channeld: Cleaner error messages
What the developer wrote
Authored by Dusty Daemon
channeld: Cleaner error messages
Since handling commit sig batches is coming for multiple locations now, add more explicity error handling so log messages are more useful.
What changed, and why it matters
This commit adds a safety check in Core Lightning's channel daemon to verify that incoming peer messages are actually the expected 'commitment signed' type before processing them. If a different message type arrives, the daemon now logs a clear error and fails the peer connection rather than potentially misinterpreting the data. It is a defensive hardening change, not a fix for a known exploitable bug.
Treat as routine defensive hardening. No urgent action required unless follow-up commits or disclosures indicate this guard was added in response to a specific vulnerability.
Security signals we found
Added explicit message-type validation before deserialization
Added diagnostic peer failure path for unexpected wire types
Defensive hardening around batch commitment_signed handling
Evidence from the diff
In channeld/channeld.c, handle_peer_commit_sig_batch() now calls check_tx_abort() and fromwire_peektype() to inspect the message before attempting to decode it as a commitment_signed. If the wire type does not match WIRE_COMMITMENT_SIGNED, it calls peer_failed_err() with an explicit diagnostic string. This improves error diagnostics and adds a type-validation guard at the entry point of batch commit-sig handling.
Changed components
channeld/channeld.chandle_peer_commit_sig_batch()Inspect captured patch +6 / −0
diff --git a/channeld/channeld.c b/channeld/channeld.c
index fde5e382..efbf4800 100644
--- a/channeld/channeld.c
+++ b/channeld/channeld.c
@@ -2270,6 +2270,12 @@ static struct commitsig_info *handle_peer_commit_sig_batch(struct peer *peer,
struct tlv_commitment_signed_tlvs *cs_tlv
= tlv_commitment_signed_tlvs_new(tmpctx);
status_debug("fromwire_commitment_signed(%p) primary", msg);
+ check_tx_abort(peer, msg, NULL);
+ type = fromwire_peektype(msg);
+ if (type != WIRE_COMMITMENT_SIGNED)
+ peer_failed_err(peer->pps, &peer->channel_id,
+ "Expected WIRE_COMMITMENT_SIGNED but got %s.",
+ peer_wire_name(type));
if (!fromwire_commitment_signed(tmpctx, msg,
&channel_id, &commit_sig.s, &raw_sigs,
&cs_tlv))
Why this scored 26/100
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