consensus: avoid race in accessing channel (#8149)

internal/consensus/reactor.go

@@ -348,6 +348,8 @@ func (r *Reactor) broadcastHasVoteMessage(ctx context.Context, vote *types.Vote)
 // internal pubsub defined in the consensus state to broadcast them to peers
 // upon receiving.
 func (r *Reactor) subscribeToBroadcastEvents() {
+	onStopCh := r.state.getOnStopCh()
+
 	err := r.state.evsw.AddListenerForEvent(
 		listenerIDConsensus,
 		types.EventNewRoundStepValue,
@@ -356,7 +358,7 @@ func (r *Reactor) subscribeToBroadcastEvents() {
 				return err
 			}
 			select {
-			case r.state.onStopCh <- data.(*cstypes.RoundState):
+			case onStopCh <- data.(*cstypes.RoundState):
 				return nil
 			case <-ctx.Done():
 				return ctx.Err()

internal/consensus/state.go

@@ -493,12 +493,19 @@ func (cs *State) loadWalFile(ctx context.Context) error {
 	return nil
 }
 
+func (cs *State) getOnStopCh() chan *cstypes.RoundState {
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
+
+	return cs.onStopCh
+}
+
 // OnStop implements service.Service.
 func (cs *State) OnStop() {
 	// If the node is committing a new block, wait until it is finished!
 	if cs.GetRoundState().Step == cstypes.RoundStepCommit {
 		select {
-		case <-cs.onStopCh:
+		case <-cs.getOnStopCh():
 		case <-time.After(cs.config.TimeoutCommit):
 			cs.logger.Error("OnStop: timeout waiting for commit to finish", "time", cs.config.TimeoutCommit)
 		}