Submission Details
Severity:
Missing Token Balance Check in Oracle Registration
Summary
The register() function in LLMOracleRegistry only checks the allowance but not the actual token balance of the registrant.
This could lead to failed transfers when users have insufficient tokens despite having set the required allowance.
Vulnerability Details
Current implementation only checks allowance before attempting transfer:
function register(LLMOracleKind kind) public {
uint256 amount = getStakeAmount(kind);
// ensure the user is not already registered
if (isRegistered(msg.sender, kind)) {
revert AlreadyRegistered(msg.sender);
}
// Only checks allowance, not balance
if (token.allowance(msg.sender, address(this)) < amount) {
revert InsufficientFunds();
}
// Transfer will fail if balance is insufficient
token.transferFrom(msg.sender, address(this), amount);
registrations[msg.sender][kind] = amount;
emit Registered(msg.sender, kind);
}
Impact
This vulnerability leads to wasted gas fees for users who attempt to register without sufficient token balance.
Additionally, the lack of a balance check may cause unexpected transaction failures
Tools Used
Manual Review
Recommendations
Add balance check before transfer:
function register(LLMOracleKind kind) public {
uint256 amount = getStakeAmount(kind);
if (isRegistered(msg.sender, kind)) {
revert AlreadyRegistered(msg.sender);
}
// Check both allowance and balance
if (token.allowance(msg.sender, address(this)) < amount) {
revert InsufficientAllowance(msg.sender, amount);
}
if (token.balanceOf(msg.sender) < amount) {
revert InsufficientBalance(msg.sender, amount);
}
// Transfer is more likely to succeed now
token.transferFrom(msg.sender, address(this), amount);
registrations[msg.sender][kind] = amount;
emit Registered(msg.sender, kind);
}
Prize pool breakdown
Total prize
21,000 USDC
nSLOC
1,03420
USDC / LOC
20,000 USDC
1,000 USDC
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