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genericaliasobject.c: Two NULL dereference bugs #148222

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genericaliasobject.c: Two NULL dereference bugs#148222
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interpreter-core(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or error

Description

@prakashsellathurai
prakashsellathurai
opened on Apr 7, 2026

Bug report

Bug description:

Parent: #146102

https://gist.github.com/devdanzin/266ca45099796a2373866a07447d5ebf

Summary

  1. ga_vectorcall (line 653): PyVectorcall_Function(alias->origin) can return NULL, immediately called as function pointer → segfault.
  2. _Py_make_parameters (line 243-245): After _PyTuple_Resize fails, parameters is NULL but Py_DECREF(parameters) is called → crash.

Fix

  1. Add NULL check and fallback to PyObject_Vectorcall.
  2. Change Py_DECREF(parameters) to Py_XDECREF(parameters) at line 245.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

Activity

  1. prakashsellathurai
    added
    type-bugAn unexpected behavior, bug, or error
    on Apr 7, 2026
  2. StanFromIreland
    added a parent issue on Apr 7, 2026
  3. StanFromIreland
    added
    interpreter-core(Objects, Python, Grammar, and Parser dirs)
    on Apr 7, 2026
  4. JelleZijlstra
    added a commit that references this issue on Apr 18, 2026

    gh-148222: Fix NULL dereference bugs in genericaliasobject.c (#148226)

    634568d
  5. miss-islington
    added a commit that references this issue on Apr 18, 2026

    pythongh-148222: Fix NULL dereference bugs in genericaliasobject.c (pâ€Ķ

    559c63c
  6. JelleZijlstra
    added a commit that references this issue on Apr 18, 2026

    [3.14] gh-148222: Fix NULL dereference bugs in genericaliasobject.c (Gâ€Ķ

    67100b3
  7. prakashsellathurai
    added 4 commits that reference this issue on Apr 18, 2026

    pythongh-148222: Fix NULL dereference bugs in genericaliasobject.c (pâ€Ķ

    6a8f75a

    [3.13] pythongh-148222: Fix NULL dereference bugs in genericaliasobjeâ€Ķ

    83552a6

    Revert "[3.13] pythongh-148222: Fix NULL dereference bugs in genericaâ€Ķ

    6690865

    [3.13] pythongh-148222: Fix NULL dereference bugs in genericaliasobjeâ€Ķ

    7aca63f
  8. JelleZijlstra
    added a commit that references this issue on Apr 18, 2026

    [3.13] gh-148222: Fix NULL dereference bugs in genericaliasobject.c (Gâ€Ķ

    0ca5390
  9. prakashsellathurai
    closed this as completedon Apr 18, 2026
  10. ljfp
    added a commit that references this issue on Apr 25, 2026

    pythongh-148222: Fix NULL dereference bugs in genericaliasobject.c (pâ€Ķ

    aab45e0
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