Commit 29d0a309 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

[TCP]: Fix two off-by-one errors in fackets_out adjusting logic 



1) Passing wrong skb to tcp_adjust_fackets_out could corrupt
fastpath_cnt_hint as tcp_skb_pcount(next_skb) is not included
to it if hint points exactly to the next_skb (it's lagging
behind, see sacktag).

2) When fastpath_skb_hint is put backwards to avoid dangling
skb reference, the skb's pcount must also be removed from count
(not included like above).

Reported by Cedric Le Goater <legoater@free.fr>

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 182f6ed5

net/ipv4/tcp_output.c

+4 −2
Original line number Diff line number Diff line
@@ -1755,14 +1755,16 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m 
		if (tcp_is_reno(tp) && tp->sacked_out)

			tcp_dec_pcount_approx(&tp->sacked_out, next_skb);



		tcp_adjust_fackets_out(tp, skb, tcp_skb_pcount(next_skb));

		tcp_adjust_fackets_out(tp, next_skb, tcp_skb_pcount(next_skb));

		tp->packets_out -= tcp_skb_pcount(next_skb);



		/* changed transmit queue under us so clear hints */

		tcp_clear_retrans_hints_partial(tp);

		/* manually tune sacktag skb hint */

		if (tp->fastpath_skb_hint == next_skb)

		if (tp->fastpath_skb_hint == next_skb) {

			tp->fastpath_skb_hint = skb;

			tp->fastpath_cnt_hint -= tcp_skb_pcount(skb);

		}



		sk_stream_free_skb(sk, next_skb);

	}