From: Zackery Spytz <zspytz@gmail.com>
Date: Thu, 21 Feb 2019 07:47:14 +0000 (-0700)
Subject: bpo-33989: Ensure that ms.key_compare is always initialized in list_sort_impl().... 
X-Git-Tag: v3.8.0a2~31
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ebc793d6acb9650b9f497808e059805892031d74;p=thirdparty%2FPython%2Fcpython.git

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 000000000000..056a71c480ad
--- /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 a08b3b50dd9a..cbd6e81ea472 100644
--- 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;