Date: Sun, 24 Nov 1996 04:54:49 CST From: Kent Vander Velden <graphix@iastate.edu> To: Tom Samplonius <tom@sdf.com> Cc: hackers@freefall.freebsd.org Subject: Re: ping and freebsd crashes Message-ID: <9611241054.AA19315@spiff.cc.iastate.edu> In-Reply-To: Your message of "Sun, 24 Nov 1996 00:39:40 PST." <Pine.NEB.3.94.961124003102.10075A-100000@misery.sdf.com>
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In message <Pine.NEB.3.94.961124003102.10075A-100000@misery.sdf.com>, tom@sdf.c om writes: > >On Sat, 23 Nov 1996, Kent Vander Velden wrote: > >> After reading the url that was mentioned earlier about ping I tried to >> crash an Irix 5.2 machine. I used OSF/1 v3.2 'ping -q -f -l 200 -s >> 5000'. The network appeared to take quite a beating. Sort of related >> to wanting to try this was that I have been working on a network packet >> analyzer and wanted to see how much of a load this pinging would cause. >> The network analyzer runs on a freebsd machine and uses libpcap. The >> interesting part of all this is the freebsd machine crashed and in fact >> crashed really hard. In the worst case a user's home directory and 50% >> of /bin and misc. was removed. I must point out that the freebsd >> machine was not being pinged nor was it doing the pinging it was simply >> a machine on the network with it's interface running in promiscuous mode. >> I also tried tcpdump to make sure that it was not my program that was >> causing problems with the same result. > > Was your analyzer doing disk i/o at the same time? To the affected >filesystems? It is capable of doing disk i/o. If a sigint was sent to it it would have dumped some information. > How much memory does the test machine have in it? 20M and used for very little. There is not really a load on it. >> There where many >> "lnc0: missed packet -- no receive buffer" >> and >> "lnc0: Framming error" >> messages with the killer appearing to be >> "panic brelse: free buffer onto another queue?" > > Have you tried some other kind of ethernet card? It could be driver >related. No, I have not. >> Perhaps this problems is no longer present. I wish I could tell you >> the version of the os that I had but that was lost when I installed the >> 961014 snap to reclaim the binaries lost during the crashes. I will try >> to find if this problem is present with this snapshot as soon as I am in >> a position that I will not lose network connectivity if the machine does >> not come back up. >> >> This would seem like a rather serious problem. > > Not really. It involves putting the ethernet device in promiscous mode. >This is rare and involves root access. It has always been risky, because >some hardware doesn't like it. I've seen some NE2000s get stuck in >promiscous mode and do all kinds of strange things. > If the interface is not in promiscuous mode the system does not crash but instead reports the mentioned errors over and over. Unfort. some of my systems have to be in promiscuous mode all the time since they have rarpd (or is it rbootd that does it) running on them. Seemed nasty that I could remotely crash a system in this way :) --- Kent Vander Velden graphix@iastate.edu
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