Prevent users from sending more than the required amount of ether in `L1EthBridge.sol#deposit`

[code423n4]

Lines of code

https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol#L96
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol#L107

Vulnerability details

Description

When a user deposits via the deposit function in L1EthBridge.sol, the function checks if msg.value >= _amount. As a result, if a user accidentally sends more ether than he has to (_amount), only the _amount defined in the function call will be deposited.

Proof of Concept

msg.value must be >= than _amount

	uint256 zkSyncFee = msg.value - _amount;

https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol#L96

	depositAmount[msg.sender][txHash] = _amount;

https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol#L107

Recommended Mitigation Steps

Consider adding the following requirement: require(msg.value == _amount).

[GalloDaSballo]

Self inflicted

[c4-judge]

GalloDaSballo marked the issue as duplicate of #115

[GalloDaSballo]

L

[c4-judge]

Duplicate of #110