PyMemoryView_FromBuffer discards owner reference from Py_buffer

Bug report

Bug description:

https://github.com/python/cpython/blob/0274d8304e5eec23de100d827eb4da06ab7fd8aa/Objects/memoryobject.c#L769-L788

This means that if you use PyMemoryView_FromBuffer with a buffer that requires an owner to be kept alive, you get a UAF hazard here.

This is not mentioned in the documentation: https://docs.python.org/3/c-api/memoryview.html#c.PyMemoryView_FromBuffer

An extremely cursory didn't find any vulnerable callers within CPython itself, however this was discovered in the process of implementing https://github.com/PyO3/pyo3/pull/5937 where it definitely would have been an issue.

It seems like there's two possible choices here:

• Change this to keep owner around -- potentially breaks existing callers?
• Document this, and introduce a new API with clearer semantics here.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Inizia da Objects/memoryobject.c, nell’implementazione collegata di PyMemoryView_FromBuffer, e leggi la documentazione della C-API PyMemoryView_FromBuffer. Esamina la pull request #5937 di PyO3 per comprendere il requisito relativo alla durata dell’owner, quindi confronta le implicazioni di compatibilità del mantenimento dell’owner con quelle dell’introduzione di una nuova API. Il lavoro è completo quando la semantica dell’ownership è stata decisa, documentata e coperta da test CPython appropriati.