diff options
| author | Douglas Caetano dos Santos <douglascs@taghos.com.br> | 2016-09-22 15:52:04 -0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-09-23 07:55:02 -0400 |
| commit | 2fe664f1fcf7c4da6891f95708a7a56d3c024354 (patch) | |
| tree | 44bf1c6e889204e43ae18c85be64e0713d451782 | |
| parent | f44ace4d06aab8210d29c731f70b657a7524198b (diff) | |
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>
| -rw-r--r-- | net/ipv4/tcp_output.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 5288cec4a2b2..d48d5571e62a 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1966,12 +1966,14 @@ static int tcp_mtu_probe(struct sock *sk) len = 0; tcp_for_write_queue_from_safe(skb, next, sk) { copy = min_t(int, skb->len, probe_size - len); - if (nskb->ip_summed) + if (nskb->ip_summed) { skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); - else - nskb->csum = skb_copy_and_csum_bits(skb, 0, - skb_put(nskb, copy), - copy, nskb->csum); + } else { + __wsum csum = skb_copy_and_csum_bits(skb, 0, + skb_put(nskb, copy), + copy, 0); + nskb->csum = csum_block_add(nskb->csum, csum, len); + } if (skb->len <= copy) { /* We've eaten all the data from this skb. |