linux-cve-announce - CVE-2025-40242: gfs2: Fix unlikely race in gdlm_put

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Message-ID: <2025120403-CVE-2025-40242-8f73@gregkh>
Date: Thu,  4 Dec 2025 16:32:17 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40242: gfs2: Fix unlikely race in gdlm_put_lock

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

gfs2: Fix unlikely race in gdlm_put_lock

In gdlm_put_lock(), there is a small window of time in which the
DFL_UNMOUNT flag has been set but the lockspace hasn't been released,
yet.  In that window, dlm may still call gdlm_ast() and gdlm_bast().
To prevent it from dereferencing freed glock objects, only free the
glock if the lockspace has actually been released.

The Linux kernel CVE team has assigned CVE-2025-40242 to this issue.


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

	Fixed in 6.12.56 with commit 279bde3bbb0ac0bad5c729dfa85983d75a5d7641
	Fixed in 6.17.6 with commit 64c61b4ac645222fa7b724cef616c1f862a72a40
	Fixed in 6.18 with commit 28c4d9bc0708956c1a736a9e49fee71b65deee81

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-2025-40242
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/gfs2/lock_dlm.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/279bde3bbb0ac0bad5c729dfa85983d75a5d7641
	https://git.kernel.org/stable/c/64c61b4ac645222fa7b724cef616c1f862a72a40
	https://git.kernel.org/stable/c/28c4d9bc0708956c1a736a9e49fee71b65deee81