Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
===========================================================================
AUSCERT External Security Bulletin Redistribution
ESB-2013.1570
Xen Security Advisory XSA-73
5 November 2013
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Xen
Publisher: Xen
Operating System: UNIX variants (UNIX, Linux, OSX)
Xen
Impact/Access: Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2013-4494
Original Bulletin:
http://xenbits.xen.org/xsa/advisory-73.html
- --------------------------BEGIN INCLUDED TEXT--------------------
- -----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Xen Security Advisory CVE-2013-4494 / XSA-73
version 3
Lock order reversal between page allocation and grant table locks
UPDATES IN VERSION 3
====================
The issue has been assigned CVE-2013-4494.
NOTE REGARDING LACK OF EMBARGO
==============================
While the response to this issue was being prepared by the security
team, the bug was independently discovered by a third party who
publicly disclosed it without realising the security impact.
ISSUE DESCRIPTION
=================
The locks page_alloc_lock and grant_table.lock are not always taken in
the same order. This opens the possibility of deadlock.
IMPACT
======
A malicious guest administrator can deny service to the entire host.
VULNERABLE SYSTEMS
==================
Xen versions going back to at least Xen 3.2 are vulnerable.
To exploit the vulnerability, the attacker must have control of more
than one vcpu, either by controlling a malicious multi-vcpu guest, or
by controlling more than one guest.
MITIGATION
==========
There is no practical mitigation for this issue.
CREDITS
=======
This issue was discovered by Coverity Scan and diagnosed by Andrew
Cooper.
RESOLUTION
==========
Applying the appropriate attached patch resolves this issue.
xsa73-4.3-unstable.patch Xen 4.3.x, xen-unstable
xsa73-4.2.patch Xen 4.2.x
xsa73-4.1.patch Xen 4.1.x
$ sha256sum xsa73*.patch
519eb1d2815c41d73c775324f43d1a7d75615775194bd0f6584147b45d04250b xsa73-4.1.patch
9eab1db170dc13bdd4da76bc2184399f705d124acd14b364428f012ea5c3a281 xsa73-4.2.patch
1c070e66d1bea3c109f22ea4db2e8828f0f4b016d51d6d88667b775eec340514 xsa73-4.3-unstable.patch
$
- -----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)
iQEcBAEBAgAGBQJSd53SAAoJEIP+FMlX6CvZAMgH/1JgLDhHB5A7w0iVJbHSv4ff
9oxmch/DfMFj1A+Cuhq5YU25I19ocSiqiEU4n7IuADCH4UCetH6UMXqRQ7qj/HPq
RZTGxmPkBNkIVkZd9IqRZEoWy4ENDhdDOa8ViNLqXCTCra0swfeTAav+BtTanpFQ
jca18Ry0o4qo9A/ZNZniAgMV1OXxZkETRm6jVc7tCNzx0daPyAo4xesUDLNJ/EcW
yYv7pIRY1Ct7X5CD3carkRBm0k3PmZ0IClZf5aBWKV8PE95oOk/m8HBIPFGvBp7o
cPBHt7Nra2pWDG76Vtzg0QZuV9XPwaRtPk4U4w9s9K4BpRwDza8mXCBgaRLX9aU=
=RphO
- -----END PGP SIGNATURE-----
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.
NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
http://www.auscert.org.au/render.html?cid=1980
===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072
Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
===========================================================================
-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967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=UOiv
-----END PGP SIGNATURE-----