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gh-137422: Fix race condition in PyImport_AddModuleRef #141822

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Merged
merged 2 commits into from
Nov 21, 2025
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gh-137422: Fix race condition in PyImport_AddModuleRef #141822

merged 2 commits into from
Nov 21, 2025

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@colesbury colesbury commented Nov 21, 2025 •
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colesbury commented Nov 21, 2025

It ended up being easier to use Py_BEGIN_CRITICAL_SECTION than trying to use PyDict_SetDefaultRef:

It's tricky to correctly handle the case where there's an existing entry that fails the PyModule_Check(m) test with PyDict_SetDefaultRef.

Even though interp->modules is always a PyDictObject, a bunch of the code was changed a few years ago to use the abstract API, so I didn't want to mess with it. See:

@colesbury colesbury marked this pull request as ready for review November 21, 2025 15:46
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LGTM

@colesbury colesbury merged commit 2d50dd2 into python:main Nov 21, 2025
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miss-islington-app bot commented Nov 21, 2025

Thanks @colesbury for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

@colesbury colesbury deleted the gh-137422-pyimport-addmoduleref branch November 21, 2025 18:30
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Nov 21, 2025
@colesbury @miss-islington
pythongh-137422: Fix race condition in PyImport_AddModuleRef (pythong…
33056f9 
…h-141822)

(cherry picked from commit 2d50dd2)

Co-authored-by: Sam Gross <colesbury@gmail.com>
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bedevere-app bot commented Nov 21, 2025

GH-141830 is a backport of this pull request to the 3.14 branch.

@bedevere-app bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Nov 21, 2025
colesbury added a commit that referenced this pull request Nov 21, 2025
@miss-islington @colesbury
[3.14] gh-137422: Fix race condition in PyImport_AddModuleRef (gh-141822
5bca7f4 
) (gh-141830)

(cherry picked from commit 2d50dd2)

Co-authored-by: Sam Gross <colesbury@gmail.com>
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