This is supposed to be a backport for v4.14.y and older. Sorry for the confusion.

Guenter

On 06/17/2018 10:37 PM, Guenter Roeck wrote:

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 Signed-off-by: Guenter Roeck linux@roeck-us.net

---

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

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 125b49c166a4..f0caff3139ed 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -647,7 +647,7 @@ void tcp_rcv_space_adjust(struct sock *sk) 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;