They are, but you should double check your cereal, marshmallows, white chocolate and vanilla to make sure that the brand you purchase is gluten free.  In my research I found that Jet-Puffed Marshmallows, Ghirardelli white chocolate ,and McCormick vanilla extract are made without gluten and do not have cross-contamination, but if you are strictly gluten-intolerant you should double check for each ingredient.