From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 25 Apr 2019 12:05:34 +0530
Subject: qxl: check release info object

When releasing spice resources in release_resource() routine,
if release info object 'ext.info' is null, it leads to null
pointer dereference. Add check to avoid it.

Reported-by: Bugs SysSec <bugs-syssec@rub.de>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 20190425063534.32747-1-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit d52680fc932efb8a2f334cc6993e705ed1e31e99)
[LY: BSC#1135902 CVE-2019-12155]
Signed-off-by: Liang Yan <lyan@suse.com>
---
 hw/display/qxl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index 5c38e6e906..3880a7410b 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -768,6 +768,9 @@ static void interface_release_resource(QXLInstance *sin,
     uint32_t prod;
     uint64_t id;
 
+    if (!ext.info) {
+        return;
+    }
     if (ext.group_id == MEMSLOT_GROUP_HOST) {
         /* host group -> vga mode update request */
         QXLCommandExt *cmdext = (void *)(intptr_t)(ext.info->id);