oss-security - Xen Security Advisory 58 (CVE-2013-1432) - Page reference counting error due to XSA-45/CVE-2013-1918 fixes

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

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

Message-Id: <E1Urpcz-000275-5T@xenbits.xen.org>
Date: Wed, 26 Jun 2013 13:19:17 +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 58 (CVE-2013-1432) - Page reference
 counting error due to XSA-45/CVE-2013-1918 fixes

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

             Xen Security Advisory CVE-2013-1432 / XSA-58
                            version 2

        Page reference counting error due to XSA-45/CVE-2013-1918 fixes

UPDATES IN VERSION 2
====================

Public release.  Credits section added.

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

The XSA-45/CVE-2013-1918 patch making error handling paths preemptible broke
page reference counting by not retaining a reference on pages stored for
deferred cleanup. This would lead to the hypervisor prematurely attempting to
free the page, generally crashing upon finding the page still in use.

CREDITS
=======

Thanks to Andrew Cooper and the Citrix XenServer team for discovering
and reporting this vulnerability, and helping investigate it.

IMPACT
======

Malicious or buggy PV guest kernels can mount a denial of service attack
affecting the whole system. It can't be excluded that this could also be
exploited to mount a privilege escalation attack.

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

All Xen versions having the XSA-45/CVE-2013-1918 fixes applied are vulnerable.

The vulnerability is only exposed by PV guests.

MITIGATION
==========

Running only HVM guests, or PV guests with trusted kernels, will avoid this
vulnerability.

RESOLUTION
==========

Applying the appropriate attached patch resolves this issue.

xsa58-4.1.patch             Xen 4.1.x
xsa58-4.2.patch             Xen 4.2.x
xsa58-unstable.patch        xen-unstable

$ sha256sum xsa58*.patch
3623ec87e5a2830f0d41de19a8e448d618954973c3264727a1f3a095f15a8641  xsa58-4.1.patch
194d6610fc38b767d643e5d58a1268f45921fb35e309b47aca6a388b861311c2  xsa58-4.2.patch
2c94b099d7144d03c0f7f44e892a521537fc040d11bc46f84a2438eece46a0f5  xsa58-unstable.patch
$
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (GNU/Linux)

iQEcBAEBAgAGBQJRyuoNAAoJEIP+FMlX6CvZY3EH/04uBhD797FdBhCRkq/y1ACc
Dvg1BRZ4lHkURDp97gD4Fdyf95Lw4qtniYBq8H/kpVPWJgN7+Dmj8uoluWhOI62Y
Q7a97CZ3O39VcuNRQnZG8c6dduGwMTzbJMkftG0CcltygAxVVRU4uHSG4+MHQ5PZ
N1xauljWrbw49iZz0shxZv4BA/1MQyuyZGFIpOaYoom0vV67pfrQJ2kgCMDUctmq
WXNkVcOiS7lwS/+++goPIboSEy6UJCIVrhZmL7GhbNfiznlOFVgExMttQRcUDi/D
4SS4ghl3IyB34TwoX1P7TPEeHGbfonObGpzBQNduBIJDM32nqO7P8097XG0j0Tw=
=aw1s
-----END PGP SIGNATURE-----

Download attachment "xsa58-4.1.patch" of type "application/octet-stream" (4208 bytes)

Download attachment "xsa58-4.2.patch" of type "application/octet-stream" (4629 bytes)

Download attachment "xsa58-unstable.patch" of type "application/octet-stream" (4621 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.