IPv6 route mutex recursion (crash) and fix

[Brian Fundakowski Feldman]

On Fri, Sep 24, 2004 at 03:47:22AM +0900, JINMEI Tatuya / ?$B?@L at C#:H wrote:
> >>>>> On Tue, 21 Sep 2004 22:09:57 -0400, 
> >>>>> Brian Fundakowski Feldman <green at FreeBSD.org> said:
> 
> > I've already made noise about this before, so I'll be brief.  I plan on
> > committing the following fix that prevents the routing code from being
> > recursed upon such that RTM_RESOLVE causes the embryonic new route to
> > be looked up again.  I realize that probably no one will bother trying
> > to see this bug in action, but all you need to do is send some UDP6 to
> > ff02::1%<if> as a user, with INVARIANTS turned on.
> 
> > Are there any objections?  It would be nice to have this in 5-STABLE,
> > in case anyone actually wants to have IPv6.
> 
> The patch itself looks okay with the rationale you explained in a
> follow-up message.  However, I have some related comments.
> 
> As commented in nd6_rtrequest(), the purpose for checking
> nd6_is_addr_neighbor() in this function was to avoid creating a
> neighbor cache for the destination of some special host-routes.  For
> FreeBSD, this can happen with the route which has the RTF_PRCLONING
> flag.  However, since recent versions of FreeBSD (seems to) have got
> rid of this flag, we might even remove the check in nd6_rtrequest()
> altogether.  (Then we'd not need to modify nd6_is_addr_neighbor().)
> 
> But removing the check may be too radical and may have unexpected
> side-effect.  Also, it'd be nice if we could keep the difference
> between the FreeBSD repository code and the KAME snap code as small as
> possible, in terms of future merge efforts.  In this sense, removing
> the nd6_is_addr_neighbor() check from nd6_rtrequest() might be a
> suboptimal solution.
> 
> So, as a result, I tend to think the proposed patch is a reasonable
> fix to the problem.  But please add the rationale as comments, since
> the background intent is a bit vague as shown by the question from
> George.

Thank you for your review.  As you certainly are more knowledgable in KAME
code than I am, would you mind redoing this so that the style is more
closely matched; then I could take the change from the KAME repository?

-- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green at FreeBSD.org                               \  The Power to Serve! \
 Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\