Linux Kernel up to 6.16.0 rdev_addable null pointer dereference

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.16.0. It has been classified as critical. This affects the function rdev_addable. Performing a manipulation results in null pointer dereference. This vulnerability is identified as CVE-2025-38621. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.16.0. It has been classified as critical. This affects the function rdev_addable. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-38621 since 04/16/2025. The exploitability is told to be difficult. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 260278 (Linux Distros Unpatched Vulnerability : CVE-2025-38621), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.16.1 or 6.17-rc1 eliminates this vulnerability. Applying the patch b5fbe940862339cdcc34dea7a057ad18d18fa137/13017b427118f4311471ee47df74872372ca8482 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (260278) and CERT Bund (WID-SEC-2025-1898). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Debian Linux
• Google Cloud Platform
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• NetApp AFF
• NetApp ActiveIQ Unified Manager
• SUSE openSUSE
• Dell Avamar
• NetApp FAS
• Open Source Linux Kernel
• Dell NetWorker
• Dell Secure Connect Gateway
• Dell ECS

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16.0

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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