Date: Fri, 23 Jul 1999 20:58:28 +0300 From: Maxim Sobolev <sobomax@altavista.net> To: Alfred Perlstein <bright@rush.net> Cc: stable@FreeBSD.ORG Subject: Re: Tun interface related panic Message-ID: <3798AD44.EF14A396@altavista.net> References: <Pine.BSF.3.96.990723123524.27774N-100000@cygnus.rush.net>
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Alfred Perlstein wrote:
> On Fri, 23 Jul 1999, Maxim Sobolev wrote:
>
> > Alfred Perlstein wrote:
> >
> > > when entering gdb, please try to show me the variables in the
> > > tunwrite function, for some reason i think it's barfing becasue
> > > of a zero length write but i'm unsure.
> > >
> > > use the "up" command to get to tunwrite
> > > then "list" and try to show me the output
> > > of "print uio, top, mp" seperate though.
> > >
> > > try to give me as many vars as possible in the function via print.
> >
> > Following is information you have requested (if I did something wrong, please
> > let me know with exact instructions):
> [Piece of debug print skipped....]
> oops, ok, I wasn't clear, I need to know the contents of the structs
> that those pointers point to, try this:
>
> print *uio
> print *top
> print **mp
>
> in, the meanwhile, try this patch:
>
> cvs diff: Diffing .
> Index: if_tun.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/net/if_tun.c,v
> retrieving revision 1.51
> diff -u -r1.51 if_tun.c
> --- if_tun.c 1999/01/17 20:53:47 1.51
> +++ if_tun.c 1999/07/23 20:42:34
> @@ -521,7 +521,7 @@
>
> TUNDEBUG("%s%d: tunwrite\n", ifp->if_name, ifp->if_unit);
>
> - if (uio->uio_resid < 0 || uio->uio_resid > TUNMRU) {
> + if (uio->uio_resid <= 0 || uio->uio_resid > TUNMRU) {
> TUNDEBUG("%s%d: len=%d!\n", ifp->if_name, ifp->if_unit,
> uio->uio_resid);
> return EIO;
>
> please please tell me if it works for you so I can file a proper PR.
Yeah! It works! It seems that I'm the one who have detected this problem because
I'm using latest ppp snapshot instead of standard one. I just tested ppp from
-stable and discovered that it doesn't make this panic (version of libalias doesn't
matter though). However it would be great if you can commit this patch because new
version of ppp have some really nice features on which I rely hardly. This also
rising a question to the Brian Somers or any other who can look and find what is
wrong with the current ppp (PPP Version 2.22 - $Date: 1999/06/23 16:48:19 $).
Anyway, to have some belts in the kernel should not make any harm. Following is the
ppp output which probably before your patch would kill my box (I never seen this
message before - so to speak..):
TCP/IP: IN UDP: 208.147.89.229:18422 ---> 192.168.1.1:7070
Error: ip_Input: deflink: wrote 0, got Input/output error
If you still want to see prints, you can see it at the end of this message.
In the case if my assistance in debugging ppp will be necessary please let me know.
Sincerely,
Maxim
--
"We believe in the Power and the Might!"
(Manowar, 1996)
----------------------------------------
Maxim V. Sobolev, Financial Analyst,
Vega International Capital
Phone: +380-(44)-246-6396
Fax: +380-(44)-220-8715
E-mail: sobomax@altavista.net
ICQ: #42290709
----------------------------------------
(kgdb) up
#5 0xc01630f9 in tunwrite (dev=13312, uio=0xc2d15f14, flag=1)
at ../../net/if_tun.c:559
559 top->m_pkthdr.len = tlen;
(kgdb) print *uio
$1 = {uio_iov = 0xc2d15f0c, uio_iovcnt = 1, uio_offset = 38962, uio_resid = 0,
uio_segflg = UIO_USERSPACE, uio_rw = UIO_WRITE, uio_procp = 0xc2cc32e0}
(kgdb) print *top
Cannot access memory at address 0x0.
(kgdb) print **mp
Cannot access memory at address 0x0.
(kgdb) q
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