recent current panic
sam at errno.com
Thu Nov 27 11:47:54 PST 2003
On Thursday 27 November 2003 06:38 am, Bjoern A. Zeeb wrote:
> On Thu, 27 Nov 2003, Yuriy Tsibizov wrote:
> > >i got a panic on recent -CURRENT:
> > >
> > ># tcpdump -i lo0 port 23 &
> > > 507
> > >listening on lo0
> > >
> > ># telnet localhost
> > >Trying ::1...
> > >
> > >Wed Nov 26 14:51:23 MSK 2003
> > >Debugger+0x55: xchgl %ebx,in_Debugger.0
> > [....]
> > It looks very similar to
> > http://www.freebsd.org/cgi/query-pr.cgi?pr=59576. You can revert to
> > version 1.28 of net/bpf.h if you need tcpdump on lo, tun, ic, plip, disc
> > or gif interface right now.
> just to note: I ran tcpdump on tunN (which was a pppoe interface) w/o
> problems two days ago (with a recent world) while debugging and
> testing other net related things.
As was noted earlier, the issue is the addition of M_ASSERTVALID to the
BPF_MTAP macro. This fails in numerous cases because existing practice was
to allocate a "fake mbuf" on the stack for passing local data in to bpf. If
this mbuf is not zero'd (or at least m_flags) then the assertion may trip.
It's arguable what the correct solution is for these problems but you should
be able to safely remove the assert until we can make a sweep over the
drivers as the existing code has been around for a while (not to imply this
makes it right :)).
More information about the freebsd-current