diff options
| author | Douglas Caetano dos Santos <douglascs@taghos.com.br> | 2016-09-22 15:52:04 -0300 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2016-11-24 16:24:02 +0100 |
| commit | 511ad85e5eb023f16494d703446f3d7b7f09e879 (patch) | |
| tree | bcd9924a7fe63f67199380dc93ac5297c044c736 | |
| parent | 1497fd0e23a1cbf0bfda0af3107d825166d98e3d (diff) | |
| download | lwn-511ad85e5eb023f16494d703446f3d7b7f09e879.tar.gz lwn-511ad85e5eb023f16494d703446f3d7b7f09e879.zip | |
tcp: fix wrong checksum calculation on MTU probing
[ Upstream commit 2fe664f1fcf7c4da6891f95708a7a56d3c024354 ]
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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -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 f08921156be8..c807d5790ca1 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1762,12 +1762,14 @@ 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. |