evmzero: Add check for range in blockHash op (#461)

* Add range and overflow checks in BlockHash and edge cases unit test
Fantom-foundation · May 27, 2024 · 7051d20 · 7051d20
1 parent 07963e1
commit 7051d20
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Showing 3 changed files with 121 additions and 4 deletions.
diff --git a/cpp/vm/evmzero/interpreter.cc b/cpp/vm/evmzero/interpreter.cc
@@ -864,8 +864,27 @@ struct Impl<OpCode::BLOCKHASH> {
   constexpr static OpInfo kInfo = UnaryOp(20);
 
   static OpResult Run(uint256_t* top, Context& ctx) noexcept {
+    if (top[0] > std::numeric_limits<int64_t>::max()) {
+      top[0] = 0;
+      return {};
+    }
+
     int64_t number = static_cast<int64_t>(top[0]);
-    top[0] = ToUint256(ctx.host->get_block_hash(number));
+    int64_t upper, lower;
+    upper = int64_t(ctx.host->get_tx_context().block_number);
+    // BLOCKHASH description states that it gets the hash of a block not older
+    // than 256 in comparison with the current block. and in case the current
+    // block number is less than 256, then the lower boundary is 0.
+    if (upper < 257) {
+      lower = 0;
+    } else {
+      lower = upper - 256;
+    }
+    if (number >= lower && number < upper) {
+      top[0] = ToUint256(ctx.host->get_block_hash(number));
+    } else {
+      top[0] = 0;
+    }
     return {};
   }
 };

diff --git a/cpp/vm/evmzero/interpreter_test.cc b/cpp/vm/evmzero/interpreter_test.cc
@@ -2834,9 +2834,13 @@ TEST(InterpreterTest, EXTCODEHASH_StackError) {
 
 ///////////////////////////////////////////////////////////
 // BLOCKHASH
-TEST(InterpreterTest, BLOCKHASH) {
+TEST(InterpreterTest, BLOCKHASH_inRange) {
+  const uint64_t block_number = 1000;
   MockHost host;
-  EXPECT_CALL(host, get_block_hash(21))  //
+  EXPECT_CALL(host, get_tx_context())  //
+      .Times(1)
+      .WillOnce(Return(evmc_tx_context{.block_number = block_number}));
+  EXPECT_CALL(host, get_block_hash(block_number - 1))  //
       .Times(1)
       .WillOnce(Return(evmc::bytes32(0x0a0b0c0d)));
 
@@ -2845,12 +2849,83 @@ TEST(InterpreterTest, BLOCKHASH) {
       .state_after = RunState::kDone,
       .gas_before = 40,
       .gas_after = 20,
-      .stack_before = {21},
+      .stack_before = {block_number - 1},
       .stack_after = {0x0a0b0c0d},
       .host = &host,
   });
 }
 
+TEST(InterpreterTest, BLOCKHASH_firstInRange) {
+  const uint64_t block_number = 1000;
+  MockHost host;
+  EXPECT_CALL(host, get_tx_context())  //
+      .Times(1)
+      .WillOnce(Return(evmc_tx_context{.block_number = block_number}));
+  EXPECT_CALL(host, get_block_hash(block_number - 256))  //
+      .Times(1)
+      .WillOnce(Return(evmc::bytes32(0x0a0b0c0d)));
+
+  RunInterpreterTest({
+      .code = {op::BLOCKHASH},
+      .state_after = RunState::kDone,
+      .gas_before = 40,
+      .gas_after = 20,
+      .stack_before = {block_number - 256},
+      .stack_after = {0x0a0b0c0d},
+      .host = &host,
+  });
+}
+
+TEST(InterpreterTest, BLOCKHASH_outOfRange) {
+  const uint64_t block_number = 1000;
+  MockHost host;
+  EXPECT_CALL(host, get_tx_context())  //
+      .Times(1)
+      .WillOnce(Return(evmc_tx_context{.block_number = block_number}));
+
+  RunInterpreterTest({
+      .code = {op::BLOCKHASH},
+      .state_after = RunState::kDone,
+      .gas_before = 40,
+      .gas_after = 20,
+      .stack_before = {block_number - 257},
+      .stack_after = {0},
+      .host = &host,
+  });
+}
+
+TEST(InterpreterTest, BLOCKHASH_sameAsCurrent) {
+  const uint64_t block_number = 1000;
+  MockHost host;
+  EXPECT_CALL(host, get_tx_context())  //
+      .Times(1)
+      .WillOnce(Return(evmc_tx_context{.block_number = block_number}));
+
+  RunInterpreterTest({
+      .code = {op::BLOCKHASH},
+      .state_after = RunState::kDone,
+      .gas_before = 40,
+      .gas_after = 20,
+      .stack_before = {block_number},
+      .stack_after = {0},
+      .host = &host,
+  });
+}
+
+TEST(InterpreterTest, BLOCKHASH_overflow) {
+  MockHost host;
+
+  RunInterpreterTest({
+      .code = {op::BLOCKHASH},
+      .state_after = RunState::kDone,
+      .gas_before = 40,
+      .gas_after = 20,
+      .stack_before = {uint256_t{0x0000000000000001, 0x0000000000000384}},
+      .stack_after = {0},
+      .host = &host,
+  });
+}
+
 TEST(InterpreterTest, BLOCKHASH_OutOfGas) {
   RunInterpreterTest({
       .code = {op::BLOCKHASH},

diff --git a/regression_inputs/blockhash_#461.json b/regression_inputs/blockhash_#461.json
@@ -0,0 +1,23 @@
+{
+  "Status": "running",
+  "Revision": "Istanbul",
+  "ReadOnly": true,
+  "Pc": 8,
+  "Gas": 20,
+  "GasRefund": -227234023154315042,
+  "Code": "66750be9068df1f6408bbef5686da975769e56d9c234c26308561e54671ef3bf29a5c7dfa0be5587f58ba5cdae3ecb7423edccae610551c586da8a405f51a3a946ad926b095fd2626dc2bfb119899d3838b041a1ee2f52a00d71302f93562cc2",
+  "Stack": [
+    "4ae34574e9825110 de832ae81b410c8b dba36e64a329105c 32bb930fbfeafc82",
+    "0000000000000000 0000000000000000 0000000000000000 0000000000000004"
+  ],
+  "BlockContext": {
+    "BaseFee": "ddb99751cdafe03b db1282bd243a8724 f8020d59eb04c225 74f9aaa2fbcd2aa8",
+    "BlockNumber": 0,
+    "ChainID": "1af9d83701ad0e63 4de99a69a7ccb803 4a5005c9bf10e0a7 af17726db99a2e08",
+    "CoinBase": "0xd774bd9070705b43cc0e869b651027f2e1d5a4a0",
+    "GasLimit": 452038407889421009,
+    "GasPrice": "7769b4568916bcdc 95f45a0b8e86a9cc 84a2c7aac56289ae 0929506dcb3ed222",
+    "Difficulty": "4712f1af585ea1d8 7f6e4125fbe56924 21ae13d6e2d673e2 f57beecfb640f15b",
+    "TimeStamp": 4864479995436506094
+  }
+}