Submitted by TerrierLover
An attacker can make the contract unusable when totalSupply is 0. Specifically,  bumpExchangeRate function does not work correctly which results in making stake, unstake and migrateSource functions that do not work as expected.
Here are steps on how the gALCX contract can be unusable.
gALCX.sol#L73-L75
uint balance = alcx.balanceOf(address(this));
gALCX.sol#L76
Add handling when totalSupply is 0 but alcx.balanceOf(address(this)) is more than 0.
0xfoobar (Alchemix) acknowledged and commented:
0xleastwood (judge) commented:
