30ed5ce1ff
Certain interfaces (e.g. pfsync0) do not have ip6 addresses (in other words, ifp->if_afdata[AF_INET6] is NULL). Ensure we don't panic when the MTU is updated. pfsync interfaces will never have ip6 support, because it's explicitly disabled in in6_domifattach(). PR: 205194 Reviewed by: melifaro, hrs Differential Revision: https://reviews.freebsd.org/D4522