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    Subject[PATCH 3.18 37/85] tcp: do not overshoot window_clamp in tcp_rcv_space_adjust()
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Dumazet <edumazet@google.com>

    commit 02db55718d53f9d426cee504c27fb768e9ed4ffe upstream.

    While rcvbuf is properly clamped by tcp_rmem[2], rcvwin
    is left to a potentially too big value.

    It has no serious effect, since :
    1) tcp_grow_window() has very strict checks.
    2) window_clamp can be mangled by user space to any value anyway.

    tcp_init_buffer_space() and companions use tcp_full_space(),
    we use tcp_win_from_space() to avoid reloading sk->sk_rcvbuf

    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
    Acked-by: Wei Wang <weiwan@google.com>
    Acked-by: Neal Cardwell <ncardwell@google.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Cc: Benjamin Gilbert <benjamin.gilbert@coreos.com>
    Signed-off-by: Guenter Roeck <linux@roeck-us.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/ipv4/tcp_input.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/net/ipv4/tcp_input.c
    +++ b/net/ipv4/tcp_input.c
    @@ -605,7 +605,7 @@ void tcp_rcv_space_adjust(struct sock *s
    sk->sk_rcvbuf = rcvbuf;

    /* Make the window clamp follow along. */
    - tp->window_clamp = rcvwin;
    + tp->window_clamp = tcp_win_from_space(rcvbuf);
    }
    }
    tp->rcvq_space.space = copied;

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