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Date:      Fri, 30 Apr 1999 11:09:03 -0700 (PDT)
From:      "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>
To:        jdp@polstra.com (John Polstra)
Cc:        freebsd-current@FreeBSD.ORG
Subject:   Re: Any action on PR 10570 ? getting closer to 65K :-(
Message-ID:  <199904301809.LAA25759@GndRsh.aac.dev.com>
In-Reply-To: <XFMail.990430072914.jdp@polstra.com> from John Polstra at "Apr 30, 99 07:29:14 am"

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> Pierre Beyssac wrote:
> 
> > Wouldn't it be sensible to issue a warning (or panic) when
> > increasing the reference count reaches 0, rather than causing a
> > later kernel segfault? It would involve some overhead though, and
> > I'm not sure having 2^32 routes is currently realistic since most
> > machines don't even have that many bytes of RAM, but it might be
> > true one day...
> 
> It would be pretty hard to create 2^32 routes, given that IPv4 only
> has 32-bit addresses. :-) Also, if you time it I suspect you'll find
> that it would take a geological lifetime on a fast machine to add that
> many routes.

But some of us are playing with IPv6 and it is easy to create >2^32
routes in that environment.

> 
> I think it makes more sense to increase the size of the reference
> count as discussed, rather than adding checks that add more complexity
> and overhead.

The checks could be added _today_ with very little testing needed,
simple return an error if attempting to wrap the route ref count
from 65536->0.  At least then we don't blow chunks latter and end
up segfaulting.

This is a real bug fix.  Even when the variable is increased in size
to an int32_t it _should_ have an overflow test, not doing so is poor
programming no matter how you cut it.


-- 
Rod Grimes - KD7CAX - (RWG25)                   rgrimes@gndrsh.aac.dev.com
Accurate Automation, Inc.                   Reliable computers for FreeBSD
http://www.aai.dnsmgr.com


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