---
id: CVE-2026-90209
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/debug: Fix deadlock during unregister

  Unregistering an s390dbf debug area while one of the associated debugfs
  files is being written to can cause a deadlock:

  $ e…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/debug: Fix deadlock during unregister

  Unregistering an s390dbf debug area while one of the associated debugfs
  files is being written to can cause a deadlock:

  $ e…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    a214c3dacc779b2afcb0ac9c8001e45ee4ffb2ed
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    183f8f6d64bb0510070c856b9927618c53014a7b
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    a08b70ed2d1ec907353a72f15163b8e34ff4b2f8
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    45bb341d1b73eb293e0dd43d9b72bbc8b615d0ba
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    5d83f3faa3fb7f23f298cfd40382611999de5d1d
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    54e1259b75d6402a1d0cfb822b9bb2c507e53dab
  - >-
    Linux >= 9372a82892c2caa6bccab9a4081166fa769699f8 <
    445c31ac638fd1af203d79bdf25fc0cb3149fbbc
  - Linux c68ba4a708fbd0efdc384cd29250bb292a45e559
  - Linux 86f9980909f31ab205323eeeb290fe3cbb4952b4
  - Linux fe5793e90d3f572a87ba67fe2f0e1679fdff14f8
  - Linux e234f66168f0d50c0d28154fb983a14e85c3c526
  - Linux >= 5.4.146 < 5.5
  - Linux >= 5.10.65 < 5.11
  - Linux >= 5.13.17 < 5.14
  - Linux >= 5.14.4 < 5.15
  - Linux 5.15
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:16.060'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90209'
references:
  - url: 'https://git.kernel.org/stable/c/183f8f6d64bb0510070c856b9927618c53014a7b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/445c31ac638fd1af203d79bdf25fc0cb3149fbbc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/45bb341d1b73eb293e0dd43d9b72bbc8b615d0ba'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/54e1259b75d6402a1d0cfb822b9bb2c507e53dab'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5d83f3faa3fb7f23f298cfd40382611999de5d1d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a08b70ed2d1ec907353a72f15163b8e34ff4b2f8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a214c3dacc779b2afcb0ac9c8001e45ee4ffb2ed'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.858Z'
epss: 0.00215
epssPercentile: 0.10583
---

## Overview

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

s390/debug: Fix deadlock during unregister

Unregistering an s390dbf debug area while one of the associated debugfs
files is being written to can cause a deadlock:

$ echo >.../vmur/level    $ rmmod vmur
===================================================
debugfs write
debugfs_file_get()
                          debug_unregister()
                          mutex_lock(debug_mutex)
                          debugfs_remove()
                          wait for debugfs_file_put()
debug_file_ops.write()
debug_input()
mutex_lock(debug_mutex) ==> DEADLOCK

Fix this by splitting debug_unregister() into an s390dbf and debugfs
part, and running only the s390dbf part with debug_mutex locked.

## Remediation

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