bpo-33989: Ensure that ms.key_compare is always initialized in list_sort_impl(). (GH-8710)
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-08-08-20-52-55.bpo-33989.TkLBui.rst b/Misc/NEWS.d/next/Core and Builtins/2018-08-08-20-52-55.bpo-33989.TkLBui.rst
new file mode 100644
index 0000000..056a71c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-08-08-20-52-55.bpo-33989.TkLBui.rst
@@ -0,0 +1,2 @@
+Fix a possible crash in :meth:`list.sort` when sorting objects with
+``ob_type->tp_richcompare == NULL``. Patch by Zackery Spytz.
diff --git a/Objects/listobject.c b/Objects/listobject.c
index a08b3b5..cbd6e81 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2334,6 +2334,9 @@
else if ((ms.key_richcompare = key_type->tp_richcompare) != NULL) {
ms.key_compare = unsafe_object_compare;
}
+ else {
+ ms.key_compare = safe_object_compare;
+ }
}
else {
ms.key_compare = safe_object_compare;