CVE-2024-42104 nilfs2: add missing check for inode numbers on directory entries
A use-after-free vulnerability in the nilfs2 filesystem allows attackers to cause a kernel crash or potentially execute code via corrupted filesystem images.
- 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-2024-42104?
CVE-2024-42104 is a high-severity use after free vulnerability in Linux kernel, published on 30 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:
nilfs2: add missing check for inode numbers on directory entries
Syzbot reported that mounting and unmounting a specific pattern of corrupted nilfs2 filesystem images causes a use-after-free of metadata file inodes, which triggers a kernel bug in lru_add_fn().
As Jan Kara pointed out, this is because the link count of a metadata file gets corrupted to 0, and nilfs_evict_inode(), which is called from iput(), tries to delete that inode (ifile inode in this case).
The inconsistency occurs because directories containing the inode numbers of these metadata files that should not be visible in the namespace are read without checking.
Fix this issue by treating the inode numbers of these internal files as errors in the sanity check helper when reading directory folios/pages.
Also thanks to Hillf Danton and Matthew Wilcox for their initial mm-layer analysis.
Weakness: CWE-416
Which versions are affected by CVE-2024-42104?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-42104?
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-2024-42104 being exploited?
There is no known exploitation of CVE-2024-42104 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-42104, DEBIAN-CVE-2024-42104, GHSA-7hm7-x364-qr2m, UBUNTU-CVE-2024-42104.