NULL pointer dereference bug triggered by netmap

[Marius Strobl]

On Mon, Jul 03, 2017 at 05:08:09PM +0200, Vincenzo Maffione wrote:
> Details here:
> 
> https://github.com/luigirizzo/netmap/issues/322
> 
> Is it acceptable to commit the proposed patch?

As suggested by hselasky@, the outliner problem at hand is better solved
by a dummy if_start method in order to not hurt the fast-path. Thus, if
anything at all, a KASSERT(ifp->if_start != NULL, "no if_start method")
should be added to if_handoff() and if_start().

Marius