4.8-stable kernel panic

[Robert Watson]

If one of you has had a chance to test this properly, please go ahead and
commit.  I don't have remote -STABLE development boxes, so haven't been
able to do any -STABLE merging since I went to BSDCon.  I did get RE
permission to MFC this change.

FYI, I have a bunch more related changes in a patch that I can dig up once
I'm caught up on work re-mail.  There are a number of M_TRYWAIT scenarios
where we don't test the return value -- some easier to fix than others. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Network Associates Laboratories

On Mon, 15 Sep 2003, Maxim Konovalov wrote:

> On Sun, 14 Sep 2003, 23:05-0500, Mike Silbersack wrote:
> 
> >
> > On Sun, 14 Sep 2003 sysadmin at wvths.com wrote:
> >
> > > Hello,
> > >
> > > It's been almost a month now since I posted the original message on the
> > > list and I'm wondering about the progress on resolving this problem.
> > >
> > > I still can reproduce the panics after cvs-supping to RELENG_4 ~ 23:00 EDT
> > > today.
> > >
> > > Thanks much.
> >
> > Ooops, I forgot to follow up on this.
> >
> > Ok, a few questions:
> >
> > 1.  Can you compile INVARIANTS and INVARIANT_SUPPORT into your kernel?
> > That might help us track down the problem.
> >
> > 2.  What does your network setup look like?  Are you using divert sockets,
> > is there ppp in action, etc.
> >
> > I believe that I tried out your script at the time, and I couldn't find it
> > to cause any problems on my system.
> 
> rwatson has fixed this panic in rev. 1.115 in -current:
> 
> revision 1.115
> date: 2003/08/26 14:11:48;  author: rwatson;  state: Exp;  lines: +2 -0
> M_PREPEND() with an argument of M_TRYWAIT can fail, meaning the
> returned mbuf can be NULL.  Check for NULL in rip_output() when
> prepending an IP header.  This prevents mbuf exhaustion from
> causing a local kernel panic when sending raw IP packets.
> 
> PR:             kern/55886
> Reported by:    Pawel Malachowski <pawmal-posting at freebsd.lublin.pl>
> MFC after:      3 days
> 
> and haven't MFCed it yet.  Here is a patch for -stable:
> 
> Index: sys/netinet/raw_ip.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/netinet/raw_ip.c,v
> retrieving revision 1.64.2.17
> diff -u -r1.64.2.17 raw_ip.c
> --- sys/netinet/raw_ip.c	9 Sep 2003 19:09:22 -0000	1.64.2.17
> +++ sys/netinet/raw_ip.c	15 Sep 2003 04:21:59 -0000
> @@ -257,6 +257,8 @@
>  			return(EMSGSIZE);
>  		}
>  		M_PREPEND(m, sizeof(struct ip), M_WAIT);
> +		if (m == NULL)
> +			return(ENOBUFS);
>  		ip = mtod(m, struct ip *);
>  		ip->ip_tos = inp->inp_ip_tos;
>  		ip->ip_off = 0;
> %%%
> 
> -- 
> Maxim Konovalov, maxim at macomnet.ru, maxim at FreeBSD.org
>