Supplemental Agricultural Disaster Assistance Extension Act of 2012 - Extends through FY2012: (1) the supplemental agricultural disaster assistance program; (2) the supplemental revenue assistance payments (SURE) program; (3) the livestock indemnity program; (4) the livestock forage disaster program; (5) the emergency assistance for livestock, honey bees, and farm-raised fish; (6) the tree assistance program; and (7) the Agricultural Disaster Relief Trust Fund.