# CVE-2022-50755: udf: Avoid double brelse() in udf_rename()

> A double free vulnerability in the Linux kernel UDF filesystem allows local attackers to cause a system crash via a specific rename operation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 24 Dec 2025
- **Updated:** 15 Oct 2026
- **Also known as:** DEBIAN-CVE-2022-50755, GHSA-4xw5-xvv7-qcv6, UBUNTU-CVE-2022-50755

## What is CVE-2022-50755?

CVE-2022-50755 is a high-severity memory corruption vulnerability in Linux, published on 24 Dec 2025. 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:

udf: Avoid double brelse() in udf_rename()

syzbot reported a warning like below [1]:

VFS: brelse: Trying to free free buffer
WARNING: CPU: 2 PID: 7301 at fs/buffer.c:1145 __brelse+0x67/0xa0
...
Call Trace:
 <TASK>
 invalidate_bh_lru+0x99/0x150
 smp_call_function_many_cond+0xe2a/0x10c0
 ? generic_remap_file_range_prep+0x50/0x50
 ? __brelse+0xa0/0xa0
 ? __mutex_lock+0x21c/0x12d0
 ? smp_call_on_cpu+0x250/0x250
 ? rcu_read_lock_sched_held+0xb/0x60
 ? lock_release+0x587/0x810
 ? __brelse+0xa0/0xa0
 ? generic_remap_file_range_prep+0x50/0x50
 on_each_cpu_cond_mask+0x3c/0x80
 blkdev_flush_mapping+0x13a/0x2f0
 blkdev_put_whole+0xd3/0xf0
 blkdev_put+0x222/0x760
 deactivate_locked_super+0x96/0x160
 deactivate_super+0xda/0x100
 cleanup_mnt+0x222/0x3d0
 task_work_run+0x149/0x240
 ? task_work_cancel+0x30/0x30
 do_exit+0xb29/0x2a40
 ? reacquire_held_locks+0x4a0/0x4a0
 ? do_raw_spin_lock+0x12a/0x2b0
 ? mm_update_next_owner+0x7c0/0x7c0
 ? rwlock_bug.part.0+0x90/0x90
 ? zap_other_threads+0x234/0x2d0
 do_group_exit+0xd0/0x2a0
 __x64_sys_exit_group+0x3a/0x50
 do_syscall_64+0x34/0xb0
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The cause of the issue is that brelse() is called on both ofibh.sbh
and ofibh.ebh by udf_find_entry() when it returns NULL.  However,
brelse() is called by udf_rename(), too.  So, b_count on buffer_head
becomes unbalanced.

This patch fixes the issue by not calling brelse() by udf_rename()
when udf_find_entry() returns NULL.

## Which versions are affected by CVE-2022-50755?


## How do I fix CVE-2022-50755?

Apply the vendor's patch.

## Is CVE-2022-50755 being exploited?

There is no known exploitation of CVE-2022-50755 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-50755 and fix it if it is affected.

What it is: CVE-2022-50755 is a high-severity memory corruption vulnerability in Linux, published on 24 Dec 2025. 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-2022-50755 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-2022-50755/ (Markdown: https://insights.sbomify.com/CVE-2022-50755/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50755
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50755
- OSV: https://osv.dev/vulnerability/CVE-2022-50755

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50755/
Summaries are generated and may contain mistakes; the official description above is the record.