It's said that the leave instruction is the same as :
mov esp,ebp
pop ebp
But what is mov esp,ebp here for? It doesn't seem valid to me...
Answer
mov esp,ebp sets the stack pointer to the base frame address, effectively releasing the whole frame. (Don't forget that this is Intel syntax, the destination comes first.) If you didn't do it, once you call ret, you would still be using the called function's stack frame with your calling function, with crashtastic consequences.
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