Bug 1342529 (CVE-2016-5242, xsa181) - CVE-2016-5242 xsa181 xen: arm: Host crash caused by VMID exhaustion (XSA-181)
Summary: CVE-2016-5242 xsa181 xen: arm: Host crash caused by VMID exhaustion (XSA-181)
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2016-5242, xsa181
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:
Depends On: 1342530
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-06-03 12:27 UTC by Adam Mariš
Modified: 2019-09-29 13:50 UTC (History)
11 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
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Clone Of:
Environment:
Last Closed: 2016-06-03 12:29:32 UTC


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Description Adam Mariš 2016-06-03 12:27:22 UTC
ISSUE DESCRIPTION
=================

VMIDs are a finite hardware resource, and allocated as part of domain
creation.  If no free VMIDs are available when trying to create a new domain,
a bug in the error path causes a NULL pointer to be used, resulting in a Data
Abort and host crash.

IMPACT
======

Attempting to create too many concurrent domains causes a host crash rather
than a graceful error.  A malicious device driver domain can hold references
to domains, preventing its VMID being released.

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

Xen versions 4.4 and later are affected.  Older Xen versions are unaffected.

x86 systems are not affected.

Only arm systems with less-privileged device driver domains can expose this
vulnerability.

MITIGATION
==========

There is no mitigation.  Not using driver domains reclassifies the problem,
but does not fix it.

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

The crash was discussed publicly on xen-devel, before it was appreciated
that there was a security problem.

CREDITS
=======

This issue was discovered by Aaron Cornelius of DornerWorks.

External References:

http://xenbits.xen.org/xsa/advisory-181.html

Acknowledgements:

Name: the Xen project
Upstream: Aaron Cornelius (DornerWorks)

Comment 1 Adam Mariš 2016-06-03 12:27:54 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1342530]

Comment 2 Fedora Update System 2016-06-17 15:57:28 UTC
xen-4.5.3-8.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Comment 3 Fedora Update System 2016-06-18 18:44:07 UTC
xen-4.6.1-11.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.


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