As Hitler rambled on, becoming more and more Soviet unfriendly (in the time leading up to the attack), Stalin sent more and more resources to appease him. That is a fact.
That included quite large shipments of oil and grain (actually a serious issue since Germany can't feed itself, even with Denmark supplying her). And I believe he also sent nikkel and molybdenum, both of which Germany had a very hard time getting hold of.

Rumania, while supplying a lot of oil, could not satisfy Germany's hunger. Why do you think Hitler gunned for the Caucasus when he couldn't cut off the head of the snake in 41? He wanted the oil.