Linux Kernel up to 6.12.10 fs/afs/addr_prefs.c afs_split_string locking

Summaryinfo

A vulnerability identified as problematic has been detected in Linux Kernel up to 6.12.10. This affects the function afs_split_string of the file fs/afs/addr_prefs.c. This manipulation causes locking. This vulnerability is tracked as CVE-2025-21672. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel up to 6.12.10. Affected by this vulnerability is the function afs_split_string of the file fs/afs/addr_prefs.c. The manipulation with an unknown input leads to a locking vulnerability. The CWE definition for the vulnerability is CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: afs: Fix merge preference rule failure condition syzbot reported a lock held when returning to userspace[1]. This is because if argc is less than 0 and the function returns directly, the held inode lock is not released. Fix this by store the error in ret and jump to done to clean up instead of returning directly. [dh: Modified Lizhi Xu's original patch to make it honour the error code from afs_split_string()] [1] WARNING: lock held when returning to user space! 6.13.0-rc3-syzkaller-00209-g499551201b5f #0 Not tainted ------------------------------------------------ syz-executor133/5823 is leaving the kernel with locks still held! 1 lock held by syz-executor133/5823: #0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline] #0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: afs_proc_addr_prefs_write+0x2bb/0x14e0 fs/afs/addr_prefs.c:388

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2025-21672 since 12/29/2024. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 234757 (Ubuntu 24.04 LTS / 24.10 : Linux kernel vulnerabilities (USN-7445-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.11 eliminates this vulnerability. Applying the patch 22be1d90a6211c88dd093b25d1f3aa974d0d9f9d/17a4fde81d3a7478d97d15304a6d61094a10c2e3 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 (234757) and CERT Bund (WID-SEC-2025-0232). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• RESF Rocky Linux
• Dell NetWorker
• Dell Avamar
• Dell PowerProtect Data Domain
• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

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