Some dogs regularly produce pups with white on the chest, which usually diminishes at least somewhat with age, and some also produce the white tipped paws. As mentioned above, a fault in the show ring only. He is a very nice looking pup and I would not be at all concerned that he is not purebred if you got him from a reputable breeder. I know of one male that produced several pups with those markings recently with a female that had never had pups with white, so it happens.
Kairo v Wolfstraum, BH, TR 1, ATB Halcyon v Wolfstraum