================
@@ -0,0 +1,260 @@
+#include "clang/AST/Attr.h"
+#include "clang/Analysis/Analyses/LifetimeSafety/LifetimeAnnotations.h"
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace ento;
+
+REGISTER_SET_FACTORY_WITH_PROGRAMSTATE(LifetimeSourceSet, const MemRegion *)
+REGISTER_MAP_WITH_PROGRAMSTATE(LifetimeBoundMap, SVal, LifetimeSourceSet)
+
+namespace {
+class UseAfterLifetimeEnd
+ : public Checker<check::PostCall, check::EndFunction, check::DeadSymbols> {
+public:
+ void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
+ void printState(raw_ostream &Out, ProgramStateRef State, const char *NL,
+ const char *Sep) const override;
+ void reportDanglingSource(const MemRegion *Region, ExplodedNode *N,
+ CheckerContext &C) const;
+ void checkReturnedBorrower(SVal Val, ProgramStateRef State,
+ CheckerContext &C) const;
+ void checkEndFunction(const ReturnStmt *RS, CheckerContext &C) const;
+ void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
+ const BugType BugMsg{this, "UseAfterLifetimeEnd", "LifetimeBound"};
+};
+
+} // namespace
+
+static ProgramStateRef bindValues(ProgramStateRef State, SVal RetVal,
+ const MemRegion *Source) {
+ LifetimeSourceSet::Factory &F = State->get_context<LifetimeSourceSet>();
+
+ const LifetimeSourceSet *LSet = State->get<LifetimeBoundMap>(RetVal);
+ LifetimeSourceSet Set = LSet ? *LSet : F.getEmptySet();
+ Set = F.add(Set, Source);
+ State = State->set<LifetimeBoundMap>(RetVal, Set);
+ return State;
+}
+
+void UseAfterLifetimeEnd::checkPostCall(const CallEvent &Call,
+ CheckerContext &C) const {
+ ProgramStateRef State = C.getState();
+
+ const auto *FC = dyn_cast<AnyFunctionCall>(&Call);
+ if (!FC)
+ return;
+
+ const FunctionDecl *FD = FC->getDecl();
+ if (!FD)
+ return;
+
+ SVal RetVal = Call.getReturnValue();
+
+ for (const ParmVarDecl *PVD : FD->parameters()) {
+ if (PVD->hasAttr<LifetimeBoundAttr>()) {
+ unsigned Idx = PVD->getFunctionScopeIndex();
+ SVal Arg = Call.getArgSVal(Idx);
+ if (const MemRegion *ArgValRegion = Arg.getAsRegion())
+ State = bindValues(State, RetVal, ArgValRegion);
+ }
+ }
+
+ if (const auto *IC = dyn_cast<CXXInstanceCall>(&Call)) {
+ if (lifetimes::implicitObjectParamIsLifetimeBound(FD)) {
+ if (const MemRegion *AttrRegion = IC->getCXXThisVal().getAsRegion()) {
+ State = bindValues(State, RetVal, AttrRegion);
+ }
+ }
+ }
+ C.addTransition(State);
+}
+
+static bool hasDanglingSource(const MemRegion *Source, ProgramStateRef State,
+ CheckerContext &C) {
+ // FIXME: The checker currently handles stack-region sources. Other
+ // region kinds require separate methodology. For example, heap
+ // regions do not go out of scope at the end of a stack frame, so
+ // in order to detect those type of dangling sources the function
+ // needs to be expanded to an event-driven approach as well.
+ if (const auto *StackSpace =
+ Source->getMemorySpaceAs<StackSpaceRegion>(State)) {
+ const StackFrame *SF = StackSpace->getStackFrame();
+ const StackFrame *CurrentSF = C.getStackFrame();
+ if (SF == CurrentSF || !SF->isParentOf(CurrentSF))
+ return true;
+ }
+ return false;
+}
+
+void UseAfterLifetimeEnd::checkReturnedBorrower(SVal Val, ProgramStateRef
State,
+ CheckerContext &C) const {
+ if (auto *SourceSet = State->get<LifetimeBoundMap>(Val)) {
+ ExplodedNode *N = nullptr;
+ for (const MemRegion *Region : *SourceSet) {
+ if (hasDanglingSource(Region, State, C)) {
+ if (!N)
+ N = C.generateNonFatalErrorNode();
+ if (!N)
+ return;
+ reportDanglingSource(Region, N, C);
+ }
+ }
+ }
+}
+
+void UseAfterLifetimeEnd::checkEndFunction(const ReturnStmt *RS,
+ CheckerContext &C) const {
+ if (!RS)
+ return;
+
+ ProgramStateRef State = C.getState();
+ auto LBMap = State->get<LifetimeBoundMap>();
+
+ if (LBMap.isEmpty())
+ return;
+
+ const Expr *RetExpr = RS->getRetValue();
+ if (!RetExpr)
+ return;
+
+ RetExpr = RetExpr->IgnoreParens();
+ SVal RetVal = C.getSVal(RetExpr);
+ checkReturnedBorrower(RetVal, State, C);
+}
+
+void UseAfterLifetimeEnd::reportDanglingSource(const MemRegion *Region,
+ ExplodedNode *N,
+ CheckerContext &C) const {
+ auto BR = std::make_unique<PathSensitiveBugReport>(
+ BugMsg,
+ (llvm::Twine("Returning value bound to '") + Region->getString() +
+ "' that will go out of scope"),
+ N);
+ C.emitReport(std::move(BR));
+}
+
+void UseAfterLifetimeEnd::checkDeadSymbols(SymbolReaper &SymReaper,
+ CheckerContext &C) const {
+ ProgramStateRef State = C.getState();
+ LifetimeBoundMapTy LBMap = State->get<LifetimeBoundMap>();
+
+ for (SVal Val : llvm::make_first_range(LBMap)) {
+ if (const MemRegion *ValRegion = Val.getAsRegion()) {
+ if (!SymReaper.isLiveRegion(ValRegion))
+ State = State->remove<LifetimeBoundMap>(Val);
+ } else if (SymbolRef ValRef =
+ Val.getAsSymbol(/*IncludeBaseRegions=*/true)) {
+ if (!SymReaper.isLive(ValRef))
+ State = State->remove<LifetimeBoundMap>(Val);
+ }
+ }
+
+ C.addTransition(State);
+}
+
+void UseAfterLifetimeEnd::printState(raw_ostream &Out, ProgramStateRef State,
+ const char *NL, const char *Sep) const {
+ auto LBMap = State->get<LifetimeBoundMap>();
+
+ if (LBMap.isEmpty())
+ return;
+
+ Out << Sep << "LifetimeBound bindings:" << NL;
+ for (auto &&[OriginSym, SourceSet] : LBMap) {
+ for (const auto *Region : SourceSet)
+ Out << " Origin " << OriginSym << " contains Loan " << Region << NL;
+ }
+}
+
+namespace {
+class DebugUseAfterLifetimeEnd : public Checker<eval::Call> {
+public:
+ bool evalCall(const CallEvent &Call, CheckerContext &C) const;
+ void analyzerDumpLifetimeOriginsOf(const CallEvent &Call,
+ CheckerContext &C) const;
+
+ const BugType BugMsg{this, "DebugUseAfterLifetimeEnd",
+ "DebugUseAfterLifetimeEnd"};
+ using FnCheck = void (DebugUseAfterLifetimeEnd::*)(const CallEvent &Call,
+ CheckerContext &C) const;
+
+ const CallDescriptionMap<FnCheck> Callbacks = {
+ {{CDM::SimpleFunc, {"clang_analyzer_dumpLifetimeOriginsOf"}},
+ &DebugUseAfterLifetimeEnd::analyzerDumpLifetimeOriginsOf},
+ };
+};
+
+} // namespace
+
+bool DebugUseAfterLifetimeEnd::evalCall(const CallEvent &Call,
+ CheckerContext &C) const {
+ const auto *CE = dyn_cast_if_present<CallExpr>(Call.getOriginExpr());
+ if (!CE)
+ return false;
+
+ const FnCheck *Handler = Callbacks.lookup(Call);
+ if (!Handler)
+ return false;
+
+ (this->*(*Handler))(Call, C);
+ return true;
+}
+
+void DebugUseAfterLifetimeEnd::analyzerDumpLifetimeOriginsOf(
+ const CallEvent &Call, CheckerContext &C) const {
+ ProgramStateRef State = C.getState();
+
+ if (Call.getNumArgs() != 1) {
+ if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
+ auto BR = std::make_unique<PathSensitiveBugReport>(
+ BugMsg,
+ "clang_analyzer_dumpLifetimeOriginsOf requires exactly 1 argument",
+ N);
+ C.emitReport(std::move(BR));
+ }
+ return;
+ }
+
+ SVal ArgSVal = Call.getArgSVal(0);
+ const LifetimeSourceSet *SourceSet = State->get<LifetimeBoundMap>(ArgSVal);
+
+ if (!SourceSet)
+ return;
+
+ llvm::SmallString<128> Str;
+ llvm::raw_svector_ostream OS(Str);
+ OS << " Origin " << ArgSVal << " bound to ";
+
+ if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
+ bool First = true;
+ for (const MemRegion *Region : *SourceSet) {
+ if (!First)
+ OS << ", ";
+ OS << Region;
+ First = false;
+ }
+ C.emitReport(std::make_unique<PathSensitiveBugReport>(BugMsg, OS.str(),
N));
+ }
----------------
steakhal wrote:
The order of the `*SourceSet` elements are non-deterministic, thus we must sort
them.
Here is how I would do it.
```suggestion
if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
llvm::SmallVector<std::string> RegionNames =
to_vector(map_range(llvm::make_pointee_range(*SourceSet),
std::mem_fn(&MemRegion::getString)));
llvm::sort(RegionNames);
llvm::SmallString<128> Str;
llvm::raw_svector_ostream OS(Str);
OS << " Origin " << ArgSVal << " bound to ";
llvm::interleaveComma(RegionNames, OS);
C.emitReport(std::make_unique<PathSensitiveBugReport>(BugMsg, OS.str(), N));
}
```
https://github.com/llvm/llvm-project/pull/205521
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