[3.13] gh-143378: Fix use-after-free when BytesIO is concurrently mutated during write operations (GH-143408) #143600
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…ly mutated during write operations (pythonGH-143408) PyObject_GetBuffer() can execute user code (e.g. via __buffer__), which may close or otherwise mutate a BytesIO object while write() or writelines() is in progress. This could invalidate the internal buffer and lead to a use-after-free. Ensure that PyObject_GetBuffer() is called before validation checks. (cherry picked from commit 6d54b6a) Co-authored-by: zhong <60600792+superboy-zjc@users.noreply.github.com>
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PyObject_GetBuffer() can execute user code (e.g. via buffer), which may close or otherwise mutate a BytesIO object while write() or writelines() is in progress. This could invalidate the internal buffer and lead to a use-after-free.
Ensure that PyObject_GetBuffer() is called before validation checks. (cherry picked from commit 6d54b6a)
_io.BytesIO.writelinesvia re-entrant__buffer__close #143378