Bug 624126 (CVE-2017-10919)

Summary:	<app-emulation/xen-4.7.3: ARM guest disabling interrupt may crash Xen
Product:	Gentoo Security	Reporter:	Christopher Díaz Riveros (RETIRED) <chrisadr>
Component:	Vulnerabilities	Assignee:	Gentoo Security <security>
Status:	RESOLVED FIXED
Severity:	minor	CC:	xen
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
URL:	https://xenbits.xen.org/xsa/advisory-223.html
Whiteboard:	~3 [noglsa cve]
Package list:		Runtime testing required:	---

Description Christopher Díaz Riveros (RETIRED) gentoo-dev

2017-07-07 15:00:33 UTC

From $URL:

ISSUE DESCRIPTION
=================

Virtual interrupt injection could be triggered by a guest when sending
an SGI (e.g IPI) to any vCPU or by configuring timers. When the virtual
interrupt is masked, a missing check in the injection path may result in
reading invalid hardware register or crashing the host.

IMPACT
======

A guest may cause a hypervisor crash, resulting in a Denial of Service
(DoS).

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

All Xen versions which support ARM are affected.

x86 systems are not affected.

MITIGATION
==========

On systems where the guest kernel is controlled by the host rather than
guest administrator, running only kernels which do not disable SGI and
PPI (i.e IRQ < 32) will prevent untrusted guest users from exploiting
this issue. However untrusted guest administrators can still trigger it
unless further steps are taken to prevent them from loading code into
the kernel (e.g by disabling loadable modules etc) or from using other
mechanisms which allow them to run code at kernel privilege.

CREDITS
=======

This issue was discovered by Julien Grall of ARM.

RESOLUTION
==========

Applying the attached patch resolves this issue.

xsa223.patch           xen-unstable, Xen 4.8.x, Xen 4.7.x, Xen 4.6.x, Xen 4.5.x

$ sha256sum xsa223*
b5c8d8e8dac027069bec7dd812cff3f6f99e5949dd4a8ee729255c38274958b1  xsa223.patch
$

DEPLOYMENT DURING EMBARGO
=========================

Deployment of the patches and/or mitigations described above (or
others which are substantially similar) is permitted during the
embargo, even on public-facing systems with untrusted guest users and
administrators.

But: Distribution of updated software is prohibited (except to other
members of the predisclosure list).

Predisclosure list members who wish to deploy significantly different
patches and/or mitigations, please contact the Xen Project Security
Team.

(Note: this during-embargo deployment notice is retained in
post-embargo publicly released Xen Project advisories, even though it
is then no longer applicable.  This is to enable the community to have
oversight of the Xen Project Security Team's decisionmaking.)

Comment 1 Yixun Lan archtester

2017-07-12 07:32:54 UTC

commit 7a8fc554850ee501e1ad705b4154874adf102947 
Author: Yixun Lan <dlan@gentoo.org>             
Date:   Wed Jul 12 15:15:52 2017 +0800          

    app-emulation/xen: security bump            
                        
    fix XSA-217,218,219,220,221,222,223,224,225 
                        
    Gentoo-Bug: 624112,624114,624116,624118,624120,624122,624124,624126,624130                  
    Package-Manager: Portage-2.3.6, Repoman-2.3.2                                               

:100644 100644 6534404116c... 49df2654a33... M  app-emulation/xen/Manifest                      
:000000 100644 00000000000... f66bd1b70f8... A  app-emulation/xen/xen-4.7.3.ebuild              
:000000 100644 00000000000... bf73951bc39... A  app-emulation/xen/xen-4.8.1-r2.ebuild

Comment 2 Christopher Díaz Riveros (RETIRED) gentoo-dev

2017-07-21 04:23:00 UTC

Thank you Yixun Lan

Arches please let us know when all is stable

Comment 3 Yury German Gentoo Infrastructure

2017-08-20 21:59:11 UTC

Re-Categorized since affects only arm.
Even though non stable is not in GLSA, including since we have a GLSA pending.

Maintainer(s), please drop the vulnerable version(s).