Backport fix for crash reported in #88181

clang/docs/ReleaseNotes.rst

@@ -1474,6 +1474,10 @@ Crash and bug fixes
 - Fix false positive in mutation check when using pointer to member function.
   (`#66204 <https://github.com/llvm/llvm-project/issues/66204>`_)
 
+- Fixed a crash in ``security.cert.env.InvalidPtr`` checker when accidentally
+  matched user-defined ``strerror`` and similar library functions.
+  (`#88181 <https://github.com/llvm/llvm-project/issues/88181>`_)
+
 Improvements
 ^^^^^^^^^^^^
 

clang/lib/StaticAnalyzer/Checkers/cert/InvalidPtrChecker.cpp

@@ -205,8 +205,12 @@ void InvalidPtrChecker::postPreviousReturnInvalidatingCall(
       CE, LCtx, CE->getType(), C.blockCount());
   State = State->BindExpr(CE, LCtx, RetVal);
 
+  const auto *SymRegOfRetVal =
+      dyn_cast_or_null<SymbolicRegion>(RetVal.getAsRegion());
+  if (!SymRegOfRetVal)
+    return;
+
   // Remember to this region.
-  const auto *SymRegOfRetVal = cast<SymbolicRegion>(RetVal.getAsRegion());
   const MemRegion *MR = SymRegOfRetVal->getBaseRegion();
   State = State->set<PreviousCallResultMap>(FD, MR);
 

clang/test/Analysis/invalid-ptr-checker.cpp

@@ -0,0 +1,10 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,security.cert.env.InvalidPtr -verify %s
+
+// expected-no-diagnostics
+
+namespace other {
+int strerror(int errnum); // custom strerror
+void no_crash_on_custom_strerror() {
+  (void)strerror(0); // no-crash
+}
+} // namespace other