kernel: tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for_sock()

A flaw was found in the Linux kernel’s TLS implementation net/tls/tlsdevice.c. The function getnetdevforsock is invoked during setsockopt, which is not executed under RCU Read-Copy-Update protection. It previously used skdstgetsk-dev, which can lead to a use-after-free UAF if the sk’s destination...