The former Brighton & Hove Albion played for the Whites on loan from Sunderland from the start of October until last month.
Buckley failed to make an impact at Elland Road and could make just four appearances in the Championship for the West Yorkshire outfit.
The Englishman failed to score a goal or create a chance, had a pass accuracy of 76%, and won two tackles.
Sunderland are second from bottom in the Premier League table at the moment with 12 points from 18 matches.
Meanwhile, Forest currently find themselves 15th in the Championship table with 28 points from 22 games.