Bug 1995249 (CVE-2021-3732)

Summary:	CVE-2021-3732 kernel: overlayfs: Mounting overlayfs inside an unprivileged user namespace can reveal files
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
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, allarkin, bhu, brdeoliv, bskeggs, chwhite, crwood, dhoward, dvlasenk, fhrbata, fpacheco, hdegoede, hkrzesin, jarod, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, nmurray, ptalbert, qzhao, rvrbovsk, steved, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.14 rc6	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the Linux kernel’s OverlayFS subsystem in the way the user mounts the TmpFS filesystem with OverlayFS. This flaw allows a local user to gain access to hidden files that should not be accessible.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-11-09 21:53:49 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:	1993131, 1996405, 1996406, 2000964
Bug Blocks:	1995250, 2003966

Description Pedro Sampaio 2021-08-18 16:53:59 UTC

A flaw was found in the Linux kernels implementation of overlayfs where a local attacker with an unpriviledged account who has the ability to mount a filesystem can abuse a logic bug in the overlayfs code which can inadvertantly reveal files hidden in the orignal mount.


References:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=427215d85e8d
https://bugzilla.redhat.com/show_bug.cgi?id=1993131

Comment 6 juneau 2021-08-23 13:52:22 UTC

Marking Hosted OCP 4.x affected/delegated. (3.x unaffected)

Comment 8 Petr Matousek 2021-09-03 12:16:03 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2000964]

Comment 9 Justin M. Forbes 2021-09-03 15:18:40 UTC

This was fixed for Fedora with the 5.13.11 stable kernel update.

Comment 11 errata-xmlrpc 2021-11-09 17:24:03 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 12 errata-xmlrpc 2021-11-09 18:28:03 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 13 Product Security DevOps Team 2021-11-09 21:53:45 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-2021-3732