Bug 2502204 (CVE-2026-53381)

Summary:	CVE-2026-53381 kernel: virtiofs: fix UAF on submount umount
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the virtiofs component of the Linux kernel. A use-after-free (UAF) vulnerability exists during submount unmount operations. This occurs because the `iput()` function, called from `fuse_release_end()`, can attempt to access a super block that has already been destroyed. This can lead to a kernel panic, resulting in a denial of service.	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:

Description OSIDB Bzimport 2026-07-19 13:01:43 UTC

In the Linux kernel, the following vulnerability has been resolved:

virtiofs: fix UAF on submount umount

iput() called from fuse_release_end() can Oops if the super block has
already been destroyed.  Normally this is prevented by waiting for
num_waiting to go down to zero before commencing with super block shutdown.

This only works, however, for the last submount instance, as the wait
counter is per connection, not per superblock.

Revert to using synchronous release requests for the auto_submounts case,
which is virtiofs only at this time.

Comment 1 Keith Grant 2026-07-20 13:21:46 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071931-CVE-2026-53381-73c3@gregkh/T