CVE-2024-41012 filelock: Remove locks reliably when fcntl/close race is detected
A race condition in Linux kernel file locking allows attackers to read arbitrary kernel memory via use-after-free when accessing /proc/locks.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-41012?
CVE-2024-41012 is a high-severity use after free vulnerability in Linux kernel, published on 23 Jul 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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().
Weakness: CWE-416
Which versions are affected by CVE-2024-41012?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-41012?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2024-41012 being exploited?
There is no known exploitation of CVE-2024-41012 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-41012, DEBIAN-CVE-2024-41012, GHSA-c77m-wh63-vhch, UBUNTU-CVE-2024-41012.