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Eric Dumazet authored
Juha-Matti Tilli reported that malicious peers could inject tiny packets in out_of_order_queue, forcing very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet. out_of_order_queue rb-tree can contain thousands of nodes, iterating over all of them is not nice. Before linux-4.9, we would have pruned all packets in ofo_queue in one go, every XXXX packets. XXXX depends on sk_rcvbuf and skbs truesize, but is about 7000 packets with tcp_rmem[2] default of 6 MB. Since we plan to increase tcp_rmem[2] in the future to cope with modern BDP, can not revert to the old behavior, without great pain. Strategy taken in this patch is to purge ~12.5 % of the queue capacity. Fixes: 36a6503f ("tcp: refine tcp_prune_ofo_queue() to not drop all packets") Signed-off-by:
Eric Dumazet <edumazet@google.com> Reported-by:
Juha-Matti Tilli <juha-matti.tilli@iki.fi> Acked-by:
Yuchung Cheng <ycheng@google.com> Acked-by:
Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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