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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
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.
Sources
Also known as DEBIAN-CVE-2022-50564, GHSA-pxfr-7m9j-39vf, UBUNTU-CVE-2022-50564.