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

Commencez par Objects/memoryobject.c, au niveau de l’implémentation liée de PyMemoryView_FromBuffer, et lisez la documentation de la C-API PyMemoryView_FromBuffer. Consultez la pull request #5937 de PyO3 pour comprendre l’exigence relative à la durée de vie de l’owner, puis comparez les implications en matière de compatibilité du maintien de l’owner avec celles de l’introduction d’une nouvelle API. La tâche est terminée lorsque la sémantique d’ownership est décidée, documentée et couverte par des tests CPython appropriés.