The Packers first free agent signing of the off-season is with one of their own.  Veteran defensive back Jarrett Bush, with the Packers since 2006, has agreed to a three year contract extension.  Terms of the deal weren't immediately announced.  His agent, Derrick Fox, says Bush visited with the Arizona Diamondbacks and New York Jets since becomming an unrestricted free agent earlier this month.   Fox told the Associated Press that Bush would have left Green Bay if he was guaranteed a starting job but when none were promised, he was more than happy to return to Green Bay.   Bush has appeared in 94 games since joining Green Bay has a free agent after being waived by Carolina in his rookie year as an undrafted free agent out of Utah State.  He has made 7 starts in the secondary and has three career interceptions, two of them coming last season.  Bush also intercepted Ben Roethlisberger in the Pack's 31-25 Super Bowl victory over the Pittsburgh Steelers two years ago.  While a role player in the secondary, Bush has become one of the unquestioned leaders of the Special Teams, having been elected captain of the units in each of the past two playoff years.