Armature bone deformations. Modelling or weight painting problem?

Hello everyone,
I’m comparably new to modelling and I’ve attempted to create a character model and rigging it. I’ve used automatic weights, and haven’t moved on to the step of weight painting yet, so I have a rather basic question: Is the following a modelling problem or a weight painting problem? As in, can I fix these problems solely with weight painting, or do I need to remodel a certain part/whole model etc? Here are the deformations:

Note: The only steps I’ve took in this character model are modelling (with mirror on) and making a basic, non IK rig.

add more geometry

Thanks alot!