Re: [PATCH nf] netfilter: check SCTP_CID_SHUTDOWN_ACK for vtag setting in sctp_new

Xin Long [off-list ref] wrote:

The annotation says in sctp_new(): "If it is a shutdown ack OOTB packet, we
expect a return shutdown complete, otherwise an ABORT Sec 8.4 (5) and (8)".
However, it does not check SCTP_CID_SHUTDOWN_ACK before setting vtag[REPLY]
in the conntrack entry(ct).

Because of that, if the ct in Router disappears for some reason in [1]
with the packet sequence like below:

 
Seems to be day 0 bug, so
Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.")