The fix referenced below causes a crash when an ERSPAN tunnel is created
without passing IFLA_INFO_DATA. Fix by validating passed-in data in the
same way as ipgre does.
Fixes: 60f0595fdbc4 ("net: ip_gre: Separate ERSPAN newlink / changelink callbacks") Reported-by: syzbot+1b4ebf4dae4e510dd219@syzkaller.appspotmail.com Signed-off-by: Petr Machata <petrm@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>