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Auction:claimArbitrage no underflow checks needed #149

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code423n4 opened this issue Nov 29, 2021 · 1 comment
Open

Auction:claimArbitrage no underflow checks needed #149

code423n4 opened this issue Nov 29, 2021 · 1 comment
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bug Something isn't working G (Gas Optimization) sponsor confirmed Sponsor agrees this is a problem and intends to fix it (OK to use w/ "disagree with severity")

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@code423n4
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GiveMeTestEther

Vulnerability details

Vulnerability details

Impact

The else block on L241 satisfies amountTokens <= unclaimedArbTokens and therefore we don't need to do a safe subtraction (underflow check).

The else block on L247 satisfies amountTokens <= claimableArbitrageRewards and therefore we don't need to do a safe subtraction (underflow check).

Proof of Concept

https://github.com/code-423n4/2021-11-malt/blob/c3a204a2c0f7c653c6c2dda9f4563fd1dc1cecf3/src/contracts/Auction.sol#L216
https://github.com/code-423n4/2021-11-malt/blob/c3a204a2c0f7c653c6c2dda9f4563fd1dc1cecf3/src/contracts/Auction.sol#L247

Tools Used

Recommended Mitigation Steps

  • rewrite L241 as: unclaimedArbTokens = unclaimedArbTokens - amountTokens;
  • rewrite L274 as: claimableArbitrageRewards = claimableArbitrageRewards - amountTokens-;
@code423n4 code423n4 added bug Something isn't working G (Gas Optimization) labels Nov 29, 2021
code423n4 added a commit that referenced this issue Nov 29, 2021
@code423n4
GiveMeTestEther issue #149
db5d2a2
@0xScotch 0xScotch added the sponsor confirmed Sponsor agrees this is a problem and intends to fix it (OK to use w/ "disagree with severity") label Dec 9, 2021
@GalloDaSballo
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Agree with the finding

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bug Something isn't working G (Gas Optimization) sponsor confirmed Sponsor agrees this is a problem and intends to fix it (OK to use w/ "disagree with severity")
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@GalloDaSballo @0xScotch @code423n4