Snowman Merkle Airdrop
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Submission Details
Severity: low
Valid

### [M-1] Unnecessary ```s_earntimer``` State Update in ```Snow::buySnow``` Function.

Author Revealed upon completion

[M-1] Unnecessary s_earntimer State Update in Snow::buySnow Function.

Description

The s_earntimer State gets Update in Snow::buySnow Function ,even when the transaction
involves an amount of zero . As per documentation, users can either buy or can mint their free tokens.
Due to s_earntimer state updation users cannot claim their first week Free Tokens,
Resulting into loss of one Token .

Impact:

1.Users cannot mint their first week free token ,leading to loss of one token.

2.Unnecessary state updats without efficient checks leads to more gas consumption.

3.Unfair to users who did not complete their valid token purchase.

Proof of Concept

  1. Here we try to buy token with zero amount,and it got executed.

2.No Tokens we minted by Bob.

3.Despite of zero amount,s_earntimer got update ,which prevents bob to mint its
first week Free Token till first week.

function test_lossoffirstweektoken() public {
vm.deal(bob, 10 ether);
vm.startPrank(bob);
//buying token with amount zero
snow.buySnow{value: 1e18}(0);
snow.earnSnow();
vm.stopPrank();
/*
Ran 1 test for test/Owntest.sol:OwnTest
[FAIL: S__Timer()] test_lossoffirstweektoken() (gas: 82999)
Traces:
[82999] OwnTest::test_lossoffirstweektoken()
├─ [0] VM::deal(bob: [0x1D96F2f6BeF1202E4Ce1Ff6Dad0c2CB002861d3e], 10000000000000000000 [1e19])
│ └─ ← [Return]
├─ [0] VM::startPrank(bob: [0x1D96F2f6BeF1202E4Ce1Ff6Dad0c2CB002861d3e])
│ └─ ← [Return]
├─ [60096] Snow::buySnow{value: 1000000000000000000}(0)
│ ├─ [16355] MockWETH::transferFrom(bob: [0x1D96F2f6BeF1202E4Ce1Ff6Dad0c2CB002861d3e], Snow: [0x2e234DAe75C793f67A35089C9d99245E1C58470b], 0)
│ │ ├─ emit Transfer(from: bob: [0x1D96F2f6BeF1202E4Ce1Ff6Dad0c2CB002861d3e], to: Snow: [0x2e234DAe75C793f67A35089C9d99245E1C58470b], value: 0)
│ │ └─ ← [Return] true
│ ├─ emit Transfer(from: 0x0000000000000000000000000000000000000000, to: bob: [0x1D96F2f6BeF1202E4Ce1Ff6Dad0c2CB002861d3e], value: 0)
│ ├─ emit SnowBought(buyer: bob: [0x1D96F2f6BeF1202E4Ce1Ff6Dad0c2CB002861d3e], amount: 0)
│ └─ ← [Return]
├─ [1315] Snow::earnSnow()
│ └─ ← [Revert] S__Timer()
└─ ← [Revert] S__Timer()
*/
}

Recommended Mitigation

​
function buySnow(uint256 amount) external payable canFarmSnow {
if (msg.value == (s_buyFee * amount)) {
+ if (amount > 0) {
_mint(msg.sender, amount);
s_earnTimer = block.timestamp;
}
} else {
+ if (amount > 0) {
i_weth.safeTransferFrom(
msg.sender,
address(this),
(s_buyFee * amount)
);
_mint(msg.sender, amount);
s_earnTimer = block.timestamp;
}
}
​
emit SnowBought(msg.sender, amount);
}
​
Updates

Lead Judging Commences

yeahchibyke Lead Judge about 20 hours ago
Submission Judgement Published
Validated
Assigned finding tags:

buying of snow resets global timer thus affecting earning of free snow

When buySnow is successfully called, the global timer is reset. This inadvertently affects the earning of snow as that particular action also depends on the global timer.

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