My Study Permit Expired After I Applied for an Extension
"If your study permit expires after you have submitted your application for an extension but before you receive a decision on your application, you can stay in Canada under what’s called implied status. That means the law implies you are a temporary resident. That status lasts until CIC decides on your new permit application. However, you must respect the following requirements.
If you applied for another study permit:
If you applied for a different kind of permit:
You cannot do any of the activities allowed by the original study permit. For example, you may have come to Canada as a student and then applied for a work permit. If so, you must stop studying once your study permit expires. After that, you cannot work or study until you get a new permit.
If you have applied to extend your study permit and plan on traveling outside Canada while your application is in process, you can leave Canada and come back. However, one of three things will happen when you return to Canada:
You may be admitted to Canada as a temporary resident visitor, if CIC has not yet decided to extend your study permit. If so, you cannot study until you receive your new permit. The officer at the port of entry may ask you to prove you have enough money to support yourself in Canada.
You may be admitted to Canada as a student, if the officer at the port of entry can confirm that CIC extended your study permit while you were away.
You may be asked to apply for a new study permit at the port of entry.
Note: It is possible that you will not be able to enter Canada. The final decision is made at the border by the border services officer."
Information culled from: www.cic.gc.ca