Comment Samba has a license for many of the key patents (Score 5, Informative) 139
Samba and any other free software project (via the PFIF) has a royalty free license to most of the patents that are important for these protocols.
There are some patents that are excluded from this (see appendix 4 of the agreement for a list of the excluded patents), and we do indeed need to avoid infringement of those patents. That has not so far proved to be an insurmountable obstacle, although it is an inconvenience.
Cheers, Tridge