Hello cherrywood. I have not built a smokehouse. From reading posts on here, Most folks line theirs with Durock. It's available at Lowe's. You can also seal the seams with high temp food grade silicone for some added piece of mind. Good luck. Keep Smokin!
I considered this post when thinking up ideas for mine and am going to use unfaced/durock as Dave suggested. One other suggestion, as this is what I am going to do is if you plan on installing an air vent I would recommend using some High Temp Oven Paint on any exposed wood areas.