---
id: CVE-2026-74395
title: 'RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference

  MLX5_IB_METHOD_DEVX_SUBSCRIBE_EVENT() links event_sub into sub_list
  before initializing the fields used by …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    6e15b770461eeaa0ff73934922cb670a6a9db04e
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    9be9aca28424228586fe9211c373ebdb826ebb6c
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    f345e744b6b087188cde2377da5cbe9713b61353
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    1025dc2f7ba29b04b8687790fa91f9cd1a53141e
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    7921821fc2b19c01588311f6e7468ae5b68b1f61
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    5100febf8e9d6c8c5ba8dc6534c6a5e3376e5989
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    78b9589fda266c71f0f9d0c858d4fa7381a890a5
  - >-
    Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 <
    43f8f7946814c8e5f464518246fdbc69b6e32326
  - Linux 5.3
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:56:51.877996Z'
published: '2026-08-15'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T17:05:45.306Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74395'
references:
  - url: 'https://git.kernel.org/stable/c/6e15b770461eeaa0ff73934922cb670a6a9db04e'
  - url: 'https://git.kernel.org/stable/c/9be9aca28424228586fe9211c373ebdb826ebb6c'
  - url: 'https://git.kernel.org/stable/c/f345e744b6b087188cde2377da5cbe9713b61353'
  - url: 'https://git.kernel.org/stable/c/1025dc2f7ba29b04b8687790fa91f9cd1a53141e'
  - url: 'https://git.kernel.org/stable/c/7921821fc2b19c01588311f6e7468ae5b68b1f61'
  - url: 'https://git.kernel.org/stable/c/5100febf8e9d6c8c5ba8dc6534c6a5e3376e5989'
  - url: 'https://git.kernel.org/stable/c/78b9589fda266c71f0f9d0c858d4fa7381a890a5'
  - url: 'https://git.kernel.org/stable/c/43f8f7946814c8e5f464518246fdbc69b6e32326'
tags:
  - cve.org
epss: 0.0022
epssPercentile: 0.12557
ingestedAt: '2026-11-06T18:00:12.564Z'
---

## Overview

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

RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference

MLX5_IB_METHOD_DEVX_SUBSCRIBE_EVENT() links event_sub into sub_list
before initializing the fields used by the shared error path.

If eventfd_ctx_fdget() then fails, the unwind path dereferences
event_sub->ev_file in uverbs_uobject_put() and calls
subscribe_event_xa_dealloc() with an unset xa_key_level1.

subscribe_event_xa_alloc() creates the XA entry exactly once for a given
key_level1, on the first occurrence of that key. The unwind path must
therefore call subscribe_event_xa_dealloc() exactly once for it as well.

Enforce that by adding devx_key_in_sub_list() and calling
subscribe_event_xa_dealloc() only when the last matching pending entry is
being cleaned up.

## Affected

- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 6e15b770461eeaa0ff73934922cb670a6a9db04e`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 9be9aca28424228586fe9211c373ebdb826ebb6c`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < f345e744b6b087188cde2377da5cbe9713b61353`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 1025dc2f7ba29b04b8687790fa91f9cd1a53141e`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 7921821fc2b19c01588311f6e7468ae5b68b1f61`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 5100febf8e9d6c8c5ba8dc6534c6a5e3376e5989`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 78b9589fda266c71f0f9d0c858d4fa7381a890a5`
- `Linux >= 7597385371425febdaa8c6a1da3625d4ffff16f5 < 43f8f7946814c8e5f464518246fdbc69b6e32326`
- `Linux 5.3`

## Remediation

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