The Continuation War ran from 1941 through 1944. Soviet offensives in 1944 had essentially fully exhausted Finnish reserves; although Finland had managed to withstand the final one, they judged that they couldn't withstand one more. At that point, the Finns sued for peace (the peace terms being a slightly upgraded (for the Soviets) version of the treaty at the end of the Winter War).

So Russia almost certainly could have rolled into Finland in 1945.