microcorruption: level 4 - cusco

First stack overflow
 
Again, notice how It says the password has to be between 8 and 16 characters? Good clue.
Furthermore, inputting 17 characters causes the program to crash
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Looking through the code we can see there are no cmp functions. It is therefore reasonable to believe a overflow is required to redirect input to the unlock function.
Entering x > 16 shows the stack being overwritten which confirms a stack overflow:

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​We can input the value of unlock_door function to overwrite the stack and open the door
 
Password: 414141414141414141414141414141414644