linux-cve-announce - CVE-2025-21955: ksmbd: prevent connection release during oplock break notification

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Message-ID: <2025040143-CVE-2025-21955-c393@gregkh>
Date: Tue,  1 Apr 2025 16:45:40 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21955: ksmbd: prevent connection release during oplock break notification

Description
===========

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

ksmbd: prevent connection release during oplock break notification

ksmbd_work could be freed when after connection release.
Increment r_count of ksmbd_conn to indicate that requests
are not finished yet and to not release the connection.

The Linux kernel CVE team has assigned CVE-2025-21955 to this issue.


Affected and fixed versions
===========================

	Fixed in 6.6.84 with commit 09aeab68033161cb54f194da93e51a11aee6144b
	Fixed in 6.12.20 with commit a4261bbc33fbf99b99c80aa3a2c5097611802980
	Fixed in 6.13.8 with commit f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa
	Fixed in 6.14 with commit 3aa660c059240e0c795217182cf7df32909dd917

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-21955
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/smb/server/connection.c
	fs/smb/server/connection.h
	fs/smb/server/oplock.c
	fs/smb/server/server.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/09aeab68033161cb54f194da93e51a11aee6144b
	https://git.kernel.org/stable/c/a4261bbc33fbf99b99c80aa3a2c5097611802980
	https://git.kernel.org/stable/c/f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa
	https://git.kernel.org/stable/c/3aa660c059240e0c795217182cf7df32909dd917