fix(tvm): canonicalize ModExp zero modulus output (TIP-871)

actuator/src/main/java/org/tron/core/vm/PrecompiledContracts.java

@@ -705,6 +705,9 @@ public Pair<Boolean, byte[]> execute(byte[] data) {
 
       // check if modulus is zero
       if (isZero(mod)) {
+        if (VMConfig.allowTvmOsaka()) {
+          return Pair.of(true, new byte[modLen]);
+        }
         return Pair.of(true, EMPTY_BYTE_ARRAY);
       }
 

actuator/src/main/java/org/tron/core/vm/program/Program.java

@@ -1616,6 +1616,10 @@ public ProgramTrace getTrace() {
   }
 
   public void createContract2(DataWord value, DataWord memStart, DataWord memSize, DataWord salt) {
+    if (VMConfig.allowTvmOsaka()) {
+      returnDataBuffer = null; // reset return buffer right before the call
+    }
+
     byte[] senderAddress;
     if (VMConfig.allowTvmCompatibleEvm() && getCallDeep() == MAX_DEPTH) {
       stackPushZero();

framework/src/test/java/org/tron/common/runtime/vm/AllowTvmOsakaTest.java

@@ -66,12 +66,25 @@ public void testEIP7823() {
    * Build ModExp input data for energy calculation testing.
    */
   private static byte[] buildModExpData(int baseLen, int expLen, int modLen, byte[] expValue) {
+    return buildModExpData(baseLen, expLen, modLen, new byte[]{}, expValue, new byte[]{});
+  }
+
+  private static byte[] buildModExpData(int baseLen, int expLen, int modLen, byte[] baseValue,
+      byte[] expValue, byte[] modValue) {
     byte[] base = new byte[baseLen];
+    if (baseValue.length > 0 && baseLen > 0) {
+      System.arraycopy(baseValue, 0, base, 0,
+          StrictMathWrapper.min(baseValue.length, baseLen));
+    }
     byte[] exp = new byte[expLen];
     if (expValue.length > 0 && expLen > 0) {
       System.arraycopy(expValue, 0, exp, 0, StrictMathWrapper.min(expValue.length, expLen));
     }
     byte[] mod = new byte[modLen];
+    if (modValue.length > 0 && modLen > 0) {
+      System.arraycopy(modValue, 0, mod, 0,
+          StrictMathWrapper.min(modValue.length, modLen));
+    }
     return ByteUtil.merge(toLenBytes(baseLen), toLenBytes(expLen), toLenBytes(modLen),
         base, exp, mod);
   }
@@ -80,6 +93,72 @@ private static long getEnergy(int baseLen, int expLen, int modLen, byte[] expVal
     return modExp.getEnergyForData(buildModExpData(baseLen, expLen, modLen, expValue));
   }
 
+  @Test
+  public void testModExpZeroModulusOutputLengthGatedByOsaka() {
+    ConfigLoader.disable = true;
+
+    byte[] modLenZero = buildModExpData(1, 1, 0, new byte[]{0x02}, new byte[]{0x03},
+        new byte[]{});
+    byte[] modLenOne = buildModExpData(1, 1, 1, new byte[]{0x02}, new byte[]{0x03},
+        new byte[]{0x00});
+    byte[] modLen32 = buildModExpData(1, 1, 32, new byte[]{0x02}, new byte[]{0x03},
+        new byte[]{});
+
+    try {
+      VMConfig.initAllowTvmOsaka(0);
+      Pair<Boolean, byte[]> result = modExp.execute(modLenZero);
+      Assert.assertTrue(result.getLeft());
+      Assert.assertEquals(0, result.getRight().length);
+
+      result = modExp.execute(modLenOne);
+      Assert.assertTrue(result.getLeft());
+      Assert.assertEquals(0, result.getRight().length);
+
+      result = modExp.execute(modLen32);
+      Assert.assertTrue(result.getLeft());
+      Assert.assertEquals(0, result.getRight().length);
+
+      VMConfig.initAllowTvmOsaka(1);
+      result = modExp.execute(modLenZero);
+      Assert.assertTrue(result.getLeft());
+      Assert.assertEquals(0, result.getRight().length);
+
+      result = modExp.execute(modLenOne);
+      Assert.assertTrue(result.getLeft());
+      Assert.assertArrayEquals(new byte[1], result.getRight());
+
+      result = modExp.execute(modLen32);
+      Assert.assertTrue(result.getLeft());
+      Assert.assertArrayEquals(new byte[32], result.getRight());
+    } finally {
+      VMConfig.initAllowTvmOsaka(0);
+      ConfigLoader.disable = false;
+    }
+  }
+
+  @Test
+  public void testModExpZeroModulusEnergyMatchesNonZeroModulus() {
+    ConfigLoader.disable = true;
+
+    byte[] zeroModulus = buildModExpData(1, 1, 32, new byte[]{0x02}, new byte[]{0x03},
+        new byte[]{});
+    byte[] nonZeroModulus = buildModExpData(1, 1, 32, new byte[]{0x02}, new byte[]{0x03},
+        new byte[]{0x05});
+
+    try {
+      VMConfig.initAllowTvmOsaka(0);
+      Assert.assertEquals(modExp.getEnergyForData(nonZeroModulus),
+          modExp.getEnergyForData(zeroModulus));
+
+      VMConfig.initAllowTvmOsaka(1);
+      Assert.assertEquals(modExp.getEnergyForData(nonZeroModulus),
+          modExp.getEnergyForData(zeroModulus));
+    } finally {
+      VMConfig.initAllowTvmOsaka(0);
+      ConfigLoader.disable = false;
+    }
+  }
+
   @Test
   public void testEIP7883ModExpPricing() {
     ConfigLoader.disable = true;

framework/src/test/java/org/tron/common/runtime/vm/TvmIssueVerifierTest.java

@@ -0,0 +1,180 @@
+package org.tron.common.runtime.vm;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.math.BigInteger;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import lombok.extern.slf4j.Slf4j;
+import org.bouncycastle.util.encoders.Hex;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.tron.common.runtime.TVMTestResult;
+import org.tron.common.runtime.TvmTestUtils;
+import org.tron.common.utils.WalletUtil;
+import org.tron.common.utils.client.utils.AbiUtil;
+import org.tron.core.exception.ContractExeException;
+import org.tron.core.exception.ContractValidateException;
+import org.tron.core.exception.ReceiptCheckErrException;
+import org.tron.core.exception.VMIllegalException;
+import org.tron.core.vm.config.ConfigLoader;
+import org.tron.protos.Protocol.Transaction;
+
+@Slf4j
+public class TvmIssueVerifierTest extends VMTestBase {
+
+  private static final int WORD_SIZE = 32;
+
+  private static final String ABI = loadResource("solidity/TvmIssueVerifier.abi");
+
+  private static final String BYTECODE = loadResource("solidity/TvmIssueVerifier.bin");
+
+  @Before
+  public void enableVmFeatures() {
+    ConfigLoader.disable = false;
+    manager.getDynamicPropertiesStore().saveAllowTvmTransferTrc10(1);
+    manager.getDynamicPropertiesStore().saveAllowTvmConstantinople(1);
+    manager.getDynamicPropertiesStore().saveAllowTvmIstanbul(1);
+    manager.getDynamicPropertiesStore().saveAllowTvmLondon(1);
+    manager.getDynamicPropertiesStore().saveAllowTvmCompatibleEvm(1);
+    manager.getDynamicPropertiesStore().saveAllowTvmOsaka(1);
+  }
+
+  @Test
+  public void verifyTvmOsakaFixesWithSolidity()
+      throws ContractExeException, ReceiptCheckErrException,
+      VMIllegalException, ContractValidateException {
+    byte[] verifierAddress = deployVerifier();
+
+    manager.getDynamicPropertiesStore().saveAllowTvmOsaka(0);
+
+    TVMTestResult modExpResult = trigger(verifierAddress, "modexpZeroModulus()",
+        Collections.emptyList(), 100_000_000L);
+    byte[] modExpReturn = modExpResult.getRuntime().getResult().getHReturn();
+    Assert.assertNull(modExpResult.getRuntime().getRuntimeError());
+    Assert.assertEquals(BigInteger.ONE, word(modExpReturn, 0));
+    Assert.assertEquals("MODEXP zero modulus currently returns empty returndata",
+        BigInteger.ZERO, word(modExpReturn, 1));
+
+    TVMTestResult create2Result = trigger(verifierAddress,
+        "failedCreate2KeepsPriorReturnData(bytes,uint256)", Arrays.asList("00", 7L),
+        100_000_000L);
+    byte[] create2Return = create2Result.getRuntime().getResult().getHReturn();
+    Assert.assertNull(create2Result.getRuntime().getRuntimeError());
+    Assert.assertEquals(BigInteger.valueOf(32), word(create2Return, 0));
+    Assert.assertEquals(BigInteger.ZERO, word(create2Return, 1));
+    Assert.assertEquals("failed CREATE2 keeps the previous 32-byte return data buffer",
+        BigInteger.valueOf(32), word(create2Return, 2));
+
+    TVMTestResult preOsakaCreate2SuccessResult = trigger(verifierAddress,
+        "successfulCreate2KeepsPriorReturnData(bytes,uint256)",
+        Arrays.asList(initCodeReturningRuntime("00"), 8L), 100_000_000L);
+    byte[] preOsakaCreate2SuccessReturn =
+        preOsakaCreate2SuccessResult.getRuntime().getResult().getHReturn();
+    Assert.assertNull(preOsakaCreate2SuccessResult.getRuntime().getRuntimeError());
+    Assert.assertEquals(BigInteger.valueOf(32), word(preOsakaCreate2SuccessReturn, 0));
+    Assert.assertTrue(word(preOsakaCreate2SuccessReturn, 1).signum() != 0);
+    Assert.assertEquals(BigInteger.valueOf(32), word(preOsakaCreate2SuccessReturn, 2));
+    Assert.assertEquals(BigInteger.ONE, word(preOsakaCreate2SuccessReturn, 3));
+
+    manager.getDynamicPropertiesStore().saveAllowTvmOsaka(1);
+
+    modExpResult = trigger(verifierAddress, "modexpZeroModulus()",
+        Collections.emptyList(), 100_000_000L);
+    modExpReturn = modExpResult.getRuntime().getResult().getHReturn();
+    Assert.assertNull(modExpResult.getRuntime().getRuntimeError());
+    Assert.assertEquals(BigInteger.ONE, word(modExpReturn, 0));
+    Assert.assertEquals("MODEXP zero modulus returns modLen bytes after Osaka",
+        BigInteger.ONE, word(modExpReturn, 1));
+
+    create2Result = trigger(verifierAddress,
+        "failedCreate2KeepsPriorReturnData(bytes,uint256)", Arrays.asList("00", 7L),
+        100_000_000L);
+    create2Return = create2Result.getRuntime().getResult().getHReturn();
+    Assert.assertNull(create2Result.getRuntime().getRuntimeError());
+    Assert.assertEquals(BigInteger.valueOf(32), word(create2Return, 0));
+    Assert.assertEquals(BigInteger.ZERO, word(create2Return, 1));
+    Assert.assertEquals("failed CREATE2 clears the previous return data buffer after Osaka",
+        BigInteger.ZERO, word(create2Return, 2));
+
+    TVMTestResult create2SuccessResult = trigger(verifierAddress,
+        "successfulCreate2KeepsPriorReturnData(bytes,uint256)",
+        Arrays.asList(initCodeReturningRuntime("00"), 9L), 100_000_000L);
+    byte[] create2SuccessReturn = create2SuccessResult.getRuntime().getResult().getHReturn();
+    Assert.assertNull(create2SuccessResult.getRuntime().getRuntimeError());
+    Assert.assertEquals(BigInteger.valueOf(32), word(create2SuccessReturn, 0));
+    Assert.assertTrue(word(create2SuccessReturn, 1).signum() != 0);
+    Assert.assertEquals("successful CREATE2 clears the previous return data buffer after Osaka",
+        BigInteger.ZERO, word(create2SuccessReturn, 2));
+    Assert.assertEquals(BigInteger.ONE, word(create2SuccessReturn, 3));
+  }
+
+  private byte[] deployVerifier()
+      throws ContractExeException, ReceiptCheckErrException,
+      VMIllegalException, ContractValidateException {
+    byte[] owner = Hex.decode(OWNER_ADDRESS);
+    Transaction trx = TvmTestUtils.generateDeploySmartContractAndGetTransaction(
+        "TvmIssueVerifier", owner, ABI, BYTECODE, 0, 1_000_000_000L, 0, null);
+    byte[] contractAddress = WalletUtil.generateContractAddress(trx);
+    runtime = TvmTestUtils.processTransactionAndReturnRuntime(trx, rootRepository, null);
+    Assert.assertNull(runtime.getRuntimeError());
+    return contractAddress;
+  }
+
+  private TVMTestResult trigger(byte[] contractAddress, String method, List<Object> args,
+      long feeLimit)
+      throws ContractExeException, ReceiptCheckErrException,
+      VMIllegalException, ContractValidateException {
+    String input = AbiUtil.parseMethod(method, args);
+    return TvmTestUtils.triggerContractAndReturnTvmTestResult(Hex.decode(OWNER_ADDRESS),
+        contractAddress, Hex.decode(input), 0, feeLimit, manager, null);
+  }
+
+  private static BigInteger word(byte[] data, int index) {
+    int start = index * WORD_SIZE;
+    return new BigInteger(1, Arrays.copyOfRange(data, start, start + WORD_SIZE));
+  }
+
+  private static String initCodeReturningRuntime(String runtimeCode) {
+    byte[] runtime = Hex.decode(runtimeCode);
+    Assert.assertTrue(runtime.length <= 255);
+
+    byte[] initCode = new byte[12 + runtime.length];
+    initCode[0] = 0x60;
+    initCode[1] = (byte) runtime.length;
+    initCode[2] = 0x60;
+    initCode[3] = 0x0c;
+    initCode[4] = 0x60;
+    initCode[5] = 0x00;
+    initCode[6] = 0x39;
+    initCode[7] = 0x60;
+    initCode[8] = (byte) runtime.length;
+    initCode[9] = 0x60;
+    initCode[10] = 0x00;
+    initCode[11] = (byte) 0xf3;
+    System.arraycopy(runtime, 0, initCode, 12, runtime.length);
+
+    return Hex.toHexString(initCode);
+  }
+
+  private static String loadResource(String resource) {
+    try (InputStream in = TvmIssueVerifierTest.class.getClassLoader()
+        .getResourceAsStream(resource)) {
+      if (in == null) {
+        throw new IllegalStateException("Missing test resource: " + resource);
+      }
+      ByteArrayOutputStream out = new ByteArrayOutputStream();
+      byte[] buffer = new byte[4096];
+      int read;
+      while ((read = in.read(buffer)) >= 0) {
+        out.write(buffer, 0, read);
+      }
+      return out.toString("UTF-8").trim();
+    } catch (IOException e) {
+      throw new IllegalStateException("Cannot read test resource: " + resource, e);
+    }
+  }
+}

framework/src/test/resources/solidity/TvmIssueVerifier.abi

@@ -0,0 +1 @@
+[{"inputs":[{"internalType":"bytes","name":"code","type":"bytes"},{"internalType":"uint256","name":"salt","type":"uint256"}],"name":"failedCreate2KeepsPriorReturnData","outputs":[{"internalType":"uint256","name":"beforeSize","type":"uint256"},{"internalType":"address","name":"created","type":"address"},{"internalType":"uint256","name":"afterSize","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"modexpZeroModulus","outputs":[{"internalType":"uint256","name":"ok","type":"uint256"},{"internalType":"uint256","name":"sizeAfter","type":"uint256"},{"internalType":"bytes32","name":"copiedWord","type":"bytes32"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"bytes","name":"code","type":"bytes"},{"internalType":"uint256","name":"salt","type":"uint256"}],"name":"successfulCreate2KeepsPriorReturnData","outputs":[{"internalType":"uint256","name":"beforeSize","type":"uint256"},{"internalType":"address","name":"created","type":"address"},{"internalType":"uint256","name":"afterSize","type":"uint256"},{"internalType":"uint256","name":"createdSize","type":"uint256"}],"stateMutability":"nonpayable","type":"function"}]

framework/src/test/resources/solidity/TvmIssueVerifier.bin

@@ -0,0 +1 @@
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

framework/src/test/resources/solidity/TvmIssueVerifier.sol

@@ -0,0 +1,55 @@
+pragma solidity ^0.8.25;
+
+contract TvmIssueVerifier {
+    function modexpZeroModulus()
+        public
+        returns (uint256 ok, uint256 sizeAfter, bytes32 copiedWord)
+    {
+        bytes memory input = new bytes(99);
+
+        assembly {
+            let p := add(input, 0x20)
+            mstore(p, 1)
+            mstore(add(p, 0x20), 1)
+            mstore(add(p, 0x40), 1)
+            mstore8(add(p, 0x60), 2)
+            mstore8(add(p, 0x61), 3)
+            mstore8(add(p, 0x62), 0)
+            mstore(0, not(0))
+
+            ok := call(gas(), 5, 0, p, 99, 0, 32)
+            sizeAfter := returndatasize()
+            copiedWord := mload(0)
+        }
+    }
+
+    function failedCreate2KeepsPriorReturnData(bytes memory code, uint256 salt)
+        public
+        returns (uint256 beforeSize, address created, uint256 afterSize)
+    {
+        assembly {
+            mstore(0, 0x1234)
+            pop(call(gas(), 4, 0, 0, 32, 0, 32))
+            beforeSize := returndatasize()
+
+            created := create2(1, add(code, 0x20), mload(code), salt)
+            afterSize := returndatasize()
+        }
+    }
+
+    function successfulCreate2KeepsPriorReturnData(bytes memory code, uint256 salt)
+        public
+        returns (uint256 beforeSize, address created, uint256 afterSize, uint256 createdSize)
+    {
+        assembly {
+            mstore(0, 0x1234)
+            pop(call(gas(), 4, 0, 0, 32, 0, 32))
+            beforeSize := returndatasize()
+
+            created := create2(0, add(code, 0x20), mload(code), salt)
+            afterSize := returndatasize()
+            createdSize := extcodesize(created)
+        }
+    }
+
+}