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[gentoo-announce] [ GLSA 201703-07 ] Xen: Privilege Escalation

Posted on 28 March 2017
Gentoo-announce

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From: Yury German <blueknight@gentoo.org>
To: gentoo-announce@lists.gentoo.org
Message-ID: <d9400384-ca62-9cb9-1716-c51fe26eb235@gentoo.org>
Subject: [ GLSA 201703-07 ] Xen: Privilege Escalation

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Gentoo Linux Security Advisory GLSA 201703-07
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https://security.gentoo.org/
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Severity: Normal
Title: Xen: Privilege Escalation
Date: March 28, 2017
Bugs: #609120
ID: 201703-07

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Synopsis
========
A vulnerability in Xen's bundled QEMU version might allow privilege
escalation.

Background
==========
Xen is a bare-metal hypervisor.

Affected packages
=================
-------------------------------------------------------------------
Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 app-emulation/xen-tools < 4.7.1-r8 >= 4.7.1-r8

Description
===========
In CIRRUS_BLTMODE_MEMSYSSRC mode the bitblit copy routine
cirrus_bitblt_cputovideo fails to check wethehr the specified memory
region is safe.

Impact
======
A local attacker could potentially execute arbitrary code with
privileges of Xen (QEMU) process on the host, gain privileges on the
host system, or cause a Denial of Service condition.

Workaround
==========
Running guests in Paravirtualization (PV) mode, or running guests in
Hardware-assisted virtualizion (HVM) utilizing stub domains mitigate
the issue.

Running HVM guests with the device model in a stubdomain will mitigate
the issue.

Changing the video card emulation to stdvga (stdvga=1, vga="stdvga", =in
the xl domain configuration) will avoid the vulnerability.

Resolution
==========
All Xen Tools users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot -v ">=app-emulation/xen-tools-4.7.1-r8"

References
==========
[ 1 ] CVE-2017-2620
http://nvd.nist.gov/nvd.cfm?cvename=CVE-2017-2620

Availability
============
This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

https://security.gentoo.org/glsa/201703-07

Concerns?
=========
Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users' machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org.

License
=======
Copyright 2017 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5


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