Subject to authorization if you intend to sell, but they certainly can't stop you from painting their image for your own use and showing it to your friends. The Stones lawyers can be a pain in the ass sometimes, but I don't think they would take any action unless you opened a gallery or widely sold your work, published it into a national magazine or put the images on a t-shirt, etc. I have a Keith art page which has some drawings submitted by Kathy Harris:

http://www.thekeithshrine.com/~Blue_Lena/art.html