gh-156689: Fix out-of-bounds read in PyAst_CheckMode() for mode='func_type'

[StanFromIreland]

• Issue: stack-buffer-overflow when parsing ast.FunctionType with mode='func_type' #156689

[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #34309227 | 📁 Comparing dbcae36 against main (03503dc)

  🔍 Preview build  

2 files changed

± library/ast.html
± whatsnew/changelog.html

[pablogsal]

LGTM!

[miss-islington-app]

Thanks @StanFromIreland for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[miss-islington-app]

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

[miss-islington-app]

Thanks @StanFromIreland for the PR 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @StanFromIreland, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker d7f9c6400f49633221983d0c454cf27ecb0302ba 3.13

[bedevere-app]

GH-156704 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-156705 is a backport of this pull request to the 3.15 branch.

[StanFromIreland]

Can't reproduce on 3.13.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 CentOS9 Refleaks 3.x (tier-1) has failed when building commit d7f9c64.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/853/builds/4189) and take a look at the build logs.
4. Check if the failure is related to this commit (d7f9c64) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/853/builds/4189

Summary of the results of the build (if available):

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Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at d7f9c6400f49 gh-156689: Fix out-of-bounds read in `PyAst_CheckMode()` for `mode='func_type'` (#156697)
Switched to and reset branch 'main'

make: *** [Makefile:2480: buildbottest] Error 3