CVE-2024-41012: filelock: Remove locks reliably when fcntl/close race is detected

Severity: medium (CVSS 6.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-23 · updated 2026-08-04
Weakness: CWE-416

Description

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().

Affected products

Linux kernel: from 2.6.13 before 4.19.319; from 4.20 before 5.4.281; from 5.5 before 5.10.223; from 5.11 before 5.15.164; from 5.16 before 6.1.101; from 6.2 before 6.6.42 — fixed in 4.19.319, 5.10.223, 5.15.164, 5.4.281, 6.1.101, 6.6.42

How to fix

Upgrade to a fixed version: Linux kernel 4.19.319, 5.10.223, 5.15.164, 5.4.281. Check the vendor advisory for mitigations.

References

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