# CVE-2022-50636: PCI: Fix pci_device_is_present() for VFs by checking PF

> Local attackers with high privileges can cause a denial of service by triggering a hang in virtio I/O operations during driver unbinding or VF removal.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-50636, GHSA-m8h5-vf45-h85r, UBUNTU-CVE-2022-50636

## What is CVE-2022-50636?

CVE-2022-50636 is a denial of service vulnerability in Linux, published on 9 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:

PCI: Fix pci_device_is_present() for VFs by checking PF

pci_device_is_present() previously didn't work for VFs because it reads the
Vendor and Device ID, which are 0xffff for VFs, which looks like they
aren't present.  Check the PF instead.

Wei Gong reported that if virtio I/O is in progress when the driver is
unbound or "0" is written to /sys/.../sriov_numvfs, the virtio I/O
operation hangs, which may result in output like this:

  task:bash state:D stack:    0 pid: 1773 ppid:  1241 flags:0x00004002
  Call Trace:
   schedule+0x4f/0xc0
   blk_mq_freeze_queue_wait+0x69/0xa0
   blk_mq_freeze_queue+0x1b/0x20
   blk_cleanup_queue+0x3d/0xd0
   virtblk_remove+0x3c/0xb0 [virtio_blk]
   virtio_dev_remove+0x4b/0x80
   ...
   device_unregister+0x1b/0x60
   unregister_virtio_device+0x18/0x30
   virtio_pci_remove+0x41/0x80
   pci_device_remove+0x3e/0xb0

This happened because pci_device_is_present(VF) returned "false" in
virtio_pci_remove(), so it called virtio_break_device().  The broken vq
meant that vring_interrupt() skipped the vq.callback() that would have
completed the virtio I/O operation via virtblk_done().

[bhelgaas: commit log, simplify to always use pci_physfn(), add stable tag]

## Which versions are affected by CVE-2022-50636?


## How do I fix CVE-2022-50636?

Apply the vendor's patch.

## Is CVE-2022-50636 being exploited?

There is no known exploitation of CVE-2022-50636 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-50636 and fix it if it is affected.

What it is: CVE-2022-50636 is a denial of service vulnerability in Linux, published on 9 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-2022-50636 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-2022-50636/ (Markdown: https://insights.sbomify.com/CVE-2022-50636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50636
- OSV: https://osv.dev/vulnerability/CVE-2022-50636

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50636/
Summaries are generated and may contain mistakes; the official description above is the record.