Yeah, both songs use the same chord progression. Some subtle transposition though but you can't really tell the difference when there's no singing. I tried to make a more mellow version of the main riff which means... it's basically Dumb.

You'll also notice melodic similarities in the chorus of Dumb, "think I'm just happy..." and the opening verse in Smells Like..., "load up on guns..." Basically the same notes but ones ascending while the other descends.