If I remember correctly LIN does not do airside transfers (Not even between Schengen flights). So you would exit through passport control into Italy, then go through regular security to enter the Schengen departure zone.

While 85 minutes is not a lot, LIN is only a small airport and if everything runs on time I'd assume this to be possible. And in case you do miss the connection (assuming all was booked as one ticket) the airline is responsible to rebook you onto the next available flight for free.