core/vm: fixed clearing issue on return data

core/vm/interpreter.go

@@ -231,9 +231,9 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
 		case !operation.jumps:
 			pc++
 		}
-		// if the operation returned a value make sure that is also set
-		// the last return data.
-		if res != nil {
+		// if the operation clears the return data (e.g. it has returning data)
+		// set the last return to the result of the operation.
+		if operation.clearsReturndata {
 			in.returnData = res
 		}
 	}

core/vm/jump_table.go

@@ -53,6 +53,8 @@ type operation struct {
 	valid bool
 	// reverts determined whether the operation reverts state
 	reverts bool
+	// clearsReturndata determines whether the opertions clears the return data
+	clearsReturndata bool
 }
 
 var (
@@ -887,6 +889,7 @@ func NewFrontierInstructionSet() [256]operation {
 			memorySize:       memoryCreate,
 			valid:            true,
 			writes:           true,
+			clearsReturndata: true,
 		},
 		CALL: {
 			execute:          opCall,
@@ -894,6 +897,7 @@ func NewFrontierInstructionSet() [256]operation {
 			validateStack:    makeStackFunc(7, 1),
 			memorySize:       memoryCall,
 			valid:            true,
+			clearsReturndata: true,
 		},
 		CALLCODE: {
 			execute:          opCallCode,
@@ -901,6 +905,7 @@ func NewFrontierInstructionSet() [256]operation {
 			validateStack:    makeStackFunc(7, 1),
 			memorySize:       memoryCall,
 			valid:            true,
+			clearsReturndata: true,
 		},
 		RETURN: {
 			execute:       opReturn,