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-//= 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/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 = llvm::make_unique<BugReport>(*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 = llvm::make_unique<BugReport>(*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 = llvm::make_unique<BugReport>(*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 LangOptions &LO) { \
- return true; \
- }
-
-REGISTER_CHECKER(UnixAPIMisuseChecker)
-REGISTER_CHECKER(UnixAPIPortabilityChecker)
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-31 03:02:25 +0000