CS-BOLD-010 Low 5.13: Shutdown Can Be Triggered Twice

[bingen]

The shutdown function in BorrowerOperations is used to shut down the branch when the TCR falls below the SCR. If the branch is already shut down, the function will revert.

However, the function calls priceFeed.fetchPrice(), which can also shut down the branch if the price feed is failing.

This means that if the oracle fails at the same time that the branch's TCR falls below the SCR, the branch can be shut down twice. This will emit both the ShutDown and ShutDownFromOracleFailure events, which should be mutually exclusive and may not be handled correctly by off-chain infrastructure. There don't seem to be any other side effects, as the _applyShutdown will have no additional effect if it is called twice in the same block.