tree bda55b33236870d871bc3402abc8b14f4f262f56
parent e551c32d57c88923f99f8f010e89ca7ed0735e83
author Eric Dumazet <edumazet@google.com> 1477764156 -0700
committer David S. Miller <davem@davemloft.net> 1477942151 -0400

net: mangle zero checksum in skb_checksum_help()

Sending zero checksum is ok for TCP, but not for UDP.

UDPv6 receiver should by default drop a frame with a 0 checksum,
and UDPv4 would not verify the checksum and might accept a corrupted
packet.

Simply replace such checksum by 0xffff, regardless of transport.

This error was caught on SIT tunnels, but seems generic.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>