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Date: Thu, 10 Oct 2013 12:22:55 +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 70 (CVE-2013-4371) - use-after-free in
 libxl_list_cpupool under memory pressure

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

             Xen Security Advisory CVE-2013-4371 / XSA-70
                               version 2

      use-after-free in libxl_list_cpupool under memory pressure

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

Public release.

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

If realloc(3) fails then libxl_list_cpupool will incorrectly return
the now-free original pointer.

IMPACT
======

An attacker may be able to cause a multithreaded toolstack using this
function to race against itself leading to heap corruption and a
potential DoS.

Depending on the malloc implementation code execution cannot be ruled
out.

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

The flaw is present in Xen 4.2 onwards.

Systems using the libxl toolstack library are vulnerable.

MITIGATION
==========

Not calling the libxl_list_cpupool function will avoid this issue.

Not allowing untrusted users access to toolstack functionality will
avoid this issue.

CREDITS
=======

This issue was discovered by Coverity Scan and Matthew Daley.

RESOLUTION
==========

Applying the attached patch resolves this issue.

xsa70.patch             Xen 4.3.x, Xen 4.2.x, xen-unstable


$ sha256sum xsa70*.patch
2582d3d545903af475436145f7e459414ad9d9c61d5720992eeeec42de8dde56  xsa70.patch
$
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Download attachment "xsa70.patch" of type "application/octet-stream" (1050 bytes)

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