# CVE-2026-64594: usb: gadget: f_fs: initialize reset_work at allocation time

> A missing initialization in the Linux kernel USB gadget driver causes a null pointer dereference during unmount, leading to a system crash.

- **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:** 6 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64594, DEBIAN-CVE-2026-64594, GHSA-28fc-4vwx-pr32, UBUNTU-CVE-2026-64594

## What is CVE-2026-64594?

CVE-2026-64594 is a vulnerability in Linux, published on 6 Aug 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:

usb: gadget: f_fs: initialize reset_work at allocation time

ffs_fs_kill_sb() unconditionally calls cancel_work_sync() on
ffs->reset_work when a functionfs instance is unmounted:

	ffs_data_reset(ffs);
	cancel_work_sync(&ffs->reset_work);

However ffs->reset_work is only ever initialized via INIT_WORK() in
ffs_func_set_alt() and ffs_func_disable(), and only on the
FFS_DEACTIVATED path. That state is reached solely by ffs_data_closed()
when the instance is mounted with the "no_disconnect" option, so for the
common case (no "no_disconnect", or mounted and unmounted without ever
being deactivated) reset_work is never initialized.

ffs_data_new() allocates the ffs_data with kzalloc_obj() and does not
initialize reset_work, and ffs_data_reset()/ffs_data_clear() do not touch
it either, so reset_work.func is left NULL. cancel_work_sync() on such a
work then trips the WARN_ON(!work->func) guard in __flush_work():

  WARNING: kernel/workqueue.c:4301 at __flush_work+0x330/0x360, CPU#3: umount
  Call trace:
   __flush_work
   cancel_work_sync
   ffs_fs_kill_sb [usb_f_fs]
   deactivate_locked_super
   deactivate_super
   cleanup_mnt
   __cleanup_mnt
   task_work_run
   exit_to_user_mode_loop
   el0_svc

On older kernels cancel_work_sync() on a zero-initialized work struct was
a silent no-op, which hid the missing initialization.

Initialize reset_work once in ffs_data_new() so it is always valid for
the lifetime of the ffs_data, and drop the now-redundant INIT_WORK()
calls from the two deactivation paths.

## Which versions are affected by CVE-2026-64594?


## How do I fix CVE-2026-64594?

Apply the vendor's patch.

## Is CVE-2026-64594 being exploited?

There is no known exploitation of CVE-2026-64594 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64594 and fix it if it is affected.

What it is: CVE-2026-64594 is a vulnerability in Linux, published on 6 Aug 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-2026-64594 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-2026-64594/ (Markdown: https://insights.sbomify.com/CVE-2026-64594/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64594
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64594
- OSV: https://osv.dev/vulnerability/CVE-2026-64594

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64594/
Summaries are generated and may contain mistakes; the official description above is the record.