NULL Pointer Dereference Affecting kernel-bootwrapper package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.02% (4th percentile)

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  • Snyk IDSNYK-RHEL6-KERNELBOOTWRAPPER-12179577
  • published25 Aug 2025
  • disclosed22 Aug 2025

Introduced: 22 Aug 2025

NewCVE-2025-38621  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:6 kernel-bootwrapper.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-bootwrapper package and not the kernel-bootwrapper package as distributed by RHEL. See How to fix? for RHEL:6 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1