---
id: CVE-2026-80548
title: 's390/vfio_ccw: Selectively expand io_mutex'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/vfio_ccw: Selectively expand io_mutex

  The io_mutex was defined to serialize the io_regions, but then has
  also sort of been associated with the I/O themselves beca…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    56d7488533ceac4e986e96e15c9e487a2245bc01
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    f72a51810d49411bd8cad0c2df8592320a2fe5cc
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    b6aecea4b2b246f9fbd98a5712daa1193a60818e
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    2a5ac0c0f1f7da33929211a2e41911bf72ee35d8
  - >-
    Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 <
    34f4feff3e90bd09308fad0974e97113b23b812a
  - Linux 5.2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T19:17:03.411109Z'
published: '2026-08-26'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:26:25.857Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80548'
references:
  - url: 'https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0'
  - url: 'https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01'
  - url: 'https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc'
  - url: 'https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd'
  - url: 'https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e'
  - url: 'https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8'
  - url: 'https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a'
tags:
  - cve.org
epss: 0.00176
epssPercentile: 0.06641
ingestedAt: '2026-10-16T19:46:24.318Z'
---

## Overview

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

s390/vfio_ccw: Selectively expand io_mutex

The io_mutex was defined to serialize the io_regions, but then has
also sort of been associated with the I/O themselves because of
the close relationship they share.

With the handful of races that are possible, the choices are either to:
 A) expand the scope of io_mutex to close these remaining windows, or
 B) reduce the scope of io_mutex to just io_region, and introduce a new
    lock mechanism for the remaining I/O resources

This patch implements A, since B brings with it a lot more interactions
that would need to be tracked and kept in a correct hierarchy. It also
takes advantage of the workqueue element for cp_free() that now gets
called out of fsm_notoper(), which could be invoked out of an interrupt
context and thus cannot acquire a mutex itself.

## Affected

- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0`
- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < 56d7488533ceac4e986e96e15c9e487a2245bc01`
- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < f72a51810d49411bd8cad0c2df8592320a2fe5cc`
- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < 2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd`
- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < b6aecea4b2b246f9fbd98a5712daa1193a60818e`
- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < 2a5ac0c0f1f7da33929211a2e41911bf72ee35d8`
- `Linux >= 4f76617378ee97c557b526cb58d3c61eb0a9c963 < 34f4feff3e90bd09308fad0974e97113b23b812a`
- `Linux 5.2`

## Remediation

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