bpo-46025: Fix a crash in the atexit module for auto-unregistering functions (GH-30002)

1 files changed, 4 insertions, 1 deletions

diff --git a/Modules/atexitmodule.c b/Modules/atexitmodule.c
index e536b4a..95c653c 100644
--- a/Modules/atexitmodule.c
+++ b/Modules/atexitmodule.c
@@ -93,13 +93,16 @@ atexit_callfuncs(struct atexit_state *state)
             continue;
         }
 
+        // bpo-46025: Increment the refcount of cb->func as the call itself may unregister it
+        PyObject* the_func = Py_NewRef(cb->func);
         PyObject *res = PyObject_Call(cb->func, cb->args, cb->kwargs);
         if (res == NULL) {
-            _PyErr_WriteUnraisableMsg("in atexit callback", cb->func);
+            _PyErr_WriteUnraisableMsg("in atexit callback", the_func);
         }
         else {
             Py_DECREF(res);
         }
+        Py_DECREF(the_func);
     }
 
     atexit_cleanup(state);