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psbt: also check witness UTXO if both are set

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A wallet that has patched the CVE-2020-14199 vulnerability will always
include a non-witness UTXO, even for witness inputs. In the signer, we
detect that the input we spend is a witness input and copy over the
TxOut to the witness UTXO field. Therefore it is possible that both UTXO
fields are set at the same time. We need to adjust the sanity checks
when adding a partial signature to account for that.
This commit is contained in:
Oliver Gugger 2020-07-20 15:02:05 +02:00
parent b283b0eb92
commit c7b6a5aace
No known key found for this signature in database
GPG key ID: 8E4256593F177720
1 changed files with 15 additions and 5 deletions
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20
psbt/updater.go
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@ -102,6 +102,11 @@ func (p *Updater) addPartialSignature(inIndex int, sig []byte,
} }
} }
// Attaching signature without utxo field is not allowed.
if pInput.WitnessUtxo == nil && pInput.NonWitnessUtxo == nil {
return ErrInvalidPsbtFormat
}
// Next, we perform a series of additional sanity checks. // Next, we perform a series of additional sanity checks.
if pInput.NonWitnessUtxo != nil { if pInput.NonWitnessUtxo != nil {
if len(p.Upsbt.UnsignedTx.TxIn) < inIndex+1 { if len(p.Upsbt.UnsignedTx.TxIn) < inIndex+1 {
@ -136,7 +141,16 @@ func (p *Updater) addPartialSignature(inIndex int, sig []byte,
} }
} }
} else if pInput.WitnessUtxo != nil { }
// It could be that we set both the non-witness and witness UTXO fields
// in case it's from a wallet that patched the CVE-2020-14199
// vulnerability. We detect whether the input being spent is actually a
// witness input and then copy it over to the witness UTXO field in the
// signer. Run the witness checks as well, even if we might already have
// checked the script hash. But that should be a negligible performance
// penalty.
if pInput.WitnessUtxo != nil {
scriptPubKey := pInput.WitnessUtxo.PkScript scriptPubKey := pInput.WitnessUtxo.PkScript
var script []byte var script []byte
@ -196,10 +210,6 @@ func (p *Updater) addPartialSignature(inIndex int, sig []byte,
return ErrInvalidSignatureForInput return ErrInvalidSignatureForInput
} }
} }
} else {
// Attaching signature without utxo field is not allowed.
return ErrInvalidPsbtFormat
} }
p.Upsbt.Inputs[inIndex].PartialSigs = append( p.Upsbt.Inputs[inIndex].PartialSigs = append(