fix(push): right pad if push parameter + PC +1 exceeds code length (#7834)

* fix(push): right pad if push parameter exceeds code length
* test: add push operation padding tests
* better perf rightPadding thnks to Ameziane

Signed-off-by: F Bojarski <ceciestunepoubelle@protonmail.ch>
Co-authored-by: Ameziane H. <ameziane.hamlat@consensys.net>

evm/src/main/java/org/hyperledger/besu/evm/operation/PushOperation.java

@@ -68,13 +68,21 @@ public class PushOperation extends AbstractFixedCostOperation {
    */
   public static OperationResult staticOperation(
       final MessageFrame frame, final byte[] code, final int pc, final int pushSize) {
-    int copyStart = pc + 1;
+    final int copyStart = pc + 1;
     Bytes push;
     if (code.length <= copyStart) {
       push = Bytes.EMPTY;
     } else {
       final int copyLength = Math.min(pushSize, code.length - pc - 1);
-      push = Bytes.wrap(code, copyStart, copyLength);
+      final int rightPad = pushSize - copyLength;
+      if (rightPad == 0) {
+        push = Bytes.wrap(code, copyStart, copyLength);
+      } else {
+        // Right Pad the push with 0s up to pushSize if greater than the copyLength
+        var bytecodeLocal = new byte[pushSize];
+        System.arraycopy(code, copyStart, bytecodeLocal, 0, copyLength);
+        push = Bytes.wrap(bytecodeLocal);
+      }
     }
     frame.pushStackItem(push);
     frame.setPC(pc + pushSize);

evm/src/test/java/org/hyperledger/besu/evm/operation/PushOperationTest.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright ConsenSys AG.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.evm.operation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.hyperledger.besu.evm.operation.PushOperation.staticOperation;
+
+import org.hyperledger.besu.datatypes.Address;
+import org.hyperledger.besu.datatypes.Hash;
+import org.hyperledger.besu.datatypes.Wei;
+import org.hyperledger.besu.evm.code.CodeV0;
+import org.hyperledger.besu.evm.frame.MessageFrame;
+import org.hyperledger.besu.evm.toy.ToyBlockValues;
+import org.hyperledger.besu.evm.toy.ToyWorld;
+
+import org.apache.tuweni.bytes.Bytes;
+import org.apache.tuweni.bytes.Bytes32;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+@ExtendWith(MockitoExtension.class)
+public class PushOperationTest {
+
+  private static final byte[] byteCode = new byte[] {0x00, 0x01, 0x02, 0x03};
+  private static final MessageFrame frame =
+      MessageFrame.builder()
+          .worldUpdater(new ToyWorld())
+          .originator(Address.ZERO)
+          .gasPrice(Wei.ONE)
+          .blobGasPrice(Wei.ONE)
+          .blockValues(new ToyBlockValues())
+          .miningBeneficiary(Address.ZERO)
+          .blockHashLookup((l) -> Hash.ZERO)
+          .type(MessageFrame.Type.MESSAGE_CALL)
+          .initialGas(1)
+          .address(Address.ZERO)
+          .contract(Address.ZERO)
+          .inputData(Bytes32.ZERO)
+          .sender(Address.ZERO)
+          .value(Wei.ZERO)
+          .apparentValue(Wei.ZERO)
+          .code(CodeV0.EMPTY_CODE)
+          .completer(messageFrame -> {})
+          .build();
+  ;
+
+  @Test
+  void unpaddedPushDoesntReachEndCode() {
+    staticOperation(frame, byteCode, 0, byteCode.length - 2);
+    assertThat(frame.getStackItem(0).equals(Bytes.fromHexString("0x0102"))).isTrue();
+  }
+
+  @Test
+  void unpaddedPushUpReachesEndCode() {
+    staticOperation(frame, byteCode, 0, byteCode.length - 1);
+    assertThat(frame.getStackItem(0).equals(Bytes.fromHexString("0x010203"))).isTrue();
+  }
+
+  @Test
+  void paddedPush() {
+    staticOperation(frame, byteCode, 1, byteCode.length - 1);
+    assertThat(frame.getStackItem(0).equals(Bytes.fromHexString("0x020300"))).isTrue();
+  }
+
+  @Test
+  void oobPush() {
+    staticOperation(frame, byteCode, byteCode.length, byteCode.length - 1);
+    assertThat(frame.getStackItem(0).equals(Bytes.EMPTY)).isTrue();
+  }
+}