core: check negative value transactions. Closes #1109

core/transaction_pool.go

@@ -25,6 +25,7 @@ var (
 	ErrInsufficientFunds  = errors.New("Insufficient funds for gas * price + value")
 	ErrIntrinsicGas       = errors.New("Intrinsic gas too low")
 	ErrGasLimit           = errors.New("Exceeds block gas limit")
+	ErrNegativeValue      = errors.New("Negative value")
 )
 
 const txPoolQueueSize = 50
@@ -125,6 +126,10 @@ func (pool *TxPool) ValidateTransaction(tx *types.Transaction) error {
 		return ErrGasLimit
 	}
 
+	if tx.Amount.Cmp(common.Big0) < 0 {
+		return ErrNegativeValue
+	}
+
 	total := new(big.Int).Mul(tx.Price, tx.GasLimit)
 	total.Add(total, tx.Value())
 	if pool.currentState().GetBalance(from).Cmp(total) < 0 {