CVE-2024-47699 nilfs2: fix potential null-ptr-deref in nilfs_btree_insert()
A local attacker with a corrupted filesystem image can trigger a null pointer dereference in the nilfs2 kernel module, causing a system crash.
- 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-2024-47699?
CVE-2024-47699 is a medium-severity vulnerability in Linux kernel, published on 21 Oct 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: fix potential null-ptr-deref in nilfs_btree_insert()
Patch series "nilfs2: fix potential issues with empty b-tree nodes".
This series addresses three potential issues with empty b-tree nodes that can occur with corrupted filesystem images, including one recently discovered by syzbot.
This patch (of 3):
If a b-tree is broken on the device, and the b-tree height is greater than 2 (the level of the root node is greater than 1) even if the number of child nodes of the b-tree root is 0, a NULL pointer dereference occurs in nilfs_btree_prepare_insert(), which is called from nilfs_btree_insert().
This is because, when the number of child nodes of the b-tree root is 0, nilfs_btree_do_lookup() does not set the block buffer head in any of path[x].bp_bh, leaving it as the initial value of NULL, but if the level of the b-tree root node is greater than 1, nilfs_btree_get_nonroot_node(), which accesses the buffer memory of path[x].bp_bh, is called.
Fix this issue by adding a check to nilfs_btree_root_broken(), which performs sanity checks when reading the root node from the device, to detect this inconsistency.
Thanks to Lizhi Xu for trying to solve the bug and clarifying the cause early on.
Weakness: CWE-476
Which versions are affected by CVE-2024-47699?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-47699?
Apply the vendor's patch.
Is CVE-2024-47699 being exploited?
There is no known exploitation of CVE-2024-47699 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-50842, AZL-50993, BELL-CVE-2024-47699, DEBIAN-CVE-2024-47699, GHSA-839p-pc8m-rw47, UBUNTU-CVE-2024-47699.