Bug 1012550 - (CVE-2013-4368) CVE-2013-4368 xen: information leak through outs instruction emulation (XSA-67)
CVE-2013-4368 xen: information leak through outs instruction emulation (XSA-67)
Status: CLOSED ERRATA
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
impact=moderate,public=20131010,repor...
: Security
Depends On: 1012958 1012959 1017843
Blocks: 1012558
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Reported: 2013-09-26 11:52 EDT by Vincent Danen
Modified: 2015-02-16 10:50 EST (History)
15 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2014-06-10 06:00:07 EDT
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Description Vincent Danen 2013-09-26 11:52:00 EDT
The emulation of the outs instruction for 64-bit PV guests uses an
uninitialized variable as the segment base for the source data if an FS: or
GS: segment override is used, and if the segment descriptor the respective
non-null selector in the corresponding selector register points to cannot be
read by the emulation code (this is possible if the segment register was
loaded before a more recent GDT or LDT update, i.e. the segment register
contains stale data).

A malicious guest might be able to get hold of contents of the hypervisor
stack, through the fault address passed to the page fault handler if the outs
raises such a fault (which is mostly under guest control). Other methods for
indirectly deducing information also exist.

A malicious 64-bit PV guest might conceivably gain access to sensitive data
relating to other guests.


Acknowledgements:

Red Hat would like to thank the Xen project for reporting this issue.
Comment 6 Vincent Danen 2013-10-10 12:19:57 EDT
External References:

http://xenbits.xen.org/xsa/advisory-67.html
Comment 7 Vincent Danen 2013-10-10 12:22:34 EDT
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1017843]
Comment 8 errata-xmlrpc 2013-10-22 13:31:21 EDT
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2013:1449 https://rhn.redhat.com/errata/RHSA-2013-1449.html
Comment 9 Fedora Update System 2013-10-22 23:34:09 EDT
xen-4.2.3-4.fc18 has been pushed to the Fedora 18 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 10 Fedora Update System 2013-10-22 23:41:03 EDT
xen-4.2.3-4.fc19 has been pushed to the Fedora 19 stable repository.  If problems still persist, please make note of it in this bug report.

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