linux-cve-announce - CVE-2025-21672: afs: Fix merge preference rule failure condition

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Message-ID: <2025013100-CVE-2025-21672-cd35@gregkh>
Date: Fri, 31 Jan 2025 12:31:04 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21672: afs: Fix merge preference rule failure condition

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

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

afs: Fix merge preference rule failure condition

syzbot reported a lock held when returning to userspace[1].  This is
because if argc is less than 0 and the function returns directly, the held
inode lock is not released.

Fix this by store the error in ret and jump to done to clean up instead of
returning directly.

[dh: Modified Lizhi Xu's original patch to make it honour the error code
from afs_split_string()]

[1]
WARNING: lock held when returning to user space!
6.13.0-rc3-syzkaller-00209-g499551201b5f #0 Not tainted
------------------------------------------------
syz-executor133/5823 is leaving the kernel with locks still held!
1 lock held by syz-executor133/5823:
 #0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: afs_proc_addr_prefs_write+0x2bb/0x14e0 fs/afs/addr_prefs.c:388

The Linux kernel CVE team has assigned CVE-2025-21672 to this issue.


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

	Fixed in 6.12.11 with commit 22be1d90a6211c88dd093b25d1f3aa974d0d9f9d
	Fixed in 6.13 with commit 17a4fde81d3a7478d97d15304a6d61094a10c2e3

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-2025-21672
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/afs/addr_prefs.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/22be1d90a6211c88dd093b25d1f3aa974d0d9f9d
	https://git.kernel.org/stable/c/17a4fde81d3a7478d97d15304a6d61094a10c2e3