) {
ExplodedNode *N = C.generateErrorNode(stateTrue);
if (!N)
return;
const char *description;
if (FuncII == Retain)
description = "Null pointer argument in call to CFRetain";
else if (FuncII == Release)
description = "Null pointer argument in call to CFRelease";
else if (FuncII == MakeCollectable)
description = "Null pointer argument in call to CFMakeCollectable";
else if (FuncII == Autorelease)
description = "Null pointer argument in call to CFAutorelease";
else
llvm_unreachable("impossible case");
auto report = llvm::make_unique<BugReport>(*BT, description, N);
report->addRange(Arg->getSourceRange());
bugreporter::trackNullOrUndefValue(N, Arg, *report);
C.emitReport(std::move(report));
return;
}
// From here on, we know the argument is non-null.
C.addTransition(stateFalse);
}
//===----------------------------------------------------------------------===//
// Check for sending 'retain', 'release', or 'autorelease' directly to a Class.
//===----------------------------------------------------------------------===//
namespace {
class ClassReleaseChecker : public Checker<check::PreObjCMessage> {
mutable Selector releaseS;
mutable Selector retainS;
mutable Selector autoreleaseS;
mutable Selector drainS;
mutable std::unique_ptr<BugType> BT;
public:
void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
};
} // end anonymous namespace
void ClassReleaseChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
CheckerContext &C) const {
if (!BT) {
BT.reset(new APIMisuse(
this, "message incorrectly sent to class instead of class instance"));
ASTContext &Ctx = C.getASTContext();
releaseS = GetNullarySelector("release", Ctx);
retainS = GetNullarySelector("retain", Ctx);
autoreleaseS = GetNullarySelector("autorelease", Ctx);
drainS = GetNullarySelector("drain", Ctx);
}
if (msg.isInstanceMessage())
return;
const ObjCInterfaceDecl *Class = msg.getReceiverInterface();
assert(Class);
Selector S = msg.getSelector();
if (!(S == releaseS || S == retainS || S == autoreleaseS || S == drainS))
return;
if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
SmallString<200> buf;
llvm::raw_svector_ostream os(buf);
os << "The '";
S.print(os);
os << "' message should be sent to instances "
"of class '" << Class->getName()
<< "' and not the class directly";
auto report = llvm::make_unique<BugReport>(*BT, os.str(), N);
report->addRange(msg.getSourceRange());
C.emitReport(std::move(report));
}
}
//===----------------------------------------------------------------------===//
// Check for passing non-Objective-C types to variadic methods that expect
// only Objective-C types.
//===----------------------------------------------------------------------===//
namespace {
class VariadicMethodTypeChecker : public Checker<check::PreObjCMessage> {
mutable Selector arrayWithObjectsS;
mutable Selector dictionaryWithObjectsAndKeysS;
mutable Selector setWithObjectsS;
mutable Selector orderedSetWithObjectsS;
mutable Selector initWithObjectsS;
mutable Selector initWithObjectsAndKeysS;
mutable std::unique_ptr<BugType> BT;
bool isVariadicMessage(const ObjCMethodCall &msg) const;
public:
void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
};
} // end anonymous namespace
/// isVariadicMessage - Returns whether the given message is a variadic message,
/// where all arguments must be Objective-C types.
bool
VariadicMethodTypeChecker::isVariadicMessage(const ObjCMethodCall &msg) const {
const ObjCMethodDecl *MD = msg.getDecl();
if (!MD || !MD->isVariadic() || isa<ObjCProtocolDecl>(MD->getDeclContext()))
return false;
Selector S = msg.getSelector();
if (msg.isInstanceMessage()) {
// FIXME: Ideally we'd look at the receiver interface here, but that's not
// useful for init, because alloc returns 'id'. In theory, this could lead
// to false positives, for example if there existed a class that had an
// initWithObjects: implementation that does accept non-Objective-C pointer
// types, but the chance of that happening is pretty small compared to the
// gains that this analysis gives.
const ObjCInterfaceDecl *Class = MD->getClassInterface();
switch (findKnownClass(Class)) {
case FC_NSArray:
case FC_NSOrderedSet:
case FC_NSSet:
return S == initWithObjectsS;
case FC_NSDictionary:
return S == initWithObjectsAndKeysS;
default:
return false;
}
} else {
const ObjCInterfaceDecl *Class = msg.getReceiverInterface();
switch (findKnownClass(Class)) {
case FC_NSArray:
return S == arrayWithObjectsS;
case FC_NSOrderedSet:
return S == orderedSetWithObjectsS;
case FC_NSSet:
return S == setWithObjectsS;
case FC_NSDictionary:
return S == dictionaryWithObjectsAndKeysS;
default:
return false;
}
}
}
void VariadicMethodTypeChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
CheckerContext &C) const {
if (!BT) {
BT.reset(new APIMisuse(this,
"Arguments passed to variadic method aren't all "
"Objective-C pointer types"));
ASTContext &Ctx = C.getASTContext();
arrayWithObjectsS = GetUnarySelector("arrayWithObjects", Ctx);
dictionaryWithObjectsAndKeysS =
GetUnarySelector("dictionaryWithObjectsAndKeys", Ctx);
setWithObjectsS = GetUnarySelector("setWithObjects", Ctx);
orderedSetWithObjectsS = GetUnarySelector("orderedSetWithObjects", Ctx);
initWithObjectsS = GetUnarySelector("initWithObjects", Ctx);
initWithObjectsAndKeysS = GetUnarySelector("initWithObjectsAndKeys", Ctx);
}
if (!isVariadicMessage(msg))
return;
// We are not interested in the selector arguments since they have
// well-defined types, so the compiler will issue a warning for them.
unsigned variadicArgsBegin = msg.getSelector().getNumArgs();
// We're not interested in the last argument since it has to be nil or the
// compiler would have issued a warning for it elsewhere.
unsigned variadicArgsEnd = msg.getNumArgs() - 1;
if (variadicArgsEnd <= variadicArgsBegin)
return;
// Verify that all arguments have Objective-C types.
Optional<ExplodedNode*> errorNode;
for (unsigned I = variadicArgsBegin; I != variadicArgsEnd; ++I) {
QualType ArgTy = msg.getArgExpr(I)->getType();
if (ArgTy->isObjCObjectPointerType())
continue;
// Block pointers are treaded as Objective-C pointers.
if (ArgTy->isBlockPointerType())
continue;
// Ignore pointer constants.
if (msg.getArgSVal(I).getAs<loc::ConcreteInt>())
continue;
// Ignore pointer types annotated with 'NSObject' attribute.
if (C.getASTContext().isObjCNSObjectType(ArgTy))
continue;
// Ignore CF references, which can be toll-free bridged.
if (coreFoundation::isCFObjectRef(ArgTy))
continue;
// Generate only one error node to use for all bug reports.
if (!errorNode.hasValue())
errorNode = C.generateNonFatalErrorNode();
if (!errorNode.getValue())
continue;
SmallString<128> sbuf;
llvm::raw_svector_ostream os(sbuf);
StringRef TypeName = GetReceiverInterfaceName(msg);
if (!TypeName.empty())
os << "Argument to '" << TypeName << "' method '";
else
os << "Argument to method '";
msg.getSelector().print(os);
os << "' should be an Objective-C pointer type, not '";
ArgTy.print(os, C.getLangOpts());
os << "'";
auto R = llvm::make_unique<BugReport>(*BT, os.str(), errorNode.getValue());
R->addRange(msg.getArgSourceRange(I));
C.emitReport(std::move(R));
}
}
//===----------------------------------------------------------------------===//
// Improves the modeling of loops over Cocoa collections.
//===----------------------------------------------------------------------===//
// The map from container symbol to the container count symbol.
// We currently will remember the last countainer count symbol encountered.
REGISTER_MAP_WITH_PROGRAMSTATE(ContainerCountMap, SymbolRef, SymbolRef)
REGISTER_MAP_WITH_PROGRAMSTATE(ContainerNonEmptyMap, SymbolRef, bool)
namespace {
class ObjCLoopChecker
: public Checker<check::PostStmt<ObjCForCollectionStmt>,
check::PostObjCMessage,
check::DeadSymbols,
check::PointerEscape > {
mutable IdentifierInfo *CountSelectorII;
bool isCollectionCountMethod(const ObjCMethodCall &M,
CheckerContext &C) const;
public:
ObjCLoopChecker() : CountSelectorII(nullptr) {}
void checkPostStmt(const ObjCForCollectionStmt *FCS, CheckerContext &C) const;
void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
ProgramStateRef checkPointerEscape(ProgramStateRef State,
const InvalidatedSymbols &Escaped,
const CallEvent *Call,
PointerEscapeKind Kind) const;
};
} // end anonymous namespace
static bool isKnownNonNilCollectionType(QualType T) {
const ObjCObjectPointerType *PT = T->getAs<ObjCObjectPointerType>();
if (!PT)
return false;
const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
if (!ID)
return false;
switch (findKnownClass(ID)) {
case FC_NSArray:
case FC_NSDictionary:
case FC_NSEnumerator:
case FC_NSOrderedSet:
case FC_NSSet:
return true;
default:
return false;
}
}
/// Assumes that the collection is non-nil.
///
/// If the collection is known to be nil, returns NULL to indicate an infeasible
/// path.
static ProgramStateRef checkCollectionNonNil(CheckerContext &C,
ProgramStateRef State,
const ObjCForCollectionStmt *FCS) {
if (!State)
return nullptr;
SVal CollectionVal = C.getSVal(FCS->getCollection());
Optional<DefinedSVal> KnownCollection = CollectionVal.getAs<DefinedSVal>();
if (!KnownCollection)
return State;
ProgramStateRef StNonNil, StNil;
std::tie(StNonNil, StNil) = State->assume(*KnownCollection);
if (StNil && !StNonNil) {
// The collection is nil. This path is infeasible.
return nullptr;
}
return StNonNil;
}
/// Assumes that the collection elements are non-nil.
///
/// This only applies if the collection is one of those known not to contain
/// nil values.
static ProgramStateRef checkElementNonNil(CheckerContext &C,
ProgramStateRef State,
const ObjCForCollectionStmt *FCS) {
if (!State)
return nullptr;
// See if the collection is one where we /know/ the elements are non-nil.
if (!isKnownNonNilCollectionType(FCS->getCollection()->getType()))
return State;
const LocationContext *LCtx = C.getLocationContext();
const Stmt *Element = FCS->getElement();
// FIXME: Copied from ExprEngineObjC.
Optional<Loc> ElementLoc;
if (const DeclStmt *DS = dyn_cast<DeclStmt>(Element)) {
const VarDecl *ElemDecl = cast<VarDecl>(DS->getSingleDecl());
assert(ElemDecl->getInit() == nullptr);
ElementLoc = State->getLValue(ElemDecl, LCtx);
} else {
ElementLoc = State->getSVal(Element, LCtx).getAs<Loc>();
}
if (!ElementLoc)
return State;
// Go ahead and assume the value is non-nil.
SVal Val = State->getSVal(*ElementLoc);
return State->assume(Val.castAs<DefinedOrUnknownSVal>(), true);
}
/// Returns NULL state if the collection is known to contain elements
/// (or is known not to contain elements if the Assumption parameter is false.)
static ProgramStateRef
assumeCollectionNonEmpty(CheckerContext &C, ProgramStateRef State,
SymbolRef CollectionS, bool Assumption) {
if (!State || !CollectionS)
return State;
const SymbolRef *CountS = State->get<ContainerCountMap>(CollectionS);
if (!CountS) {
const bool *KnownNonEmpty = State->get<ContainerNonEmptyMap>(CollectionS);
if (!KnownNonEmpty)
return State->set<ContainerNonEmptyMap>(CollectionS, Assumption);
return (Assumption == *KnownNonEmpty) ? State : nullptr;
}
SValBuilder &SvalBuilder = C.getSValBuilder();
SVal CountGreaterThanZeroVal =
SvalBuilder.evalBinOp(State, BO_GT,
nonloc::SymbolVal(*CountS),
SvalBuilder.makeIntVal(0, (*CountS)->getType()),
SvalBuilder.getConditionType());
Optional<DefinedSVal> CountGreaterThanZero =
CountGreaterThanZeroVal.getAs<DefinedSVal>();
if (!CountGreaterThanZero) {
// The SValBuilder cannot construct a valid SVal for this condition.
// This means we cannot properly reason about it.
return State;
}
return State->assume(*CountGreaterThanZero, Assumption);
}
static ProgramStateRef
assumeCollectionNonEmpty(CheckerContext &C, ProgramStateRef State,
const ObjCForCollectionStmt *FCS,
bool Assumption) {
if (!State)
return nullptr;
SymbolRef CollectionS =
State->getSVal(FCS->getCollection(), C.getLocationContext()).getAsSymbol();
return assumeCollectionNonEmpty(C, State, CollectionS, Assumption);
}
/// If the fist block edge is a back edge, we are reentering the loop.
static bool alreadyExecutedAtLeastOneLoopIteration(const ExplodedNode *N,
const ObjCForCollectionStmt *FCS) {
if (!N)
return false;
ProgramPoint P = N->getLocation();
if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
return BE->getSrc()->getLoopTarget() == FCS;
}
// Keep looking for a block edge.
for (ExplodedNode::const_pred_iterator I = N->pred_begin(),
E = N->pred_end(); I != E; ++I) {
if (alreadyExecutedAtLeastOneLoopIteration(*I, FCS))
return true;
}
return false;
}
void ObjCLoopChecker::checkPostStmt(const ObjCForCollectionStmt *FCS,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
// Check if this is the branch for the end of the loop.
SVal CollectionSentinel = C.getSVal(FCS);
if (CollectionSentinel.isZeroConstant()) {
if (!alreadyExecutedAtLeastOneLoopIteration(C.getPredecessor(), FCS))
State = assumeCollectionNonEmpty(C, State, FCS, /*Assumption*/false);
// Otherwise, this is a branch that goes through the loop body.
} else {
State = checkCollectionNonNil(C, State, FCS);
State = checkElementNonNil(C, State, FCS);
State = assumeCollectionNonEmpty(C, State, FCS, /*Assumption*/true);
}
if (!State)
C.generateSink(C.getState(), C.getPredecessor());
else if (State != C.getState())
C.addTransition(State);
}
bool ObjCLoopChecker::isCollectionCountMethod(const ObjCMethodCall &M,
CheckerContext &C) const {
Selector S = M.getSelector();
// Initialize the identifiers on first use.
if (!CountSelectorII)
CountSelectorII = &C.getASTContext().Idents.get("count");
// If the method returns collection count, record the value.
return S.isUnarySelector() &&
(S.getIdentifierInfoForSlot(0) == CountSelectorII);
}
void ObjCLoopChecker::checkPostObjCMessage(const ObjCMethodCall &M,
CheckerContext &C) const {
if (!M.isInstanceMessage())
return;
const ObjCInterfaceDecl *ClassID = M.getReceiverInterface();
if (!ClassID)
return;
FoundationClass Class = findKnownClass(ClassID);
if (Class != FC_NSDictionary &&
Class != FC_NSArray &&
Class != FC_NSSet &&
Class != FC_NSOrderedSet)
return;
SymbolRef ContainerS = M.getReceiverSVal().getAsSymbol();
if (!ContainerS)
return;
// If we are processing a call to "count", get the symbolic value returned by
// a call to "count" and add it to the map.
if (!isCollectionCountMethod(M, C))
return;
const Expr *MsgExpr = M.getOriginExpr();
SymbolRef CountS = C.getSVal(MsgExpr).getAsSymbol();
if (CountS) {
ProgramStateRef State = C.getState();
C.getSymbolManager().addSymbolDependency(ContainerS, CountS);
State = State->set<ContainerCountMap>(ContainerS, CountS);
if (const bool *NonEmpty = State->get<ContainerNonEmptyMap>(ContainerS)) {
State = State->remove<ContainerNonEmptyMap>(ContainerS);
State = assumeCollectionNonEmpty(C, State, ContainerS, *NonEmpty);
}
C.addTransition(State);
}
}
static SymbolRef getMethodReceiverIfKnownImmutable(const CallEvent *Call) {
const ObjCMethodCall *Message = dyn_cast_or_null<ObjCMethodCall>(Call);
if (!Message)
return nullptr;
const ObjCMethodDecl *MD = Message->getDecl();
if (!MD)
return nullptr;
const ObjCInterfaceDecl *StaticClass;
if (isa<ObjCProtocolDecl>(MD->getDeclContext())) {
// We can't find out where the method was declared without doing more work.
// Instead, see if the receiver is statically typed as a known immutable
// collection.
StaticClass = Message->getOriginExpr()->getReceiverInterface();
} else {
StaticClass = MD->getClassInterface();
}
if (!StaticClass)
return nullptr;
switch (findKnownClass(StaticClass, /*IncludeSuper=*/false)) {
case FC_None:
return nullptr;
case FC_NSArray:
case FC_NSDictionary:
case FC_NSEnumerator:
case FC_NSNull:
case FC_NSOrderedSet:
case FC_NSSet:
case FC_NSString:
break;
}
return Message->getReceiverSVal().getAsSymbol();
}
ProgramStateRef
ObjCLoopChecker::checkPointerEscape(ProgramStateRef State,
const InvalidatedSymbols &Escaped,
const CallEvent *Call,
PointerEscapeKind Kind) const {
SymbolRef ImmutableReceiver = getMethodReceiverIfKnownImmutable(Call);
// Remove the invalidated symbols form the collection count map.
for (InvalidatedSymbols::const_iterator I = Escaped.begin(),
E = Escaped.end();
I != E; ++I) {
SymbolRef Sym = *I;
// Don't invalidate this symbol's count if we know the method being called
// is declared on an immutable class. This isn't completely correct if the
// receiver is also passed as an argument, but in most uses of NSArray,
// NSDictionary, etc. this isn't likely to happen in a dangerous way.
if (Sym == ImmutableReceiver)
continue;
// The symbol escaped. Pessimistically, assume that the count could have
// changed.
State = State->remove<ContainerCountMap>(Sym);
State = State->remove<ContainerNonEmptyMap>(Sym);
}
return State;
}
void ObjCLoopChecker::checkDeadSymbols(SymbolReaper &SymReaper,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
// Remove the dead symbols from the collection count map.
ContainerCountMapTy Tracked = State->get<ContainerCountMap>();
for (ContainerCountMapTy::iterator I = Tracked.begin(),
E = Tracked.end(); I != E; ++I) {
SymbolRef Sym = I->first;
if (SymReaper.isDead(Sym)) {
State = State->remove<ContainerCountMap>(Sym);
State = State->remove<ContainerNonEmptyMap>(Sym);
}
}
C.addTransition(State);
}
namespace {
/// \class ObjCNonNilReturnValueChecker
/// \brief The checker restricts the return values of APIs known to
/// never (or almost never) return 'nil'.
class ObjCNonNilReturnValueChecker
: public Checker<check::PostObjCMessage,
check::PostStmt<ObjCArrayLiteral>,
check::PostStmt<ObjCDictionaryLiteral>,
check::PostStmt<ObjCBoxedExpr> > {
mutable bool Initialized;
mutable Selector ObjectAtIndex;
mutable Selector ObjectAtIndexedSubscript;
mutable Selector NullSelector;
public:
ObjCNonNilReturnValueChecker() : Initialized(false) {}
ProgramStateRef assumeExprIsNonNull(const Expr *NonNullExpr,
ProgramStateRef State,
CheckerContext &C) const;
void assumeExprIsNonNull(const Expr *E, CheckerContext &C) const {
C.addTransition(assumeExprIsNonNull(E, C.getState(), C));
}
void checkPostStmt(const ObjCArrayLiteral *E, CheckerContext &C) const {
assumeExprIsNonNull(E, C);
}
void checkPostStmt(const ObjCDictionaryLiteral *E, CheckerContext &C) const {
assumeExprIsNonNull(E, C);
}
void checkPostStmt(const ObjCBoxedExpr *E, CheckerContext &C) const {
assumeExprIsNonNull(E, C);
}
void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
};
} // end anonymous namespace
ProgramStateRef
ObjCNonNilReturnValueChecker::assumeExprIsNonNull(const Expr *NonNullExpr,
ProgramStateRef State,
CheckerContext &C) const {
SVal Val = State->getSVal(NonNullExpr, C.getLocationContext());
if (Optional<DefinedOrUnknownSVal> DV = Val.getAs<DefinedOrUnknownSVal>())
return State->assume(*DV, true);
return State;
}
void ObjCNonNilReturnValueChecker::checkPostObjCMessage(const ObjCMethodCall &M,
CheckerContext &C)
const {
ProgramStateRef State = C.getState();
if (!Initialized) {
ASTContext &Ctx = C.getASTContext();
ObjectAtIndex = GetUnarySelector("objectAtIndex", Ctx);
ObjectAtIndexedSubscript = GetUnarySelector("objectAtIndexedSubscript", Ctx);
NullSelector = GetNullarySelector("null", Ctx);
}
// Check the receiver type.
if (const ObjCInterfaceDecl *Interface = M.getReceiverInterface()) {
// Assume that object returned from '[self init]' or '[super init]' is not
// 'nil' if we are processing an inlined function/method.
//
// A defensive callee will (and should) check if the object returned by
// '[super init]' is 'nil' before doing it's own initialization. However,
// since 'nil' is rarely returned in practice, we should not warn when the
// caller to the defensive constructor uses the object in contexts where
// 'nil' is not accepted.
if (!C.inTopFrame() && M.getDecl() &&
M.getDecl()->getMethodFamily() == OMF_init &&
M.isReceiverSelfOrSuper()) {
State = assumeExprIsNonNull(M.getOriginExpr(), State, C);
}
FoundationClass Cl = findKnownClass(Interface);
// Objects returned from
// [NSArray|NSOrderedSet]::[ObjectAtIndex|ObjectAtIndexedSubscript]
// are never 'nil'.
if (Cl == FC_NSArray || Cl == FC_NSOrderedSet) {
Selector Sel = M.getSelector();
if (Sel == ObjectAtIndex || Sel == ObjectAtIndexedSubscript) {
// Go ahead and assume the value is non-nil.
State = assumeExprIsNonNull(M.getOriginExpr(), State, C);
}
}
// Objects returned from [NSNull null] are not nil.
if (Cl == FC_NSNull) {
if (M.getSelector() == NullSelector) {
// Go ahead and assume the value is non-nil.
State = assumeExprIsNonNull(M.getOriginExpr(), State, C);
}
}
}
C.addTransition(State);
}
//===----------------------------------------------------------------------===//
// Check registration.
//===----------------------------------------------------------------------===//
void ento::registerNilArgChecker(CheckerManager &mgr) {
mgr.registerChecker<NilArgChecker>();
}
void ento::registerCFNumberChecker(CheckerManager &mgr) {
mgr.registerChecker<CFNumberChecker>();
}
void ento::registerCFRetainReleaseChecker(CheckerManager &mgr) {
mgr.registerChecker<CFRetainReleaseChecker>();
}
void ento::registerClassReleaseChecker(CheckerManager &mgr) {
mgr.registerChecker<ClassReleaseChecker>();
}
void ento::registerVariadicMethodTypeChecker(CheckerManager &mgr) {
mgr.registerChecker<VariadicMethodTypeChecker>();
}
void ento::registerObjCLoopChecker(CheckerManager &mgr) {
mgr.registerChecker<ObjCLoopChecker>();
}
void
ento::registerObjCNonNilReturnValueChecker(CheckerManager &mgr) {
mgr.registerChecker<ObjCNonNilReturnValueChecker>();
}
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