Bug 628828

Summary:	Fix hot-unplug handling of virtio-console ports
Product:	Red Hat Enterprise Linux 5	Reporter:	Amit Shah <amit.shah>
Component:	kernel	Assignee:	Amit Shah <amit.shah>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	medium	Docs Contact:
Priority:	low
Version:	5.6	CC:	bburns, ehabkost, jarod, jwilson, kbaker, llim, lwang, pmatouse, security-response-team, tburke
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:	628805	Environment:
Last Closed:	2011-01-13 21:14:08 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:	628805
Bug Blocks:

Comment 1 RHEL Program Management 2010-09-22 15:29:15 UTC

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

Comment 2 Amit Shah 2010-09-23 03:39:09 UTC

The current version of virtio-console doesn't handle hot-unplug properly: it
leads to accessing memory outside the driver's memory area and can cause guest
kernel panics.

There are a few ways to trigger this, one of them:

1. Open a virtio-console port in the guest (eg /dev/vport0p1)
2. Block the port on read (eg cat /dev/vport0p1 with host chardev connected)
3. Hot-unplug the port (using the device_del command for the qemu monitor)
4. Close the port in the guest

Patches are queued for inclusion upstream.

Note that by default only root is allowed to open a virtio-console port, so
this can't be triggered by an unprivileged user in the default setup.

Comment 4 Jarod Wilson 2010-10-14 14:03:06 UTC

in kernel-2.6.18-227.el5
You can download this test kernel (or newer) from http://people.redhat.com/jwilson/el5

Detailed testing feedback is always welcomed.

Comment 7 errata-xmlrpc 2011-01-13 21:14:08 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0017.html