Bug 1970536 (CVE-2021-28691)

Summary:	CVE-2021-28691 xen: guest triggered use-after-free in Linux xen-netback (XSA-374)
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bskeggs, hdegoede, jarodwilson, jeremy, jforbes, jglisse, jonathan, josef, jwboyer, kernel-maint, lgoncalv, linville, masami256, m.a.young, mchehab, ptalbert, steved
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-06-10 21:04:03 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:	1970537, 1971599
Bug Blocks:	1970612

Description Guilherme de Almeida Suckevicz 2021-06-10 16:29:31 UTC

A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

Reference:
https://xenbits.xen.org/xsa/advisory-374.html

Comment 1 Guilherme de Almeida Suckevicz 2021-06-10 16:30:02 UTC

Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1970537]

Comment 2 Product Security DevOps Team 2021-06-10 21:04:03 UTC

This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.

Comment 3 Petr Matousek 2021-06-14 12:21:10 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1971599]

Comment 4 Justin M. Forbes 2021-06-15 15:33:02 UTC

This was fixed for Fedora with the 5.12.10 stable kernel updates.