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AUSCERT External Security Bulletin Redistribution
ESB-2015.0243
Xen Security Advisory XSA-118
2 February 2015
===========================================================================
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
Original Bulletin:
http://xenbits.xen.org/xsa/advisory-118.html
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Xen Security Advisory XSA-118
arm: vgic: incorrect rate limiting of guest triggered logging
ISSUE DESCRIPTION
=================
On ARM systems the code which deals with virtualising the GIC
distributor would, under various circumstances, log messages on a
guest accessible code path without appropriate rate limiting.
IMPACT
======
A malicious guest could cause repeated logging to the hypervisor
console, leading to a Denial of Service attack.
VULNERABLE SYSTEMS
==================
Xen 4.4 and later systems running on ARM hardware are vulnerable.
x86 systems are not affected.
MITIGATION
==========
The problematic log messages are issued with priority Warning.
Therefore they can be rate limited by adding "loglvl=error/warning" to the
hypervisor command line or suppressed entirely by adding "loglvl=error".
NOTE REGARDING LACK OF EMBARGO
==============================
This bug was publicly reported on xen-devel, before it was appreciated
that there was a security problem.
CREDITS
=======
This issue was discovered by Julien Grall.
RESOLUTION
==========
Applying the appropriate attached patch(es) resolves this issue.
xsa118-unstable-4.5-{1,2}.patch xen-unstable, Xen 4.5.x
xsa118-4.4.patch Xen 4.4.x
$ sha256sum xsa118*.patch
5741cfe408273bd80e1a03c21a5650f963d7103fd022c688730f55dcf5373433 xsa118-4.4.patch
ee24a4c5e12b67d7539f08b644080c87797f31b4402215cd4efbbc6114bffc25 xsa118-4.5-unstable-1.patch
bd532e3cd535fcdea51f43631a519012baff068cb62d2205fc25f2c823f031eb xsa118-4.5-unstable-2.patch
$
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