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Missing approve(0) #141

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code423n4 opened this issue May 15, 2022 · 2 comments
Closed

Missing approve(0) #141

code423n4 opened this issue May 15, 2022 · 2 comments
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bug Something isn't working duplicate This issue or pull request already exists QA (Quality Assurance) Assets are not at risk. State handling, function incorrect as to spec, issues with clarity, syntax

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@code423n4
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Lines of code

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L221

Vulnerability details

Impact

IERC20.approve() function is called only once without setting the allowance to zero. Some tokens, like USDT, require first reducing the address' allowance to zero by calling approve(_spender, 0). Transactions will revert when using an unsupported token like USDT

Proof of Concept

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L221

Tools Used

Manual review

Recommended Mitigation Steps

Use approve(_spender, 0) to set the allowance to zero immediately before each of the existing approve() calls.
@code423n4 code423n4 added 2 (Med Risk) Assets not at direct risk, but function/availability of the protocol could be impacted or leak value bug Something isn't working labels May 15, 2022
code423n4 added a commit that referenced this issue May 15, 2022
@code423n4
cryptphi issue #141
cf39cd3
@sforman2000
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Duplicate of #112

@sforman2000 sforman2000 marked this as a duplicate of #112 May 18, 2022
@code423n4 code423n4 mentioned this issue May 18, 2022
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@itsmetechjay itsmetechjay added the duplicate This issue or pull request already exists label May 18, 2022
@HickupHH3
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Grouping this with the warden’s QA report: #149

@HickupHH3 HickupHH3 added QA (Quality Assurance) Assets are not at risk. State handling, function incorrect as to spec, issues with clarity, syntax and removed 2 (Med Risk) Assets not at direct risk, but function/availability of the protocol could be impacted or leak value labels Jun 3, 2022
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bug Something isn't working duplicate This issue or pull request already exists QA (Quality Assurance) Assets are not at risk. State handling, function incorrect as to spec, issues with clarity, syntax
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@sforman2000 @code423n4 @itsmetechjay @HickupHH3