inet: frags: fix defragmented packet's IP header for af_packet
inet: frags: fix defragmented packet's IP header for af_packet

When ip_frag_queue() computes positions, it assumes that the passed
sk_buff does not contain L2 headers.

However, when PACKET_FANOUT_FLAG_DEFRAG is used, IP reassembly
functions can be called on outgoing packets that contain L2 headers.

Also, IPv4 checksum is not corrected after reassembly.

Fixes: 7736d33f4262 ("packet: Add pre-defragmentation support for ipv4 fanouts.")
Signed-off-by: Edward Hyunkoo Jee <37cb19c7a46630b2441c47b5e3cc166a1579cb00@google.com>
Signed-off-by: Eric Dumazet <312c7d941f03386814be517ffdb3e0eb6624e275@google.com>
Cc: Willem de Bruijn <1ee125182537a91f90180f97fc3b3cb011bdf78a@google.com>
Cc: Jerry Chu <029109f918fd79983f4074d68beabccb17fb66a9@google.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs