CVE-2017-7718 Qemu: display: cirrus: OOB read access issue

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

  Hello,

Quick emulator(Qemu) built with the Cirrus CLGD 54xx VGA Emulator support is 
vulnerable to an out-of-bounds access issue. It could occur while copying VGA 
data via bitblt functions cirrus_bitblt_rop_fwd_transp_ and/or 
cirrus_bitblt_rop_fwd_.

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

Upstream patch
--------------
  -> http://git.qemu-project.org/?p=qemu.git;a=commitdiff;h=215902d7b6fb50c6fc216fc74f770858278ed904

Reference:
----------
  -> https://bugzilla.redhat.com/show_bug.cgi?id=1443441

This issue was reported by Jiangxin of PSIRT Huawei Inc.

'CVE-2017-7718' assigned via -> http://cveform.mitre.org/

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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