Add comment editing to the permission scheme

Only the person who commented in the review files can modify the comment. Lets say while reviewing I have raised a defect and that defect has some fields associated with it. But If other wants to update the field of the defect he should have edit permission to the defect which is only available to the creator of that defect (i.e, to the person who created that comment as defect). This default permission should be customizable.