[3.13] gh-122527: Fix a crash on deallocation of PyStructSequence (GH-122577)
#122625
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…ythonGH-122577) The `PyStructSequence` destructor would crash if it was deallocated after its type's dictionary was cleared by the GC, because it couldn't compute the "real size" of the instance. This could occur with relatively straightforward code in the free-threaded build or with a reference cycle involving the type in the default build, due to differing orders in which `tp_clear()` was called. Account for the non-sequence fields in `tp_basicsize` and use that, along with `Py_SIZE()`, to compute the "real" size of a `PyStructSequence` in the dealloc function. This avoids the accesses to the type's dictionary during dealloc, which were unsafe. (cherry picked from commit 4b63cd1) Co-authored-by: Sam Gross <[email protected]>
This was referenced Aug 2, 2024
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serhiy-storchaka
approved these changes
Aug 12, 2024
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Out of curious, would this patch be included in Python 3.13.0rc2? |
12 tasks
Yes. |
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The
PyStructSequencedestructor would crash if it was deallocated afterits type's dictionary was cleared by the GC, because it couldn't compute
the "real size" of the instance. This could occur with relatively
straightforward code in the free-threaded build or with a reference
cycle involving the type in the default build, due to differing orders
in which
tp_clear()was called.Account for the non-sequence fields in
tp_basicsizeand use that,along with
Py_SIZE(), to compute the "real" size of aPyStructSequencein the dealloc function. This avoids the accesses tothe type's dictionary during dealloc, which were unsafe.
(cherry picked from commit 4b63cd1)
Co-authored-by: Sam Gross [email protected]