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Submission Details
Severity: gas
Valid

Proper check-effect-interactions pattern not followed all over the protocol

0x11singh99

Proper check-effect-interactions pattern not followed all over the protocol it make vulnerable to re-entrancy and no re-entrancy guard also used.

https://github.com/Cyfrin/2023-07-beedle/blob/main/src/Lender.sol It is all over this file

Example:
Transferring the loanToken to lender before updating pools mapping

159: IERC20(p.loanToken).transfer(
p.lender,
currentBalance - p.poolBalance
);
}
​
emit PoolBalanceUpdated(poolId, p.poolBalance);
​
if (pools[poolId].lender == address(0)) {
// if the pool doesn't exist then create it
emit PoolCreated(poolId, p);
} else {
// if the pool does exist then update it
emit PoolUpdated(poolId, p);
}
​
175: pools[poolId] = p;
}

https://github.com/Cyfrin/2023-07-beedle/blob/main/src/Lender.sol#L159C13-L176C6
And
Updating the state before transferringFrom loanToken from lender to the protocol.

function addToPool(bytes32 poolId, uint256 amount) external {
if (pools[poolId].lender != msg.sender) revert Unauthorized();
if (amount == 0) revert PoolConfig();
_updatePoolBalance(poolId, pools[poolId].poolBalance + amount);
// transfer the loan tokens from the lender to the contract
IERC20(pools[poolId].loanToken).transferFrom(
msg.sender,
address(this),
amount
);
}

https://github.com/Cyfrin/2023-07-beedle/blob/main/src/Lender.sol#L182C5-L192C6

Recommendation:
Use Proper check-effect-interactions pattern and use openzeppelin re-entrancy guard wherever transferring assets to outside the protocol and use safeTransfer and safeTransferFrom of openzeppelin instead of simple transfers functions of ERC20.

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