Prepare cake mix according to package directions, using two 8- or 9-inch round baking pans. Cool cakes in pans on wire rack for 10 minutes. Remove cakes from pans. Cool completely.
When cakes are cool, spread half of the cherry pie filing on top of one of the cake layers. Top with remaining cake layer. Frost sides only of cake with whipped topping. Spread the remaining pie filing on top of the cake.