From: Eric Dumazet Date: Wed, 23 May 2012 17:51:37 +0000 (+0000) Subject: tcp: take care of overlaps in tcp_try_coalesce() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1ca7ee30630e1022dbcf1b51be20580815ffab73;p=linux-beck.git tcp: take care of overlaps in tcp_try_coalesce() Sergio Correia reported following warning : WARNING: at net/ipv4/tcp.c:1301 tcp_cleanup_rbuf+0x4f/0x110() WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq), "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n", tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt); It appears TCP coalescing, and more specifically commit b081f85c297 (net: implement tcp coalescing in tcp_queue_rcv()) should take care of possible segment overlaps in receive queue. This was properly done in the case of out_or_order_queue by the caller. For example, segment at tail of queue have sequence 1000-2000, and we add a segment with sequence 1500-2500. This can happen in case of retransmits. In this case, just don't do the coalescing. Reported-by: Sergio Correia Signed-off-by: Eric Dumazet Tested-by: Sergio Correia Signed-off-by: David S. Miller --- diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index cfa2aa128342..b224eb8bce8b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4555,6 +4555,11 @@ static bool tcp_try_coalesce(struct sock *sk, if (tcp_hdr(from)->fin) return false; + + /* Its possible this segment overlaps with prior segment in queue */ + if (TCP_SKB_CB(from)->seq != TCP_SKB_CB(to)->end_seq) + return false; + if (!skb_try_coalesce(to, from, fragstolen, &delta)) return false;