cannon: Handle div by zero in MIPS.sol (#10468)

* cannon: Handle div by zero in MIPS.sol

* fix revert stmt style

packages/contracts-bedrock/semver-lock.json

@@ -116,8 +116,8 @@
     "sourceCodeHash": "0x73aa5934e56ba2a45f368806c5db1d442bf5713d51b2184749f4638eaceb832e"
   },
   "src/cannon/MIPS.sol": {
-    "initCodeHash": "0xd447743c7a3c1babe141050603dd643467ada00bd90465a52ef3093445ee1b02",
-    "sourceCodeHash": "0xe37efbb893e0a7499fcd565f8495f6ba911611ba36795ac131738474f116fce5"
+    "initCodeHash": "0xa5d36fc67170ad87322f358f612695f642757bbf5280800d5d878da21402579a",
+    "sourceCodeHash": "0x75701f3efb7a9c16079ba0a4ed2867999aab7d95bfa0fe5ebb131cfc278593aa"
   },
   "src/cannon/PreimageOracle.sol": {
     "initCodeHash": "0xe5db668fe41436f53995e910488c7c140766ba8745e19743773ebab508efd090",

packages/contracts-bedrock/src/cannon/MIPS.sol

@@ -43,8 +43,8 @@ contract MIPS is ISemver {
     uint32 public constant BRK_START = 0x40000000;
 
     /// @notice The semantic version of the MIPS contract.
-    /// @custom:semver 1.0.0
-    string public constant version = "1.0.0";
+    /// @custom:semver 1.0.1
+    string public constant version = "1.0.1";
 
     uint32 internal constant FD_STDIN = 0;
     uint32 internal constant FD_STDOUT = 1;
@@ -422,6 +422,9 @@ contract MIPS is ISemver {
             // Stores the quotient in LO
             // And the remainder in HI
             else if (_func == 0x1a) {
+                if (int32(_rt) == 0) {
+                    revert("MIPS: division by zero");
+                }
                 state.hi = uint32(int32(_rs) % int32(_rt));
                 state.lo = uint32(int32(_rs) / int32(_rt));
             }
@@ -429,6 +432,9 @@ contract MIPS is ISemver {
             // Stores the quotient in LO
             // And the remainder in HI
             else if (_func == 0x1b) {
+                if (_rt == 0) {
+                    revert("MIPS: division by zero");
+                }
                 state.hi = _rs % _rt;
                 state.lo = _rs / _rt;
             }

packages/contracts-bedrock/test/cannon/MIPS.t.sol

@@ -892,6 +892,26 @@ contract MIPS_Test is CommonTest {
         assertEq(postState, outputState(expect), "unexpected post state");
     }
 
+    function test_div_byZero_fails() external {
+        uint32 insn = encodespec(0x9, 0xa, 0x0, 0x1a); // div t1, t2
+        (MIPS.State memory state, bytes memory proof) = constructMIPSState(0, insn, 0x4, 0);
+        state.registers[9] = 5; // t1
+        state.registers[10] = 0; // t2
+
+        vm.expectRevert("MIPS: division by zero");
+        mips.step(encodeState(state), proof, 0);
+    }
+
+    function test_divu_byZero_fails() external {
+        uint32 insn = encodespec(0x9, 0xa, 0x0, 0x1b); // divu t1, t2
+        (MIPS.State memory state, bytes memory proof) = constructMIPSState(0, insn, 0x4, 0);
+        state.registers[9] = 5; // t1
+        state.registers[10] = 0; // t2
+
+        vm.expectRevert("MIPS: division by zero");
+        mips.step(encodeState(state), proof, 0);
+    }
+
     function test_beq_succeeds() external {
         uint16 boff = 0x10;
         uint32 insn = encodeitype(0x4, 0x9, 0x8, boff); // beq $t0, $t1, 16