From 2227589f9b4baea159fb0ef4db385b252f4093d9 Mon Sep 17 00:00:00 2001
From: Marius van der Wijden <m.vanderwijden@live.de>
Date: Thu, 2 Jun 2022 13:15:17 +0200
Subject: [PATCH] eth/catalyst: return 0x0 on Invalid block on top of pow block
 (#25006)

---
 eth/catalyst/api.go      | 7 ++++++-
 eth/catalyst/api_test.go | 3 ++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/eth/catalyst/api.go b/eth/catalyst/api.go
index 5702726ee..4ed5093d8 100644
--- a/eth/catalyst/api.go
+++ b/eth/catalyst/api.go
@@ -354,7 +354,12 @@ func computePayloadId(headBlockHash common.Hash, params *beacon.PayloadAttribute
 func (api *ConsensusAPI) invalid(err error, latestValid *types.Block) beacon.PayloadStatusV1 {
 	currentHash := api.eth.BlockChain().CurrentBlock().Hash()
 	if latestValid != nil {
-		currentHash = latestValid.Hash()
+		// Set latest valid hash to 0x0 if parent is PoW block
+		currentHash = common.Hash{}
+		if latestValid.Difficulty().BitLen() == 0 {
+			// Otherwise set latest valid hash to parent hash
+			currentHash = latestValid.Hash()
+		}
 	}
 	errorMsg := err.Error()
 	return beacon.PayloadStatusV1{Status: beacon.INVALID, LatestValidHash: &currentHash, ValidationError: &errorMsg}
diff --git a/eth/catalyst/api_test.go b/eth/catalyst/api_test.go
index e593a280a..6171c14c4 100644
--- a/eth/catalyst/api_test.go
+++ b/eth/catalyst/api_test.go
@@ -647,7 +647,8 @@ func TestEmptyBlocks(t *testing.T) {
 	if status.Status != beacon.INVALID {
 		t.Errorf("invalid status: expected INVALID got: %v", status.Status)
 	}
-	expected := commonAncestor.Hash()
+	// Expect 0x0 on INVALID block on top of PoW block
+	expected := common.Hash{}
 	if !bytes.Equal(status.LatestValidHash[:], expected[:]) {
 		t.Fatalf("invalid LVH: got %v want %v", status.LatestValidHash, expected)
 	}