Removed hasInvalidBlock filtering, as this was unnecessary risk now that the original bug in comparePeers() is fixed.

src/main/java/org/qortal/controller/Controller.java

@@ -722,44 +722,6 @@ public class Controller extends Thread {
 		return lastMisbehaved != null && lastMisbehaved > NTP.getTime() - MISBEHAVIOUR_COOLOFF;
 	};
 
-	public static final Predicate<Peer> hasInvalidBlock = peer -> {
-		synchronized (peer.peerInfoLock) {
-			final PeerChainTipData peerChainTipData = peer.getChainTipData();
-			Map<ByteArray, Long> invalidBlockSignatures = Synchronizer.getInstance().getInvalidBlockSignatures();
-			List<byte[]> peerSignatures = new ArrayList<>();
-
-			// Add peer's latest block signature
-			if (peerChainTipData != null) {
-				peerSignatures.add(peerChainTipData.getLastBlockSignature());
-			}
-
-			// Add peer's blocks since common block
-			if (peer.getCommonBlockData() != null) {
-				List<BlockSummaryData> peerSummaries = peer.getCommonBlockData().getBlockSummariesAfterCommonBlock();
-				if (peerSummaries != null) {
-					for (BlockSummaryData blockSummaryData : peerSummaries) {
-						peerSignatures.add(blockSummaryData.getSignature());
-					}
-				}
-			}
-
-			// Shortcut if no data
-			if (peerSignatures.isEmpty() || invalidBlockSignatures == null || invalidBlockSignatures.isEmpty()) {
-				return false;
-			}
-
-			// Loop through our known invalid blocks and check each one against supplied block summaries
-			for (ByteArray invalidSignature : invalidBlockSignatures.keySet()) {
-				for (byte[] peerSignature : peerSignatures) {
-					if (Arrays.equals(peerSignature, invalidSignature.value)) {
-						return true;
-					}
-				}
-			}
-			return false;
-		}
-	};
-
 	public static final Predicate<Peer> hasNoRecentBlock = peer -> {
 		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
 		final PeerChainTipData peerChainTipData = peer.getChainTipData();

src/main/java/org/qortal/controller/Synchronizer.java

@@ -241,10 +241,6 @@ public class Synchronizer extends Thread {
 		// Compare the peers against each other, and against our chain, which will return an updated list excluding those without common blocks
 		peers = Synchronizer.getInstance().comparePeers(peers);
 
-		// Disregard peers that hold invalid blocks
-		// Make sure this is after findCommonBlocksWithPeers() so that peers' summaries can be updated
-		peers.removeIf(Controller.hasInvalidBlock);
-
 		// We may have added more inferior chain tips when comparing peers, so remove any peers that are currently on those chains
 		peers.removeIf(Controller.hasInferiorChainTip);
 

src/main/java/org/qortal/network/Peer.java

@@ -121,7 +121,7 @@ public class Peer {
 
     // Peer info
 
-    public final Object peerInfoLock = new Object();
+    private final Object peerInfoLock = new Object();
 
     private String peersNodeId;
     private byte[] peersPublicKey;