Bug 670858 (CVE-2018-18883, XSA-282)

Summary:	<app-emulation/xen-{4.10.2-r1,4.11.0-r3}: multiple vulnerabilities (XSA-{278,282})
Product:	Gentoo Security	Reporter:	GLSAMaker/CVETool Bot <glsamaker>
Component:	Vulnerabilities	Assignee:	Gentoo Security <security>
Status:	RESOLVED FIXED
Severity:	minor	CC:	hydrapolic, xen
Priority:	Normal	Flags:	stable-bot: sanity-check+
Version:	unspecified
Hardware:	All
OS:	Linux
Whiteboard:	B3 [noglsa cve]
Package list:	app-emulation/xen-pvgrub-4.10.2 amd64 x86 app-emulation/xen-tools-4.10.2-r1 amd64 x86 app-emulation/xen-4.10.2-r1 amd64	Runtime testing required:	---

Description GLSAMaker/CVETool Bot gentoo-dev

2018-11-10 21:23:12 UTC

CVE-2018-18883 (https://nvd.nist.gov/vuln/detail/CVE-2018-18883):
  An issue was discovered in Xen 4.9.x through 4.11.x, on Intel x86 platforms,
  allowing x86 HVM and PVH guests to cause a host OS denial of service (NULL
  pointer dereference) or possibly have unspecified other impact because
  nested VT-x is not properly restricted.


IMPACT
======

Guest software which blindly plays with the VT-x instructions can cause Xen to operate on uninitialised data.  As the backing memory is zeroed, this causes Xen to suffer a NULL pointer dereference, causing a host Denial of Service.

Other behaviours such as memory corruption or privilege escalation have not been ruled out.

Comment 1 Mikle Kolyada (RETIRED) archtester

2018-11-11 10:57:25 UTC

amd64 stable

Comment 2 Thomas Deutschmann (RETIRED) gentoo-dev

2018-11-12 01:16:30 UTC

x86 stable

Comment 3 Tomáš Mózes 2018-11-12 04:57:23 UTC

Please also stabilize app-emulation/xen-pvgrub on amd64, x86, thanks.

Comment 4 Mikle Kolyada (RETIRED) archtester

2018-11-12 07:06:29 UTC

amd64 stable

Comment 5 Yury German Gentoo Infrastructure

2018-11-13 05:41:37 UTC

XSA-282 - Awaiting CVE
https://xenbits.xen.org/xsa/advisory-282.html

Comment 6 Thomas Deutschmann (RETIRED) gentoo-dev

2018-11-15 15:51:42 UTC

x86 stable

Comment 7 D'juan McDonald (domhnall) 2018-11-25 01:32:26 UTC

(In reply to Yury German from comment #5)
>XSA-282 - Awaiting CVE 

CVE  	CVE-2017-17044 assigned.

 Xen Security Advisory XSA-282

             guest use of HLE constructs may lock up host

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

Various Intel CPU models have an erratum listed under the title
"Processor May Hang When Executing Code In an HLE Transaction".  It
describes a potential hang when using instructions with the XACQUIRE
prefix on the host physical memory range covering the first 4 MiB
starting at the 1GiB boundary.

IMPACT
======

A malicious or buggy guest may cause a CPU to hang, resulting in a DoS
(Denial of Service) affecting the entire host.

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

All Xen versions are affected.

Only Intel based x86 systems are affected.  Please refer to Intel
documentation as to which specific CPU models are affected.

AMD x86 systems as well as Arm ones are not affected.

MITIGATION
==========

There is no known mitigation.  A BIOS update may be available for some
systems, working around the issue at the firmware level.

RESOLUTION
==========

Applying the appropriate pair of attached patches works around this issue
for the CPU models known to be affected at the time of writing.

xsa282-?.patch                              xen-unstable
xsa282-4.11-1.patch + xsa282-2.patch        Xen 4.11.x, Xen 4.10.x
xsa282-4.9-1.patch + xsa282-2.patch         Xen 4.9.x
xsa282-4.9-1.patch + xsa282-4.8-2.patch     Xen 4.8.x, Xen 4.7.x