Bug 1418277 (CVE-2017-14431, xsa207)

Summary: CVE-2017-14431 xsa207 xen: memory leak when destroying guest without PT devices (XSA-207)
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED WONTFIX QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-06-08 03:06:44 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1422492    
Bug Blocks:    

Description Adam Mariš 2017-02-01 12:38:56 UTC 
ISSUE DESCRIPTION
=================

Certain internal state is set up, during domain construction, in
preparation for possible pass-through device assignment.  On ARM and
AMD V-i hardware this setup includes memory allocation.  On guest
teardown, cleanup was erroneously only performed when the guest
actually had a pass-through device assigned.

IMPACT
======

A malicious guest may, by frequently rebooting over extended periods
of time, run the system out of memory, resulting in a Denial of
Service (DoS).

The leak is no more than 4kbytes per guest boot.

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

Xen versions 3.3 and later are affected.

ARM systems, and x86 AMD systems, are affected.  Intel systems, and
systems without IOMMU/SMMU hardware, are unaffected.

All guest kinds can exploit this vulnerability.

MITIGATION
==========

Limiting the frequency with which a guest is able to reboot, will
limit the memory leak.

Rebooting each host (after migrating its guests) periodically will
reclaim the leaked space.

External References:

http://xenbits.xen.org/xsa/advisory-207.html

Acknowledgements:

Name: the Xen project
Comment 1 Andrej Nemec 2017-02-15 12:22:21 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1422492]
Comment 2 Andrej Nemec 2017-02-15 12:22:33 UTC 
Public via:

http://seclists.org/oss-sec/2017/q1/440