op-node: guard against panics in the gossip validator

op-node/p2p/gossip.go

@@ -165,6 +165,18 @@ func logValidationResult(self peer.ID, msg string, log log.Logger, fn pubsub.Val
 	}
 }
 
+func guardGossipValidator(log log.Logger, fn pubsub.ValidatorEx) pubsub.ValidatorEx {
+	return func(ctx context.Context, id peer.ID, message *pubsub.Message) (result pubsub.ValidationResult) {
+		defer func() {
+			if err := recover(); err != nil {
+				log.Error("gossip validation panic", "err", err, "peer", id)
+				result = pubsub.ValidationReject
+			}
+		}()
+		return fn(ctx, id, message)
+	}
+}
+
 type seenBlocks struct {
 	sync.Mutex
 	blockHashes []common.Hash
@@ -358,7 +370,7 @@ func (p *publisher) Close() error {
 }
 
 func JoinGossip(p2pCtx context.Context, self peer.ID, ps *pubsub.PubSub, log log.Logger, cfg *rollup.Config, gossipIn GossipIn) (GossipOut, error) {
-	val := logValidationResult(self, "validated block", log, BuildBlocksValidator(log, cfg))
+	val := guardGossipValidator(log, logValidationResult(self, "validated block", log, BuildBlocksValidator(log, cfg)))
 	blocksTopicName := blocksTopicV1(cfg)
 	err := ps.RegisterTopicValidator(blocksTopicName,
 		val,

op-node/p2p/gossip_test.go

+package p2p
+
+import (
+	"context"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/log"
+	pubsub "github.com/libp2p/go-libp2p-pubsub"
+	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ethereum-optimism/optimism/op-node/testlog"
+)
+
+func TestGuardGossipValidator(t *testing.T) {
+	logger := testlog.Logger(t, log.LvlCrit)
+	val := guardGossipValidator(logger, func(ctx context.Context, id peer.ID, message *pubsub.Message) pubsub.ValidationResult {
+		if id == "mallory" {
+			panic("mallory was here")
+		}
+		if id == "bob" {
+			return pubsub.ValidationIgnore
+		}
+		return pubsub.ValidationAccept
+	})
+	// Test that panics from mallory are recovered and rejected,
+	// and test that we can continue to ignore bob and accept alice.
+	require.Equal(t, pubsub.ValidationAccept, val(context.Background(), "alice", nil))
+	require.Equal(t, pubsub.ValidationReject, val(context.Background(), "mallory", nil))
+	require.Equal(t, pubsub.ValidationIgnore, val(context.Background(), "bob", nil))
+	require.Equal(t, pubsub.ValidationReject, val(context.Background(), "mallory", nil))
+	require.Equal(t, pubsub.ValidationAccept, val(context.Background(), "alice", nil))
+	require.Equal(t, pubsub.ValidationIgnore, val(context.Background(), "bob", nil))
+}