Crash using tun device

[Pete Carah]

I now (cvsup as of a day ago, and also from a week ago) see a
spontaneous reboot when using the tun device from userland ppp.  This
occurs with either umodem or an ssh tunnel on the serial side, and
crashes immediately after the IP addresses are set.  I don't know if it
is in route setting or not; the ssh tunnel script doesn't set the
default route via the tunnel (shoot self in foot, anyone?).

I didn't see this a month or two ago afaik, though it has been a while
since I had to use ppp on either laptop.

This also occurs whether if_tun is compiled into the kernel or
kldloaded, and on a i386 and amd64 at exactly the same time.  I'm
presuming the problem isn't in /dev/tty or ucom since the ssh tunnel and
my terminal interfaces both use tty, and I've done much raw-mode stuff
with ucom lately.  That leaves if_tun and its routing/arp interface.
(though ppp doesn't use arp...), and various kernel interfaces to/from
it (note that broadcast networks (ethernet and wlan) work fine.  I
haven't tried vlan lately in -current, though.

The ppp.log shows the ip address setting line and nothing further as far
as I can see (though the crash is VERY quick after that line shows up.)

-- Pete