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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-10-22 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.32

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/f13d870fce90f01cf930bfaffecc8185ae0be21c
- https://git.kernel.org/stable/c/eccc88c0efe407e579291792ad07a7dedc0f63f0
- https://git.kernel.org/stable/c/85d392710275355425df8618ccbebbc336f5acc5
- https://git.kernel.org/stable/c/4bee3c75d5bf7c2b5dc0b520410eb40449e5da31
- https://git.kernel.org/stable/c/3ac0217ca9186c2f9af9a0113a331a42aa847894
- https://git.kernel.org/stable/c/dfbf0122ea1b9b3e73fa22c8ff6bd888935c54fc
- https://git.kernel.org/stable/c/e7a849f740e3576e79cba403697e916f4c3a6f12
- https://git.kernel.org/stable/c/d034fa43af92fc46a81d882f46d9cc3e4ffdbbcc
- https://git.kernel.org/stable/c/88d86d18d7cf7e9137c95f9d212bb9fff8a1b4be

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