SANTA CLARA, Calif. (AP) — The San Francisco 49ers have signed cornerback Leon Hall to a one-year deal. The 49ers placed cornerback Asa Jackson on injured reserve Tuesday with a hamstring injury to make room for Hall on the roster. San Francisco was short-handed at cornerback with Jackson and Ahkello Witherspoon (concussion) both hurt and starter Rashard Robinson leaving last week's game twice with cramps. The 32-year-old Hall was originally a first-round pick by Cincinnati in 2007.