panic: m_copm, length > size of mbuf chain

Andre Oppermann andre at
Mon Jan 26 05:21:50 PST 2004

sebastian ssmoller wrote:
> hi,
> my system ran stable for several days now but suddenly this error occured. At this moment i did nothing special - just surfing the net ...
> cause i have no serial line attached i could only get the following infos:
> Debugger(...) at Debugger+0x54
> panic(...) at panic+0xd5
> m_copym(...)
> ip_fragment(...)
> ip_output(...)
> ip_forward(...)
> i didnt want to write down all these numbers(addresses) by hand, should i ?
> it seems to have to do something with inet/ip so i possibly should mention that i disabled "option inet6" in kernel and that i use "pf" as
> packet filter.
> $ uname -a
> FreeBSD tyrael.linnet 5.2-CURRENT FreeBSD 5.2-CURRENT #2: Mon Jan 19 22:26:43 CET 2004     root at tyrael.linnet:/usr/obj/usr/src-current/sys/DEBUG  i386
> i can provide more info if needed...

This looks like a host/network byte order problem in relation with the 'pf' packet
filter.  ip_output() expects the ip_off field to be in host byte order.  If this is
not the case you will get bogus length values for fragmentation.


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