Fix off-by-one error in delay proof

OffchainLabs · Oct 23, 2024 · d83a5f2 · d83a5f2
1 parent b6b5d6b
commit d83a5f2
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/arbnode/delay_buffer.go b/arbnode/delay_buffer.go
@@ -57,7 +57,10 @@ func GetDelayBufferConfig(ctx context.Context, sequencerInbox *bridgegen.Sequenc
 func GenDelayProof(ctx context.Context, message *arbostypes.MessageWithMetadata, inbox *InboxTracker) (
 	*bridgegen.DelayProof, error) {
 
-	seqNum := message.DelayedMessagesRead
+	if message.DelayedMessagesRead == 0 {
+		return nil, fmt.Errorf("BUG: trying to generate delay proof without delayed message")
+	}
+	seqNum := message.DelayedMessagesRead - 1
 	var beforeDelayedAcc common.Hash
 	if seqNum > 0 {
 		var err error