tree 8638841a4e39647569a24e5021bfa45586c90a3b
parent b718e8c8f4f5920aaddc2e52d5e32f494c91129c
author Soheil Hassas Yeganeh <soheil@google.com> 1528512430 -0400
committer David S. Miller <davem@davemloft.net> 1528665170 -0700

tcp: limit sk_rcvlowat by the maximum receive buffer

The user-provided value to setsockopt(SO_RCVLOWAT) can be
larger than the maximum possible receive buffer. Such values
mute POLLIN signals on the socket which can stall progress
on the socket.

Limit the user-provided value to half of the maximum receive
buffer, i.e., half of sk_rcvbuf when the receive buffer size
is set by the user, or otherwise half of sysctl_tcp_rmem[2].

Fixes: d1361840f8c5 ("tcp: fix SO_RCVLOWAT and RCVBUF autotuning")
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>