Click on the
? in-front of "Upload Photo" on your EE profile. It says exact specs the photo should be in. its 35x45.
I just found out that I uploaded the photo in 50x70, which is too big..
I got panicked and looked around.

and found this..
Request for photos
Applicants and their accompanying dependents are required to submit electronic photos as part of their complete e-application. Applicants are asked to ensure that these photos conform with Citizenship and Immigration Canada’s (CIC’s)
Permanent Resident Card Photo Specifications (PDF, 614.24KB).
At this time, the electronic photos uploaded by applicants cannot be used for the permanent residence card; therefore, CIC will not reject an application as incomplete if the photos submitted do not comply with CIC’s prescribed photo specifications.
The ‘Passport Request’ letter, therefore, includes a request for hard copy photos. Applicants are instructed to mail these photos to CIC.
This says the photo size should be 50x70.
Do some searching in this forum and find out whats the exact size is before you upload.
Either-way, i don't think they make a big fuss about the size of the photo it as long as its according to their photo requirements.