Definition max_inv mf := forall b ofs, Mem.valid_block mf b ->
                                    permission_at mf b ofs Max = Some Freeable.

Lemma setPermBlock_lt: forall pmap m b ofs sz p (Hinv: max_inv m) (Hvalid: Mem.valid_block m b) (Hlt: permMapLt pmap (getMaxPerm m)), permMapLt (setPermBlock p b ofs pmap sz) (getMaxPerm m).