# CVE-2025-68258: comedi: multiq3: sanitize config options in multiq3\_attach()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-16 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.30

## 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 ...

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/f9ff87aac7b37d462246c46d28912d382a8e2ea6
- https://git.kernel.org/stable/c/4cde9a7e025cc09b88097c70606f6b30c22880f4
- https://git.kernel.org/stable/c/ad7ed3c9c7b8408e8612697bc43a5441fe386c71
- https://git.kernel.org/stable/c/049f14557450351750f929ebfff36d849511e132
- 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

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