gh-120384: Fix array-out-of-bounds crash in list_ass_subscript

[sobolevn]

Thank a lot to @MechanicPig for the reproducer and detailed bug description.

• Issue: Array out of bounds assignment in list_ass_subscript #120384

[sobolevn]

and there's a leak now, fixing.

[serhiy-storchaka]

LGTM.

[sobolevn]

Thank you, very helpful review 👍

[miss-islington-app]

Thanks @sobolevn for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[miss-islington-app]

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

[bedevere-app]

GH-120825 is a backport of this pull request to the 3.12 branch.

[bedevere-app]

GH-120826 is a backport of this pull request to the 3.13 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot iOS ARM64 Simulator 3.x has failed when building commit 8334a1b.

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/all/#builders/1380/builds/655) and take a look at the build logs.
4. Check if the failure is related to this commit (8334a1b) 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/all/#builders/1380/builds/655

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

Click to see traceback logs

remote: Enumerating objects: 13, done. remote: Counting objects: 8% (1/12) remote: Counting objects: 16% (2/12) remote: Counting objects: 25% (3/12) remote: Counting objects: 33% (4/12) remote: Counting objects: 41% (5/12) remote: Counting objects: 50% (6/12) remote: Counting objects: 58% (7/12) remote: Counting objects: 66% (8/12) remote: Counting objects: 75% (9/12) remote: Counting objects: 83% (10/12) remote: Counting objects: 91% (11/12) remote: Counting objects: 100% (12/12) remote: Counting objects: 100% (12/12), done. remote: Compressing objects: 8% (1/12) remote: Compressing objects: 16% (2/12) remote: Compressing objects: 25% (3/12) remote: Compressing objects: 33% (4/12) remote: Compressing objects: 41% (5/12) remote: Compressing objects: 50% (6/12) remote: Compressing objects: 58% (7/12) remote: Compressing objects: 66% (8/12) remote: Compressing objects: 75% (9/12) remote: Compressing objects: 83% (10/12) remote: Compressing objects: 91% (11/12) remote: Compressing objects: 100% (12/12) remote: Compressing objects: 100% (12/12), done. remote: Total 13 (delta 0), reused 0 (delta 0), pack-reused 1  From https://github.com/python/cpython * branch main -> FETCH_HEAD Note: switching to '8334a1b55c93068f5d243852029baa83377ff6c9'. You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by switching back to a branch. If you want to create a new branch to retain commits you create, you may do so (now or later) by using -c with the switch command. Example: git switch -c <new-branch-name> Or undo this operation with: git switch - Turn off this advice by setting config variable advice.detachedHead to false HEAD is now at 8334a1b55c gh-120384: Fix array-out-of-bounds crash in `list_ass_subscript` (#120442) Switched to and reset branch 'main' configure: WARNING: no system libmpdecimal found; falling back to bundled libmpdecimal (deprecated and scheduled for removal in Python 3.15)configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.configure: WARNING: no system libmpdecimal found; falling back to bundled libmpdecimal (deprecated and scheduled for removal in Python 3.15)configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly. ../../Modules/_sqlite/connection.c:1307:14: warning: 'sqlite3_create_window_function' is only available on iOS 13.0 or newer [-Wunguarded-availability-new] rc = sqlite3_create_window_function(self->db, name, num_params, flags, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/include/sqlite3.h:5533:16: note: 'sqlite3_create_window_function' has been marked as being introduced in iOS 13.0 here, but the deployment target is iOS 12.0.0 SQLITE_API int sqlite3_create_window_function( ^ ../../Modules/_sqlite/connection.c:1307:14: note: enclose 'sqlite3_create_window_function' in a __builtin_available check to silence this warning rc = sqlite3_create_window_function(self->db, name, num_params, flags, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../../Modules/_sqlite/connection.c:1315:14: warning: 'sqlite3_create_window_function' is only available on iOS 13.0 or newer [-Wunguarded-availability-new] rc = sqlite3_create_window_function(self->db, name, num_params, flags, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/include/sqlite3.h:5533:16: note: 'sqlite3_create_window_function' has been marked as being introduced in iOS 13.0 here, but the deployment target is iOS 12.0.0 SQLITE_API int sqlite3_create_window_function( ^ ../../Modules/_sqlite/connection.c:1315:14: note: enclose 'sqlite3_create_window_function' in a __builtin_available check to silence this warning rc = sqlite3_create_window_function(self->db, name, num_params, flags, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2 warnings generated. --- xcodebuild: WARNING: Using the first of multiple matching destinations:{platform:iOS Simulator, id:C6AEA11C-C34A-47B8-BD67-AF0403ECA353, OS:17.5, name:iPhone SE (3rd generation) }{platform:iOS Simulator, id:C6AEA11C-C34A-47B8-BD67-AF0403ECA353, OS:17.5, name:iPhone SE (3rd generation) } 2024-06-21 11:16:45.090 xcodebuild[33218:87319398] [MT] IDETestOperationsObserverDebug: 1075.762 elapsed -- Testing started completed. 2024-06-21 11:16:45.090 xcodebuild[33218:87319398] [MT] IDETestOperationsObserverDebug: 0.000 sec, +0.000 sec -- start 2024-06-21 11:16:45.090 xcodebuild[33218:87319398] [MT] IDETestOperationsObserverDebug: 1075.762 sec, +1075.762 sec -- end Failing tests: -[iOSTestbedTests testPython] ** TEST FAILED ** make: *** [testios] Error 1