[ABI] Out-of-bound access fixed

[hyunsooda]

Proposed changes

A loop that unpacks a dynamic type (e.g., string, bytes, etc.) with a fixed-size array type did not account for the offset boundary. This modification resolves a crash caused by a buffer overrun and includes the addition of a new test case.

panic: runtime error: slice bounds out of range [4095:544] [recovered]
        panic: runtime error: slice bounds out of range [4095:544]

goroutine 31 [running]:
testing.tRunner.func1.2({0x77d8a0, 0xc00014bad0})
        /usr/local/go/src/testing/testing.go:1526 +0x24e
testing.tRunner.func1()
        /usr/local/go/src/testing/testing.go:1529 +0x39f
panic({0x77d8a0, 0xc00014bad0})
        /usr/local/go/src/runtime/panic.go:884 +0x213
github.com/klaytn/klaytn/accounts/abi.toGoType(0x20, {0xc00026a680, 0x3, 0x5, {0xc0002720f0, 0x9}, {0x0, 0x0}, {0x0, 0x0, ...}, ...}, ...)
        fuzzing/klaytn/accounts/abi/unpack.go:234 +0xa85
github.com/klaytn/klaytn/accounts/abi.Arguments.UnpackValues({0xc0002658c0?, 0x2, 0x416e3a?}, {0xc000140480, 0x220, 0x480})
        fuzzing/klaytn/accounts/abi/argument.go:184 +0x2f8
github.com/klaytn/klaytn/accounts/abi.Arguments.Unpack({0xc0002658c0, 0x2, 0x4}, {0x72a900?, 0xc000169100?}, {0xc000140480?, 0x0?, 0xa6d5a0?})
        fuzzing/klaytn/accounts/abi/argument.go:90 +0x129
github.com/klaytn/klaytn/accounts/abi.ABI.Unpack({{{0x0, 0x0}, {0x0, 0x0}, 0x0, {0xc000272000, 0xa}, 0x0, 0x0, {0xa6d5a0, ...}, ...}, ...}, ...)
        fuzzing/klaytn/accounts/abi/abi.go:98 +0x2de
github.com/klaytn/klaytn/accounts/abi.TestUnpackEventOffsetBound(0xc00023b040)
        fuzzing/klaytn/accounts/abi/abi_test.go:800 +0x250
testing.tRunner(0xc00023b040, 0x7da9e0)
        /usr/local/go/src/testing/testing.go:1576 +0x10b
created by testing.(*T).Run
        /usr/local/go/src/testing/testing.go:1629 +0x3ea

I investigated the possibility of users providing arbitrary input to the Unpack() function in the network and RPC packages. However, I found that there is currently no such gateway available, as all of the Unpack() usages are hardcoded.

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• New feature or enhancement
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Further comments

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[blukat29]

Thanks! LGTM except minor

[hyunsooda]

@blukat29, refacotred. PTAL. Thanks.