Stack popping issue: Index out of bounds

[mratsim]

In some 2 specific cases:

• fixture tests/fixtures/VMTests/vmArithmeticTest/mulUnderFlow.json
• fixture tests/fixtures/VMTests/vmArithmeticTest/sdiv_dejavu.json

popping the stack eads to an out-of-bounds exception.

Traceback

test_helpers.nim(48)     test_vm_json
computation.nim(278)     testFixture
computation.nim(272)     :anonymous
stack.nim(135)           mul
stack.nim(116)           internalPopTuple2
system.nim(2445)         pop
system.nim(2843)         sysFatal

    Unhandled exception: index out of bounds

test_helpers.nim(48)     test_vm_json
computation.nim(278)     testFixture
computation.nim(272)     :anonymous
stack.nim(135)           sdiv
stack.nim(116)           internalPopTuple2
system.nim(2445)         pop
system.nim(2843)         sysFatal

    Unhandled exception: index out of bounds

[mratsim]

Using the opcode tool of etherscan, mulUnderflow pushes only one value on the stack (intentionally malformed input?):

0x600102600155
------
[1] PUSH1 0x01 
[2] MUL 
[4] PUSH1 0x01 
[5] SSTORE 

vs

0x6003600202600055
------
[1] PUSH1 0x03 
[3] PUSH1 0x02 
[4] MUL 
[6] PUSH1 0x00 
[7] SSTORE 

[mratsim]

Checking in the yellow paper, this is a situation called Stack Underflow. EVM should consume gas but rollback to preceding state.
.

In Py-EVM this is called InsufficientStack and raised by the pop method.

In Nimbus ensurePop does the same but is not used within the internalPopTuple macro at the moment:

https://github.com/status-im/nimbus/blob/43797485e5c50d94fef5a4b9afba858632190896/src/vm/stack.nim#L93-L118

Additionally, this is an expected exception, I'm not sure how to automatically create expect(InsufficientStack): body tests for such illformed inputs (i.e. differentiate between features that throws an exception because that is what we want to test and the others):

{
    "mulUnderFlow" : {
        "_info" : {
            "comment" : "",
            "filledwith" : "cpp-1.3.0+commit.6e0ce939.Linux.g++",
            "lllcversion" : "Version: 0.4.18-develop.2017.9.25+commit.a72237f2.Linux.g++",
            "source" : "src/VMTestsFiller/vmArithmeticTest/mulUnderFlowFiller.json",
            "sourceHash" : "c4dc43a2d2480a375b5f4cde0ff0b1059f36577d7c555b2ee92db62aad36aea2"
        },
        "env" : {
            "currentCoinbase" : "0x2adc25665018aa1fe0e6bc666dac8fc2697ff9ba",
            "currentDifficulty" : "0x0100",
            "currentGasLimit" : "0x0f4240",
            "currentNumber" : "0x00",
            "currentTimestamp" : "0x01"
        },
        "exec" : {
            "address" : "0x0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6",
            "caller" : "0xcd1722f2947def4cf144679da39c4c32bdc35681",
            "code" : "0x600102600155",
            "data" : "0x",
            "gas" : "0x0186a0",
            "gasPrice" : "0x5af3107a4000",
            "origin" : "0xcd1722f2947def4cf144679da39c4c32bdc35681",
            "value" : "0x0de0b6b3a7640000"
        },
        "pre" : {
            "0x0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6" : {
                "balance" : "0x0de0b6b3a7640000",
                "code" : "0x600102600155",
                "nonce" : "0x00",
                "storage" : {
                }
            }
        }
    }
}