From: Xin Long <lucien.xin@xxxxxxxxx>
Date: Fri, 8 Mar 2019 15:49:16 +0800
> syzbot reported a NULL-ptr deref caused by that sched->init() in
> sctp_stream_init() set stream->rr_next = NULL.
>
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> RIP: 0010:sctp_sched_rr_dequeue+0xd3/0x170 net/sctp/stream_sched_rr.c:141
> Call Trace:
> sctp_outq_dequeue_data net/sctp/outqueue.c:90 [inline]
> sctp_outq_flush_data net/sctp/outqueue.c:1079 [inline]
> sctp_outq_flush+0xba2/0x2790 net/sctp/outqueue.c:1205
>
> All sched info is saved in sout->ext now, in sctp_stream_init()
> sctp_stream_alloc_out() will not change it, there's no need to
> call sched->init() again, since sctp_outq_init() has already
> done it.
>
> Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations")
> Reported-by: syzbot+4c9934f20522c0efd657@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Applied and queued up for -stable, thanks.
