# CVE-2025-68332: comedi: c6xdigio: Fix invalid PNP driver unregistration

> A local attacker can trigger a kernel warning and potential instability by exploiting improper PNP driver unregistration in the c6xdigio Comedi driver.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-68332, DEBIAN-CVE-2025-68332, GHSA-g8jv-c3w8-hc32, ROOT-OS-DEBIAN-12-CVE-2025-68332, ROOT-OS-DEBIAN-13-CVE-2025-68332, ROOT-OS-UBUNTU-2204-CVE-2025-68332, ROOT-OS-UBUNTU-2404-CVE-2025-68332, UBUNTU-CVE-2025-68332

## What is CVE-2025-68332?

CVE-2025-68332 is a vulnerability in Linux, published on 22 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

comedi: c6xdigio: Fix invalid PNP driver unregistration

The Comedi low-level driver "c6xdigio" seems to be for a parallel port
connected device.  When the Comedi core calls the driver's Comedi
"attach" handler `c6xdigio_attach()` to configure a Comedi to use this
driver, it tries to enable the parallel port PNP resources by
registering a PNP driver with `pnp_register_driver()`, but ignores the
return value.  (The `struct pnp_driver` it uses has only the `name` and
`id_table` members filled in.)  The driver's Comedi "detach" handler
`c6xdigio_detach()` unconditionally unregisters the PNP driver with
`pnp_unregister_driver()`.

It is possible for `c6xdigio_attach()` to return an error before it
calls `pnp_register_driver()` and it is possible for the call to
`pnp_register_driver()` to return an error (that is ignored).  In both
cases, the driver should not be calling `pnp_unregister_driver()` as it
does in `c6xdigio_detach()`.  (Note that `c6xdigio_detach()` will be
called by the Comedi core if `c6xdigio_attach()` returns an error, or if
the Comedi core decides to detach the Comedi device from the driver for
some other reason.)

The unconditional call to `pnp_unregister_driver()` without a previous
successful call to `pnp_register_driver()` will cause
`driver_unregister()` to issue a warning "Unexpected driver
unregister!".  This was detected by Syzbot [1].

Also, the PNP driver registration and unregistration should be done at
module init and exit time, respectively, not when attaching or detaching
Comedi devices to the driver.  (There might be more than one Comedi
device being attached to the driver, although that is unlikely.)

Change the driver to do the PNP driver registration at module init time,
and the unregistration at module exit time.  Since `c6xdigio_detach()`
now only calls `comedi_legacy_detach()`, remove the function and change
the Comedi driver "detach" handler to `comedi_legacy_detach`.

-------------------------------------------
[1] Syzbot sample crash report:
Unexpected driver unregister!
WARNING: CPU: 0 PID: 5970 at drivers/base/driver.c:273 driver_unregister drivers/base/driver.c:273 [inline]
WARNING: CPU: 0 PID: 5970 at drivers/base/driver.c:273 driver_unregister+0x90/0xb0 drivers/base/driver.c:270
Modules linked in:
CPU: 0 UID: 0 PID: 5970 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:driver_unregister drivers/base/driver.c:273 [inline]
RIP: 0010:driver_unregister+0x90/0xb0 drivers/base/driver.c:270
Code: 48 89 ef e8 c2 e6 82 fc 48 89 df e8 3a 93 ff ff 5b 5d e9 c3 6d d9 fb e8 be 6d d9 fb 90 48 c7 c7 e0 f8 1f 8c e8 51 a2 97 fb 90 <0f> 0b 90 90 5b 5d e9 a5 6d d9 fb e8 e0 f4 41 fc eb 94 e8 d9 f4 41
RSP: 0018:ffffc9000373f9a0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffffffff8ff24720 RCX: ffffffff817b6ee8
RDX: ffff88807c932480 RSI: ffffffff817b6ef5 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffffffff8ff24660
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88814cca0000
FS:  000055556dab1500(0000) GS:ffff8881249d9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f77f285cd0 CR3: 000000007d871000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 comedi_device_detach_locked+0x12f/0xa50 drivers/comedi/drivers.c:207
 comedi_device_detach+0x67/0xb0 drivers/comedi/drivers.c:215
 comedi_device_attach+0x43d/0x900 drivers/comedi/drivers.c:1011
 do_devconfig_ioctl+0x1b1/0x710 drivers/comedi/comedi_fops.c:872
 comedi_unlocked_ioctl+0x165d/0x2f00 drivers/comedi/comedi_fops.c:2178
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_sys
---truncated---

## Which versions are affected by CVE-2025-68332?


## How do I fix CVE-2025-68332?

Apply the vendor's patch.

## Is CVE-2025-68332 being exploited?

There is no known exploitation of CVE-2025-68332 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68332 and fix it if it is affected.

What it is: CVE-2025-68332 is a vulnerability in Linux, published on 22 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-68332 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-68332/ (Markdown: https://insights.sbomify.com/CVE-2025-68332/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68332
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68332
- OSV: https://osv.dev/vulnerability/CVE-2025-68332

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68332/
Summaries are generated and may contain mistakes; the official description above is the record.