Bug 2013242 (CVE-2021-20321) - CVE-2021-20321 kernel: In Overlayfs missing a check for a negative dentry before calling vfs_rename()
Summary: CVE-2021-20321 kernel: In Overlayfs missing a check for a negative dentry bef...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2021-20321
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2010887 2011181 2013304 2013305 2013317 2013318 2013713 2016378 2026897
Blocks: 2011920 2013544
TreeView+ depends on / blocked
 
Reported: 2021-10-12 12:36 UTC by Alex
Modified: 2022-05-17 09:38 UTC (History)
44 users (show)

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.
Clone Of:
Environment:
Last Closed: 2022-05-11 11:16:31 UTC


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:5227 0 None None None 2021-12-21 09:42:47 UTC
Red Hat Product Errata RHSA-2021:5241 0 None None None 2021-12-21 09:30:33 UTC

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.

Reference:
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):

https://access.redhat.com/security/cve/cve-2021-20321


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