Is it safe to recieve Econet data into MBUFS?

I am hunting an insidious bug in a DCI4 version of the DCI2/RISCiX ip over Econet encapsulation and it crossed my mind to wonder if the mbuf manager moves data that its managing about in the background while adjusting the struct mbuf fields to match. Thus the client’s view of the data remains the same but the locations that its stored at could change without warning. Since I am receiving Econet data into MBUFS this could be a bad thing.

The insidious bit is the bug is packet size dependent, normal ping is ok, ping with 1024 bytes and its bye bye machine. The damage seems to get done receiving the packet though it doesn’t manifest until freeing the reply. The pinging machine will receive the reply and say 0% packet loss but the target will be stone dead by now.

Things like telnet are fine as is pcnfsd and nfs v2 mount but opening the filer window & its stone dead again.

If anybody knows if receiving Econet into mbufs is safe or not that would usefully rule one thing in or out.