Bug 1941762 (CVE-2021-28950)

Summary:	CVE-2021-28950 kernel: fuse: stall on CPU can occur because a retry loop continually finds the same bad inode
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bdettelb, bhu, blc, bmasney, brdeoliv, bskeggs, chwhite, crwood, dhoward, dvlasenk, fhrbata, fpacheco, hdegoede, hkrzesin, ikent, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jpazdziora, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rvrbovsk, steved, tomckay, 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 denial of service in the kernel side of the FUSE functionality can allow a local system to create a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-11-15 11:31:29 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:	1946535, 1941763, 1944483, 1944484, 1944489, 1949873, 2015840, 2015841
Bug Blocks:	1941764

Description Guilherme de Almeida Suckevicz 2021-03-22 18:10:47 UTC

An issue was discovered in fs/fuse/fuse_i.h in the Linux kernel before 5.11.8. A "stall on CPU" can occur because a retry loop continually finds the same bad inode.

Reference and upstream patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=775c5033a0d164622d9d10dd0f0a5531639ed3ed

Comment 1 Guilherme de Almeida Suckevicz 2021-03-22 18:11:34 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1941763]

Comment 5 Wade Mealing 2021-03-30 02:18:11 UTC

Mitigation:


As the FUSE module will be auto-loaded when required, its use can be disabled  by preventing the module from loading with the following instructions:

# echo "install fuse /bin/true" >> /etc/modprobe.d/disable-fuse.conf

The system will need to be restarted if the FUSE modules are loaded. In most circumstances, the CIFS kernel modules will be unable to be unloaded while the FUSE filesystems are in  use.

If the system requires this module to work correctly, this mitigation may not be suitable.

If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services.

Comment 24 errata-xmlrpc 2021-11-09 17:21:54 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4140 https://access.redhat.com/errata/RHSA-2021:4140

Comment 25 errata-xmlrpc 2021-11-09 18:24:14 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4356 https://access.redhat.com/errata/RHSA-2021:4356

Comment 26 errata-xmlrpc 2021-11-15 10:13:09 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Extended Update Support

Via RHSA-2021:4648 https://access.redhat.com/errata/RHSA-2021:4648

Comment 27 errata-xmlrpc 2021-11-15 11:06:06 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Extended Update Support

Via RHSA-2021:4650 https://access.redhat.com/errata/RHSA-2021:4650

Comment 28 Product Security DevOps Team 2021-11-15 11:31:25 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-2021-28950