CVE-2026-98495: net: arp: terminate device name before lookup

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

net: arp: terminate device name before lookup

The ARP ioctl copies a user-provided struct arpreq into a stack object. Its arpdev field may contain IFNAMSIZ bytes without a NUL terminator.

Such input is passed to devgetbynamercu() or devgetbyname(), where strcmp() can read past the end of the stack object when a matching alternative interface name exists.

Terminate the field before the lookup to prevent the out-of-bounds read.