You can renew your passport early but the remaining balance of the months will be added to 5 years for example if your passport is still have 12 months or more validity left and you intend to renew it earlier, we have no problem in doing it so but bear in mind that the new passport validity will start from the day you coming to renew it and whatever the balance from your previous passport will be added up to maximum of 6 months. So if you have 12 months valid from your old passport we will only reimburse only 6 months on new passport and you will have a new passport that is valid 5 years and 6 months.
Even if you do not travel whilst you are abroad (living outside Malaysia) both passport and permit to stay must be valid. Under general travel rule (Geneva Convention) and airline policy all travellers must have more than 6 months validity on their passport. If the airline are not happy with either validity or condition of your passport they have the right to refuse you from boarding the aircraft.