CVE-2022-50564

In the Linux kernel, the following vulnerability has been resolved:

s390/netiucv: Fix return type of netiucv_tx()

With clangs 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 prototypes 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.

Affected Software

References

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