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Concurrent calls to Counter.update can cause a use after free #151633

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#151634
Open
Concurrent calls to Counter.update can cause a use after free#151633
#151634
Labels
type-crashA hard crash of the interpreter, possibly with a core dump
@KowalskiThomas

Description

@KowalskiThomas
KowalskiThomas
opened on Jun 18, 2026

Crash report

What happened?

In Counter.update, _collections__count_elements_impl (called through _count_elements then _collections__count_elements) has a fast path for plain dicts that uses _PyDict_GetItem_KnownHash to obtain a borrowed reference to the current value. The current value is then incremented using PyNumber_Add (but after the dict lock is released).

cpython/Modules/_collectionsmodule.c

Lines 2598 to 2614 in d986124

oldval = _PyDict_GetItem_KnownHash(mapping, key, hash);
if (oldval == NULL) {
if (PyErr_Occurred())
goto done;
if (_PyDict_SetItem_KnownHash(mapping, key, one, hash) < 0)
goto done;
} else {
/* oldval is a borrowed reference. Keep it alive across
PyNumber_Add(), which can execute arbitrary user code and
mutate (or even clear) the underlying dict. */
Py_INCREF(oldval);
newval = PyNumber_Add(oldval, one);
Py_DECREF(oldval);
if (newval == NULL)
goto done;
if (_PyDict_SetItem_KnownHash(mapping, key, newval, hash) < 0)
goto done;

When multiple threads call update on the same Counter concurrently, this can cause a user after free.

  • _PyDict_GetItem_KnownHash acquires the per-dict lock, looks up oldval, then releases the lock before returning the borrowed reference. Between that return and the next Py_INCREF(oldval), a second thread can:
    • call _PyDict_GetItem_KnownHash on the same key and get the same oldval
    • do Py_INCREF(oldval) / PyNumber_Add(oldval, one) / _PyDict_SetItem_KnownHash
    • then cause the dict to decref and free oldval (if the dict held the last reference).
  • The first thread then executes Py_INCREF(oldval) and PyNumber_Add(oldval, one) on an oldval that has been freed.

The following reproducer run under TSan shows many reports, but simply running it on a free-threaded build produces a hard crash.

import threading
from collections import Counter

def do() -> None:
    c: Counter[str] = Counter()
    data = ["x"] * 5000

    def worker() -> None:
        c.update(data)

    threads = [threading.Thread(target=worker) for _ in range(4)]
    for t in threads: t.start()
    for t in threads: t.join()

for _ in range(50):
    do()

Under free-threaded Python

$ ./python.exe ./new_bug_counter.py 
zsh: segmentation fault  ../cpython-nogil/python.exe ./new_bug_counter.py

Under TSAN (CPython main, free-threaded build):

Details 
==================
WARNING: ThreadSanitizer: data race (pid=69202)
  Read of size 8 at 0x0001120401e0 by thread T4:
    #0 _PyFreeList_PopNoStats pycore_freelist.h:80 (python.exe:arm64+0x1000f2318)
    #1 _PyFreeList_Pop pycore_freelist.h:89 (python.exe:arm64+0x1000f2318)
    #2 _PyLong_FromMedium longobject.c:256 (python.exe:arm64+0x1000f2318)
    #3 _PyLong_FromSTwoDigits longobject.c:320 (python.exe:arm64+0x1000ffb7c)
    #4 long_add longobject.c:3838 (python.exe:arm64+0x1000ffb7c)
    #5 long_add_method longobject.c:3878 (python.exe:arm64+0x10010277c)
    #6 binary_op1 abstract.c:974 (python.exe:arm64+0x10005edb4)
    #7 PyNumber_Add abstract.c:1140 (python.exe:arm64+0x10005eb10)
    #8 _collections__count_elements_impl _collectionsmodule.c:2602 (python.exe:arm64+0x1003f51c8)
    #9 _collections__count_elements _collectionsmodule.c.h:593 (python.exe:arm64+0x1003f51c8)
    #10 cfunction_vectorcall_FASTCALL methodobject.c:449 (python.exe:arm64+0x1001379dc)
    #11 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100090e80)
    #12 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090e80)
    #13 _Py_VectorCallInstrumentation_StackRefSteal ceval.c:766 (python.exe:arm64+0x100290968)
    #14 _PyEval_EvalFrameDefault generated_cases.c.h:1846 (python.exe:arm64+0x100295ff8)
    #15 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #16 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #17 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #18 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #19 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #20 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #21 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1002dce38)
    #22 context_run context.c:728 (python.exe:arm64+0x1002dce38)
    #23 method_vectorcall_FASTCALL_KEYWORDS descrobject.c:421 (python.exe:arm64+0x1000a8644)
    #24 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100090e80)
    #25 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090e80)
    #26 _Py_VectorCallInstrumentation_StackRefSteal ceval.c:766 (python.exe:arm64+0x100290968)
    #27 _PyEval_EvalFrameDefault generated_cases.c.h:1846 (python.exe:arm64+0x100295ff8)
    #28 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #29 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #30 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #31 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #32 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #33 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #34 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x10009112c)
    #35 _PyObject_Call call.c:348 (python.exe:arm64+0x10009112c)
    #36 PyObject_Call call.c:373 (python.exe:arm64+0x1000911a4)
    #37 thread_run _threadmodule.c:388 (python.exe:arm64+0x10044df04)
    #38 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x10038a12c)

  Previous atomic write of size 8 at 0x0001120401e0 by thread T2:
    #0 _Py_atomic_store_ptr_relaxed pyatomic_gcc.h:509 (python.exe:arm64+0x1000ffcb0)
    #1 _PyFreeList_Push pycore_freelist.h:56 (python.exe:arm64+0x1000ffcb0)
    #2 _PyFreeList_Free pycore_freelist.h:69 (python.exe:arm64+0x1000ffcb0)
    #3 long_dealloc longobject.c:3664 (python.exe:arm64+0x1000ffcb0)
    #4 _Py_Dealloc object.c:3312 (python.exe:arm64+0x10013fd5c)
    #5 _Py_DecRefSharedDebug object.c:426 (python.exe:arm64+0x10013ff34)
    #6 _Py_DecRefShared object.c:433 (python.exe:arm64+0x10013ff34)
    #7 Py_DECREF refcount.h:385 (python.exe:arm64+0x1003f5228)
    #8 _collections__count_elements_impl _collectionsmodule.c:2603 (python.exe:arm64+0x1003f5228)
    #9 _collections__count_elements _collectionsmodule.c.h:593 (python.exe:arm64+0x1003f5228)
    #10 cfunction_vectorcall_FASTCALL methodobject.c:449 (python.exe:arm64+0x1001379dc)
    #11 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100090e80)
    #12 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090e80)
    #13 _Py_VectorCallInstrumentation_StackRefSteal ceval.c:766 (python.exe:arm64+0x100290968)
    #14 _PyEval_EvalFrameDefault generated_cases.c.h:1846 (python.exe:arm64+0x100295ff8)
    #15 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #16 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #17 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #18 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #19 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #20 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #21 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1002dce38)
    #22 context_run context.c:728 (python.exe:arm64+0x1002dce38)
    #23 method_vectorcall_FASTCALL_KEYWORDS descrobject.c:421 (python.exe:arm64+0x1000a8644)
    #24 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100090e80)
    #25 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090e80)
    #26 _Py_VectorCallInstrumentation_StackRefSteal ceval.c:766 (python.exe:arm64+0x100290968)
    #27 _PyEval_EvalFrameDefault generated_cases.c.h:1846 (python.exe:arm64+0x100295ff8)
    #28 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #29 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #30 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #31 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #32 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #33 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #34 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x10009112c)
    #35 _PyObject_Call call.c:348 (python.exe:arm64+0x10009112c)
    #36 PyObject_Call call.c:373 (python.exe:arm64+0x1000911a4)
    #37 thread_run _threadmodule.c:388 (python.exe:arm64+0x10044df04)
    #38 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x10038a12c)

  Thread T4 (tid=18691961, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64+0x31d84)
    #1 do_start_joinable_thread thread_pthread.h:281 (python.exe:arm64+0x100389300)
    #2 PyThread_start_joinable_thread thread_pthread.h:323 (python.exe:arm64+0x100389138)
    #3 ThreadHandle_start _threadmodule.c:475 (python.exe:arm64+0x10044dd10)
    #4 do_start_new_thread _threadmodule.c:1919 (python.exe:arm64+0x10044d7dc)
    #5 thread_PyThread_start_joinable_thread _threadmodule.c:2042 (python.exe:arm64+0x10044c844)
    #6 cfunction_call methodobject.c:564 (python.exe:arm64+0x100138744)
    #7 _PyObject_MakeTpCall call.c:242 (python.exe:arm64+0x10009030c)
    #8 _PyObject_VectorcallTstate pycore_call.h:142 (python.exe:arm64+0x100090f14)
    #9 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090f14)
    #10 _Py_VectorCall_StackRefSteal ceval.c:724 (python.exe:arm64+0x100290228)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:3528 (python.exe:arm64+0x100299d1c)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fa34)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fa34)
    #14 PyEval_EvalCode ceval.c:677 (python.exe:arm64+0x10028fa34)
    #15 run_eval_code_obj pythonrun.c:1369 (python.exe:arm64+0x100366a70)
    #16 run_mod pythonrun.c:1472 (python.exe:arm64+0x1003667cc)
    #17 pyrun_file pythonrun.c:1296 (python.exe:arm64+0x100361d38)
    #18 _PyRun_SimpleFileObject pythonrun.c:518 (python.exe:arm64+0x100361d38)
    #19 _PyRun_AnyFileObject pythonrun.c:81 (python.exe:arm64+0x1003614c8)
    #20 pymain_run_file_obj main.c:411 (python.exe:arm64+0x1003a3328)
    #21 pymain_run_file main.c:430 (python.exe:arm64+0x1003a3328)
    #22 pymain_run_python main.c:715 (python.exe:arm64+0x1003a2658)
    #23 Py_RunMain main.c:796 (python.exe:arm64+0x1003a2658)
    #24 pymain_main main.c:826 (python.exe:arm64+0x1003a2bd0)
    #25 Py_BytesMain main.c:850 (python.exe:arm64+0x1003a2cd0)
    #26 main python.c:15 (python.exe:arm64+0x100000a78)

  Thread T2 (tid=18691959, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64+0x31d84)
    #1 do_start_joinable_thread thread_pthread.h:281 (python.exe:arm64+0x100389300)
    #2 PyThread_start_joinable_thread thread_pthread.h:323 (python.exe:arm64+0x100389138)
    #3 ThreadHandle_start _threadmodule.c:475 (python.exe:arm64+0x10044dd10)
    #4 do_start_new_thread _threadmodule.c:1919 (python.exe:arm64+0x10044d7dc)
    #5 thread_PyThread_start_joinable_thread _threadmodule.c:2042 (python.exe:arm64+0x10044c844)
    #6 cfunction_call methodobject.c:564 (python.exe:arm64+0x100138744)
    #7 _PyObject_MakeTpCall call.c:242 (python.exe:arm64+0x10009030c)
    #8 _PyObject_VectorcallTstate pycore_call.h:142 (python.exe:arm64+0x100090f14)
    #9 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090f14)
    #10 _Py_VectorCall_StackRefSteal ceval.c:724 (python.exe:arm64+0x100290228)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:3528 (python.exe:arm64+0x100299d1c)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fa34)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fa34)
    #14 PyEval_EvalCode ceval.c:677 (python.exe:arm64+0x10028fa34)
    #15 run_eval_code_obj pythonrun.c:1369 (python.exe:arm64+0x100366a70)
    #16 run_mod pythonrun.c:1472 (python.exe:arm64+0x1003667cc)
    #17 pyrun_file pythonrun.c:1296 (python.exe:arm64+0x100361d38)
    #18 _PyRun_SimpleFileObject pythonrun.c:518 (python.exe:arm64+0x100361d38)
    #19 _PyRun_AnyFileObject pythonrun.c:81 (python.exe:arm64+0x1003614c8)
    #20 pymain_run_file_obj main.c:411 (python.exe:arm64+0x1003a3328)
    #21 pymain_run_file main.c:430 (python.exe:arm64+0x1003a3328)
    #22 pymain_run_python main.c:715 (python.exe:arm64+0x1003a2658)
    #23 Py_RunMain main.c:796 (python.exe:arm64+0x1003a2658)
    #24 pymain_main main.c:826 (python.exe:arm64+0x1003a2bd0)
    #25 Py_BytesMain main.c:850 (python.exe:arm64+0x1003a2cd0)
    #26 main python.c:15 (python.exe:arm64+0x100000a78)

SUMMARY: ThreadSanitizer: data race pycore_freelist.h:80 in _PyFreeList_PopNoStats
==================
==================
WARNING: ThreadSanitizer: data race (pid=69202)
  Read of size 8 at 0x000116040540 by thread T8:
    #0 _PyFreeList_PopNoStats pycore_freelist.h:80 (python.exe:arm64+0x1000f2318)
    #1 _PyFreeList_Pop pycore_freelist.h:89 (python.exe:arm64+0x1000f2318)
    #2 _PyLong_FromMedium longobject.c:256 (python.exe:arm64+0x1000f2318)
    #3 _PyLong_FromSTwoDigits longobject.c:320 (python.exe:arm64+0x1000ffb7c)
    #4 long_add longobject.c:3838 (python.exe:arm64+0x1000ffb7c)
    #5 long_add_method longobject.c:3878 (python.exe:arm64+0x10010277c)
    #6 binary_op1 abstract.c:974 (python.exe:arm64+0x10005edb4)
    #7 PyNumber_Add abstract.c:1140 (python.exe:arm64+0x10005eb10)
    #8 _collections__count_elements_impl _collectionsmodule.c:2602 (python.exe:arm64+0x1003f51c8)
    #9 _collections__count_elements _collectionsmodule.c.h:593 (python.exe:arm64+0x1003f51c8)
    #10 _Py_BuiltinCallFast_StackRef ceval.c:815 (python.exe:arm64+0x1002976c0)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:2420 (python.exe:arm64+0x1002976c0)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #14 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #15 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #16 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #17 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #18 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1002dce38)
    #19 context_run context.c:728 (python.exe:arm64+0x1002dce38)
    #20 _PyCallMethodDescriptorFastWithKeywords_StackRef ceval.c:881 (python.exe:arm64+0x10029ac0c)
    #21 _PyEval_EvalFrameDefault generated_cases.c.h:4022 (python.exe:arm64+0x10029ac0c)
    #22 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #23 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #24 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #25 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #26 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #27 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #28 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x10009112c)
    #29 _PyObject_Call call.c:348 (python.exe:arm64+0x10009112c)
    #30 PyObject_Call call.c:373 (python.exe:arm64+0x1000911a4)
    #31 thread_run _threadmodule.c:388 (python.exe:arm64+0x10044df04)
    #32 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x10038a12c)

  Previous atomic write of size 8 at 0x000116040540 by thread T7:
    #0 _Py_atomic_store_ptr_relaxed pyatomic_gcc.h:509 (python.exe:arm64+0x1000ffcb0)
    #1 _PyFreeList_Push pycore_freelist.h:56 (python.exe:arm64+0x1000ffcb0)
    #2 _PyFreeList_Free pycore_freelist.h:69 (python.exe:arm64+0x1000ffcb0)
    #3 long_dealloc longobject.c:3664 (python.exe:arm64+0x1000ffcb0)
    #4 _Py_Dealloc object.c:3312 (python.exe:arm64+0x10013fd5c)
    #5 _Py_DecRefSharedDebug object.c:426 (python.exe:arm64+0x10013ff34)
    #6 _Py_DecRefShared object.c:433 (python.exe:arm64+0x10013ff34)
    #7 Py_DECREF refcount.h:385 (python.exe:arm64+0x1003f5228)
    #8 _collections__count_elements_impl _collectionsmodule.c:2603 (python.exe:arm64+0x1003f5228)
    #9 _collections__count_elements _collectionsmodule.c.h:593 (python.exe:arm64+0x1003f5228)
    #10 _Py_BuiltinCallFast_StackRef ceval.c:815 (python.exe:arm64+0x1002976c0)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:2420 (python.exe:arm64+0x1002976c0)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #14 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #15 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #16 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #17 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #18 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1002dce38)
    #19 context_run context.c:728 (python.exe:arm64+0x1002dce38)
    #20 _PyCallMethodDescriptorFastWithKeywords_StackRef ceval.c:881 (python.exe:arm64+0x10029ac0c)
    #21 _PyEval_EvalFrameDefault generated_cases.c.h:4022 (python.exe:arm64+0x10029ac0c)
    #22 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #23 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #24 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #25 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #26 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #27 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #28 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x10009112c)
    #29 _PyObject_Call call.c:348 (python.exe:arm64+0x10009112c)
    #30 PyObject_Call call.c:373 (python.exe:arm64+0x1000911a4)
    #31 thread_run _threadmodule.c:388 (python.exe:arm64+0x10044df04)
    #32 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x10038a12c)

  Thread T8 (tid=18691990, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64+0x31d84)
    #1 do_start_joinable_thread thread_pthread.h:281 (python.exe:arm64+0x100389300)
    #2 PyThread_start_joinable_thread thread_pthread.h:323 (python.exe:arm64+0x100389138)
    #3 ThreadHandle_start _threadmodule.c:475 (python.exe:arm64+0x10044dd10)
    #4 do_start_new_thread _threadmodule.c:1919 (python.exe:arm64+0x10044d7dc)
    #5 thread_PyThread_start_joinable_thread _threadmodule.c:2042 (python.exe:arm64+0x10044c844)
    #6 cfunction_call methodobject.c:564 (python.exe:arm64+0x100138744)
    #7 _PyObject_MakeTpCall call.c:242 (python.exe:arm64+0x10009030c)
    #8 _PyObject_VectorcallTstate pycore_call.h:142 (python.exe:arm64+0x100090f14)
    #9 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090f14)
    #10 _Py_VectorCall_StackRefSteal ceval.c:724 (python.exe:arm64+0x100290228)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:3528 (python.exe:arm64+0x100299d1c)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fa34)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fa34)
    #14 PyEval_EvalCode ceval.c:677 (python.exe:arm64+0x10028fa34)
    #15 run_eval_code_obj pythonrun.c:1369 (python.exe:arm64+0x100366a70)
    #16 run_mod pythonrun.c:1472 (python.exe:arm64+0x1003667cc)
    #17 pyrun_file pythonrun.c:1296 (python.exe:arm64+0x100361d38)
    #18 _PyRun_SimpleFileObject pythonrun.c:518 (python.exe:arm64+0x100361d38)
    #19 _PyRun_AnyFileObject pythonrun.c:81 (python.exe:arm64+0x1003614c8)
    #20 pymain_run_file_obj main.c:411 (python.exe:arm64+0x1003a3328)
    #21 pymain_run_file main.c:430 (python.exe:arm64+0x1003a3328)
    #22 pymain_run_python main.c:715 (python.exe:arm64+0x1003a2658)
    #23 Py_RunMain main.c:796 (python.exe:arm64+0x1003a2658)
    #24 pymain_main main.c:826 (python.exe:arm64+0x1003a2bd0)
    #25 Py_BytesMain main.c:850 (python.exe:arm64+0x1003a2cd0)
    #26 main python.c:15 (python.exe:arm64+0x100000a78)

  Thread T7 (tid=18691989, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64+0x31d84)
    #1 do_start_joinable_thread thread_pthread.h:281 (python.exe:arm64+0x100389300)
    #2 PyThread_start_joinable_thread thread_pthread.h:323 (python.exe:arm64+0x100389138)
    #3 ThreadHandle_start _threadmodule.c:475 (python.exe:arm64+0x10044dd10)
    #4 do_start_new_thread _threadmodule.c:1919 (python.exe:arm64+0x10044d7dc)
    #5 thread_PyThread_start_joinable_thread _threadmodule.c:2042 (python.exe:arm64+0x10044c844)
    #6 cfunction_call methodobject.c:564 (python.exe:arm64+0x100138744)
    #7 _PyObject_MakeTpCall call.c:242 (python.exe:arm64+0x10009030c)
    #8 _PyObject_VectorcallTstate pycore_call.h:142 (python.exe:arm64+0x100090f14)
    #9 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090f14)
    #10 _Py_VectorCall_StackRefSteal ceval.c:724 (python.exe:arm64+0x100290228)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:3528 (python.exe:arm64+0x100299d1c)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fa34)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fa34)
    #14 PyEval_EvalCode ceval.c:677 (python.exe:arm64+0x10028fa34)
    #15 run_eval_code_obj pythonrun.c:1369 (python.exe:arm64+0x100366a70)
    #16 run_mod pythonrun.c:1472 (python.exe:arm64+0x1003667cc)
    #17 pyrun_file pythonrun.c:1296 (python.exe:arm64+0x100361d38)
    #18 _PyRun_SimpleFileObject pythonrun.c:518 (python.exe:arm64+0x100361d38)
    #19 _PyRun_AnyFileObject pythonrun.c:81 (python.exe:arm64+0x1003614c8)
    #20 pymain_run_file_obj main.c:411 (python.exe:arm64+0x1003a3328)
    #21 pymain_run_file main.c:430 (python.exe:arm64+0x1003a3328)
    #22 pymain_run_python main.c:715 (python.exe:arm64+0x1003a2658)
    #23 Py_RunMain main.c:796 (python.exe:arm64+0x1003a2658)
    #24 pymain_main main.c:826 (python.exe:arm64+0x1003a2bd0)
    #25 Py_BytesMain main.c:850 (python.exe:arm64+0x1003a2cd0)
    #26 main python.c:15 (python.exe:arm64+0x100000a78)

SUMMARY: ThreadSanitizer: data race pycore_freelist.h:80 in _PyFreeList_PopNoStats
==================
ThreadSanitizer:DEADLYSIGNAL
==================
WARNING: ThreadSanitizer: data race (pid=69202)
  Write of size 8 at 0x00011e04af40 by thread T5:
    #0 _PyLong_SetSignAndDigitCount pycore_long.h:307 (python.exe:arm64+0x1000f242c)
    #1 _PyLong_FromMedium longobject.c:267 (python.exe:arm64+0x1000f242c)
    #2 _PyLong_FromSTwoDigits longobject.c:320 (python.exe:arm64+0x1000ffb7c)
    #3 long_add longobject.c:3838 (python.exe:arm64+0x1000ffb7c)
    #4 long_add_method longobject.c:3878 (python.exe:arm64+0x10010277c)
    #5 binary_op1 abstract.c:974 (python.exe:arm64+0x10005edb4)
    #6 PyNumber_Add abstract.c:1140 (python.exe:arm64+0x10005eb10)
    #7 _collections__count_elements_impl _collectionsmodule.c:2602 (python.exe:arm64+0x1003f51c8)
    #8 _collections__count_elements _collectionsmodule.c.h:593 (python.exe:arm64+0x1003f51c8)
    #9 _Py_BuiltinCallFast_StackRef ceval.c:815 (python.exe:arm64+0x1002976c0)
    #10 _PyEval_EvalFrameDefault generated_cases.c.h:2420 (python.exe:arm64+0x1002976c0)
    #11 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #12 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #13 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #14 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #15 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #16 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #17 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1002dce38)
    #18 context_run context.c:728 (python.exe:arm64+0x1002dce38)
    #19 _PyCallMethodDescriptorFastWithKeywords_StackRef ceval.c:881 (python.exe:arm64+0x10029ac0c)
    #20 _PyEval_EvalFrameDefault generated_cases.c.h:4022 (python.exe:arm64+0x10029ac0c)
    #21 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #22 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #23 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #24 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #25 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #26 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #27 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x10009112c)
    #28 _PyObject_Call call.c:348 (python.exe:arm64+0x10009112c)
    #29 PyObject_Call call.c:373 (python.exe:arm64+0x1000911a4)
    #30 thread_run _threadmodule.c:388 (python.exe:arm64+0x10044df04)
    #31 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x10038a12c)

  Previous write of size 8 at 0x00011e04af40 by thread T6:
    #0 _PyLong_SetSignAndDigitCount pycore_long.h:307 (python.exe:arm64+0x1000f242c)
    #1 _PyLong_FromMedium longobject.c:267 (python.exe:arm64+0x1000f242c)
    #2 _PyLong_FromSTwoDigits longobject.c:320 (python.exe:arm64+0x1000ffb7c)
    #3 long_add longobject.c:3838 (python.exe:arm64+0x1000ffb7c)
    #4 long_add_method longobject.c:3878 (python.exe:arm64+0x10010277c)
    #5 binary_op1 abstract.c:974 (python.exe:arm64+0x10005edb4)
    #6 PyNumber_Add abstract.c:1140 (python.exe:arm64+0x10005eb10)
    #7 _collections__count_elements_impl _collectionsmodule.c:2602 (python.exe:arm64+0x1003f51c8)
    #8 _collections__count_elements _collectionsmodule.c.h:593 (python.exe:arm64+0x1003f51c8)
    #9 _Py_BuiltinCallFast_StackRef ceval.c:815 (python.exe:arm64+0x1002976c0)
    #10 _PyEval_EvalFrameDefault generated_cases.c.h:4022 (python.exe:arm64+0x1002976c0)
    #11 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #12 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #13 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #14 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #15 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #16 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #17 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x1002dce38)
    #18 context_run context.c:728 (python.exe:arm64+0x1002dce38)
    #19 _PyCallMethodDescriptorFastWithKeywords_StackRef ceval.c:881 (python.exe:arm64+0x10029ac0c)
    #20 _PyEval_EvalFrameDefault generated_cases.c.h:4022 (python.exe:arm64+0x10029ac0c)
    #21 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fe5c)
    #22 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fe5c)
    #23 _PyFunction_Vectorcall call.c (python.exe:arm64+0x1000914bc)
    #24 _PyObject_VectorcallTstate pycore_call.h:144 (python.exe:arm64+0x100092c3c)
    #25 _PyObject_VectorcallPrepend call.c:855 (python.exe:arm64+0x100092c3c)
    #26 method_vectorcall classobject.c:55 (python.exe:arm64+0x100095fdc)
    #27 _PyVectorcall_Call call.c:273 (python.exe:arm64+0x10009112c)
    #28 _PyObject_Call call.c:348 (python.exe:arm64+0x10009112c)
    #29 PyObject_Call call.c:373 (python.exe:arm64+0x1000911a4)
    #30 thread_run _threadmodule.c:388 (python.exe:arm64+0x10044df04)
    #31 pythread_wrapper thread_pthread.h:234 (python.exe:arm64+0x10038a12c)

  Thread T5 (tid=18691987, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64+0x31d84)
    #1 do_start_joinable_thread thread_pthread.h:281 (python.exe:arm64+0x100389300)
    #2 PyThread_start_joinable_thread thread_pthread.h:323 (python.exe:arm64+0x100389138)
    #3 ThreadHandle_start _threadmodule.c:475 (python.exe:arm64+0x10044dd10)
    #4 do_start_new_thread _threadmodule.c:1919 (python.exe:arm64+0x10044d7dc)
    #5 thread_PyThread_start_joinable_thread _threadmodule.c:2042 (python.exe:arm64+0x10044c844)
    #6 cfunction_call methodobject.c:564 (python.exe:arm64+0x100138744)
    #7 _PyObject_MakeTpCall call.c:242 (python.exe:arm64+0x10009030c)
    #8 _PyObject_VectorcallTstate pycore_call.h:142 (python.exe:arm64+0x100090f14)
    #9 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090f14)
    #10 _Py_VectorCall_StackRefSteal ceval.c:724 (python.exe:arm64+0x100290228)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:3528 (python.exe:arm64+0x100299d1c)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fa34)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fa34)
    #14 PyEval_EvalCode ceval.c:677 (python.exe:arm64+0x10028fa34)
    #15 run_eval_code_obj pythonrun.c:1369 (python.exe:arm64+0x100366a70)
    #16 run_mod pythonrun.c:1472 (python.exe:arm64+0x1003667cc)
    #17 pyrun_file pythonrun.c:1296 (python.exe:arm64+0x100361d38)
    #18 _PyRun_SimpleFileObject pythonrun.c:518 (python.exe:arm64+0x100361d38)
    #19 _PyRun_AnyFileObject pythonrun.c:81 (python.exe:arm64+0x1003614c8)
    #20 pymain_run_file_obj main.c:411 (python.exe:arm64+0x1003a3328)
    #21 pymain_run_file main.c:430 (python.exe:arm64+0x1003a3328)
    #22 pymain_run_python main.c:715 (python.exe:arm64+0x1003a2658)
    #23 Py_RunMain main.c:796 (python.exe:arm64+0x1003a2658)
    #24 pymain_main main.c:826 (python.exe:arm64+0x1003a2bd0)
    #25 Py_BytesMain main.c:850 (python.exe:arm64+0x1003a2cd0)
    #26 main python.c:15 (python.exe:arm64+0x100000a78)

  Thread T6 (tid=18691988, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64+0x31d84)
    #1 do_start_joinable_thread thread_pthread.h:281 (python.exe:arm64+0x100389300)
    #2 PyThread_start_joinable_thread thread_pthread.h:323 (python.exe:arm64+0x100389138)
    #3 ThreadHandle_start _threadmodule.c:475 (python.exe:arm64+0x10044dd10)
    #4 do_start_new_thread _threadmodule.c:1919 (python.exe:arm64+0x10044d7dc)
    #5 thread_PyThread_start_joinable_thread _threadmodule.c:2042 (python.exe:arm64+0x10044c844)
    #6 cfunction_call methodobject.c:564 (python.exe:arm64+0x100138744)
    #7 _PyObject_MakeTpCall call.c:242 (python.exe:arm64+0x10009030c)
    #8 _PyObject_VectorcallTstate pycore_call.h:142 (python.exe:arm64+0x100090f14)
    #9 PyObject_Vectorcall call.c:327 (python.exe:arm64+0x100090f14)
    #10 _Py_VectorCall_StackRefSteal ceval.c:724 (python.exe:arm64+0x100290228)
    #11 _PyEval_EvalFrameDefault generated_cases.c.h:3528 (python.exe:arm64+0x100299d1c)
    #12 _PyEval_EvalFrame pycore_ceval.h:122 (python.exe:arm64+0x10028fa34)
    #13 _PyEval_Vector ceval.c:2134 (python.exe:arm64+0x10028fa34)
    #14 PyEval_EvalCode ceval.c:677 (python.exe:arm64+0x10028fa34)
    #15 run_eval_code_obj pythonrun.c:1369 (python.exe:arm64+0x100366a70)
    #16 run_mod pythonrun.c:1472 (python.exe:arm64+0x1003667cc)
    #17 pyrun_file pythonrun.c:1296 (python.exe:arm64+0x100361d38)
    #18 _PyRun_SimpleFileObject pythonrun.c:518 (python.exe:arm64+0x100361d38)
    #19 _PyRun_AnyFileObject pythonrun.c:81 (python.exe:arm64+0x1003614c8)
    #20 pymain_run_file_obj main.c:411 (python.exe:arm64+0x1003a3328)
    #21 pymain_run_file main.c:430 (python.exe:arm64+0x1003a3328)
    #22 pymain_run_python main.c:715 (python.exe:arm64+0x1003a2658)
    #23 Py_RunMain main.c:796 (python.exe:arm64+0x1003a2658)
    #24 pymain_main main.c:826 (python.exe:arm64+0x1003a2bd0)
    #25 Py_BytesMain main.c:850 (python.exe:arm64+0x1003a2cd0)
    #26 main python.c:15 (python.exe:arm64+0x100000a78)

SUMMARY: ThreadSanitizer: data race pycore_long.h:307 in _PyLong_SetSignAndDigitCount
==================
ThreadSanitizer:DEADLYSIGNAL
ThreadSanitizer: nested bug in the same thread, aborting.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Output from running 'python -VV' on the command line:

No response

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    type-crashA hard crash of the interpreter, possibly with a core dump

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