Bug 1346976

Summary:	Regression from CVE-2016-3712: windows installer fails to start [rhel-7.3]
Product:	Red Hat Enterprise Linux 7	Reporter:	Ademar Reis <areis>
Component:	qemu-kvm-rhev	Assignee:	Gerd Hoffmann <kraxel>
Status:	CLOSED ERRATA	QA Contact:	Guo, Zhiyi <zhguo>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.2	CC:	ailan, chayang, jen, jherrman, juzhang, mgoldboi, virt-maint
Target Milestone:	rc	Keywords:	Regression, ZStream
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	qemu-kvm-rhev-2.6.0-7.el7	Doc Type:	Bug Fix
Doc Text:	After applying the fix for security issue CVE-2016-3712, the installation of Windows 7 guests on Red Hat Enterprise Virtualization Hypervisor was not possible due to unmodifiable registers. This update introduces a new register set, sr_vbe, to be used instead of vga registers in Windows 7 guests. As a result, the vga registers no longer cause the guest installation to fail.	Story Points:	---
Clone Of:
Clones:	1346981 1346982 1347185 (view as bug list)		Environment:
Last Closed:	2016-11-07 21:17:52 UTC	Type:	Bug
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:
Bug Blocks:	1346981, 1346982, 1347185

Description Ademar Reis 2016-06-15 18:04:11 UTC

The fix for CVE-2016-3712 introduced a regression and we'll have to push a new update.

From the upstream patch:

"""
From: Gerd Hoffmann <kraxel>
Subject: [Qemu-devel] [PATCH] vga: add sr_vbe register set

Commit "fd3c136 vga: make sure vga register setup for vbe stays intact
(CVE-2016-3712)." causes a regression.  The win7 installer is unhappy
because it can't freely modify vga registers any more while in vbe mode.

This patch introduces a new sr_vbe register set.  The vbe_update_vgaregs
will fill sr_vbe[] instead of sr[].  Normal vga register reads and
writes go to sr[].  Any sr register read access happens through a new
sr() helper function which will read from sr_vbe[] with vbe active and
from sr[] otherwise.

This way we can allow guests update sr[] registers as they want, without
allowing them disrupt vbe video modes that way.

Reported-by: Thomas Lamprecht <thomas>
Signed-off-by: Gerd Hoffmann <kraxel>
"""

Comment 1 Miroslav Rezanina 2016-06-16 05:45:09 UTC

Fix included in qemu-kvm-rhev-2.6.0-7.el7

Comment 4 Guo, Zhiyi 2016-08-22 09:33:43 UTC

Reproduced on 7.3 host with
kernel: 3.10.0-468.el7.x86_64
qemu:qemu-kvm-rhev-2.6.0-6.el7.x86_64

Trying to install win7/win2008r2 guests, results:

iso:en_windows_7_ultimate_with_sp1_x86_dvd_u_677460.iso result: stuck at "starting windows"
iso:en_windows_7_ultimate_with_sp1_x64_dvd_u_677332.iso result: stuck at "starting windows" 
iso:en_windows_server_2008_r2_standard_enterprise_datacenter_and_web_with_sp1_x64_dvd_617601.iso result: stuck at "starting windows" 

Install win10 guests for comparing, win10 guests install and work well, isos used:
en_windows_10_enterprise_x64_dvd_6851151.iso
en_windows_10_enterprise_x86_dvd_6851156.iso

Verify against qemu-kvm-rhev-2.6.0-7.el7.x86_64

Both windows7/win2008r2 guests install and work well.
Install win10 guests for comparing, win10 guests install and work well also.

Comment 5 Guo, Zhiyi 2016-08-22 09:36:58 UTC

Move to verified per comment 4

Comment 7 errata-xmlrpc 2016-11-07 21:17:52 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-2673.html