Backport Debian Bullseye Security/Updates

Signed-off-by: Ritesh Raj Sarraf ritesh.sarraf@collabora.com

debian/patches/20_Xi-fix-potential-use-after-free-in-DeepCopyPointerCl.patch

+From 7150ba655c0cc08fa6ded309b81265bb672f2869 Mon Sep 17 00:00:00 2001
+From: Peter Hutterer <peter.hutterer@who-t.net>
+Date: Wed, 25 Jan 2023 11:41:40 +1000
+Subject: [PATCH xserver] Xi: fix potential use-after-free in
+ DeepCopyPointerClasses
+
+CVE-2023-0494, ZDI-CAN 19596
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+
+Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
+---
+ Xi/exevents.c |    4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+--- a/Xi/exevents.c
++++ b/Xi/exevents.c
+@@ -575,8 +575,10 @@ DeepCopyPointerClasses(DeviceIntPtr from
+             memcpy(to->button->xkb_acts, from->button->xkb_acts,
+                    sizeof(XkbAction));
+         }
+-        else
++        else {
+             free(to->button->xkb_acts);
++            to->button->xkb_acts = NULL;
++        }
+ 
+         memcpy(to->button->labels, from->button->labels,
+                from->button->numButtons * sizeof(Atom));