pythongh-118272: set stacktop to 0 before freeing contents, to avoid …

…access to invalid objects during GC (python#118478)
colesbury · May 1, 2024 · 6763bfc · 6763bfc
1 parent 1161ab9
commit 6763bfc
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/Python/frame.c b/Python/frame.c
@@ -98,10 +98,11 @@ void
 _PyFrame_ClearLocals(_PyInterpreterFrame *frame)
 {
     assert(frame->stacktop >= 0);
-    for (int i = 0; i < frame->stacktop; i++) {
+    int stacktop = frame->stacktop;
+    frame->stacktop = 0;
+    for (int i = 0; i < stacktop; i++) {
         Py_XDECREF(frame->localsplus[i]);
     }
-    frame->stacktop = 0;
     Py_CLEAR(frame->f_locals);
 }