# 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.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 13 Jan 2026
- **Updated:** 11 May 2026
- **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, ROOT-OS-UBUNTU-2204-CVE-2025-68771, ROOT-OS-UBUNTU-2404-CVE-2025-68771, UBUNTU-CVE-2025-68771

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68771 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-68771 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-68771/ (Markdown: https://insights.sbomify.com/CVE-2025-68771/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68771
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68771
- OSV: https://osv.dev/vulnerability/CVE-2025-68771

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68771/
Summaries are generated and may contain mistakes; the official description above is the record.