tree 44bf1c6e889204e43ae18c85be64e0713d451782
parent f44ace4d06aab8210d29c731f70b657a7524198b
author Douglas Caetano dos Santos <douglascs@taghos.com.br> 1474570324 -0300
committer David S. Miller <davem@davemloft.net> 1474631702 -0400

tcp: fix wrong checksum calculation on MTU probing

With TCP MTU probing enabled and offload TX checksumming disabled,
tcp_mtu_probe() calculated the wrong checksum when a fragment being copied
into the probe's SKB had an odd length. This was caused by the direct use
of skb_copy_and_csum_bits() to calculate the checksum, as it pads the
fragment being copied, if needed. When this fragment was not the last, a
subsequent call used the previous checksum without considering this
padding.

The effect was a stale connection in one way, as even retransmissions
wouldn't solve the problem, because the checksum was never recalculated for
the full SKB length.

Signed-off-by: Douglas Caetano dos Santos <douglascs@taghos.com.br>
Signed-off-by: David S. Miller <davem@davemloft.net>