# CVE-2025-22127: f2fs: fix potential deadloop in prepare_compress_overwrite()

> A local attacker can cause a kernel hang and denial of service in the f2fs filesystem by triggering an infinite loop during compressed file writeback operations.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 16 Apr 2025
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2025-22127, DEBIAN-CVE-2025-22127, GHSA-gj5h-7fq5-56p5, ROOT-OS-DEBIAN-11-CVE-2025-22127, ROOT-OS-DEBIAN-12-CVE-2025-22127, ROOT-OS-DEBIAN-13-CVE-2025-22127, ROOT-OS-UBUNTU-2204-CVE-2025-22127, ROOT-OS-UBUNTU-2404-CVE-2025-22127, UBUNTU-CVE-2025-22127

## What is CVE-2025-22127?

CVE-2025-22127 is a medium-severity denial of service vulnerability in Linux kernel, published on 16 Apr 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:

f2fs: fix potential deadloop in prepare_compress_overwrite()

Jan Prusakowski reported a kernel hang issue as below:

When running xfstests on linux-next kernel (6.14.0-rc3, 6.12) I
encountered a problem in generic/475 test where fsstress process
gets blocked in __f2fs_write_data_pages() and the test hangs.
The options I used are:

MKFS_OPTIONS  -- -O compression -O extra_attr -O project_quota -O quota /dev/vdc
MOUNT_OPTIONS -- -o acl,user_xattr -o discard,compress_extension=* /dev/vdc /vdc

INFO: task kworker/u8:0:11 blocked for more than 122 seconds.
      Not tainted 6.14.0-rc3-xfstests-lockdep #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0    state:D stack:0     pid:11    tgid:11    ppid:2      task_flags:0x4208160 flags:0x00004000
Workqueue: writeback wb_workfn (flush-253:0)
Call Trace:
 <TASK>
 __schedule+0x309/0x8e0
 schedule+0x3a/0x100
 schedule_preempt_disabled+0x15/0x30
 __mutex_lock+0x59a/0xdb0
 __f2fs_write_data_pages+0x3ac/0x400
 do_writepages+0xe8/0x290
 __writeback_single_inode+0x5c/0x360
 writeback_sb_inodes+0x22f/0x570
 wb_writeback+0xb0/0x410
 wb_do_writeback+0x47/0x2f0
 wb_workfn+0x5a/0x1c0
 process_one_work+0x223/0x5b0
 worker_thread+0x1d5/0x3c0
 kthread+0xfd/0x230
 ret_from_fork+0x31/0x50
 ret_from_fork_asm+0x1a/0x30
 </TASK>

The root cause is: once generic/475 starts toload error table to dm
device, f2fs_prepare_compress_overwrite() will loop reading compressed
cluster pages due to IO error, meanwhile it has held .writepages lock,
it can block all other writeback tasks.

Let's fix this issue w/ below changes:
- add f2fs_handle_page_eio() in prepare_compress_overwrite() to
detect IO error.
- detect cp_error earler in f2fs_read_multi_pages().

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2025-22127?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-22127?

Apply the vendor's patch.

## Is CVE-2025-22127 being exploited?

There is no known exploitation of CVE-2025-22127 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-22127 and fix it if it is affected.

What it is: CVE-2025-22127 is a medium-severity denial of service vulnerability in Linux kernel, published on 16 Apr 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-2025-22127 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-22127/ (Markdown: https://insights.sbomify.com/CVE-2025-22127/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-22127
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-22127
- OSV: https://osv.dev/vulnerability/CVE-2025-22127

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-22127/
Summaries are generated and may contain mistakes; the official description above is the record.