Bug 1928716 (CVE-2020-27066)

Summary:	CVE-2020-27066 kernel: use after free in xfrm6_tunnel_free_spi of net/ipv6/xfrm6_tunnel.c leads to local escalation of privilege
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, allarkin, bhu, blc, bmasney, brdeoliv, bskeggs, chwhite, dhoward, dvlasenk, fhrbata, hdegoede, hkrzesin, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rvrbovsk, steved, walters, williams
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 the Linux kernel. There is a possible use after free due to improper locking. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-04-06 17:35:39 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:	1928717
Bug Blocks:	1928718

Description Marian Rehak 2021-02-15 12:46:23 UTC

In xfrm6_tunnel_free_spi of net/ipv6/xfrm6_tunnel.c, there is a possible use after free due to improper locking. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.

External Reference:

https://source.android.com/security/bulletin/pixel/2020-12-01
https://www.linuxkernelcves.com/cves/CVE-2020-27066

Comment 1 Marian Rehak 2021-02-15 12:47:08 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1928717]

Comment 5 Alex 2021-04-01 09:54:23 UTC

Statement:

This flaw is rated as having Low impact because of the need to have elevated privileges and both configuration with the usage of IPV6.

Comment 6 Alex 2021-04-01 09:57:52 UTC

Mitigation:

To mitigate this issue, prevent the module xfrm6_tunnel from being loaded.
Please see https://access.redhat.com/solutions/41278 for information on how to blacklist a kernel module to prevent it from loading automatically.

Comment 7 Product Security DevOps Team 2021-04-06 17:35:39 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-2020-27066

Comment 8 Justin M. Forbes 2021-04-13 15:59:13 UTC

This was fixed for Fedora with the 5.5.14 stable kernel updates.