core/vm: deep copy jumptable when enabling extra eips

core/vm/interpreter.go

@@ -83,14 +83,14 @@ func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter {
 		}
 		var extraEips []int
 		for _, eip := range cfg.ExtraEips {
-			copy := *cfg.JumpTable
-			if err := EnableEIP(eip, &copy); err != nil {
+			copy := copyJumpTable(cfg.JumpTable)
+			if err := EnableEIP(eip, copy); err != nil {
 				// Disable it, so caller can check if it's activated or not
 				log.Error("EIP activation failed", "eip", eip, "error", err)
 			} else {
 				extraEips = append(extraEips, eip)
 			}
-			cfg.JumpTable = &copy
+			cfg.JumpTable = copy
 		}
 		cfg.ExtraEips = extraEips
 	}

core/vm/jump_table.go

@@ -1043,3 +1043,14 @@ func newFrontierInstructionSet() JumpTable {
 
 	return validate(tbl)
 }
+
+func copyJumpTable(source *JumpTable) *JumpTable {
+	dest := *source
+	for i, op := range source {
+		if op != nil {
+			opCopy := *op
+			dest[i] = &opCopy
+		}
+	}
+	return &dest
+}

core/vm/jump_table_test.go

@@ -0,0 +1,41 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TestJumpTableCopy tests that deep copy is necessery to prevent modify shared jump table
+func TestJumpTableCopy(t *testing.T) {
+	tbl := newMergeInstructionSet()
+	require.Equal(t, uint64(0), tbl[SLOAD].constantGas)
+
+	// a deep copy won't modify the shared jump table
+	deepCopy := copyJumpTable(&tbl)
+	deepCopy[SLOAD].constantGas = 100
+	require.Equal(t, uint64(100), deepCopy[SLOAD].constantGas)
+	require.Equal(t, uint64(0), tbl[SLOAD].constantGas)
+
+	// but a shallow copy will modify the shared table
+	shallowCopy := tbl
+	shallowCopy[SLOAD].constantGas = 100
+	require.Equal(t, uint64(100), shallowCopy[SLOAD].constantGas)
+	require.Equal(t, uint64(100), tbl[SLOAD].constantGas)
+}