Bug 1566220 – CVE-2018-10471 xsa259 xen: x86 PV guest may crash Xen with XPTI

Bugzilla will be upgraded to version 5.0 on a still to be determined date in the near future. The original upgrade date has been delayed.

Bug 1566220 - (CVE-2018-10471) CVE-2018-10471 xsa259 xen: x86 PV guest may crash Xen with XPTI

Summary:	CVE-2018-10471 xsa259 xen: x86 PV guest may crash Xen with XPTI

Status:	CLOSED UPSTREAM

Aliases:	CVE-2018-10471

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	medium Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=moderate,public=20180425:1200,...
Keywords:	Security

Depends On:	1571878
Blocks:	1566223
	Show dependency tree / graph

Reported:	2018-04-11 15:36 EDT by Laura Pardo
Modified:	2018-08-28 07:25 EDT (History)
CC List:	14 users (show)

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:	An OOB write issue was found in the way Xen hypervisor handled error in the Page Table Isolation (PTI) implementation, used to fix the Meltdown issue. It could occur while processing interrupt 'INT 0x80', when PV guest's vCPU has no handler for it. A malicious guest user/process could use this flaw to crash the hypervisor resulting in denial of service issue.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2018-08-28 07:25:19 EDT
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
Add an attachment (proposed patch, testcase, etc.)

Groups: None (edit)

Description Laura Pardo 2018-04-11 15:36:32 EDT

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

The workaround for the Meltdown vulnerability (XSA-254) failed to deal
with an error code path connecting the INT 80 handling with general
exception handling. This results in an unconditional write attempt of
the value zero to an address near 2^64, in cases where a PV guest has no
handler installed for INT 80 on one of its vCPU-s.

IMPACT
======

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

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

All Xen versions which the XSA-254 fixes were applied to are vulnerable.

Only x86 systems are vulnerable. ARM systems are not vulnerable.

Only x86 PV guests can exploit the vulnerability. x86 PVH and HVM
guests cannot exploit the vulnerability.

MITIGATION
==========

Running only PVH or HVM guests avoids the vulnerability.

Comment 1 Adam Mariš 2018-04-25 10:54:14 EDT

Acknowledgments:

Name: the Xen project
Upstream: Andrew Cooper (Citrix)

Comment 2 Adam Mariš 2018-04-25 10:54:25 EDT

External References:

https://xenbits.xen.org/xsa/advisory-259.html

Comment 3 Adam Mariš 2018-04-25 11:07:20 EDT

Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1571878]

Note You need to log in before you can comment on or make changes to this bug.