Bug 1891087 (CVE-2020-27670)

Summary:	CVE-2020-27670 xen: unsafe AMD IOMMU page table updates (XSA-347)
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, ailan, bhu, bmasney, brdeoliv, dhoward, drjones, dvlasenk, fhrbata, hkrzesin, imammedo, jforbes, jshortt, jstancek, knoel, m.a.young, mrezanin, nmurray, pbonzini, ptalbert, robinlee.sysu, rvrbovsk, vkuznets, walters, xen-maint
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in Xen in the AMD IOMMU page table updates. This flaw allows a malicious guest to cause a denial of service, host data corruption, or potential privilege escalation. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-02 20:21:15 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:	1891088
Bug Blocks:	1891100

Description Guilherme de Almeida Suckevicz 2020-10-23 18:41:25 UTC

An issue was discovered in all versions of Xen allowing x86 guest OS users to cause a denial of service (data corruption), cause a data leak, or possibly gain privileges because an AMD IOMMU page-table entry can be half-updated.

Comment 1 Guilherme de Almeida Suckevicz 2020-10-23 18:41:41 UTC

Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1891088]

Comment 2 Mauro Matteo Cascella 2020-11-02 14:37:34 UTC

Acknowledgments:

Name: the Xen project

Comment 3 Mauro Matteo Cascella 2020-11-02 14:40:19 UTC

External References:

https://xenbits.xen.org/xsa/advisory-347.html

Comment 4 Mauro Matteo Cascella 2020-11-02 15:31:23 UTC

Upstream fix:
https://xenbits.xen.org/xsa/xsa347/xsa347-1.patch
https://xenbits.xen.org/xsa/xsa347/xsa347-2.patch
https://xenbits.xen.org/xsa/xsa347/xsa347-3.patch

Comment 5 Product Security DevOps Team 2020-11-02 20:21:15 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-27670

Comment 7 Mauro Matteo Cascella 2020-11-03 11:22:36 UTC

Mitigation:

Avoid passing through physical devices to untrusted guests.

Comment 8 RaTasha Tillery-Smith 2020-12-17 13:29:44 UTC

Statement:

This flaw has been rated as having a security impact of Moderate, and is not currently planned to be addressed in future updates of Red Hat Enterprise Linux 5. Red Hat Enterprise Linux 5 is now in the Extended Life Phase of the support and maintenance life cycle. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.