[TS]: builder, Fix requiredField(). Verity that the field is present in the vtable (#7739)

[jmillan]

For the example given in the bug report (#7739) CreateX would not throw when such a missing 'required' field is not present.

This bug defeats the strong typing purpose since the creation of a buffer that should throw due to not fulfilling the 'required' flag would indeed succeed and crash when accessing such non present field.

The problem is within builder.requiredField() method which does not check that the field offset is within the bounds of the vtable. This PR fixes exactly that.

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[jmillan]

@dbaileychess, thanks for the review. All suggestions have been applied.

I must say that this same problem happens in C++. And thus, maybe everywhere. I've checked the C++ side and even thought the language is not a barrier for me, I didn't find a proper way to apply the fix.

How to proceed here, considering all languages are susceptible to have this issue?

[jmillan]

I must say that this same problem happens in C++. And thus, maybe everywhere. I've checked the C++ side and even thought the language is not a barrier for me, I didn't find a proper way to apply the fix.

How to proceed here, considering all languages are susceptible to have this issue?

As said here this was a wrong assumption and C++ is not affected by this bug.

[jmillan]

Issue description updated. The problem was not the buffer creation but a missing check (whether the field offset is in the bounds of the vtable) in builder.requiredField().

[jmillan]

This PR is ready for review @dbaileychess.

[jmillan]

Hi, is there an estimated time for a new release containing this fix?