Why use 0x1111111111111111111111111111111111111100? Is it because of the short address attack issue? about useful-solidity-patterns HOT 2 CLOSED

It can be any address with the lowest 8 bits (last byte) equal to 0, such as 0x35C8C87AF6e00FB1BdC075A199f195128f49a700. UnsafeProxy and Impl are defined as two independent (uninherited) contracts so the solidity compiler will assign the state variables declared within them to overlapping storage slots. UnsafeProxy.owner will span byte offset 0-20 of slot 0 and Impl.isInitialized will span byte offset 0-1 of (also) slot 0. Therefore, writing to one state variable will overwrite the contents of the other when in the context of a delegatecall(), as is the norm with proxy pattern contracts. In this test, setting the value of owner to that address will unintentionally reset isInitialized to false because of the 0 byte in offset 0-1 of slot 0.

This is very different from a short address attack, which involves how solidity used to decode function arguments. AFAIK short address attacks haven't really been a thing since solidity 0.5.

from useful-solidity-patterns.

Thank you very much, the logic is clear now.

from useful-solidity-patterns.