Forever Victory said:
I don't see any problem. You may upload your existing passport and renew it once expired as it will be needed in the CIC process.
To add something here, I myself renewed my passport a few days after I had my medicals. When the PPR arrived, I filled in the new information of my passport on the Appendix A they attach with the email. So, it won't cause any problems even if you are already on CIC stage.
Just make sure when you receive your visa, they had input the correct information. In my case, they didn't notice that I have a new passport, they input the previous passport information on my visa and COPR and only gave me 3 months validity on my visa. I had to have it rectified in the end.