Bug 2467071 (CVE-2026-43215)

Summary:	CVE-2026-43215 kernel: cifs: Fix locking usage for tcon fields
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
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 Linux kernel's Common Internet File System (CIFS) implementation. Incorrect locking mechanisms were used for `tcon` fields, where the `cifs_tcp_ses_lock` was applied too broadly instead of more granular locks. This improper locking could lead to concurrency issues within the kernel, potentially resulting in system instability or a denial of service (DoS).	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 2026-05-06 13:02:43 UTC

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

cifs: Fix locking usage for tcon fields

We used to use the cifs_tcp_ses_lock to protect a lot of objects
that are not just the server, ses or tcon lists. We later introduced
srv_lock, ses_lock and tc_lock to protect fields within the
corresponding structs. This was done to provide a more granular
protection and avoid unnecessary serialization.

There were still a couple of uses of cifs_tcp_ses_lock to provide
tcon fields. In this patch, I've replaced them with tc_lock.

Comment 1 Keith Grant 2026-05-06 21:52:56 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050650-CVE-2026-43215-7e04@gregkh/T