Submission Details
Severity:
The `nonReentrant` modifier in `InheritanceManager`contract has major flaw making it not work as intended
Summary
The assembly code in the nonReentrantmodifier has a major flaw.
modifier nonReentrant() {
assembly {
if tload(1) { revert(0, 0) }
tstore(0, 1)
}
_;
assembly {
tstore(0, 0)
}
}
The tloadchecks if slot 1 is true or false and then sets slot 0 to true in tstore(0, 1). If there is a reentrancy attack the wrong storage slot is being checked( 1 instead of 0 ) making the modifier useless.
Vulnerability Details
Because of this flaw the nonReentrantmodifier does not protect against reentrancy attacks.
Impact
These functions would not be protected against reentrancy attacks: sendERC20, sendETH, and contractInteractions.
Tools Used
Manual code review
Recommendations
Make these changes to the nonReentrantmodifier:
modifier nonReentrant() {
assembly {
- if tload(1) { revert(0, 0) }
+ if tload(0) { revert(0, 0) }
tstore(0, 1)
}
_;
assembly {
tstore(0, 0)
}
}
Updates
Lead Judging Commences
0xtimefliez 9 months ago
Submission Judgement Published Assigned finding tags:
Wrong value in nonReentrant modifier
Rewards breakdown
nSLOC
211This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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