---
id: CVE-2025-68257
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  comedi: check device's attached status in compat ioctls

  Syzbot identified an issue [1] that crashes kernel, seemingly due to
  unexistent callback dev->get_valid_routes(…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  comedi: check device's attached status in compat ioctls

  Syzbot identified an issue [1] that crashes kernel, seemingly due to
  unexistent callback dev->get_valid_routes(…
severity: none
published: '2025-12-16'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68257'
references:
  - url: 'https://git.kernel.org/stable/c/0de7d9cd07a2671fa6089173bccc0b2afe6b93ee'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4836ba483a22ebd076c8faaf8293a7295fad4142'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/573b07d2e3d473ee7eb625ef87519922cf01168d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7141915bf0c41cb57d83cdbaf695b8c731b16b71'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/aac80e912de306815297a3b74f0426873ffa7dc3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b975f91de5f8f63cf490f0393775cc795f8b0557'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f13895c03620933a58907e3250016f087e39b78c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f6e629dfe6f590091c662a87c9fcf118b1c1c7dc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00197
epssPercentile: 0.08752
ingestedAt: '2026-10-14T13:30:58.469Z'
---

## Overview

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

comedi: check device's attached status in compat ioctls

Syzbot identified an issue [1] that crashes kernel, seemingly due to
unexistent callback dev->get_valid_routes(). By all means, this should
not occur as said callback must always be set to
get_zero_valid_routes() in __comedi_device_postconfig().

As the crash seems to appear exclusively in i386 kernels, at least,
judging from [1] reports, the blame lies with compat versions
of standard IOCTL handlers. Several of them are modified and
do not use comedi_unlocked_ioctl(). While functionality of these
ioctls essentially copy their original versions, they do not
have required sanity check for device's attached status. This,
in turn, leads to a possibility of calling select IOCTLs on a
device that has not been properly setup, even via COMEDI_DEVCONFIG.

Doing so on unconfigured devices means that several crucial steps
are missed, for instance, specifying dev->get_valid_routes()
callback.

Fix this somewhat crudely by ensuring device's attached status before
performing any ioctls, improving logic consistency between modern
and compat functions.

[1] Syzbot report:
BUG: kernel NULL pointer dereference, address: 0000000000000000
...
CR2: ffffffffffffffd6 CR3: 000000006c717000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 get_valid_routes drivers/comedi/comedi_fops.c:1322 [inline]
 parse_insn+0x78c/0x1970 drivers/comedi/comedi_fops.c:1401
 do_insnlist_ioctl+0x272/0x700 drivers/comedi/comedi_fops.c:1594
 compat_insnlist drivers/comedi/comedi_fops.c:3208 [inline]
 comedi_compat_ioctl+0x810/0x990 drivers/comedi/comedi_fops.c:3273
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
...

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.