In some email I received from Jason R Thorpe, sie wrote:
> On Wed, Sep 25, 2002 at 10:58:02PM +1000, Darren Reed wrote:
> 
>  > Ok, explain to me why we're not fixing the problem of the mbuf being
>  > badly initialised here and instead passing a 'bad mbuf' to bpf_mtap().
>  > 
>  > If M_PKTHDR is set, then the contents of m_pkthdr are *meant* to be
>  > valid or at least that's what everyone _tells me_ (hi Jason!).
> 
> I agree with darren here... if M_PKTHDR is set, then m_pkthdr MUST
> be valid.

Well, I went looking at if_ppp.c, found quite a few things that were
suspect and have committed what I hope is a correct patch for them.

I'm not sure I want to go hunting for the same problem in the IPv6 code.

Darren