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Merge branch 'rds-conn-spamming'

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Sowmini Varadhan says:

====================
RDS: TCP: connection spamming fixes

We have been testing the RDS-TCP code with a connection spammer
that sends incoming SYNs to the RDS listen port well after
an rds-tcp connection has been established, and found a few
race-windows that are fixed by this patch series.

Patch 1 avoids a null pointer deref when an incoming SYN
shows up when a netns is being dismantled, or when the
rds-tcp module is being unloaded.

Patch 2 addresses the case when a SYN is received after the
connection arbitration algorithm has converged: the incoming
SYN should not needlessly quiesce the transmit path, and it
should not result in needless TCP connection resets due to
re-execution of the connection arbitration logic.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2016-05-20 19:20:12 -04:00
commit 9a0351dfca
1 changed files with 9 additions and 4 deletions
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13
net/rds/tcp_listen.c
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@ -80,6 +80,9 @@ int rds_tcp_accept_one(struct socket *sock)
int conn_state;
struct sock *nsk;
if (!sock) /* module unload or netns delete in progress */
return -ENETUNREACH;
ret = sock_create_kern(sock_net(sock->sk), sock->sk->sk_family,
sock->sk->sk_type, sock->sk->sk_protocol,
&new_sock);
@ -129,11 +132,13 @@ int rds_tcp_accept_one(struct socket *sock)
* so we must quiesce any send threads before resetting
* c_transport_data.
*/
wait_event(conn->c_waitq,
!test_bit(RDS_IN_XMIT, &conn->c_flags));
if (ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr)) {
if (ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr) ||
!conn->c_outgoing) {
goto rst_nsk;
} else if (rs_tcp->t_sock) {
} else {
atomic_set(&conn->c_state, RDS_CONN_CONNECTING);
wait_event(conn->c_waitq,
!test_bit(RDS_IN_XMIT, &conn->c_flags));
rds_tcp_restore_callbacks(rs_tcp->t_sock, rs_tcp);
conn->c_outgoing = 0;
}