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//===-- SimpleStreamChecker.cpp -----------------------------------------*- C++ -*--//
//===-- SimpleStreamChecker.cpp -----------------------------------------*- C++ -*--//
//
//
// The LLVM Compiler Infrastructure
// The LLVM Compiler Infrastructure
//
//
// This file is distributed under the University of Illinois Open Source
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// License. See LICENSE.TXT for details.
//
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
//
//
// Defines a checker for proper use of fopen/fclose APIs.
// Defines a checker for proper use of fopen/fclose APIs.
// - If a file has been closed with fclose, it should not be accessed again.
// - If a file has been closed with fclose, it should not be accessed again.
// Accessing a closed file results in undefined behavior.
// Accessing a closed file results in undefined behavior.
// - If a file was opened with fopen, it must be closed with fclose before
// - If a file was opened with fopen, it must be closed with fclose before
// the execution ends. Failing to do so results in a resource leak.
// the execution ends. Failing to do so results in a resource leak.
//
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
using namespace clang;
using namespace clang;
using namespace ento;
using namespace ento;
namespace {
namespace {
enum SimpleStreamState { Closed, Opened };
enum SimpleStreamState { Closed, Opened };
SmartStateTrait SimpleStreamTrait;
SmartStateTrait SimpleStreamTrait;
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typedef SmallVector<
SymbolRef
, 2>
SymbolVector
;
typedef SmallVector<
const MemRegion *
, 2>
RegionVector
;
class SimpleStreamModel
class SimpleStreamModel
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: public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall
,
: public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall
> {
check::PointerEscape
> {
CallDescription OpenFn, CloseFn;
CallDescription OpenFn, CloseFn;
bool guaranteedNotToCloseFile(const CallEvent &Call) const;
bool guaranteedNotToCloseFile(const CallEvent &Call) const;
public:
public:
SimpleStreamModel() : OpenFn("fopen"), CloseFn("fclose") {}
SimpleStreamModel() : OpenFn("fopen"), CloseFn("fclose") {}
void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr,
void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr,
BugReporter &BR) const;
BugReporter &BR) const;
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
ProgramStateRef checkPointerEscape(ProgramStateRef State,
ProgramStateRef checkPointerEscape(ProgramStateRef State,
const InvalidatedSymbols &Escaped,
const InvalidatedSymbols &Escaped,
const CallEvent *Call,
const CallEvent *Call,
PointerEscapeKind Kind) const;
PointerEscapeKind Kind) const;
};
};
} // end of anonymous namespace
} // end of anonymous namespace
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bool SimpleStreamModel::guaranteedNotToCloseFile(
const CallEvent &Call) const {
// If it's not in a system header, assume it might close a file.
if (!Call.isInSystemHeader())
return false;
// Handle cases where we know a buffer's /address/ can escape.
if (Call.argumentsMayEscape())
return false;
// Note, even though fclose closes the file, we do not list it here
// since the checker is modeling the call.
return true;
}
void SimpleStreamModel::checkASTDecl(const TranslationUnitDecl *D,
void SimpleStreamModel::checkASTDecl(const TranslationUnitDecl *D,
AnalysisManager &AMgr,
AnalysisManager &AMgr,
BugReporter &BR) const {
BugReporter &BR) const {
// Once the AST context is available, we can express the fact that our trait
// Once the AST context is available, we can express the fact that our trait
// has type 'int'.
// has type 'int'.
// FIXME: This is ugly. Maybe make a separate callback, or delay registering
// FIXME: This is ugly. Maybe make a separate callback, or delay registering
// checkers until AST is constructed?
// checkers until AST is constructed?
SimpleStreamTrait.initialize("SimpleStream", AMgr.getASTContext().IntTy);
SimpleStreamTrait.initialize("SimpleStream", AMgr.getASTContext().IntTy);
}
}
void SimpleStreamModel::checkPostCall(const CallEvent &Call,
void SimpleStreamModel::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
CheckerContext &C) const {
if (!Call.isGlobalCFunction())
if (!Call.isGlobalCFunction())
return;
return;
if (Call.isCalled(OpenFn)) {
if (Call.isCalled(OpenFn)) {
// Get the symbolic value corresponding to the file handle.
// Get the symbolic value corresponding to the file handle.
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SymbolRef
FileDesc = Call.getReturnValue().
getAsSymbol
();
const MemRegion *
FileDesc = Call.getReturnValue().
getAsRegion
();
if (!FileDesc)
if (!FileDesc)
return;
return;
// Generate the next transition (an edge in the exploded graph).
// Generate the next transition (an edge in the exploded graph).
ProgramStateRef State = C.getState();
ProgramStateRef State = C.getState();
State = State->bindLoc(SimpleStreamTrait, FileDesc, Opened);
State = State->bindLoc(SimpleStreamTrait, FileDesc, Opened);
C.addTransition(State);
C.addTransition(State);
} else if (Call.isCalled(CloseFn)) {
} else if (Call.isCalled(CloseFn)) {
// Get the symbolic value corresponding to the file handle.
// Get the symbolic value corresponding to the file handle.
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SymbolRef
FileDesc = Call.getArgSVal(0).
getAsSymbol
();
const MemRegion *
FileDesc = Call.getArgSVal(0).
getAsRegion
();
if (!FileDesc)
if (!FileDesc)
return;
return;
// Generate the next transition, in which the stream is closed.
// Generate the next transition, in which the stream is closed.
ProgramStateRef State = C.getState();
ProgramStateRef State = C.getState();
State = State->bindLoc(SimpleStreamTrait, FileDesc, Closed);
State = State->bindLoc(SimpleStreamTrait, FileDesc, Closed);
C.addTransition(State);
C.addTransition(State);
}
}
}
}
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ProgramStateRef SimpleStreamModel::checkPointerEscape(
ProgramStateRef State, const InvalidatedSymbols &Escaped,
const CallEvent *Call, PointerEscapeKind Kind) const {
// If we know that the call cannot close a file, there is nothing to do.
if (Kind == PSK_DirectEscapeOnCall && guaranteedNotToCloseFile(*Call))
return State;
for (auto I = Escaped.begin(), E = Escaped.end(); I != E; ++I) {
SymbolRef Sym = *I;
// The symbol escaped. Optimistically, assume that the corresponding file
// handle will be closed somewhere else.
// FIXME: We're doing double lookup here, and we could have probably just
// deleted the binding, because our checker doesn't discriminate between
// different kind of unknowns.
if (State->hasAnyBinding(SimpleStreamTrait, Sym))
State = State->bindLoc(SimpleStreamTrait, Sym, UnknownVal());
}
return State;
}
namespace {
namespace {
class SimpleStreamChecker
class SimpleStreamChecker
: public Checker<check::PreCall, check::DeadSymbols> {
: public Checker<check::PreCall, check::DeadSymbols> {
CallDescription CloseFn;
CallDescription CloseFn;
std::unique_ptr<BugType> DoubleCloseBugType;
std::unique_ptr<BugType> DoubleCloseBugType;
std::unique_ptr<BugType> LeakBugType;
std::unique_ptr<BugType> LeakBugType;
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void reportDoubleClose(
SymbolRef
FileDesc
Sym
,
void reportDoubleClose(
const MemRegion *
FileDesc
Reg
,
const CallEvent &Call,
const CallEvent &Call,
CheckerContext &C) const;
CheckerContext &C) const;
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void reportLeaks(ArrayRef<
SymbolRef
> LeakedStreams, CheckerContext &C,
void reportLeaks(ArrayRef<
const MemRegion *
> LeakedStreams, CheckerContext &C,
ExplodedNode *ErrNode) const;
ExplodedNode *ErrNode) const;
public:
public:
SimpleStreamChecker();
SimpleStreamChecker();
/// Process fclose.
/// Process fclose.
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
/// Detect leaks.
/// Detect leaks.
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
};
};
} // end anonymous namespace
} // end anonymous namespace
SimpleStreamChecker::SimpleStreamChecker() : CloseFn("fclose", 1) {
SimpleStreamChecker::SimpleStreamChecker() : CloseFn("fclose", 1) {
// Initialize the bug types.
// Initialize the bug types.
DoubleCloseBugType.reset(
DoubleCloseBugType.reset(
new BugType(this, "Double fclose", "Unix Stream API Error"));
new BugType(this, "Double fclose", "Unix Stream API Error"));
LeakBugType.reset(
LeakBugType.reset(
new BugType(this, "Resource Leak", "Unix Stream API Error"));
new BugType(this, "Resource Leak", "Unix Stream API Error"));
// Sinks are higher importance bugs as well as calls to assert() or exit(0).
// Sinks are higher importance bugs as well as calls to assert() or exit(0).
LeakBugType->setSuppressOnSink(true);
LeakBugType->setSuppressOnSink(true);
}
}
void SimpleStreamChecker::checkPreCall(const CallEvent &Call,
void SimpleStreamChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
CheckerContext &C) const {
if (!Call.isGlobalCFunction())
if (!Call.isGlobalCFunction())
return;
return;
if (!Call.isCalled(CloseFn))
if (!Call.isCalled(CloseFn))
return;
return;
// Get the symbolic value corresponding to the file handle.
// Get the symbolic value corresponding to the file handle.
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SymbolRef
FileDesc = Call.getArgSVal(0).
getAsSymbol
();
const MemRegion *
FileDesc = Call.getArgSVal(0).
getAsRegion
();
if (!FileDesc)
if (!FileDesc)
return;
return;
// Check if the stream has already been closed.
// Check if the stream has already been closed.
ProgramStateRef State = C.getState();
ProgramStateRef State = C.getState();
SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
if (Val.isConstant(Closed)) {
if (Val.isConstant(Closed)) {
reportDoubleClose(FileDesc, Call, C);
reportDoubleClose(FileDesc, Call, C);
return;
return;
}
}
}
}
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static bool isLeaked(
SymbolRef Sym
, ProgramStateRef State) {
static bool isLeaked(
const MemRegion *Reg
, ProgramStateRef State) {
// If a symbol is NULL, assume that fopen failed on this path.
// If a symbol is NULL, assume that fopen failed on this path.
// A symbol should only be considered leaked if it is non-null.
// A symbol should only be considered leaked if it is non-null.
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ConstraintManager &CMgr = State->getConstraintManager();
if (const SymbolicRegion *SR = Reg->getSymbolicBase()) {
ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym);
SymbolRef Sym = SR->getSymbol();
return !OpenFailed.isConstrainedTrue();
ConstraintManager &CMgr = State->getConstraintManager();
ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym);
return !OpenFailed.isConstrainedTrue();
}
return false;
}
}
void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
CheckerContext &C) const {
CheckerContext &C) const {
ProgramStateRef State = C.getState();
ProgramStateRef State = C.getState();
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SymbolVector
LeakedStreams;
RegionVector
LeakedStreams;
// FIXME: Iterate through trait, not through dead symbols (might be faster)?
// FIXME: Iterate through trait, not through dead symbols (might be faster)?
for (auto I = SymReaper.dead_begin(), E = SymReaper.dead_end(); I != E; ++I) {
for (auto I = SymReaper.dead_begin(), E = SymReaper.dead_end(); I != E; ++I) {
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SymbolRef
FileDesc =
*I
;
// FIXME: This gets uglier with ghost fields.
const MemRegion *
FileDesc =
C.getSValBuilder().makeLoc(*I).getAsRegion()
;
SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
if (!Val.isConstant(Opened))
if (!Val.isConstant(Opened))
continue;
continue;
// Collect leaked symbols.
// Collect leaked symbols.
if (isLeaked(FileDesc, State))
if (isLeaked(FileDesc, State))
LeakedStreams.push_back(FileDesc);
LeakedStreams.push_back(FileDesc);
}
}
if (LeakedStreams.empty())
if (LeakedStreams.empty())
return;
return;
ExplodedNode *N = C.generateNonFatalErrorNode(State);
ExplodedNode *N = C.generateNonFatalErrorNode(State);
if (!N)
if (!N)
return;
return;
reportLeaks(LeakedStreams, C, N);
reportLeaks(LeakedStreams, C, N);
}
}
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void SimpleStreamChecker::reportDoubleClose(
SymbolRef
FileDesc
Sym
,
void SimpleStreamChecker::reportDoubleClose(
const MemRegion *
FileDesc
Reg
,
const CallEvent &Call,
const CallEvent &Call,
CheckerContext &C) const {
CheckerContext &C) const {
// We reached a bug, stop exploring the path here by generating a sink.
// We reached a bug, stop exploring the path here by generating a sink.
ExplodedNode *ErrNode = C.generateErrorNode();
ExplodedNode *ErrNode = C.generateErrorNode();
// If we've already reached this node on another path, return.
// If we've already reached this node on another path, return.
if (!ErrNode)
if (!ErrNode)
return;
return;
// Generate the report.
// Generate the report.
auto R = llvm::make_unique<BugReport>(*DoubleCloseBugType,
auto R = llvm::make_unique<BugReport>(*DoubleCloseBugType,
"Closing a previously closed file stream", ErrNode);
"Closing a previously closed file stream", ErrNode);
R->addRange(Call.getSourceRange());
R->addRange(Call.getSourceRange());
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R->markInteresting(FileDescSym);
C.emitReport(std::move(R));
C.emitReport(std::move(R));
}
}
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void SimpleStreamChecker::reportLeaks(ArrayRef<
SymbolRef
> LeakedStreams,
void SimpleStreamChecker::reportLeaks(ArrayRef<
const MemRegion *
> LeakedStreams,
CheckerContext &C,
CheckerContext &C,
ExplodedNode *ErrNode) const {
ExplodedNode *ErrNode) const {
// Attach bug reports to the leak node.
// Attach bug reports to the leak node.
// TODO: Identify the leaked file descriptor.
// TODO: Identify the leaked file descriptor.
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for (
SymbolRef
LeakedStream : LeakedStreams) {
for (
const MemRegion *
LeakedStream : LeakedStreams) {
auto R = llvm::make_unique<BugReport>(*LeakBugType,
auto R = llvm::make_unique<BugReport>(*LeakBugType,
"Opened file is never closed; potential resource leak", ErrNode);
"Opened file is never closed; potential resource leak", ErrNode);
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R->markInteresting(
LeakedStream
);
if (const SymbolicRegion *SR = LeakedStream->getSymbolicBase())
R->markInteresting(
SR->getSymbol()
);
C.emitReport(std::move(R));
C.emitReport(std::move(R));
}
}
}
}
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void ento::registerSimpleStreamCheckerV
2
(CheckerManager &mgr) {
void ento::registerSimpleStreamCheckerV
3
(CheckerManager &mgr) {
mgr.registerChecker<SimpleStreamModel>();
mgr.registerChecker<SimpleStreamModel>();
mgr.registerChecker<SimpleStreamChecker>();
mgr.registerChecker<SimpleStreamChecker>();
}
}
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//===-- SimpleStreamChecker.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 proper use of fopen/fclose APIs. // - If a file has been closed with fclose, it should not be accessed again. // Accessing a closed file results in undefined behavior. // - If a file was opened with fopen, it must be closed with fclose before // the execution ends. Failing to do so results in a resource leak. // //===----------------------------------------------------------------------===// #include "ClangSACheckers.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" using namespace clang; using namespace ento; namespace { enum SimpleStreamState { Closed, Opened }; SmartStateTrait SimpleStreamTrait; typedef SmallVector<SymbolRef, 2> SymbolVector; class SimpleStreamModel : public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall, check::PointerEscape> { CallDescription OpenFn, CloseFn; bool guaranteedNotToCloseFile(const CallEvent &Call) const; public: SimpleStreamModel() : OpenFn("fopen"), CloseFn("fclose") {} void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr, BugReporter &BR) const; void checkPostCall(const CallEvent &Call, CheckerContext &C) const; ProgramStateRef checkPointerEscape(ProgramStateRef State, const InvalidatedSymbols &Escaped, const CallEvent *Call, PointerEscapeKind Kind) const; }; } // end of anonymous namespace bool SimpleStreamModel::guaranteedNotToCloseFile( const CallEvent &Call) const { // If it's not in a system header, assume it might close a file. if (!Call.isInSystemHeader()) return false; // Handle cases where we know a buffer's /address/ can escape. if (Call.argumentsMayEscape()) return false; // Note, even though fclose closes the file, we do not list it here // since the checker is modeling the call. return true; } void SimpleStreamModel::checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr, BugReporter &BR) const { // Once the AST context is available, we can express the fact that our trait // has type 'int'. // FIXME: This is ugly. Maybe make a separate callback, or delay registering // checkers until AST is constructed? SimpleStreamTrait.initialize("SimpleStream", AMgr.getASTContext().IntTy); } void SimpleStreamModel::checkPostCall(const CallEvent &Call, CheckerContext &C) const { if (!Call.isGlobalCFunction()) return; if (Call.isCalled(OpenFn)) { // Get the symbolic value corresponding to the file handle. SymbolRef FileDesc = Call.getReturnValue().getAsSymbol(); if (!FileDesc) return; // Generate the next transition (an edge in the exploded graph). ProgramStateRef State = C.getState(); State = State->bindLoc(SimpleStreamTrait, FileDesc, Opened); C.addTransition(State); } else if (Call.isCalled(CloseFn)) { // Get the symbolic value corresponding to the file handle. SymbolRef FileDesc = Call.getArgSVal(0).getAsSymbol(); if (!FileDesc) return; // Generate the next transition, in which the stream is closed. ProgramStateRef State = C.getState(); State = State->bindLoc(SimpleStreamTrait, FileDesc, Closed); C.addTransition(State); } } ProgramStateRef SimpleStreamModel::checkPointerEscape( ProgramStateRef State, const InvalidatedSymbols &Escaped, const CallEvent *Call, PointerEscapeKind Kind) const { // If we know that the call cannot close a file, there is nothing to do. if (Kind == PSK_DirectEscapeOnCall && guaranteedNotToCloseFile(*Call)) return State; for (auto I = Escaped.begin(), E = Escaped.end(); I != E; ++I) { SymbolRef Sym = *I; // The symbol escaped. Optimistically, assume that the corresponding file // handle will be closed somewhere else. // FIXME: We're doing double lookup here, and we could have probably just // deleted the binding, because our checker doesn't discriminate between // different kind of unknowns. if (State->hasAnyBinding(SimpleStreamTrait, Sym)) State = State->bindLoc(SimpleStreamTrait, Sym, UnknownVal()); } return State; } namespace { class SimpleStreamChecker : public Checker<check::PreCall, check::DeadSymbols> { CallDescription CloseFn; std::unique_ptr<BugType> DoubleCloseBugType; std::unique_ptr<BugType> LeakBugType; void reportDoubleClose(SymbolRef FileDescSym, const CallEvent &Call, CheckerContext &C) const; void reportLeaks(ArrayRef<SymbolRef> LeakedStreams, CheckerContext &C, ExplodedNode *ErrNode) const; public: SimpleStreamChecker(); /// Process fclose. void checkPreCall(const CallEvent &Call, CheckerContext &C) const; /// Detect leaks. void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const; }; } // end anonymous namespace SimpleStreamChecker::SimpleStreamChecker() : CloseFn("fclose", 1) { // Initialize the bug types. DoubleCloseBugType.reset( new BugType(this, "Double fclose", "Unix Stream API Error")); LeakBugType.reset( new BugType(this, "Resource Leak", "Unix Stream API Error")); // Sinks are higher importance bugs as well as calls to assert() or exit(0). LeakBugType->setSuppressOnSink(true); } void SimpleStreamChecker::checkPreCall(const CallEvent &Call, CheckerContext &C) const { if (!Call.isGlobalCFunction()) return; if (!Call.isCalled(CloseFn)) return; // Get the symbolic value corresponding to the file handle. SymbolRef FileDesc = Call.getArgSVal(0).getAsSymbol(); if (!FileDesc) return; // Check if the stream has already been closed. ProgramStateRef State = C.getState(); SVal Val = State->getSVal(SimpleStreamTrait, FileDesc); if (Val.isConstant(Closed)) { reportDoubleClose(FileDesc, Call, C); return; } } static bool isLeaked(SymbolRef Sym, ProgramStateRef State) { // If a symbol is NULL, assume that fopen failed on this path. // A symbol should only be considered leaked if it is non-null. ConstraintManager &CMgr = State->getConstraintManager(); ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym); return !OpenFailed.isConstrainedTrue(); } void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const { ProgramStateRef State = C.getState(); SymbolVector LeakedStreams; // FIXME: Iterate through trait, not through dead symbols (might be faster)? for (auto I = SymReaper.dead_begin(), E = SymReaper.dead_end(); I != E; ++I) { SymbolRef FileDesc = *I; SVal Val = State->getSVal(SimpleStreamTrait, FileDesc); if (!Val.isConstant(Opened)) continue; // Collect leaked symbols. if (isLeaked(FileDesc, State)) LeakedStreams.push_back(FileDesc); } if (LeakedStreams.empty()) return; ExplodedNode *N = C.generateNonFatalErrorNode(State); if (!N) return; reportLeaks(LeakedStreams, C, N); } void SimpleStreamChecker::reportDoubleClose(SymbolRef FileDescSym, const CallEvent &Call, CheckerContext &C) const { // We reached a bug, stop exploring the path here by generating a sink. ExplodedNode *ErrNode = C.generateErrorNode(); // If we've already reached this node on another path, return. if (!ErrNode) return; // Generate the report. auto R = llvm::make_unique<BugReport>(*DoubleCloseBugType, "Closing a previously closed file stream", ErrNode); R->addRange(Call.getSourceRange()); R->markInteresting(FileDescSym); C.emitReport(std::move(R)); } void SimpleStreamChecker::reportLeaks(ArrayRef<SymbolRef> LeakedStreams, CheckerContext &C, ExplodedNode *ErrNode) const { // Attach bug reports to the leak node. // TODO: Identify the leaked file descriptor. for (SymbolRef LeakedStream : LeakedStreams) { auto R = llvm::make_unique<BugReport>(*LeakBugType, "Opened file is never closed; potential resource leak", ErrNode); R->markInteresting(LeakedStream); C.emitReport(std::move(R)); } } void ento::registerSimpleStreamCheckerV2(CheckerManager &mgr) { mgr.registerChecker<SimpleStreamModel>(); mgr.registerChecker<SimpleStreamChecker>(); }
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//===-- SimpleStreamChecker.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 proper use of fopen/fclose APIs. // - If a file has been closed with fclose, it should not be accessed again. // Accessing a closed file results in undefined behavior. // - If a file was opened with fopen, it must be closed with fclose before // the execution ends. Failing to do so results in a resource leak. // //===----------------------------------------------------------------------===// #include "ClangSACheckers.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" using namespace clang; using namespace ento; namespace { enum SimpleStreamState { Closed, Opened }; SmartStateTrait SimpleStreamTrait; typedef SmallVector<const MemRegion *, 2> RegionVector; class SimpleStreamModel : public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall> { CallDescription OpenFn, CloseFn; bool guaranteedNotToCloseFile(const CallEvent &Call) const; public: SimpleStreamModel() : OpenFn("fopen"), CloseFn("fclose") {} void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr, BugReporter &BR) const; void checkPostCall(const CallEvent &Call, CheckerContext &C) const; ProgramStateRef checkPointerEscape(ProgramStateRef State, const InvalidatedSymbols &Escaped, const CallEvent *Call, PointerEscapeKind Kind) const; }; } // end of anonymous namespace void SimpleStreamModel::checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr, BugReporter &BR) const { // Once the AST context is available, we can express the fact that our trait // has type 'int'. // FIXME: This is ugly. Maybe make a separate callback, or delay registering // checkers until AST is constructed? SimpleStreamTrait.initialize("SimpleStream", AMgr.getASTContext().IntTy); } void SimpleStreamModel::checkPostCall(const CallEvent &Call, CheckerContext &C) const { if (!Call.isGlobalCFunction()) return; if (Call.isCalled(OpenFn)) { // Get the symbolic value corresponding to the file handle. const MemRegion *FileDesc = Call.getReturnValue().getAsRegion(); if (!FileDesc) return; // Generate the next transition (an edge in the exploded graph). ProgramStateRef State = C.getState(); State = State->bindLoc(SimpleStreamTrait, FileDesc, Opened); C.addTransition(State); } else if (Call.isCalled(CloseFn)) { // Get the symbolic value corresponding to the file handle. const MemRegion *FileDesc = Call.getArgSVal(0).getAsRegion(); if (!FileDesc) return; // Generate the next transition, in which the stream is closed. ProgramStateRef State = C.getState(); State = State->bindLoc(SimpleStreamTrait, FileDesc, Closed); C.addTransition(State); } } namespace { class SimpleStreamChecker : public Checker<check::PreCall, check::DeadSymbols> { CallDescription CloseFn; std::unique_ptr<BugType> DoubleCloseBugType; std::unique_ptr<BugType> LeakBugType; void reportDoubleClose(const MemRegion *FileDescReg, const CallEvent &Call, CheckerContext &C) const; void reportLeaks(ArrayRef<const MemRegion *> LeakedStreams, CheckerContext &C, ExplodedNode *ErrNode) const; public: SimpleStreamChecker(); /// Process fclose. void checkPreCall(const CallEvent &Call, CheckerContext &C) const; /// Detect leaks. void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const; }; } // end anonymous namespace SimpleStreamChecker::SimpleStreamChecker() : CloseFn("fclose", 1) { // Initialize the bug types. DoubleCloseBugType.reset( new BugType(this, "Double fclose", "Unix Stream API Error")); LeakBugType.reset( new BugType(this, "Resource Leak", "Unix Stream API Error")); // Sinks are higher importance bugs as well as calls to assert() or exit(0). LeakBugType->setSuppressOnSink(true); } void SimpleStreamChecker::checkPreCall(const CallEvent &Call, CheckerContext &C) const { if (!Call.isGlobalCFunction()) return; if (!Call.isCalled(CloseFn)) return; // Get the symbolic value corresponding to the file handle. const MemRegion *FileDesc = Call.getArgSVal(0).getAsRegion(); if (!FileDesc) return; // Check if the stream has already been closed. ProgramStateRef State = C.getState(); SVal Val = State->getSVal(SimpleStreamTrait, FileDesc); if (Val.isConstant(Closed)) { reportDoubleClose(FileDesc, Call, C); return; } } static bool isLeaked(const MemRegion *Reg, ProgramStateRef State) { // If a symbol is NULL, assume that fopen failed on this path. // A symbol should only be considered leaked if it is non-null. if (const SymbolicRegion *SR = Reg->getSymbolicBase()) { SymbolRef Sym = SR->getSymbol(); ConstraintManager &CMgr = State->getConstraintManager(); ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym); return !OpenFailed.isConstrainedTrue(); } return false; } void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const { ProgramStateRef State = C.getState(); RegionVector LeakedStreams; // FIXME: Iterate through trait, not through dead symbols (might be faster)? for (auto I = SymReaper.dead_begin(), E = SymReaper.dead_end(); I != E; ++I) { // FIXME: This gets uglier with ghost fields. const MemRegion *FileDesc = C.getSValBuilder().makeLoc(*I).getAsRegion(); SVal Val = State->getSVal(SimpleStreamTrait, FileDesc); if (!Val.isConstant(Opened)) continue; // Collect leaked symbols. if (isLeaked(FileDesc, State)) LeakedStreams.push_back(FileDesc); } if (LeakedStreams.empty()) return; ExplodedNode *N = C.generateNonFatalErrorNode(State); if (!N) return; reportLeaks(LeakedStreams, C, N); } void SimpleStreamChecker::reportDoubleClose(const MemRegion *FileDescReg, const CallEvent &Call, CheckerContext &C) const { // We reached a bug, stop exploring the path here by generating a sink. ExplodedNode *ErrNode = C.generateErrorNode(); // If we've already reached this node on another path, return. if (!ErrNode) return; // Generate the report. auto R = llvm::make_unique<BugReport>(*DoubleCloseBugType, "Closing a previously closed file stream", ErrNode); R->addRange(Call.getSourceRange()); C.emitReport(std::move(R)); } void SimpleStreamChecker::reportLeaks(ArrayRef<const MemRegion *> LeakedStreams, CheckerContext &C, ExplodedNode *ErrNode) const { // Attach bug reports to the leak node. // TODO: Identify the leaked file descriptor. for (const MemRegion *LeakedStream : LeakedStreams) { auto R = llvm::make_unique<BugReport>(*LeakBugType, "Opened file is never closed; potential resource leak", ErrNode); if (const SymbolicRegion *SR = LeakedStream->getSymbolicBase()) R->markInteresting(SR->getSymbol()); C.emitReport(std::move(R)); } } void ento::registerSimpleStreamCheckerV3(CheckerManager &mgr) { mgr.registerChecker<SimpleStreamModel>(); mgr.registerChecker<SimpleStreamChecker>(); }
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