# CVE-2026-90144: dpll: fix NULL deref in dpll_device_ops() during teardown race

> A race condition in the Linux kernel DPLL subsystem causes a NULL pointer dereference and system crash when a device is unregistered while a pin notification is pending.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-90144, DEBIAN-CVE-2026-90144, GHSA-3x44-vfgm-9v7x, UBUNTU-CVE-2026-90144

## What is CVE-2026-90144?

CVE-2026-90144 is a vulnerability in Linux, published on 17 Sep 2026. 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:

dpll: fix NULL deref in dpll_device_ops() during teardown race

When the last owner of a dpll device unregisters while a foreign driver
still holds a pin on it via dpll_pin_on_pin_register(), the dpll object
stays alive with an empty registration list. A pin notification queued
before the unregister (e.g. ice reacting to zl3073x_i2c removal) then
walks pin->dpll_refs into dpll_device_ops(), which trips the WARN_ON and
dereferences the missing registration. dpll_lock cannot help because the
notification work was queued before the unregistering driver took the
lock.

Treat the empty registration list as a legitimate transient state. Make
dpll_priv() and dpll_device_ops() return NULL in that case and make
every pin netlink path that resolves a device from a pin skip such
dplls. dpll_cmd_pin_get_one() picks a ref with a live registration and
returns -ENODEV when there is none, the pin dumpit skips such a pin
instead of aborting the dump, dpll_msg_add_pin_dplls() and the
frequency, esync, reference sync and phase adjust set paths skip dead
refs, and dpll_pin_parent_device_set() validates the parent with
dpll_device_get_by_id(). dpll_pin_register() is the last caller that
dereferenced the device ops without a check, so move its frequency
monitor validation under dpll_lock and tolerate a missing registration
there as well.

The empty registration list is equivalent to a cleared DPLL_REGISTERED
mark, both transitions happen under dpll_lock in dpll_device_register()
and dpll_device_unregister(). A pin notification for a pin whose dplls
are all gone is now dropped with -ENODEV instead of crashing, all
callers in the core ignore that return value.

 WARNING: drivers/dpll/dpll_core.c:1092 at dpll_device_ops+0x24/0x40,
 CPU#83: kworker/u576:3/23471
 Modules linked in: ... ice ... zl3073x_i2c(-) ... zl3073x ...
 Workqueue: ice_dpll_wq ice_dpll_pin_notify_work [ice]
 RIP: 0010:dpll_device_ops+0x24/0x40
 Call Trace:
  <TASK>
  dpll_cmd_pin_get_one+0x336/0x520
  dpll_pin_event_send+0x82/0x140
  dpll_pin_on_pin_unregister+0xbb/0x160
  ice_dpll_pin_notify_work+0x1bc/0x1f0 [ice]
  process_one_work+0x19e/0x370
  worker_thread+0x1a6/0x310
  kthread+0xe4/0x120
  ret_from_fork+0x1a1/0x270
  ret_from_fork_asm+0x1a/0x30
  </TASK>
 ---[ end trace 0000000000000000 ]---
 BUG: kernel NULL pointer dereference, address: 0000000000000010
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page

## Which versions are affected by CVE-2026-90144?


## How do I fix CVE-2026-90144?

Apply the vendor's patch.

## Is CVE-2026-90144 being exploited?

There is no known exploitation of CVE-2026-90144 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90144 and fix it if it is affected.

What it is: CVE-2026-90144 is a vulnerability in Linux, published on 17 Sep 2026. 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-2026-90144 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-2026-90144/ (Markdown: https://insights.sbomify.com/CVE-2026-90144/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90144
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90144
- OSV: https://osv.dev/vulnerability/CVE-2026-90144

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90144/
Summaries are generated and may contain mistakes; the official description above is the record.