linux-cve-announce - CVE-2022-49281: cifs: fix handlecache and multiuser

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Message-ID: <2025022631-CVE-2022-49281-4365@gregkh>
Date: Wed, 26 Feb 2025 02:58:06 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49281: cifs: fix handlecache and multiuser

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

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

cifs: fix handlecache and multiuser

In multiuser each individual user has their own tcon structure for the
share and thus their own handle for a cached directory.
When we umount such a share we much make sure to release the pinned down dentry
for each such tcon and not just the master tcon.

Otherwise we will get nasty warnings on umount that dentries are still in use:
[ 3459.590047] BUG: Dentry 00000000115c6f41{i=12000000019d95,n=/}  still in use\
 (2) [unmount of cifs cifs]
...
[ 3459.590492] Call Trace:
[ 3459.590500]  d_walk+0x61/0x2a0
[ 3459.590518]  ? shrink_lock_dentry.part.0+0xe0/0xe0
[ 3459.590526]  shrink_dcache_for_umount+0x49/0x110
[ 3459.590535]  generic_shutdown_super+0x1a/0x110
[ 3459.590542]  kill_anon_super+0x14/0x30
[ 3459.590549]  cifs_kill_sb+0xf5/0x104 [cifs]
[ 3459.590773]  deactivate_locked_super+0x36/0xa0
[ 3459.590782]  cleanup_mnt+0x131/0x190
[ 3459.590789]  task_work_run+0x5c/0x90
[ 3459.590798]  exit_to_user_mode_loop+0x151/0x160
[ 3459.590809]  exit_to_user_mode_prepare+0x83/0xd0
[ 3459.590818]  syscall_exit_to_user_mode+0x12/0x30
[ 3459.590828]  do_syscall_64+0x48/0x90
[ 3459.590833]  entry_SYSCALL_64_after_hwframe+0x44/0xae

The Linux kernel CVE team has assigned CVE-2022-49281 to this issue.


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

	Fixed in 5.15.33 with commit 2fafbc198613823943c106d1ec9b516da692059f
	Fixed in 5.16.19 with commit ffa631c4bff59dde59b598011f570e27dfba3515
	Fixed in 5.17.2 with commit e71f6a3a1d5c826a30384fec587ca7503ef6bde5
	Fixed in 5.18 with commit 47178c7722ac528ea08aa82c3ef9ffa178962d7a

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-2022-49281
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/cifs/cifsfs.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/2fafbc198613823943c106d1ec9b516da692059f
	https://git.kernel.org/stable/c/ffa631c4bff59dde59b598011f570e27dfba3515
	https://git.kernel.org/stable/c/e71f6a3a1d5c826a30384fec587ca7503ef6bde5
	https://git.kernel.org/stable/c/47178c7722ac528ea08aa82c3ef9ffa178962d7a