linux-cve-announce - CVE-2025-68258: comedi: multiq3: sanitize config options in multiq3

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025121613-CVE-2025-68258-9a76@gregkh>
Date: Tue, 16 Dec 2025 15:45:15 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68258: comedi: multiq3: sanitize config options in multiq3_attach()

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

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

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

comedi: multiq3: sanitize config options in multiq3_attach()

Syzbot identified an issue [1] in multiq3_attach() that induces a
task timeout due to open() or COMEDI_DEVCONFIG ioctl operations,
specifically, in the case of multiq3 driver.

This problem arose when syzkaller managed to craft weird configuration
options used to specify the number of channels in encoder subdevice.
If a particularly great number is passed to s->n_chan in
multiq3_attach() via it->options[2], then multiple calls to
multiq3_encoder_reset() at the end of driver-specific attach() method
will be running for minutes, thus blocking tasks and affected devices
as well.

While this issue is most likely not too dangerous for real-life
devices, it still makes sense to sanitize configuration inputs. Enable
a sensible limit on the number of encoder chips (4 chips max, each
with 2 channels) to stop this behaviour from manifesting.

[1] Syzbot crash:
INFO: task syz.2.19:6067 blocked for more than 143 seconds.
...
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5254 [inline]
 __schedule+0x17c4/0x4d60 kernel/sched/core.c:6862
 __schedule_loop kernel/sched/core.c:6944 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6959
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7016
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2868
 chrdev_open+0x4cc/0x5e0 fs/char_dev.c:414
 do_dentry_open+0x953/0x13f0 fs/open.c:965
 vfs_open+0x3b/0x340 fs/open.c:1097
...

The Linux kernel CVE team has assigned CVE-2025-68258 to this issue.

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

	Issue introduced in 2.6.30 with commit 77e01cdbad5175f56027fd6fae00bd0fc175651a and fixed in 6.12.62 with commit 8952bc1973cd54158c35e06bfb8c29ace7375a48
	Issue introduced in 2.6.30 with commit 77e01cdbad5175f56027fd6fae00bd0fc175651a and fixed in 6.17.12 with commit 8dc2f02d3bada9247f00bfd2e5f61f68c389a0a3
	Issue introduced in 2.6.30 with commit 77e01cdbad5175f56027fd6fae00bd0fc175651a and fixed in 6.18.1 with commit 543f4c380c2e1f35e60528df7cb54705cda7fee3
	Issue introduced in 2.6.30 with commit 77e01cdbad5175f56027fd6fae00bd0fc175651a and fixed in 6.19-rc1 with commit f24c6e3a39fa355dabfb684c9ca82db579534e72

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-2025-68258
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:
	drivers/comedi/drivers/multiq3.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/8952bc1973cd54158c35e06bfb8c29ace7375a48
	https://git.kernel.org/stable/c/8dc2f02d3bada9247f00bfd2e5f61f68c389a0a3
	https://git.kernel.org/stable/c/543f4c380c2e1f35e60528df7cb54705cda7fee3
	https://git.kernel.org/stable/c/f24c6e3a39fa355dabfb684c9ca82db579534e72