the same Validator maybe unstake twice

[VictorECDSA]

This issue, and all previous issues, are based on the latest version of the Main branch.
Author: Jaynti Kanani jdkanani@gmail.com#mailto:jdkanani@gmail.com
Date: 6 months ago (2022/1/26 16:43:04)
Committer: GitHub noreply@github.com#mailto:noreply@github.com
Commit hash: 5dace23
Children: 61170c6#gitext://gotocommit/61170c6a824468800dc2187be73f2869ed82b82b 5d82635#gitext://gotocommit/5d82635a65fdc7c76fe5d281c3f208b3e955b6cc
Parent(s): 7c0af26#gitext://gotocommit/7c0af26ec34ccedadda6ccf5a1f57f65e03b0af2 746dfd6#gitext://gotocommit/746dfd6f61a6052c8c3985d34c408737d3bc1740

Assume that there is a Validator belong to Alice. And then Bob startAuction for this Validator.

Later, Alice is slashed to validatorStakeSlashed == 0, then _unstake.

    function slash(bytes calldata _slashingInfoList) external returns (uint256) {

//......

        for (; i < slashingInfoList.length; i++) {

//......

            if (validatorStakeSlashed == 0) {
                _unstake(validatorId, currentEpoch);

So the deactivationEpoch != 0.

    function _unstake(uint256 validatorId, uint256 exitEpoch) internal {

//......

        validators[validatorId].deactivationEpoch = exitEpoch;

And then later Bob confirmAuctionBid for this Validator. Then enter the logical branch of dethroneAndStake.

    function confirmAuctionBid(
        uint256 validatorId,
        uint256 heimdallFee, /** for new validator */
        IStakeManager stakeManager
    ) external {

//......

        if (perceivedStake >= auctionAmount && validators[validatorId].deactivationEpoch == 0) {

//......

        } else {
            stakeManager.dethroneAndStake(
                auctionUser, 
                heimdallFee,
                validatorId,
                auctionAmount,
                auction.acceptDelegation,
                auction.signerPubkey
            );
        }

And then dethroneAndStake will invoke _unstake again.

    function dethroneAndStake(
        address auctionUser,
        uint256 heimdallFee,
        uint256 validatorId,
        uint256 auctionAmount,
        bool acceptDelegation,
        bytes calldata signerPubkey
    ) external {

//......

        _unstake(validatorId, currentEpoch);

Therefore, the same Validator maybe unstake twice.