Re: [PATCH net] udp: fix IP_CHECKSUM handling

On Sun, Oct 23, 2016 at 9:03 PM, Eric Dumazet [off-list ref] wrote:

From: Eric Dumazet <edumazet@google.com>

First bug was added in commit ad6f939ab193 ("ip: Add offset parameter to
ip_cmsg_recv") : Tom missed that ipv4 udp messages could be received on
AF_INET6 socket. ip_cmsg_recv(msg, skb) should have been replaced by
ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr));

Then commit e6afc8ace6dd ("udp: remove headers from UDP packets before
queueing") forgot to adjust the offsets now UDP headers are pulled
before skb are put in receive queue.

Fixes: ad6f939ab193 ("ip: Add offset parameter to ip_cmsg_recv")
Fixes: e6afc8ace6dd ("udp: remove headers from UDP packets before queueing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Sam Kumar <redacted>
Cc: Willem de Bruijn <willemb@google.com>
---
Tom, I would appreciate your feedback on this patch, I presume
you have tests to verify IP_CHECKSUM feature ? Thanks !

Tested-by: Willem de Bruijn <willemb@google.com>

Thanks for fixing, Eric.

Tested with https://github.com/wdebruij/kerneltools/blob/master/tests/recv_cmsg_ipchecksum.c