oss-security - Xen Security Advisory 104 (CVE-2014-7154) - Race condition in HVMOP_track_dirty

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <E1XWjph-00051m-Gn@xenbits.xen.org>
Date: Wed, 24 Sep 2014 10:30:01 +0000
From: Xen.org security team <security@....org>
To: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org,
 xen-users@...ts.xen.org, oss-security@...ts.openwall.com
CC: Xen.org security team <security@....org>
Subject: Xen Security Advisory 104 (CVE-2014-7154) - Race condition in
 HVMOP_track_dirty_vram

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

            Xen Security Advisory CVE-2014-7154 / XSA-104
                              version 3

               Race condition in HVMOP_track_dirty_vram

UPDATES IN VERSION 3
====================

This issue has been assigned CVE-2014-7154.

ISSUE DESCRIPTION
=================

The routine controlling the setup of dirty video RAM tracking latches
the value of a pointer before taking the respective guarding lock, thus
making it possible for a stale pointer to be used by the time the lock
got acquired and the pointer gets dereferenced.

The hypercall providing access to the affected function is available to
the domain controlling HVM guests.

IMPACT
======

Malicious or buggy stub domain kernels or tool stacks otherwise living
outside of Domain0 can mount a denial of service attack which, if
successful, can affect the whole system.

Only domains controlling HVM guests can exploit this vulnerability.
(This includes domains providing hardware emulation services to HVM
guests.)

VULNERABLE SYSTEMS
==================

Xen versions from 4.0.0 onwards are vulnerable.

This vulnerability is only applicable to Xen systems using stub
domains or other forms of disaggregation of control domains for HVM
guests.

MITIGATION
==========

There is no mitigation available for this issue.

(The security of a Xen system using stub domains is still better than
with a qemu-dm running as an unrestricted dom0 process.  Therefore
users with these configurations should not switch to an unrestricted
dom0 qemu-dm.)

CREDITS
=======

This issue was discovered by Andrew Cooper at Citrix.

RESOLUTION
==========

Applying the attached patch resolves this issue.

xsa104.patch        xen-unstable, Xen 4.4.x, Xen 4.3.x, Xen 4.2.x

$ sha256sum xsa104*.patch
fc02f6365ca79a6ef386c882b57fab8b56aa12b54fc9b05054552f0f25e32047  xsa104.patch
$
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)

iQEcBAEBAgAGBQJUIpziAAoJEIP+FMlX6CvZO2wIAMm2konqFYzaAZXbEH25T24K
aNTRF+x+RFwZy/701GupySti6Go6HPvm4uya09qIVRyTkafH2WF+VT93rBRlROHM
z5ZFwR/wKLFj3TPr/Fhb52ynwDdRPMvFkaWGxvSvxjASBbAPxCAlE8SuTmG1nBOe
RtnHNk6cxV5UeYTZ8TosG7RvlPIVA17o82btJ6DPbXIn2tENLTJaZf9cTtNZxKPo
kIEuo9E0JFQQyje+t7lImbMQbbe216JTRtATTivVuP68AcE/TSRggLwoBxSitjUp
YNbcfbHUeg2qltftvlZKeGgvrVceQ+Vj59cFNRj4r+xRXXywAAGZkgCpZNLeQnA=
=gwmy
-----END PGP SIGNATURE-----

Download attachment "xsa104.patch" of type "application/octet-stream" (1651 bytes)

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.