CVE-2024-53143 fsnotify: Fix ordering of iput() and watched_objects decrement
A use-after-free vulnerability in the Linux kernel's fsnotify subsystem allows attackers to potentially execute code or cause a denial of service.
- 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-2024-53143?
CVE-2024-53143 is a high-severity use after free vulnerability in Linux kernel, published on 7 Dec 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:
fsnotify: Fix ordering of iput() and watched_objects decrement
Ensure the superblock is kept alive until we're done with iput(). Holding a reference to an inode is not allowed unless we ensure the superblock stays alive, which fsnotify does by keeping the watched_objects count elevated, so iput() must happen before the watched_objects decrement. This can lead to a UAF of something like sb->s_fs_info in tmpfs, but the UAF is hard to hit because race orderings that oops are more likely, thanks to the CHECK_DATA_CORRUPTION() block in generic_shutdown_super().
Also, ensure that fsnotify_put_sb_watched_objects() doesn't call fsnotify_sb_watched_objects() on a superblock that may have already been freed, which would cause a UAF read of sb->s_fsnotify_info.
Weakness: CWE-416
Which versions are affected by CVE-2024-53143?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-53143?
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-2024-53143 being exploited?
There is no known exploitation of CVE-2024-53143 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-53143, DEBIAN-CVE-2024-53143, GHSA-rfr4-95g9-6vf3, UBUNTU-CVE-2024-53143.