You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
513 lines
18 KiB
513 lines
18 KiB
//= UnixAPIChecker.h - Checks preconditions for various Unix APIs --*- C++ -*-//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This defines UnixAPIChecker, which is an assortment of checks on calls
|
|
// to various, widely used UNIX/Posix functions.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
|
|
#include "clang/Basic/TargetInfo.h"
|
|
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
|
|
#include "clang/StaticAnalyzer/Core/Checker.h"
|
|
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
|
|
#include "llvm/ADT/Optional.h"
|
|
#include "llvm/ADT/STLExtras.h"
|
|
#include "llvm/ADT/SmallString.h"
|
|
#include "llvm/ADT/StringExtras.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
|
|
using namespace clang;
|
|
using namespace ento;
|
|
|
|
enum class OpenVariant {
|
|
/// The standard open() call:
|
|
/// int open(const char *path, int oflag, ...);
|
|
Open,
|
|
|
|
/// The variant taking a directory file descriptor and a relative path:
|
|
/// int openat(int fd, const char *path, int oflag, ...);
|
|
OpenAt
|
|
};
|
|
|
|
namespace {
|
|
|
|
class UnixAPIMisuseChecker : public Checker< check::PreStmt<CallExpr> > {
|
|
mutable std::unique_ptr<BugType> BT_open, BT_pthreadOnce;
|
|
mutable Optional<uint64_t> Val_O_CREAT;
|
|
|
|
public:
|
|
DefaultBool CheckMisuse, CheckPortability;
|
|
|
|
void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
|
|
|
|
void CheckOpen(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckOpenAt(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckPthreadOnce(CheckerContext &C, const CallExpr *CE) const;
|
|
|
|
void CheckOpenVariant(CheckerContext &C,
|
|
const CallExpr *CE, OpenVariant Variant) const;
|
|
|
|
void ReportOpenBug(CheckerContext &C,
|
|
ProgramStateRef State,
|
|
const char *Msg,
|
|
SourceRange SR) const;
|
|
|
|
};
|
|
|
|
class UnixAPIPortabilityChecker : public Checker< check::PreStmt<CallExpr> > {
|
|
public:
|
|
void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
|
|
|
|
private:
|
|
mutable std::unique_ptr<BugType> BT_mallocZero;
|
|
|
|
void CheckCallocZero(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckMallocZero(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckReallocZero(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckReallocfZero(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckAllocaZero(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckAllocaWithAlignZero(CheckerContext &C, const CallExpr *CE) const;
|
|
void CheckVallocZero(CheckerContext &C, const CallExpr *CE) const;
|
|
|
|
bool ReportZeroByteAllocation(CheckerContext &C,
|
|
ProgramStateRef falseState,
|
|
const Expr *arg,
|
|
const char *fn_name) const;
|
|
void BasicAllocationCheck(CheckerContext &C,
|
|
const CallExpr *CE,
|
|
const unsigned numArgs,
|
|
const unsigned sizeArg,
|
|
const char *fn) const;
|
|
};
|
|
|
|
} //end anonymous namespace
|
|
|
|
static void LazyInitialize(const CheckerBase *Checker,
|
|
std::unique_ptr<BugType> &BT,
|
|
const char *name) {
|
|
if (BT)
|
|
return;
|
|
BT.reset(new BugType(Checker, name, categories::UnixAPI));
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// "open" (man 2 open)
|
|
//===----------------------------------------------------------------------===/
|
|
|
|
void UnixAPIMisuseChecker::checkPreStmt(const CallExpr *CE,
|
|
CheckerContext &C) const {
|
|
const FunctionDecl *FD = C.getCalleeDecl(CE);
|
|
if (!FD || FD->getKind() != Decl::Function)
|
|
return;
|
|
|
|
// Don't treat functions in namespaces with the same name a Unix function
|
|
// as a call to the Unix function.
|
|
const DeclContext *NamespaceCtx = FD->getEnclosingNamespaceContext();
|
|
if (NamespaceCtx && isa<NamespaceDecl>(NamespaceCtx))
|
|
return;
|
|
|
|
StringRef FName = C.getCalleeName(FD);
|
|
if (FName.empty())
|
|
return;
|
|
|
|
if (FName == "open")
|
|
CheckOpen(C, CE);
|
|
|
|
else if (FName == "openat")
|
|
CheckOpenAt(C, CE);
|
|
|
|
else if (FName == "pthread_once")
|
|
CheckPthreadOnce(C, CE);
|
|
}
|
|
void UnixAPIMisuseChecker::ReportOpenBug(CheckerContext &C,
|
|
ProgramStateRef State,
|
|
const char *Msg,
|
|
SourceRange SR) const {
|
|
ExplodedNode *N = C.generateErrorNode(State);
|
|
if (!N)
|
|
return;
|
|
|
|
LazyInitialize(this, BT_open, "Improper use of 'open'");
|
|
|
|
auto Report = std::make_unique<PathSensitiveBugReport>(*BT_open, Msg, N);
|
|
Report->addRange(SR);
|
|
C.emitReport(std::move(Report));
|
|
}
|
|
|
|
void UnixAPIMisuseChecker::CheckOpen(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
CheckOpenVariant(C, CE, OpenVariant::Open);
|
|
}
|
|
|
|
void UnixAPIMisuseChecker::CheckOpenAt(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
CheckOpenVariant(C, CE, OpenVariant::OpenAt);
|
|
}
|
|
|
|
void UnixAPIMisuseChecker::CheckOpenVariant(CheckerContext &C,
|
|
const CallExpr *CE,
|
|
OpenVariant Variant) const {
|
|
// The index of the argument taking the flags open flags (O_RDONLY,
|
|
// O_WRONLY, O_CREAT, etc.),
|
|
unsigned int FlagsArgIndex;
|
|
const char *VariantName;
|
|
switch (Variant) {
|
|
case OpenVariant::Open:
|
|
FlagsArgIndex = 1;
|
|
VariantName = "open";
|
|
break;
|
|
case OpenVariant::OpenAt:
|
|
FlagsArgIndex = 2;
|
|
VariantName = "openat";
|
|
break;
|
|
};
|
|
|
|
// All calls should at least provide arguments up to the 'flags' parameter.
|
|
unsigned int MinArgCount = FlagsArgIndex + 1;
|
|
|
|
// If the flags has O_CREAT set then open/openat() require an additional
|
|
// argument specifying the file mode (permission bits) for the created file.
|
|
unsigned int CreateModeArgIndex = FlagsArgIndex + 1;
|
|
|
|
// The create mode argument should be the last argument.
|
|
unsigned int MaxArgCount = CreateModeArgIndex + 1;
|
|
|
|
ProgramStateRef state = C.getState();
|
|
|
|
if (CE->getNumArgs() < MinArgCount) {
|
|
// The frontend should issue a warning for this case, so this is a sanity
|
|
// check.
|
|
return;
|
|
} else if (CE->getNumArgs() == MaxArgCount) {
|
|
const Expr *Arg = CE->getArg(CreateModeArgIndex);
|
|
QualType QT = Arg->getType();
|
|
if (!QT->isIntegerType()) {
|
|
SmallString<256> SBuf;
|
|
llvm::raw_svector_ostream OS(SBuf);
|
|
OS << "The " << CreateModeArgIndex + 1
|
|
<< llvm::getOrdinalSuffix(CreateModeArgIndex + 1)
|
|
<< " argument to '" << VariantName << "' is not an integer";
|
|
|
|
ReportOpenBug(C, state,
|
|
SBuf.c_str(),
|
|
Arg->getSourceRange());
|
|
return;
|
|
}
|
|
} else if (CE->getNumArgs() > MaxArgCount) {
|
|
SmallString<256> SBuf;
|
|
llvm::raw_svector_ostream OS(SBuf);
|
|
OS << "Call to '" << VariantName << "' with more than " << MaxArgCount
|
|
<< " arguments";
|
|
|
|
ReportOpenBug(C, state,
|
|
SBuf.c_str(),
|
|
CE->getArg(MaxArgCount)->getSourceRange());
|
|
return;
|
|
}
|
|
|
|
// The definition of O_CREAT is platform specific. We need a better way
|
|
// of querying this information from the checking environment.
|
|
if (!Val_O_CREAT.hasValue()) {
|
|
if (C.getASTContext().getTargetInfo().getTriple().getVendor()
|
|
== llvm::Triple::Apple)
|
|
Val_O_CREAT = 0x0200;
|
|
else {
|
|
// FIXME: We need a more general way of getting the O_CREAT value.
|
|
// We could possibly grovel through the preprocessor state, but
|
|
// that would require passing the Preprocessor object to the ExprEngine.
|
|
// See also: MallocChecker.cpp / M_ZERO.
|
|
return;
|
|
}
|
|
}
|
|
|
|
// Now check if oflags has O_CREAT set.
|
|
const Expr *oflagsEx = CE->getArg(FlagsArgIndex);
|
|
const SVal V = C.getSVal(oflagsEx);
|
|
if (!V.getAs<NonLoc>()) {
|
|
// The case where 'V' can be a location can only be due to a bad header,
|
|
// so in this case bail out.
|
|
return;
|
|
}
|
|
NonLoc oflags = V.castAs<NonLoc>();
|
|
NonLoc ocreateFlag = C.getSValBuilder()
|
|
.makeIntVal(Val_O_CREAT.getValue(), oflagsEx->getType()).castAs<NonLoc>();
|
|
SVal maskedFlagsUC = C.getSValBuilder().evalBinOpNN(state, BO_And,
|
|
oflags, ocreateFlag,
|
|
oflagsEx->getType());
|
|
if (maskedFlagsUC.isUnknownOrUndef())
|
|
return;
|
|
DefinedSVal maskedFlags = maskedFlagsUC.castAs<DefinedSVal>();
|
|
|
|
// Check if maskedFlags is non-zero.
|
|
ProgramStateRef trueState, falseState;
|
|
std::tie(trueState, falseState) = state->assume(maskedFlags);
|
|
|
|
// Only emit an error if the value of 'maskedFlags' is properly
|
|
// constrained;
|
|
if (!(trueState && !falseState))
|
|
return;
|
|
|
|
if (CE->getNumArgs() < MaxArgCount) {
|
|
SmallString<256> SBuf;
|
|
llvm::raw_svector_ostream OS(SBuf);
|
|
OS << "Call to '" << VariantName << "' requires a "
|
|
<< CreateModeArgIndex + 1
|
|
<< llvm::getOrdinalSuffix(CreateModeArgIndex + 1)
|
|
<< " argument when the 'O_CREAT' flag is set";
|
|
ReportOpenBug(C, trueState,
|
|
SBuf.c_str(),
|
|
oflagsEx->getSourceRange());
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// pthread_once
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
void UnixAPIMisuseChecker::CheckPthreadOnce(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
|
|
// This is similar to 'CheckDispatchOnce' in the MacOSXAPIChecker.
|
|
// They can possibly be refactored.
|
|
|
|
if (CE->getNumArgs() < 1)
|
|
return;
|
|
|
|
// Check if the first argument is stack allocated. If so, issue a warning
|
|
// because that's likely to be bad news.
|
|
ProgramStateRef state = C.getState();
|
|
const MemRegion *R = C.getSVal(CE->getArg(0)).getAsRegion();
|
|
if (!R || !isa<StackSpaceRegion>(R->getMemorySpace()))
|
|
return;
|
|
|
|
ExplodedNode *N = C.generateErrorNode(state);
|
|
if (!N)
|
|
return;
|
|
|
|
SmallString<256> S;
|
|
llvm::raw_svector_ostream os(S);
|
|
os << "Call to 'pthread_once' uses";
|
|
if (const VarRegion *VR = dyn_cast<VarRegion>(R))
|
|
os << " the local variable '" << VR->getDecl()->getName() << '\'';
|
|
else
|
|
os << " stack allocated memory";
|
|
os << " for the \"control\" value. Using such transient memory for "
|
|
"the control value is potentially dangerous.";
|
|
if (isa<VarRegion>(R) && isa<StackLocalsSpaceRegion>(R->getMemorySpace()))
|
|
os << " Perhaps you intended to declare the variable as 'static'?";
|
|
|
|
LazyInitialize(this, BT_pthreadOnce, "Improper use of 'pthread_once'");
|
|
|
|
auto report =
|
|
std::make_unique<PathSensitiveBugReport>(*BT_pthreadOnce, os.str(), N);
|
|
report->addRange(CE->getArg(0)->getSourceRange());
|
|
C.emitReport(std::move(report));
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// "calloc", "malloc", "realloc", "reallocf", "alloca" and "valloc"
|
|
// with allocation size 0
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
// FIXME: Eventually these should be rolled into the MallocChecker, but right now
|
|
// they're more basic and valuable for widespread use.
|
|
|
|
// Returns true if we try to do a zero byte allocation, false otherwise.
|
|
// Fills in trueState and falseState.
|
|
static bool IsZeroByteAllocation(ProgramStateRef state,
|
|
const SVal argVal,
|
|
ProgramStateRef *trueState,
|
|
ProgramStateRef *falseState) {
|
|
std::tie(*trueState, *falseState) =
|
|
state->assume(argVal.castAs<DefinedSVal>());
|
|
|
|
return (*falseState && !*trueState);
|
|
}
|
|
|
|
// Generates an error report, indicating that the function whose name is given
|
|
// will perform a zero byte allocation.
|
|
// Returns false if an error occurred, true otherwise.
|
|
bool UnixAPIPortabilityChecker::ReportZeroByteAllocation(
|
|
CheckerContext &C,
|
|
ProgramStateRef falseState,
|
|
const Expr *arg,
|
|
const char *fn_name) const {
|
|
ExplodedNode *N = C.generateErrorNode(falseState);
|
|
if (!N)
|
|
return false;
|
|
|
|
LazyInitialize(this, BT_mallocZero,
|
|
"Undefined allocation of 0 bytes (CERT MEM04-C; CWE-131)");
|
|
|
|
SmallString<256> S;
|
|
llvm::raw_svector_ostream os(S);
|
|
os << "Call to '" << fn_name << "' has an allocation size of 0 bytes";
|
|
auto report =
|
|
std::make_unique<PathSensitiveBugReport>(*BT_mallocZero, os.str(), N);
|
|
|
|
report->addRange(arg->getSourceRange());
|
|
bugreporter::trackExpressionValue(N, arg, *report);
|
|
C.emitReport(std::move(report));
|
|
|
|
return true;
|
|
}
|
|
|
|
// Does a basic check for 0-sized allocations suitable for most of the below
|
|
// functions (modulo "calloc")
|
|
void UnixAPIPortabilityChecker::BasicAllocationCheck(CheckerContext &C,
|
|
const CallExpr *CE,
|
|
const unsigned numArgs,
|
|
const unsigned sizeArg,
|
|
const char *fn) const {
|
|
// Sanity check for the correct number of arguments
|
|
if (CE->getNumArgs() != numArgs)
|
|
return;
|
|
|
|
// Check if the allocation size is 0.
|
|
ProgramStateRef state = C.getState();
|
|
ProgramStateRef trueState = nullptr, falseState = nullptr;
|
|
const Expr *arg = CE->getArg(sizeArg);
|
|
SVal argVal = C.getSVal(arg);
|
|
|
|
if (argVal.isUnknownOrUndef())
|
|
return;
|
|
|
|
// Is the value perfectly constrained to zero?
|
|
if (IsZeroByteAllocation(state, argVal, &trueState, &falseState)) {
|
|
(void) ReportZeroByteAllocation(C, falseState, arg, fn);
|
|
return;
|
|
}
|
|
// Assume the value is non-zero going forward.
|
|
assert(trueState);
|
|
if (trueState != state)
|
|
C.addTransition(trueState);
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckCallocZero(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
unsigned int nArgs = CE->getNumArgs();
|
|
if (nArgs != 2)
|
|
return;
|
|
|
|
ProgramStateRef state = C.getState();
|
|
ProgramStateRef trueState = nullptr, falseState = nullptr;
|
|
|
|
unsigned int i;
|
|
for (i = 0; i < nArgs; i++) {
|
|
const Expr *arg = CE->getArg(i);
|
|
SVal argVal = C.getSVal(arg);
|
|
if (argVal.isUnknownOrUndef()) {
|
|
if (i == 0)
|
|
continue;
|
|
else
|
|
return;
|
|
}
|
|
|
|
if (IsZeroByteAllocation(state, argVal, &trueState, &falseState)) {
|
|
if (ReportZeroByteAllocation(C, falseState, arg, "calloc"))
|
|
return;
|
|
else if (i == 0)
|
|
continue;
|
|
else
|
|
return;
|
|
}
|
|
}
|
|
|
|
// Assume the value is non-zero going forward.
|
|
assert(trueState);
|
|
if (trueState != state)
|
|
C.addTransition(trueState);
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckMallocZero(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
BasicAllocationCheck(C, CE, 1, 0, "malloc");
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckReallocZero(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
BasicAllocationCheck(C, CE, 2, 1, "realloc");
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckReallocfZero(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
BasicAllocationCheck(C, CE, 2, 1, "reallocf");
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckAllocaZero(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
BasicAllocationCheck(C, CE, 1, 0, "alloca");
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckAllocaWithAlignZero(
|
|
CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
BasicAllocationCheck(C, CE, 2, 0, "__builtin_alloca_with_align");
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::CheckVallocZero(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
BasicAllocationCheck(C, CE, 1, 0, "valloc");
|
|
}
|
|
|
|
void UnixAPIPortabilityChecker::checkPreStmt(const CallExpr *CE,
|
|
CheckerContext &C) const {
|
|
const FunctionDecl *FD = C.getCalleeDecl(CE);
|
|
if (!FD || FD->getKind() != Decl::Function)
|
|
return;
|
|
|
|
// Don't treat functions in namespaces with the same name a Unix function
|
|
// as a call to the Unix function.
|
|
const DeclContext *NamespaceCtx = FD->getEnclosingNamespaceContext();
|
|
if (NamespaceCtx && isa<NamespaceDecl>(NamespaceCtx))
|
|
return;
|
|
|
|
StringRef FName = C.getCalleeName(FD);
|
|
if (FName.empty())
|
|
return;
|
|
|
|
if (FName == "calloc")
|
|
CheckCallocZero(C, CE);
|
|
|
|
else if (FName == "malloc")
|
|
CheckMallocZero(C, CE);
|
|
|
|
else if (FName == "realloc")
|
|
CheckReallocZero(C, CE);
|
|
|
|
else if (FName == "reallocf")
|
|
CheckReallocfZero(C, CE);
|
|
|
|
else if (FName == "alloca" || FName == "__builtin_alloca")
|
|
CheckAllocaZero(C, CE);
|
|
|
|
else if (FName == "__builtin_alloca_with_align")
|
|
CheckAllocaWithAlignZero(C, CE);
|
|
|
|
else if (FName == "valloc")
|
|
CheckVallocZero(C, CE);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Registration.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define REGISTER_CHECKER(CHECKERNAME) \
|
|
void ento::register##CHECKERNAME(CheckerManager &mgr) { \
|
|
mgr.registerChecker<CHECKERNAME>(); \
|
|
} \
|
|
\
|
|
bool ento::shouldRegister##CHECKERNAME(const CheckerManager &mgr) { \
|
|
return true; \
|
|
}
|
|
|
|
REGISTER_CHECKER(UnixAPIMisuseChecker)
|
|
REGISTER_CHECKER(UnixAPIPortabilityChecker)
|