CVE-2025-68771 ocfs2: fix kernel BUG in ocfs2_find_victim_chain
A local attacker can trigger a kernel panic in the OCFS2 filesystem by exploiting a null dereference in the allocation chain list handling.
- 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-2025-68771?
CVE-2025-68771 is a vulnerability in Linux, published on 13 Jan 2026. 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:
ocfs2: fix kernel BUG in ocfs2_find_victim_chain
syzbot reported a kernel BUG in ocfs2_find_victim_chain() because the `cl_next_free_rec` field of the allocation chain list (next free slot in the chain list) is 0, triggring the BUG_ON(!cl->cl_next_free_rec) condition in ocfs2_find_victim_chain() and panicking the kernel.
To fix this, an if condition is introduced in ocfs2_claim_suballoc_bits(), just before calling ocfs2_find_victim_chain(), the code block in it being executed when either of the following conditions is true:
1. `cl_next_free_rec` is equal to 0, indicating that there are no free chains in the allocation chain list 2. `cl_next_free_rec` is greater than `cl_count` (the total number of chains in the allocation chain list)
Either of them being true is indicative of the fact that there are no chains left for usage.
This is addressed using ocfs2_error(), which prints the error log for debugging purposes, rather than panicking the kernel.
Which versions are affected by CVE-2025-68771?
How do I fix CVE-2025-68771?
Apply the vendor's patch.
Is CVE-2025-68771 being exploited?
There is no known exploitation of CVE-2025-68771 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-68771, DEBIAN-CVE-2025-68771, GHSA-48cw-6cgr-r587, ROOT-OS-DEBIAN-11-CVE-2025-68771, ROOT-OS-DEBIAN-12-CVE-2025-68771, ROOT-OS-DEBIAN-13-CVE-2025-68771 and 3 more.