I want to go to Hong Kong and Macau but my passport will have 5 months validity on arrival is it ok?

It is OK for entering HK. Based on my information, at least one month's validity should have for entering HK. For Macau, it is not sure, but probably has the similar requirement. If you can provide your round trip tickets, there is no big problem for entering.

In my opinion, if time is possible, you are suggested to renew your passport in advance before going to avoid problems.