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Detect underflows in build_closing_transaction #3452

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Merged
merged 2 commits into from
Dec 11, 2024
Merged

Detect underflows in build_closing_transaction #3452

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13835c0
Detect underflows in `build_closing_transaction`
arik-so Dec 9, 2024
a652980
Force-close channels on underflow
arik-so Dec 9, 2024
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4 changes: 3 additions & 1 deletion lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1501,7 +1501,7 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
// The `next_funding_txid` field allows peers to finalize the signing steps of an interactive
// transaction construction, or safely abort that transaction if it was not signed by one of the
// peers, who has thus already removed it from its state.
//
//
// If we've sent `commtiment_signed` for an interactively constructed transaction
// during a signing session, but have not received `tx_signatures` we MUST set `next_funding_txid`
// to the txid of that interactive transaction, else we MUST NOT set it.
Expand Down Expand Up @@ -4368,10 +4368,12 @@ impl<SP: Deref> Channel<SP> where
total_fee_satoshis += (-value_to_counterparty) as u64;
}

debug_assert!(value_to_counterparty >= 0);
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@TheBlueMatt TheBlueMatt Dec 9, 2024

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I mean panicing in debug is great, but we think its unreachable, we should have some code to handle it (FC the channel) in release builds as well.

if skip_remote_output || value_to_counterparty as u64 <= self.context.holder_dust_limit_satoshis {
value_to_counterparty = 0;
}

debug_assert!(value_to_holder >= 0);
if value_to_holder as u64 <= self.context.holder_dust_limit_satoshis {
value_to_holder = 0;
}
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