Description

ashm-dev

opened on Nov 14, 2025

Issue body actions

Bug report

Bug description:

UBSan reports errors such as:

modexport_create_string

Objects/moduleobject.c:546:13: runtime error: call to function modexport_create_string through pointer to incorrect function type 'struct _object *(*)(struct _object *, struct PyModuleDef *)' /home/shamil/oss/cpython/main/./Modules/_testmultiphase.c:1066:5: note: modexport_create_string defined here SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior Objects/moduleobject.c:546:13

Py_mod_state_free

Objects/moduleobject.c:1101:9: runtime error: call to function modexport_smoke_free through pointer to incorrect function type 'void (*)(void *)' /home/shamil/oss/cpython/main/./Modules/_testmultiphase.c:974: note: modexport_smoke_free defined here SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior Objects/moduleobject.c:1101:9

The functions assigned to Py_mod_state_free and modexport_create_string use incorrect signatures, causing calls through mismatched function pointer types and leading to undefined behavior.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-141553: Fix incorrect function signatures in _testmultiphase #141554

Reacted by Mikhail Efimov and Sergey Miryanov

Activity

1. ashm-dev

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Nov 14, 2025
2. mohsinm-dev commented on Nov 14, 2025

   

   mohsinm-dev

   on Nov 14, 2025

   Contributor

   More actions

   @ashm-dev I was working on the same fix.
3. ashm-dev commented on Nov 14, 2025

   

   ashm-dev

   on Nov 14, 2025

   ContributorAuthor

   More actions

   @mohsinm-dev I already have a fix)

   Reacted by Mohsin Mehmood
4. StanFromIreland

   added

   testsTests in the Lib/test dirTests in the Lib/test dir

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   on Nov 14, 2025
5. picnixz commented on Nov 14, 2025

   

   picnixz

   on Nov 14, 2025

   Member

   More actions

   I am surprised that this was not caught when this was introduced.

   Reacted by Shamil
6. picnixz

   added

   3.15bugs and security fixesbugs and security fixes

   on Nov 15, 2025
7. picnixz

   added a commit that references this issue on Nov 15, 2025

   gh-141553: Fix incorrect function signatures in `_testmultiphase` (#1…

   85f3009
8. picnixz commented on Nov 15, 2025

   

   picnixz

   on Nov 15, 2025

   Member

   More actions

   Thanks for the report & fix!

   Reacted by Mikhail Efimov

   Reacted by Shamil
9. picnixz

   closed this as completedon Nov 15, 2025
10. StanFromIreland

    added a commit that references this issue on Dec 6, 2025

    pythongh-141553: Fix incorrect function signatures in `_testmultiphas…

    90c2983

Issue actions