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| author | Eric Dumazet <edumazet@google.com> | 2018-07-27 12:08:54 +0200 |
|---|---|---|
| committer | Shirle Yuen <shirleyshukyee@google.com> | 2018-08-03 14:07:01 -0700 |
| commit | 7a6db5f06f6924e34989ad6621199b74005a3399 (patch) | |
| tree | 31d2fc60697ac25573e10be3b576b1329d1d37b8 | |
| parent | e2c50cebf061d38d9e69582b11355920aeeadd4a (diff) | |
| download | rk-v4.4-7a6db5f06f6924e34989ad6621199b74005a3399.tar.gz | |
tcp: avoid collapses in tcp_prune_queue() if possible
[ Upstream commit f4a3313d8e2ca9fd8d8f45e40a2903ba782607e7 ]
Right after a TCP flow is created, receiving tiny out of order
packets allways hit the condition :
if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
tcp_clamp_window(sk);
tcp_clamp_window() increases sk_rcvbuf to match sk_rmem_alloc
(guarded by tcp_rmem[2])
Calling tcp_collapse_ofo_queue() in this case is not useful,
and offers a O(N^2) surface attack to malicious peers.
Better not attempt anything before full queue capacity is reached,
forcing attacker to spend lots of resource and allow us to more
easily detect the abuse.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
(cherry picked from commit 1f0e4f449212a8c44279c1885bba5ee1f5c789bf)
| -rw-r--r-- | net/ipv4/tcp_input.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 038587a36edf..1f43e5fdacd7 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4877,6 +4877,9 @@ static int tcp_prune_queue(struct sock *sk) else if (tcp_under_memory_pressure(sk)) tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss); + if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) + return 0; + tcp_collapse_ofo_queue(sk); if (!skb_queue_empty(&sk->sk_receive_queue)) tcp_collapse(sk, &sk->sk_receive_queue, |