bpo-33989: Ensure that ms.key_compare is always initialized in list_sort_impl(). (GH-8710)

ZackerySpytz · serhiy-storchaka · commit ebc793d6acb9 · 2019-02-21T09:47:14.000+02:00
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
@@ -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
@@ -2334,6 +2334,9 @@ list_sort_impl(PyListObject *self, PyObject *keyfunc, int reverse)
             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;

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+Fix a possible crash in :meth:`list.sort` when sorting objects with
	`2`	+``ob_type->tp_richcompare == NULL``. Patch by Zackery Spytz.
Original file line number	Diff line number	Diff line change
`@@ -2334,6 +2334,9 @@ list_sort_impl(PyListObject self, PyObject keyfunc, int reverse)`
`2334`	`2334`	`else if ((ms.key_richcompare = key_type->tp_richcompare) != NULL) {`
`2335`	`2335`	`ms.key_compare = unsafe_object_compare;`
`2336`	`2336`	`}`
	`2337`	`+ else {`
	`2338`	`+ ms.key_compare = safe_object_compare;`
	`2339`	`+ }`
`2337`	`2340`	`}`
`2338`	`2341`	`else {`
`2339`	`2342`	`ms.key_compare = safe_object_compare;`