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IntersectMBO / cardano-ledger

The ledger implementation and specifications of the Cardano blockchain.
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Prevent duplicates in `inputsTxBodyL` and `refInputsTxBodyL` #4007

Closed lehins closed 10 months ago

lehins commented 10 months ago

Current logic for figuring out reference scripts does not care whether the same inputs is listed in inputs that are spent and reference inputs: https://github.com/IntersectMBO/cardano-ledger/blob/53d93c0878c6960982af7cdd3c2447bc34b65dfa/eras/babbage/impl/src/Cardano/Ledger/Babbage/UTxO.hs#L131

There is never a case when same input should appear in both, so we decided to add a predicate check that makes this impossible.

colll78 commented 10 months ago

Good to see this resolved. We found a smart contract exploit related to this in an auction protocol where you could only refund your bid by referencing a bid that is greater than or equal to your own.

colll78 commented 10 months ago

This change will not affect previous versions of Plutus correct? I know that there are scripts on mainnet that rely on the ability to produce an inputs as both a reference inputs and a normal input.

lehins commented 10 months ago

@colll78 Of course, we can't change the behavior of previous eras. If we did the chain would not replay.

Also, we can't make these sort of changes without a hard fork. So this will take into affect in Conway onwards.

Thank you for reminding about the ticket. This was implemented in #4024