Bug 1481762 (CVE-2017-12855, xsa230) - CVE-2017-12855 xsa230 CVE-2017-12855 xen: grant_table: possibly premature clearing of GTF_writing / GTF_reading (XSA-230)
Summary: CVE-2017-12855 xsa230 CVE-2017-12855 xen: grant_table: possibly premature cle...
Status: CLOSED WONTFIX
Alias: CVE-2017-12855, xsa230
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard: impact=moderate,public=20170815,repor...
Keywords: Security
Depends On: 1481765
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-08-15 16:07 UTC by Adam Mariš
Modified: 2019-06-08 22:14 UTC (History)
12 users (show)

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Clone Of:
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Last Closed: 2019-06-08 03:20:49 UTC


Attachments (Terms of Use)

Description Adam Mariš 2017-08-15 16:07:29 UTC
ISSUE DESCRIPTION
=================

Xen maintains the _GTF_{read,writ}ing bits as appropriate, to inform the
guest that a grant is in use.  A guest is expected not to modify the
grant details while it is in use, whereas the guest is free to
modify/reuse the grant entry when it is not in use.

Under some circumstances, Xen will clear the status bits too early,
incorrectly informing the guest that the grant is no longer in use.

IMPACT
======

A guest may prematurely believe that a granted frame is safely private
again, and reuse it in a way which contains sensitive information, while
the domain on the far end of the grant is still using the grant.

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

All systems are vulnerable.

MITIGATION
==========

There are no mitigations.

External References:

http://xenbits.xen.org/xsa/advisory-230.html

Acknowledgements:

Name: the Xen project
Upstream: Jan Beulich (SUSE)

Comment 1 Adam Mariš 2017-08-15 16:14:49 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1481765]


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