consensus: dont allow peer round states to decrease

consensus/reactor.go

@@ -797,8 +797,8 @@ func (ps *PeerState) ApplyNewRoundStepMessage(msg *NewRoundStepMessage) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 
-	// Ignore duplicate messages.
-	if ps.Height == msg.Height && ps.Round == msg.Round && ps.Step == msg.Step {
+	// Ignore duplicates or decreases
+	if CompareHRS(msg.Height, msg.Round, msg.Step, ps.Height, ps.Round, ps.Step) <= 0 {
 		return
 	}
 

consensus/state.go

@@ -1134,7 +1134,7 @@ func (cs *ConsensusState) enterCommit(height int, commitRound int) {
 
 	defer func() {
 		// Done enterCommit:
-		// keep ca.Round the same, it points to the right Precommits set.
+		// keep cs.Round the same, commitRound points to the right Precommits set.
 		cs.updateRoundStep(cs.Round, RoundStepCommit)
 		cs.CommitRound = commitRound
 		cs.newStep()