Re: [PATCH net] sctp: reinit stream if stream outcnt has been change by sinit in sendmsg

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Mon, Jan 15, 2018 at 05:01:19PM +0800, Xin Long wrote:
> 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: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

> ---
>  net/sctp/socket.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 9b01e99..15ae018 100644
> --- 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 =
> -- 
> 2.1.0
> 
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