Pre-ww2 soviet borders with a defeated Germany.

[Saladan]

Out of curiosity is there any way for the USSR to keep it's prewar borders and not have lost ww2? Basically Poland, the Baltic states, and East Prussia remain unchanged or at least don't lose any territory to the Soviet Union. along with the Soviets staying out of Eastern Europe (by force if necessary).
I could Imagine that Stalin has to never have come to power or at least died.
Also if this does happen then what are the effects?