From e747775172a2d4dc4dae794f248f9687ba793f54 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 14 Sep 2018 16:24:07 +0800 Subject: tcp: fix a stale ooo_last_skb after a replace [ Upstream commit 76f0dcbb5ae1a7c3dbeec13dd98233b8e6b0b32a ] When skb replaces another one in ooo queue, I forgot to also update tp->ooo_last_skb as well, if the replaced skb was the last one in the queue. To fix this, we simply can re-use the code that runs after an insertion, trying to merge skbs at the right of current skb. This not only fixes the bug, but also remove all small skbs that might be a subset of the new one. Example: We receive segments 2001:3001, 4001:5001 Then we receive 2001:8001 : We should replace 2001:3001 with the big skb, but also remove 4001:50001 from the queue to save space. packetdrill test demonstrating the bug 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 +0 < S 0:0(0) win 32792 +0 > S. 0:0(0) ack 1 +0.100 < . 1:1(0) ack 1 win 1024 +0 accept(3, ..., ...) = 4 +0.01 < . 1001:2001(1000) ack 1 win 1024 +0 > . 1:1(0) ack 1 +0.01 < . 1001:3001(2000) ack 1 win 1024 +0 > . 1:1(0) ack 1 Fixes: 9f5afeae5152 ("tcp: use an RB tree for ooo receive queue") Signed-off-by: Eric Dumazet Reported-by: Yuchung Cheng Cc: Yaogong Wang Signed-off-by: David S. Miller Signed-off-by: Mao Wenan Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/ipv4') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 7832d0d107cd..4cc0a53652ea 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4465,7 +4465,7 @@ coalesce_done: NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFOMERGE); __kfree_skb(skb1); - goto add_sack; + goto merge_right; } } else if (tcp_try_coalesce(sk, skb1, skb, &fragstolen)) { goto coalesce_done; @@ -4477,6 +4477,7 @@ coalesce_done: rb_link_node(&skb->rbnode, parent, p); rb_insert_color(&skb->rbnode, &tp->out_of_order_queue); +merge_right: /* Remove other segments covered by skb. */ while ((q = rb_next(&skb->rbnode)) != NULL) { skb1 = rb_entry(q, struct sk_buff, rbnode); -- cgit v1.2.3