From 952f2c2f1e2659ebe4fb4f5940832d02e5da6c4e Mon Sep 17 00:00:00 2001
From: Aayush Rajasekaran <arajasek94@gmail.com>
Date: Wed, 9 Sep 2020 05:13:51 -0400
Subject: [PATCH 1/2] Sever chainstore's dependence on the state tree

---
 chain/store/store.go | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/chain/store/store.go b/chain/store/store.go
index 20a7e3031..ad30e0324 100644
--- a/chain/store/store.go
+++ b/chain/store/store.go
@@ -18,7 +18,6 @@ import (
 	"github.com/filecoin-project/specs-actors/actors/util/adt"
 
 	"github.com/filecoin-project/lotus/api"
-	"github.com/filecoin-project/lotus/chain/state"
 	"github.com/filecoin-project/lotus/chain/vm"
 	"github.com/filecoin-project/lotus/journal"
 	bstore "github.com/filecoin-project/lotus/lib/blockstore"
@@ -767,32 +766,16 @@ type BlockMessages struct {
 func (cs *ChainStore) BlockMsgsForTipset(ts *types.TipSet) ([]BlockMessages, error) {
 	applied := make(map[address.Address]uint64)
 
-	cst := cbor.NewCborStore(cs.bs)
-	st, err := state.LoadStateTree(cst, ts.Blocks()[0].ParentStateRoot)
-	if err != nil {
-		return nil, xerrors.Errorf("failed to load state tree")
-	}
-
-	preloadAddr := func(a address.Address) error {
-		if _, ok := applied[a]; !ok {
-			act, err := st.GetActor(a)
-			if err != nil {
-				return err
-			}
-
-			applied[a] = act.Nonce
-		}
-		return nil
-	}
-
 	selectMsg := func(m *types.Message) (bool, error) {
-		if err := preloadAddr(m.From); err != nil {
-			return false, err
+		// The first match for a sender is guaranteed to have correct nonce -- the block isn't valid otherwise
+		if _, ok := applied[m.From]; !ok {
+			applied[m.From] = m.Nonce
 		}
 
 		if applied[m.From] != m.Nonce {
 			return false, nil
 		}
+
 		applied[m.From]++
 
 		return true, nil

From 937ff4e9aef0273c7ec4b9edadd3d3dea4610f82 Mon Sep 17 00:00:00 2001
From: Aayush Rajasekaran <arajasek94@gmail.com>
Date: Tue, 15 Sep 2020 20:55:11 -0400
Subject: [PATCH 2/2] Add a sync test around blocks with bad nonce messages

---
 chain/sync_test.go | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/chain/sync_test.go b/chain/sync_test.go
index 0b0d1ed00..f4c83341f 100644
--- a/chain/sync_test.go
+++ b/chain/sync_test.go
@@ -662,6 +662,49 @@ func TestDuplicateNonce(t *testing.T) {
 	require.Equal(t, includedMsg, mft[0].VMMessage().Cid(), "messages for tipset didn't contain expected message")
 }
 
+// This test asserts that a block that includes a message with bad nonce can't be synced. A nonce is "bad" if it can't
+// be applied on the parent state.
+func TestBadNonce(t *testing.T) {
+	H := 10
+	tu := prepSyncTest(t, H)
+
+	base := tu.g.CurTipset
+
+	// Produce a message from the banker with a bad nonce
+	makeBadMsg := func() *types.SignedMessage {
+
+		ba, err := tu.nds[0].StateGetActor(context.TODO(), tu.g.Banker(), base.TipSet().Key())
+		require.NoError(t, err)
+		msg := types.Message{
+			To:   tu.g.Banker(),
+			From: tu.g.Banker(),
+
+			Nonce: ba.Nonce + 5,
+
+			Value: types.NewInt(1),
+
+			Method: 0,
+
+			GasLimit:   100_000_000,
+			GasFeeCap:  types.NewInt(0),
+			GasPremium: types.NewInt(0),
+		}
+
+		sig, err := tu.g.Wallet().Sign(context.TODO(), tu.g.Banker(), msg.Cid().Bytes())
+		require.NoError(t, err)
+
+		return &types.SignedMessage{
+			Message:   msg,
+			Signature: *sig,
+		}
+	}
+
+	msgs := make([][]*types.SignedMessage, 1)
+	msgs[0] = []*types.SignedMessage{makeBadMsg()}
+
+	tu.mineOnBlock(base, 0, []int{0}, true, true, msgs)
+}
+
 func BenchmarkSyncBasic(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		runSyncBenchLength(b, 100)