releases/3.18.114/tcp-do-not-overshoot-window_clamp-in-tcp_rcv_space_adjust.patch

   1 From 02db55718d53f9d426cee504c27fb768e9ed4ffe Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Sun, 10 Dec 2017 17:55:02 -0800
   4 Subject: tcp: do not overshoot window_clamp in tcp_rcv_space_adjust()
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8 commit 02db55718d53f9d426cee504c27fb768e9ed4ffe upstream.
   9
  10 While rcvbuf is properly clamped by tcp_rmem[2], rcvwin
  11 is left to a potentially too big value.
  12
  13 It has no serious effect, since :
  14 1) tcp_grow_window() has very strict checks.
  15 2) window_clamp can be mangled by user space to any value anyway.
  16
  17 tcp_init_buffer_space() and companions use tcp_full_space(),
  18 we use tcp_win_from_space() to avoid reloading sk->sk_rcvbuf
  19
  20 Signed-off-by: Eric Dumazet <edumazet@google.com>
  21 Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
  22 Acked-by: Wei Wang <weiwan@google.com>
  23 Acked-by: Neal Cardwell <ncardwell@google.com>
  24 Signed-off-by: David S. Miller <davem@davemloft.net>
  25 Cc: Benjamin Gilbert <benjamin.gilbert@coreos.com>
  26 Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  net/ipv4/tcp_input.c |    2 +-
  31  1 file changed, 1 insertion(+), 1 deletion(-)
  32
  33 --- a/net/ipv4/tcp_input.c
  34 +++ b/net/ipv4/tcp_input.c
  35 @@ -605,7 +605,7 @@ void tcp_rcv_space_adjust(struct sock *s
  36                         sk->sk_rcvbuf = rcvbuf;
  37
  38                         /* Make the window clamp follow along.  */
  39 -                       tp->window_clamp = rcvwin;
  40 +                       tp->window_clamp = tcp_win_from_space(rcvbuf);
  41                 }
  42         }
  43         tp->rcvq_space.space = copied;