# CVE-2022-50564: s390/netiucv: Fix return type of netiucv_tx()

> A type mismatch in the s390 netiucv driver can cause kernel panics if Control Flow Integrity is enabled, leading to denial of service.

- **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:** 22 Oct 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-50564, GHSA-pxfr-7m9j-39vf, UBUNTU-CVE-2022-50564

## What is CVE-2022-50564?

CVE-2022-50564 is a vulnerability in Linux, published on 22 Oct 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:

s390/netiucv: Fix return type of netiucv_tx()

With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed. A
proposed warning in clang aims to catch these at compile time, which
reveals:

  drivers/s390/net/netiucv.c:1854:21: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
          .ndo_start_xmit         = netiucv_tx,
                                    ^~~~~~~~~~

->ndo_start_xmit() in 'struct net_device_ops' expects a return type of
'netdev_tx_t', not 'int'. Adjust the return type of netiucv_tx() to
match the prototype's to resolve the warning and potential CFI failure,
should s390 select ARCH_SUPPORTS_CFI_CLANG in the future.

Additionally, while in the area, remove a comment block that is no
longer relevant.

## Which versions are affected by CVE-2022-50564?


## How do I fix CVE-2022-50564?

Apply the vendor's patch.

## Is CVE-2022-50564 being exploited?

There is no known exploitation of CVE-2022-50564 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-50564 and fix it if it is affected.

What it is: CVE-2022-50564 is a vulnerability in Linux, published on 22 Oct 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-2022-50564 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-2022-50564/ (Markdown: https://insights.sbomify.com/CVE-2022-50564/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50564
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50564
- OSV: https://osv.dev/vulnerability/CVE-2022-50564

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50564/
Summaries are generated and may contain mistakes; the official description above is the record.