From 723dcc6e25684a75f97ed4cec8b5db5c4bb7c045 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Wed, 11 Sep 2019 17:05:56 +0300
Subject: [PATCH 1/2] vm: make APPEND push no value on stack

---
 pkg/vm/vm.go      |  8 ++++++--
 pkg/vm/vm_test.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/pkg/vm/vm.go b/pkg/vm/vm.go
index d2638f740..a3c14149d 100644
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@@ -633,10 +633,14 @@ func (v *VM) execute(ctx *Context, op Instruction) {
 		arrElem := v.estack.Pop()
 
 		switch t := arrElem.value.(type) {
-		case *ArrayItem, *StructItem:
+		case *ArrayItem:
 			arr := t.Value().([]StackItem)
 			arr = append(arr, itemElem.value)
-			v.estack.PushVal(arr)
+			t.value = arr
+		case *StructItem:
+			arr := t.Value().([]StackItem)
+			arr = append(arr, itemElem.value)
+			t.value = arr
 		case *ByteArrayItem:
 			newVal := append(t.value, itemElem.value.Value().([]byte)...)
 			v.estack.PushVal(newVal)
diff --git a/pkg/vm/vm_test.go b/pkg/vm/vm_test.go
index a75d78b50..1a7b466b4 100644
--- a/pkg/vm/vm_test.go
+++ b/pkg/vm/vm_test.go
@@ -444,6 +444,41 @@ func TestNEWSTRUCTWrongType(t *testing.T) {
 	assert.Equal(t, true, vm.state.HasFlag(faultState))
 }
 
+func TestAPPENDArray(t *testing.T) {
+	prog := makeProgram(DUP, PUSH5, APPEND)
+	vm := load(prog)
+	vm.estack.Push(&Element{value: &ArrayItem{}})
+	vm.Run()
+	assert.Equal(t, false, vm.state.HasFlag(faultState))
+	assert.Equal(t, 1, vm.estack.Len())
+	assert.Equal(t, &ArrayItem{[]StackItem{makeStackItem(5)}}, vm.estack.Pop().value)
+}
+
+func TestAPPENDStruct(t *testing.T) {
+	prog := makeProgram(DUP, PUSH5, APPEND)
+	vm := load(prog)
+	vm.estack.Push(&Element{value: &StructItem{}})
+	vm.Run()
+	assert.Equal(t, false, vm.state.HasFlag(faultState))
+	assert.Equal(t, 1, vm.estack.Len())
+	assert.Equal(t, &StructItem{[]StackItem{makeStackItem(5)}}, vm.estack.Pop().value)
+}
+
+func TestAPPENDBadNoArguments(t *testing.T) {
+	prog := makeProgram(APPEND)
+	vm := load(prog)
+	vm.Run()
+	assert.Equal(t, true, vm.state.HasFlag(faultState))
+}
+
+func TestAPPENDBad1Argument(t *testing.T) {
+	prog := makeProgram(APPEND)
+	vm := load(prog)
+	vm.estack.PushVal(1)
+	vm.Run()
+	assert.Equal(t, true, vm.state.HasFlag(faultState))
+}
+
 func TestSIGNNoArgument(t *testing.T) {
 	prog := makeProgram(SIGN)
 	vm := load(prog)

From 68c6c93980e9f593dbb9d4982de60b449b840296 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Wed, 11 Sep 2019 17:08:36 +0300
Subject: [PATCH 2/2] vm: do not allow APPEND to operate on bytearray

---
 pkg/vm/vm.go      | 3 ---
 pkg/vm/vm_test.go | 9 +++++++++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/pkg/vm/vm.go b/pkg/vm/vm.go
index a3c14149d..c9bc97d2b 100644
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@@ -641,9 +641,6 @@ func (v *VM) execute(ctx *Context, op Instruction) {
 			arr := t.Value().([]StackItem)
 			arr = append(arr, itemElem.value)
 			t.value = arr
-		case *ByteArrayItem:
-			newVal := append(t.value, itemElem.value.Value().([]byte)...)
-			v.estack.PushVal(newVal)
 		default:
 			panic("APPEND: not of underlying type Array")
 		}
diff --git a/pkg/vm/vm_test.go b/pkg/vm/vm_test.go
index 1a7b466b4..5a7f5771a 100644
--- a/pkg/vm/vm_test.go
+++ b/pkg/vm/vm_test.go
@@ -479,6 +479,15 @@ func TestAPPENDBad1Argument(t *testing.T) {
 	assert.Equal(t, true, vm.state.HasFlag(faultState))
 }
 
+func TestAPPENDWrongType(t *testing.T) {
+	prog := makeProgram(APPEND)
+	vm := load(prog)
+	vm.estack.PushVal([]byte{})
+	vm.estack.PushVal(1)
+	vm.Run()
+	assert.Equal(t, true, vm.state.HasFlag(faultState))
+}
+
 func TestSIGNNoArgument(t *testing.T) {
 	prog := makeProgram(SIGN)
 	vm := load(prog)