Assert hit in m_copydata

[sancane]

0x00007f71ceb3f9ce in m_copydata (m=0x0, off=0, len=231, cp=0x7f70a000386c "") at user_mbuf.c:1394
#4 0x00007f71ceb84a8e in sctp_copy_mbufchain (clonechain=0x0, outchain=0x7f70a0004410, endofchain=0x7f70b5ff9bc8, can_take_mbuf=0, sizeofcpy=231, copy_by_ref=0 '\000') at netinet/sctp_output.c:6996
#5 0x00007f71ceb8e481 in sctp_chunk_retransmission (inp=0x7f71700070e0, stcb=0x7f714c000920, asoc=0x7f714c000978, cnt_out=0x7f70b5ffa4dc, now=0x7f70b5ffa4c0, now_filled=0x7f70b5ffa4bc, fr_done=0x7f70b5ffa4b8, so_locked=1) at netinet/sctp_output.c:10265
#6 0x00007f71ceb8ef2c in sctp_chunk_output (inp=0x7f71700070e0, stcb=0x7f714c000920, from_where=0, so_locked=1) at netinet/sctp_output.c:10566
#7 0x00007f71ceb9a29d in sctp_lower_sosend (so=0x7f7170006e90, addr=0x7f70b5ffa8a0, uio=0x7f70b5ffa790, i_pak=0x0, control=0x0, flags=0, srcv=0x7f70b5ffa7c0) at netinet/sctp_output.c:14731
#8 0x00007f71ceb43f42 in usrsctp_sendv (so=0x7f7170006e90, data=0x7f70c4008550, len=231, to=0x7f70b5ffa8a0, addrcnt=1, info=0x7f70b5ffa8b0, infolen=infolen@entry=32, infotype=infotype@entry=4, flags=flags@entry=0) at user_socket.c:928
#9 0x00007f71cedf5f37 in association_send_data (self=self@entry=0x7f71e80a43c0, buf=0x7f70c4008550 "\001", length=231, stream_id=, ppid=ppid@entry=53, ordered=ordered@entry=0, pr=pr@entry=GST_SCTP_ASSOCIATION_PARTIAL_RELIABILITY_RTX, reliability_param=reliability_param@entry=0) at sctpassociation.c:453

It seems that the code is not expecting to be called with a null buffer. This is happening in webrtc data channels. May be this issue has something to do with bug #160