---
id: CVE-2026-89955
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/vfio-ap: Fix NULL deref in status_show() during queue probe

  When vfio_ap_mdev_probe_queue() creates the sysfs attribute group,
  the queue's driver data has not yet…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/vfio-ap: Fix NULL deref in status_show() during queue probe

  When vfio_ap_mdev_probe_queue() creates the sysfs attribute group,
  the queue's driver data has not yet…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 260f3ea141382386e97611e7c2029bc013088ab1 <
    31fa0a8a3c337ed2d200166d6926ab23c14f8b2e
  - >-
    Linux >= 260f3ea141382386e97611e7c2029bc013088ab1 <
    e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9
  - >-
    Linux >= 260f3ea141382386e97611e7c2029bc013088ab1 <
    69632952aca04caa71e49953b6949fc04e788e67
  - >-
    Linux >= 260f3ea141382386e97611e7c2029bc013088ab1 <
    7db2511fc601ca3a6e3fb1bdce02261c3c3167c3
  - >-
    Linux >= 260f3ea141382386e97611e7c2029bc013088ab1 <
    dd6f4ef6f8a37412909ad787c837332fb070159c
  - Linux 6.0
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T11:17:05.797'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89955'
references:
  - url: 'https://git.kernel.org/stable/c/31fa0a8a3c337ed2d200166d6926ab23c14f8b2e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/69632952aca04caa71e49953b6949fc04e788e67'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7db2511fc601ca3a6e3fb1bdce02261c3c3167c3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dd6f4ef6f8a37412909ad787c837332fb070159c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-16T10:53:53.961Z'
epss: 0.002
epssPercentile: 0.10127
---

## Overview

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

s390/vfio-ap: Fix NULL deref in status_show() during queue probe

When vfio_ap_mdev_probe_queue() creates the sysfs attribute group,
the queue's driver data has not yet been set. A concurrent read of
the 'status' attribute can therefore call dev_get_drvdata() and
get NULL, which is then passed directly to
vfio_ap_mdev_for_queue() where q->apqn is unconditionally
dereferenced, causing a NULL pointer dereference.

Fix this by acquiring the update locks before calling
sysfs_create_group(). The status_show() function acquires
guests_lock before reading the driver data, so any concurrent
read will block until after dev_set_drvdata() has been called
and the update locks are released.

As a bonus, the APQN no longer needs to be read from the queue
struct after allocation — it can be read directly from apdev
before allocation and stored in a local variable, which is then
assigned to q->apqn once the allocation succeeds.

## Remediation

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