---
id: CVE-2025-71182
title: >-
  can: j1939: make j1939_session_activate() fail if device is no longer
  registered
summary: >-
  In the Linux kernel, the following vulnerability has been resolved:


  can: j1939: make j1939_session_activate() fail if device is no longer
  registered


  syzbot is still reporting

    unregister_netdevice: waiting for vcan0 to become free. U…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    ebb0dfd718dd31c8d3600612ca4b7207ec3d923a
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    c3a4316e3c746af415c0fd6c6d489ad13f53714d
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    46ca9dc978923c5e1247a9e9519240ba7ace413c
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    78d87b72cebe2a993fd5b017e9f14fb6278f2eae
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    ba6f0d1832eeb5eb3a6dc5cb30e0f720b3cb3536
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    79dd3f1d9dd310c2af89b09c71f34d93973b200f
  - >-
    Linux >= 9d71dd0c70099914fcd063135da3c580865e924c <
    5d5602236f5db19e8b337a2cd87a90ace5ea776d
  - Linux 5.4
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-10T20:42:04.625425Z'
published: '2026-01-31'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T18:15:16.548Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-71182'
references:
  - url: 'https://git.kernel.org/stable/c/ebb0dfd718dd31c8d3600612ca4b7207ec3d923a'
  - url: 'https://git.kernel.org/stable/c/c3a4316e3c746af415c0fd6c6d489ad13f53714d'
  - url: 'https://git.kernel.org/stable/c/46ca9dc978923c5e1247a9e9519240ba7ace413c'
  - url: 'https://git.kernel.org/stable/c/78d87b72cebe2a993fd5b017e9f14fb6278f2eae'
  - url: 'https://git.kernel.org/stable/c/ba6f0d1832eeb5eb3a6dc5cb30e0f720b3cb3536'
  - url: 'https://git.kernel.org/stable/c/79dd3f1d9dd310c2af89b09c71f34d93973b200f'
  - url: 'https://git.kernel.org/stable/c/5d5602236f5db19e8b337a2cd87a90ace5ea776d'
tags:
  - cve.org
epss: 0.00177
epssPercentile: 0.06873
ingestedAt: '2026-10-19T18:35:50.131Z'
---

## Overview

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

can: j1939: make j1939_session_activate() fail if device is no longer registered

syzbot is still reporting

  unregister_netdevice: waiting for vcan0 to become free. Usage count = 2

even after commit 93a27b5891b8 ("can: j1939: add missing calls in
NETDEV_UNREGISTER notification handler") was added. A debug printk() patch
found that j1939_session_activate() can succeed even after
j1939_cancel_active_session() from j1939_netdev_notify(NETDEV_UNREGISTER)
has completed.

Since j1939_cancel_active_session() is processed with the session list lock
held, checking ndev->reg_state in j1939_session_activate() with the session
list lock held can reliably close the race window.

## Affected

- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < ebb0dfd718dd31c8d3600612ca4b7207ec3d923a`
- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < c3a4316e3c746af415c0fd6c6d489ad13f53714d`
- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < 46ca9dc978923c5e1247a9e9519240ba7ace413c`
- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < 78d87b72cebe2a993fd5b017e9f14fb6278f2eae`
- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < ba6f0d1832eeb5eb3a6dc5cb30e0f720b3cb3536`
- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < 79dd3f1d9dd310c2af89b09c71f34d93973b200f`
- `Linux >= 9d71dd0c70099914fcd063135da3c580865e924c < 5d5602236f5db19e8b337a2cd87a90ace5ea776d`
- `Linux 5.4`

## Remediation

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