sctp: reinit stream if stream outcnt has been change by sinit in sendmsg

After introducing sctp_stream structure, sctp uses stream->outcnt as the
out stream nums instead of c.sinit_num_ostreams.

However when users use sinit in cmsg, it only updates c.sinit_num_ostreams
in sctp_sendmsg. At that moment, stream->outcnt is still using previous
value. If it's value is not updated, the sinit_num_ostreams of sinit could
not really work.

This patch is to fix it by updating stream->outcnt and reiniting stream
if stream outcnt has been change by sinit in sendmsg.

Fixes: a83863174a61 ("sctp: prepare asoc stream for stream reconf")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 9b01e994f66108a12abc31f452482f1de8749d84..15ae018b386fbf2661e850c682d414d1b735010b 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1883,8 +1883,14 @@ static int sctp_sendmsg(struct sock *sk, struct msghdr *msg, size_t msg_len)
                 */
                if (sinit) {
                        if (sinit->sinit_num_ostreams) {
-                               asoc->c.sinit_num_ostreams =
-                                       sinit->sinit_num_ostreams;
+                               __u16 outcnt = sinit->sinit_num_ostreams;
+
+                               asoc->c.sinit_num_ostreams = outcnt;
+                               /* outcnt has been changed, so re-init stream */
+                               err = sctp_stream_init(&asoc->stream, outcnt, 0,
+                                                      GFP_KERNEL);
+                               if (err)
+                                       goto out_free;
                        }
                        if (sinit->sinit_max_instreams) {
                                asoc->c.sinit_max_instreams =