---
id: CVE-2025-38621
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  md: make rdev_addable usable for rcu mode

  Our testcase trigger panic:

  BUG: kernel NULL pointer dereference, address: 00000000000000e0
  ...
  Oops: Oops: 0000 [#1] SMP NO…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  md: make rdev_addable usable for rcu mode

  Our testcase trigger panic:

  BUG: kernel NULL pointer dereference, address: 00000000000000e0
  ...
  Oops: Oops: 0000 [#1] SMP NO…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-476
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.7, < 6.16.1'
patched:
  - linux_kernel 6.16.1
published: '2025-08-22'
updated: '2026-09-07'
sourceUpdated: '2026-09-07T16:17:27.777'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-38621'
references:
  - url: 'https://git.kernel.org/stable/c/13017b427118f4311471ee47df74872372ca8482'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b5fbe940862339cdcc34dea7a057ad18d18fa137'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d713e105a6137d3f54f09d4d9e2273482057ca17'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00159
epssPercentile: 0.04252
ingestedAt: '2026-09-07T17:14:49.694Z'
---

## Overview

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

md: make rdev_addable usable for rcu mode

Our testcase trigger panic:

BUG: kernel NULL pointer dereference, address: 00000000000000e0
...
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 2 UID: 0 PID: 85 Comm: kworker/2:1 Not tainted 6.16.0+ #94
PREEMPT(none)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.16.1-2.fc37 04/01/2014
Workqueue: md_misc md_start_sync
RIP: 0010:rdev_addable+0x4d/0xf0
...
Call Trace:
 <TASK>
 md_start_sync+0x329/0x480
 process_one_work+0x226/0x6d0
 worker_thread+0x19e/0x340
 kthread+0x10f/0x250
 ret_from_fork+0x14d/0x180
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Modules linked in: raid10
CR2: 00000000000000e0
---[ end trace 0000000000000000 ]---
RIP: 0010:rdev_addable+0x4d/0xf0

md_spares_need_change in md_start_sync will call rdev_addable which
protected by rcu_read_lock/rcu_read_unlock. This rcu context will help
protect rdev won't be released, but rdev->mddev will be set to NULL
before we call synchronize_rcu in md_kick_rdev_from_array. Fix this by
using READ_ONCE and check does rdev->mddev still alive.

## Affected

- `linux_kernel >= 6.7, < 6.16.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.16.1`