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To: Kenneth Merry <ken@plutotech.com>
cc: brian@awfulhak.org (Brian Somers), mestery@winternet.com,
        freebsd-hackers@FreeBSD.ORG
Subject: Re: Sig 12's with user PPP 
In-reply-to: Your message of "Fri, 29 Aug 1997 00:44:04 MDT."
             <199708290644.AAA28380@pluto.plutotech.com> 
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Date: Sun, 31 Aug 1997 01:44:54 +0100
From: Brian Somers <brian@awfulhak.org>
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> Brian Somers wrote...
> 
> > Sounds *really* like an installation thing.  Can you remove the UID 
> > bit on ppp and run it as root.  You should get a core with the sig 12 
> > - it would be interesting to know what the syscall problem is.
> 
> 	I'm having trouble with ppp, except I get sig 10's and 11's.  I
> also get sio overflows all the time...
> 
> sio1: 1 more silo overflow (total 1)
> sio1: 1 more silo overflow (total 2)
> pid 337 (ppp), uid 0: exited on signal 10
> pid 642 (ppp), uid 0: exited on signal 11
> pid 660 (ppp), uid 0: exited on signal 10
> sio1: 1 more silo overflow (total 3)
> sio1: 1 more silo overflow (total 4)
> 
> 	I compiled ppp with the debugging symbols in, and took the setuid
> bit off it.  Below is what happened when it crashed...gdb seems to be
> unhappy.
> 
> 	BTW, I'm running a SMP system as well.  (the kernel is from August
> 13th)
> 
> Ken
> -- 
> Kenneth Merry
> ken@plutotech.com
> 
> 
> # gdb ppp
> GDB is free software and you are welcome to distribute copies of it
>  under certain conditions; type "show copying" to see the conditions.
> There is absolutely no warranty for GDB; type "show warranty" for details.
> GDB 4.16 (i386-unknown-freebsd), 
> Copyright 1996 Free Software Foundation, Inc...
> (gdb) set args pluto
> (gdb) run
> Starting program: /usr/sbin/ppp pluto
> User Process PPP. Written by Toshiharu OHNO.
> Using interface: tun0
> Interactive mode
> Dial attempt 1 of 1
> Phone: 1234567
> dial OK!
> login OK!
> ppp ON > Packet mode.
> Warning: No password entry for this host in ppp.secret
> Warning: Manipulation is allowed by anyone
> ppp ON thunderdome> 
> PPP ON thunderdome> 
> Program received signal SIGBUS, Bus error.
> 0x183f1 in VjCompInput (bp=
> Error accessing memory address 0xefffffa4: Invalid argument.
> ) at /usr/src/usr.sbin/ppp/vjcomp.c:143
> 143     }
> (gdb) where
> #0  0x183f1 in VjCompInput (bp=
> Error accessing memory address 0xefffffa4: Invalid argument.
> ) at /usr/src/usr.sbin/ppp/vjcomp.c:143
> Error accessing memory address 0xefffff9c: Invalid argument.
> 

I dunno how much I can do with this.  Does "disable vjcomp" and 
"deny vjcomp" make the problem go away ?  If so, it looks as if 
something in the bit that uncompresses a packet is scribbling on the 
return address.  You'll need to delve a bit deeper to try to get more 
info.

I haven't heard of this problem before.
-- 
Brian <brian@awfulhak.org>, <brian@freebsd.org>
      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour....