oss-security - Xen Security Advisory 94 - ARM hypervisor crash on guest interrupt controller access

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Date: Wed, 23 Apr 2014 13:05:57 +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 94 - ARM hypervisor crash on guest
 interrupt controller access

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

                    Xen Security Advisory XSA-94

      ARM hypervisor crash on guest interrupt controller access

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

When handling a guest access to the virtual GIC distributor (interrupt
controller) Xen could dereference a pointer before checking it for
validity leading to a hypervisor crash and host Denial of Service.

IMPACT
======

A buggy or malicious guest can crash the host.

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

Both 32- and 64-bit ARM systems are vulnerable from Xen 4.4 onward.

x86 systems are not vulnerable.

MITIGATION
==========

None.

NOTE REGARDING LACK OF EMBARGO
==============================

This bug was publicly reported on xen-devel, before it was appreciated
that there was a security problem.

CREDITS
=======

The initial bug was discovered by Thomas Leonard and the security
aspect was diagnosed by Julien Grall.

RESOLUTION
==========

Applying the appropriate attached patch resolves this issue.

xsa94.patch        xen-unstable, Xen 4.4.x

$ sha256sum xsa94*.patch
ad0f20577400756a1786daeafef86fa870727ec35b48f71f565e4a30dcbda58d  xsa94.patch
$
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Download attachment "xsa94.patch" of type "application/octet-stream" (1164 bytes)

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