Bug 1012550 (CVE-2013-4368) - CVE-2013-4368 xen: information leak through outs instruction emulation (XSA-67)
Summary: CVE-2013-4368 xen: information leak through outs instruction emulation (XSA-67)
Alias: CVE-2013-4368
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1012958 1012959 1017843
Blocks: 1012558
TreeView+ depends on / blocked
Reported: 2013-09-26 15:52 UTC by Vincent Danen
Modified: 2023-05-12 00:25 UTC (History)
15 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2014-06-10 10:00:07 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2013:1449 0 normal SHIPPED_LIVE Moderate: kernel security and bug fix update 2013-10-22 21:30:54 UTC

Description Vincent Danen 2013-09-26 15:52:00 UTC
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.


Red Hat would like to thank the Xen project for reporting this issue.

Comment 6 Vincent Danen 2013-10-10 16:19:57 UTC
External References:


Comment 7 Vincent Danen 2013-10-10 16:22:34 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1017843]

Comment 8 errata-xmlrpc 2013-10-22 17:31:21 UTC
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 2013-10-23 03:34:09 UTC
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 2013-10-23 03:41:03 UTC
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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