Bug 1941804 (CVE-2021-28964)

Summary:	CVE-2021-28964 kernel: race condition in get_old_root function in fs/btrfs/ctree.c because of a lack of locking on an extent buffer before a cloning operation
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bhu, blc, bmasney, chwhite, crwood, dvlasenk, hdegoede, hkrzesin, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rkeshri, rvrbovsk, steved, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.12 rc4	Doc Type:	If docs needed, set a value
Doc Text:	A race condition flaw was found in get_old_root in fs/btrfs/ctree.c in the Linux kernel in btrfs file-system. This flaw allows a local attacker with a special user privilege to cause a denial of service due to not locking an extent buffer before a cloning operation. The highest threat from this vulnerability is to system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:		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:	1941805, 1950249, 1950250
Bug Blocks:	1941806

Description Guilherme de Almeida Suckevicz 2021-03-22 19:40:47 UTC

A race condition flaw was found in get_old_root in fs/btrfs/ctree.c in the Linux kernel in btrfs file-system. This flaw allows a local attacker with a special user privilege to cause a denial of service due to not locking an extent buffer before a cloning operation. The highest threat from this vulnerability is to system availability.

Reference and upstream patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dbcc7d57bffc0c8cac9dac11bec548597d59a6a5

Comment 1 Guilherme de Almeida Suckevicz 2021-03-22 19:41:49 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1941805]

Comment 4 Rohit Keshri 2021-04-16 08:15:00 UTC

Mitigation:

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Comment 7 Rohit Keshri 2021-04-16 08:49:54 UTC

Statement:

This issue affected Linux kernel versions as shipped with Red Hat Enterprise Linux 7  / 7-RT.