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Integer overflow in increaseApproval #1

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whiteHat001 opened this issue Jul 13, 2018 · 0 comments

whiteHat001 commented Jul 13, 2018 •

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Hello,I found an integer overflow in increaseApproval function.And it doesn't use the safe function to add value.
code addresss:
https://etherscan.io/address/0x30ceCB5461A449A90081F5a5F55db4e048397BAB
vuln code:

    function increaseApproval (address _spender, uint _addedValue) 
        returns (bool success) {
        //allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        allowed[msg.sender][_spender] += _addedValue;   //integer overflow
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
      }

Before overflow

After add value 0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff

Discovered by zhihua.yao@dbappsecurity.com.cn

The text was updated successfully, but these errors were encountered:

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