CVE request Qemu: display: cirrus_vga: a divide by zero in cirrus_do_copy

[P J P <ppandit () redhat com>]

  Hello,

Quick emulator(Qemu) built with the Cirrus CLGD 54xx VGA Emulator support is 
vulnerable to a divide by zero issue. It could occur while copying VGA data 
when cirrus graphics mode was set to be VGA.

A privileged user inside guest could use this flaw to crash the Qemu process 
instance on the host, resulting in DoS.

Upstream patch
--------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2016-12/msg00442.html

Reference:
----------
  -> https://bugzilla.redhat.com/show_bug.cgi?id=1334398

This issue was independently reported by Qinghao Tang, Li Qiang of Qihoo 
360.cn Inc. and PSIRTeam of Huawei Inc.


Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F