diff options
| -rw-r--r-- | net/ipv4/tcp_input.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 904289d2b6b..c1339d88bbf 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1027,8 +1027,15 @@ static void tcp_update_reordering(struct sock *sk, const int metric, * SACK block range validation checks that the received SACK block fits to * the expected sequence limits, i.e., it is between SND.UNA and SND.NXT. * Note that SND.UNA is not included to the range though being valid because - * it means that the receiver is rather inconsistent with itself (reports - * SACK reneging when it should advance SND.UNA). + * it means that the receiver is rather inconsistent with itself reporting + * SACK reneging when it should advance SND.UNA. Such SACK block this is + * perfectly valid, however, in light of RFC2018 which explicitly states + * that "SACK block MUST reflect the newest segment. Even if the newest + * segment is going to be discarded ...", not that it looks very clever + * in case of head skb. Due to potentional receiver driven attacks, we + * choose to avoid immediate execution of a walk in write queue due to + * reneging and defer head skb's loss recovery to standard loss recovery + * procedure that will eventually trigger (nothing forbids us doing this). * * Implements also blockage to start_seq wrap-around. Problem lies in the * fact that though start_seq (s) is before end_seq (i.e., not reversed), |