# CVE-2025-40196: fs: quota: create dedicated workqueue for quota_release_work

> A local attacker can trigger a kernel panic in the Linux kernel's quota subsystem during specific writeback operations if panic_on_warn is enabled.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Nov 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-40196, DEBIAN-CVE-2025-40196, GHSA-rpjc-phpw-vx4c, ROOT-OS-DEBIAN-11-CVE-2025-40196, ROOT-OS-DEBIAN-12-CVE-2025-40196, ROOT-OS-UBUNTU-2204-CVE-2025-40196, ROOT-OS-UBUNTU-2404-CVE-2025-40196, UBUNTU-CVE-2025-40196

## What is CVE-2025-40196?

CVE-2025-40196 is a denial of service vulnerability in Linux, published on 12 Nov 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:

fs: quota: create dedicated workqueue for quota_release_work

There is a kernel panic due to WARN_ONCE when panic_on_warn is set.

This issue occurs when writeback is triggered due to sync call for an
opened file(ie, writeback reason is WB_REASON_SYNC). When f2fs balance
is needed at sync path, flush for quota_release_work is triggered.
By default quota_release_work is queued to "events_unbound" queue which
does not have WQ_MEM_RECLAIM flag. During f2fs balance "writeback"
workqueue tries to flush quota_release_work causing kernel panic due to
MEM_RECLAIM flag mismatch errors.

This patch creates dedicated workqueue with WQ_MEM_RECLAIM flag
for work quota_release_work.

------------[ cut here ]------------
WARNING: CPU: 4 PID: 14867 at kernel/workqueue.c:3721 check_flush_dependency+0x13c/0x148
Call trace:
 check_flush_dependency+0x13c/0x148
 __flush_work+0xd0/0x398
 flush_delayed_work+0x44/0x5c
 dquot_writeback_dquots+0x54/0x318
 f2fs_do_quota_sync+0xb8/0x1a8
 f2fs_write_checkpoint+0x3cc/0x99c
 f2fs_gc+0x190/0x750
 f2fs_balance_fs+0x110/0x168
 f2fs_write_single_data_page+0x474/0x7dc
 f2fs_write_data_pages+0x7d0/0xd0c
 do_writepages+0xe0/0x2f4
 __writeback_single_inode+0x44/0x4ac
 writeback_sb_inodes+0x30c/0x538
 wb_writeback+0xf4/0x440
 wb_workfn+0x128/0x5d4
 process_scheduled_works+0x1c4/0x45c
 worker_thread+0x32c/0x3e8
 kthread+0x11c/0x1b0
 ret_from_fork+0x10/0x20
Kernel panic - not syncing: kernel: panic_on_warn set ...

## Which versions are affected by CVE-2025-40196?


## How do I fix CVE-2025-40196?

Apply the vendor's patch.

## Is CVE-2025-40196 being exploited?

There is no known exploitation of CVE-2025-40196 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40196 and fix it if it is affected.

What it is: CVE-2025-40196 is a denial of service vulnerability in Linux, published on 12 Nov 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-2025-40196 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-2025-40196/ (Markdown: https://insights.sbomify.com/CVE-2025-40196/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40196
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40196
- OSV: https://osv.dev/vulnerability/CVE-2025-40196

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40196/
Summaries are generated and may contain mistakes; the official description above is the record.