CVE-2024-53176

/// Technical description

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

smb: During unmount, ensure all cached dir instances drop their dentry

The unmount process (cifs_kill_sb() calling close_all_cached_dirs()) can

race with various cached directory operations, which ultimately results

in dentries not being dropped and these kernel BUGs:

BUG: Dentry ffff88814f37e358{i=1000000000080,n=/} still in use (2) [unmount of cifs cifs]

VFS: Busy inodes after unmount of cifs (cifs)

------------[ cut here ]------------

kernel BUG at fs/super.c:661!

This happens when a cfid is in the process of being cleaned up when, and

has been removed from the cfids->entries list, including:

- Receiving a lease break from the server

- Server reconnection triggers invalidate_all_cached_dirs(), which

removes all the cfids from the list

- The laundromat thread decides to expire an old cfid.

To solve these problems, dropping the dentry is done in queued work done

in a newly-added cfid_put_wq workqueue, and clo

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References