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 close_all_cached_dirs() flushes that workqueue after it drops all the dentries of which it's aware. This is a global workqueue (rather than scoped to a mount), but the queued work is minimal. The final cleanup work for cleaning up a cfid is performed via work queued in the serverclose_wq workqueue; this is done separate from dropping the dentries so that close_all_cached_dirs() doesn't block on any server operations. Both of these queued works expect to invoked with a cfid reference and a tcon reference to avoid those objects from being freed while the work is ongoing. While we're here, add proper locking to close_all_cached_dirs(), and locking around the freeing of cfid->dentry.
History

Thu, 13 Feb 2025 00:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-99
Metrics threat_severity

Low

threat_severity

Moderate


Mon, 30 Dec 2024 01:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low


Fri, 27 Dec 2024 14:00:00 +0000

Type Values Removed Values Added
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 close_all_cached_dirs() flushes that workqueue after it drops all the dentries of which it's aware. This is a global workqueue (rather than scoped to a mount), but the queued work is minimal. The final cleanup work for cleaning up a cfid is performed via work queued in the serverclose_wq workqueue; this is done separate from dropping the dentries so that close_all_cached_dirs() doesn't block on any server operations. Both of these queued works expect to invoked with a cfid reference and a tcon reference to avoid those objects from being freed while the work is ongoing. While we're here, add proper locking to close_all_cached_dirs(), and locking around the freeing of cfid->dentry.
Title smb: During unmount, ensure all cached dir instances drop their dentry
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2024-12-27T13:49:20.518Z

Updated: 2025-05-04T09:54:58.234Z

Reserved: 2024-11-19T17:17:25.007Z

Link: CVE-2024-53176

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2024-12-27T14:15:24.947

Modified: 2024-12-27T14:15:24.947

Link: CVE-2024-53176

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-12-27T00:00:00Z

Links: CVE-2024-53176 - Bugzilla