From 3ebaaaff737a85d38d449eadefaeaf464991b602 Mon Sep 17 00:00:00 2001
From: John Jannotti <jannotti@gmail.com>
Date: Tue, 7 Jun 2022 17:00:39 -0400
Subject: [PATCH 1/2] AVM: Allow app downgrades in old protocol versions
 (#4086)

---
 config/consensus.go            |  4 +++-
 ledger/internal/apptxn_test.go | 38 ++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/config/consensus.go b/config/consensus.go
index 07aa9ba84f..61ca55a2f8 100644
--- a/config/consensus.go
+++ b/config/consensus.go
@@ -910,6 +910,9 @@ func initConsensusProtocols() {
 	// Enable application support
 	v24.Application = true
 
+	// Although Inners were not allowed yet, this gates downgrade checks, which must be allowed
+	v24.MinInnerApplVersion = 6
+
 	// Enable rekeying
 	v24.SupportRekeying = true
 
@@ -1090,7 +1093,6 @@ func initConsensusProtocols() {
 	v31.LogicSigVersion = 6
 	v31.EnableInnerTransactionPooling = true
 	v31.IsolateClearState = true
-	v31.MinInnerApplVersion = 6
 
 	// stat proof key registration
 	v31.EnableStateProofKeyregCheck = true
diff --git a/ledger/internal/apptxn_test.go b/ledger/internal/apptxn_test.go
index 4e2b64c1a3..9194055c1e 100644
--- a/ledger/internal/apptxn_test.go
+++ b/ledger/internal/apptxn_test.go
@@ -2070,6 +2070,10 @@ func TestAppDowngrade(t *testing.T) {
 	partitiontest.PartitionTest(t)
 	t.Parallel()
 
+	two, err := logic.AssembleStringWithVersion("int 1", 2)
+	require.NoError(t, err)
+	three, err := logic.AssembleStringWithVersion("int 1", 3)
+	require.NoError(t, err)
 	four, err := logic.AssembleStringWithVersion("int 1", 4)
 	require.NoError(t, err)
 	five, err := logic.AssembleStringWithVersion("int 1", 5)
@@ -2078,6 +2082,40 @@ func TestAppDowngrade(t *testing.T) {
 	require.NoError(t, err)
 
 	genBalances, addrs, _ := ledgertesting.NewTestGenesis()
+
+	// Confirm that in old protocol version, downgrade is legal
+	// Start at 28 because we want to v4 app to downgrade to v3
+	testConsensusRange(t, 28, 30, func(t *testing.T, ver int) {
+		dl := NewDoubleLedger(t, genBalances, consensusByNumber[ver])
+		defer dl.Close()
+
+		create := txntest.Txn{
+			Type:              "appl",
+			Sender:            addrs[0],
+			ApprovalProgram:   four.Program,
+			ClearStateProgram: four.Program,
+		}
+
+		vb := dl.fullBlock(&create)
+		app := vb.Block().Payset[0].ApplicationID
+
+		update := txntest.Txn{
+			Type:              "appl",
+			ApplicationID:     app,
+			OnCompletion:      transactions.UpdateApplicationOC,
+			Sender:            addrs[0],
+			ApprovalProgram:   three.Program,
+			ClearStateProgram: three.Program,
+		}
+
+		// No change - legal
+		dl.fullBlock(&update)
+
+		update.ApprovalProgram = two.Program
+		// Also legal, and let's check mismatched version while we're at it.
+		dl.fullBlock(&update)
+	})
+
 	testConsensusRange(t, 31, 0, func(t *testing.T, ver int) {
 		dl := NewDoubleLedger(t, genBalances, consensusByNumber[ver])
 		defer dl.Close()

From adb47f944bcc6b6fcddd85c963220a58d2623cef Mon Sep 17 00:00:00 2001
From: John Lee <64482439+algojohnlee@users.noreply.github.com>
Date: Tue, 7 Jun 2022 17:33:23 -0400
Subject: [PATCH 2/2] Devops: Update buildnumber.dat (#4090)

---
 buildnumber.dat | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/buildnumber.dat b/buildnumber.dat
index 573541ac97..d00491fd7e 100644
--- a/buildnumber.dat
+++ b/buildnumber.dat
@@ -1 +1 @@
-0
+1