Bug 1228247 (CVE-2024-41012)

Summary: VUL-0: CVE-2024-41012: kernel: filelock: Remove locks reliably when fcntl/close race is detected
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Gabriel Krisman Bertazi <gabriel.bertazi>
Status: NEW --- QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P3 - Medium CC: andrea.mattiazzo, vasant.karasulli
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/414973/
Whiteboard: CVSSv3.1:SUSE:CVE-2024-41012:6.3:(AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H)
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-07-23 12:24:21 UTC 
In the Linux kernel, the following vulnerability has been resolved:

filelock: Remove locks reliably when fcntl/close race is detected

When fcntl_setlk() races with close(), it removes the created lock with
do_lock_file_wait().
However, LSMs can allow the first do_lock_file_wait() that created the lock
while denying the second do_lock_file_wait() that tries to remove the lock.
Separately, posix_lock_file() could also fail to
remove a lock due to GFP_KERNEL allocation failure (when splitting a range
in the middle).

After the bug has been triggered, use-after-free reads will occur in
lock_get_status() when userspace reads /proc/locks. This can likely be used
to read arbitrary kernel memory, but can't corrupt kernel memory.

Fix it by calling locks_remove_posix() instead, which is designed to
reliably get rid of POSIX locks associated with the given file and
files_struct and is also used by filp_flush().

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-41012
https://www.cve.org/CVERecord?id=CVE-2024-41012
https://git.kernel.org/stable/c/3cad1bc010416c6dd780643476bc59ed742436b9
https://git.kernel.org/stable/c/b6d223942c34057fdfd8f149e763fa823731b224
https://bugzilla.redhat.com/show_bug.cgi?id=2299452
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-41012.mbox