Bug 2013242 (CVE-2021-20321)

Summary: CVE-2021-20321 kernel: In Overlayfs missing a check for a negative dentry before calling vfs_rename()
Product: [Other] Security Response Reporter: Alex <allarkin>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: acaringi, adscvr, airlied, alciregi, bhu, brdeoliv, bskeggs, chwhite, dhoward, dvlasenk, eshatokhin, fhrbata, fpacheco, hdegoede, hkrzesin, jarod, jarodwilson, jburrell, jeremy, jforbes, jglisse, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mszeredi, nmurray, ptalbert, qzhao, rvrbovsk, steved, swood, vkumar, walters, williams
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: kernel 5.15-rc5 Doc Type: If docs needed, set a value
Doc Text:
A race condition accessing file object in the Linux kernel OverlayFS subsystem was found in the way users do rename in specific way with OverlayFS. A local user could use this flaw to crash the system.
Story Points: ---
Clone Of: Environment:
Last Closed: 2022-05-11 11:16:31 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 2010887, 2011181, 2013304, 2013305, 2013317, 2013318, 2013713, 2016378, 2026897    
Bug Blocks: 2011920, 2013544    

Description Alex 2021-10-12 12:36:50 UTC
An attacker with a low-privileged user on a Linux machine with an overlay mount can escalate his privileges up to root when performing rename in specific way with this overlayfs.

a295aef603e1 ("ovl: fix missing negative dentry check in ovl_rename()")

Comment 21 errata-xmlrpc 2021-12-21 09:30:29 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:5241 https://access.redhat.com/errata/RHSA-2021:5241

Comment 22 errata-xmlrpc 2021-12-21 09:42:44 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:5227 https://access.redhat.com/errata/RHSA-2021:5227

Comment 25 Product Security DevOps Team 2022-05-11 11:16:28 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):