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GeezerVison is showing github.com — instrumentation.c: Use-after-Py_DECREF comparison in call_one_instrument · Issue #151524 · python/cpython

instrumentation.c: Use-after-Py_DECREF comparison in call_one_instrument #151524

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instrumentation.c: Use-after-Py_DECREF comparison in call_one_instrument#151524
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interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

Description

@lpyu001
lpyu001
opened on Jun 16, 2026
Issue body actions

Bug report

Bug description:

Summary

At line 992-993, Py_DECREF(res) then res compared to &_PyInstrumentation_DISABLE. Using a potentially-freed pointer in comparison is UB per C standard.

This is a sub-issue of #146102 with gist details

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

  • gh-151524: Avoid using instrumentation callback result after Py_DECREF #151525
  • [3.14] gh-151524: Make it clearer that _PyInstrumentation_DISABLE is immortal in the code (GH-151525) #155349
  • [3.15] gh-151524: Make it clearer that _PyInstrumentation_DISABLE is immortal in the code (GH-151525) #155350
  • [3.13] gh-151524: Make it clearer that _PyInstrumentation_DISABLE is immortal in the code (GH-151525) #155351

Activity

  1. lpyu001
    added
    type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error
    on Jun 16, 2026
  2. lpyu001
    added a commit that references this issue on Jun 16, 2026

    pythongh-151524: Avoid using instrumentation callback result after Py…

    a4cc0af
  3. StanFromIreland
    added a parent issue on Jun 16, 2026
    • Umbrella issue: bugs found using cpython-review-toolkit #146102
  4. StanFromIreland
    added
    interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)
    on Jun 16, 2026
  5. ZeroIntensity
    added a commit that references this issue on Aug 7, 2026

    gh-151524: Make it clearer that `_PyInstrumentation_DISABLE` is immor…

    52bed26
  6. ZeroIntensity
    closed this as completedon Aug 7, 2026
  7. ZeroIntensity
    added 2 commits that reference this issue on Aug 7, 2026

    [3.13] gh-151524: Make it clearer that `_PyInstrumentation_DISABLE` i…

    2e19855

    [3.14] gh-151524: Make it clearer that `_PyInstrumentation_DISABLE` i…

    87bacf1
  8. hugovk
    added a commit that references this issue on Aug 8, 2026

    [3.15] gh-151524: Make it clearer that `_PyInstrumentation_DISABLE` i…

    a8a3b24
  9. mbeijen
    added a commit that references this issue on Aug 14, 2026

    pythongh-151524: Make it clearer that `_PyInstrumentation_DISABLE` is…

    c19e850
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    interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

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