From d52680fc932efb8a2f334cc6993e705ed1e31e99 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 25 Apr 2019 12:05:34 +0530
Subject: [PATCH] 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>

Upstream-Status: Backport
https://git.qemu.org/?p=qemu.git;a=commit;h=d52680fc932efb8a2f334cc6993e705ed1e31e99

CVE: CVE-2019-12155
Affects: <= 4.0.0
Signed-off-by: Armin Kuster <akuster@mvistra.com>
---
 hw/display/qxl.c | 3 +++
 1 file changed, 3 insertions(+)

Index: qemu-3.0.0/hw/display/qxl.c
===================================================================
--- qemu-3.0.0.orig/hw/display/qxl.c
+++ qemu-3.0.0/hw/display/qxl.c
@@ -764,6 +764,9 @@ static void interface_release_resource(Q
     QXLReleaseRing *ring;
     uint64_t *item, 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);