diff --git a/core/tx_list.go b/core/tx_list.go
index 3d237f13c1..66d00bb3b2 100644
--- a/core/tx_list.go
+++ b/core/tx_list.go
@@ -49,10 +49,12 @@ func (h *nonceHeap) Push(x interface{}) {
 
 func (h *nonceHeap) Pop() interface{} {
 	old := *h
-	n := len(old)
-	x := old[n-1]
-	*h = old[0 : n-1]
-	return x
+	if n := len(old); n > 0 {
+		x := old[n-1]
+		*h = old[0 : n-1]
+		return x
+	}
+	return nil
 }
 
 // txSortedMap is a nonce->transaction hash map with a heap based index to allow
diff --git a/core/vm/contracts_lightclient.go b/core/vm/contracts_lightclient.go
index 473d8221cf..240a767453 100644
--- a/core/vm/contracts_lightclient.go
+++ b/core/vm/contracts_lightclient.go
@@ -28,6 +28,11 @@ const (
 // 32 bytes               |                 |                   |
 func decodeTendermintHeaderValidationInput(input []byte) (*lightclient.ConsensusState, *lightclient.Header, error) {
 	csLen := binary.BigEndian.Uint64(input[consensusStateLengthBytesLength-uint64TypeLength : consensusStateLengthBytesLength])
+
+	if consensusStateLengthBytesLength+csLen < consensusStateLengthBytesLength {
+		return nil, nil, fmt.Errorf("integer overflow, csLen: %d", csLen)
+	}
+
 	if uint64(len(input)) <= consensusStateLengthBytesLength+csLen {
 		return nil, nil, fmt.Errorf("expected payload size %d, actual size: %d", consensusStateLengthBytesLength+csLen, len(input))
 	}
diff --git a/core/vm/lightclient/types.go b/core/vm/lightclient/types.go
index 93c6da070d..674085b701 100644
--- a/core/vm/lightclient/types.go
+++ b/core/vm/lightclient/types.go
@@ -270,8 +270,9 @@ func DecodeKeyValueMerkleProof(input []byte) (*KeyValueMerkleProof, error) {
 	inputLength := uint64(len(input))
 	pos := uint64(0)
 
-	if inputLength <= storeNameLengthBytesLength+keyLengthBytesLength+valueLengthBytesLength+appHashLength {
-		return nil, fmt.Errorf("input length should be no less than %d", storeNameLengthBytesLength+keyLengthBytesLength+valueLengthBytesLength+appHashLength)
+	fixedSize := storeNameLengthBytesLength + keyLengthBytesLength + valueLengthBytesLength + appHashLength
+	if inputLength <= fixedSize {
+		return nil, fmt.Errorf("input length should be no less than %d", fixedSize)
 	}
 	storeName := string(bytes.Trim(input[pos:pos+storeNameLengthBytesLength], "\x00"))
 	pos += storeNameLengthBytesLength
@@ -279,7 +280,8 @@ func DecodeKeyValueMerkleProof(input []byte) (*KeyValueMerkleProof, error) {
 	keyLength := binary.BigEndian.Uint64(input[pos+keyLengthBytesLength-8 : pos+keyLengthBytesLength])
 	pos += keyLengthBytesLength
 
-	if inputLength <= storeNameLengthBytesLength+keyLengthBytesLength+keyLength+valueLengthBytesLength {
+	fixedSize = storeNameLengthBytesLength + keyLengthBytesLength + valueLengthBytesLength
+	if inputLength <= fixedSize+keyLength || fixedSize+keyLength < fixedSize {
 		return nil, fmt.Errorf("invalid input, keyLength %d is too long", keyLength)
 	}
 	key := input[pos : pos+keyLength]
@@ -288,7 +290,10 @@ func DecodeKeyValueMerkleProof(input []byte) (*KeyValueMerkleProof, error) {
 	valueLength := binary.BigEndian.Uint64(input[pos+valueLengthBytesLength-8 : pos+valueLengthBytesLength])
 	pos += valueLengthBytesLength
 
-	if inputLength <= storeNameLengthBytesLength+keyLengthBytesLength+keyLength+valueLengthBytesLength+valueLength+appHashLength {
+	fixedSize = storeNameLengthBytesLength + keyLengthBytesLength + valueLengthBytesLength + appHashLength
+	if inputLength <= fixedSize+keyLength+valueLength ||
+		fixedSize+keyLength < fixedSize ||
+		fixedSize+keyLength+valueLength < valueLength {
 		return nil, fmt.Errorf("invalid input, valueLength %d is too long", valueLength)
 	}
 	value := input[pos : pos+valueLength]