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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Assertion failures from calling `create_builtin` with invalid object","articleBody":"# Crash report\n\n### What happened?\n\nIt's possible to abort the interpreter by running the code below:\n\n\n```python\nimport importlib\n\nclass S(str): pass\nclass A: pass\n\na = A()\na.name = S(\"123\")\nimportlib._imp.create_builtin(a)\n```\n\nIt's also possible to get a different abort by running this code:\n\n```python\nimport importlib\n\nclass S(str): pass\nclass A: pass\n\na = A()\na.name = S()\nimportlib._imp.create_builtin(a)\n```\n\n\nBacktrace for the first abort:\n```\npython: Python/import.c:2438: PyObject *create_builtin(PyThreadState *, PyObject *, PyObject *, PyModInitFunction): Assertion `is_core_module(tstate-\u003einterp, info.name, info.path)' failed.\n\nProgram received signal SIGABRT, Aborted.\n\n#0  __pthread_kill_implementation (threadid=\u003coptimized out\u003e, signo=6, no_tid=0) at ./nptl/pthread_kill.c:44\n#1  __pthread_kill_internal (threadid=\u003coptimized out\u003e, signo=6) at ./nptl/pthread_kill.c:89\n#2  __GI___pthread_kill (threadid=\u003coptimized out\u003e, signo=signo@entry=6) at ./nptl/pthread_kill.c:100\n#3  0x00007ffff7c45e2e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26\n#4  0x00007ffff7c28888 in __GI_abort () at ./stdlib/abort.c:77\n#5  0x00007ffff7c287f0 in __assert_fail_base (fmt=\u003coptimized out\u003e, assertion=\u003coptimized out\u003e, file=\u003coptimized out\u003e, line=\u003coptimized out\u003e, function=\u003coptimized out\u003e) at ./assert/assert.c:118\n#6  0x00007ffff7c3c19f in __assert_fail (assertion=\u003coptimized out\u003e, file=\u003coptimized out\u003e, line=\u003coptimized out\u003e, function=\u003coptimized out\u003e) at ./assert/assert.c:127\n#7  0x00005555558c6a4a in create_builtin (tstate=tstate@entry=0x555555d988c0 \u003c_PyRuntime+358640\u003e, name=name@entry=0x7ffff6d2f580, spec=spec@entry=0x7ffff6c222c0, initfunc=initfunc@entry=0x0)\n    at Python/import.c:2438\n#8  0x00005555558cc023 in _imp_create_builtin (module=0x7ffff6d6e840, spec=0x7ffff6c222c0) at Python/import.c:4423\n#9  0x00005555557136f5 in cfunction_vectorcall_O (func=func@entry=0x7ffff6d8a2d0, args=args@entry=0x7fffffffc468, nargsf=nargsf@entry=9223372036854775809, kwnames=kwnames@entry=0x0)\n    at Objects/methodobject.c:536\n#10 0x0000555555698e0e in _PyObject_VectorcallTstate (tstate=0x555555d988c0 \u003c_PyRuntime+358640\u003e, callable=0x7ffff6d8a2d0, args=0x7fffffffc468, nargsf=9223372036854775809, kwnames=0x0)\n    at ./Include/internal/pycore_call.h:169\n#11 0x0000555555836303 in _PyEval_EvalFrameDefault (tstate=tstate@entry=0x555555d988c0 \u003c_PyRuntime+358640\u003e, frame=\u003coptimized out\u003e, frame@entry=0x7ffff7fa7020, throwflag=throwflag@entry=0)\n    at Python/generated_cases.c.h:1620\n```\n\nBacktrace for the second abort:\n```\npython: ./Python/importdl.c:159: int _Py_ext_module_loader_info_init_for_builtin(struct _Py_ext_module_loader_info *, PyObject *): Assertion `PyUnicode_GetLength(name) \u003e 0' failed.\n\nProgram received signal SIGABRT, Aborted.\n\n#0  __pthread_kill_implementation (threadid=\u003coptimized out\u003e, signo=6, no_tid=0) at ./nptl/pthread_kill.c:44\n#1  __pthread_kill_internal (threadid=\u003coptimized out\u003e, signo=6) at ./nptl/pthread_kill.c:89\n#2  __GI___pthread_kill (threadid=\u003coptimized out\u003e, signo=signo@entry=6) at ./nptl/pthread_kill.c:100\n#3  0x00007ffff7c45e2e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26\n#4  0x00007ffff7c28888 in __GI_abort () at ./stdlib/abort.c:77\n#5  0x00007ffff7c287f0 in __assert_fail_base (fmt=\u003coptimized out\u003e, assertion=\u003coptimized out\u003e, file=\u003coptimized out\u003e, line=\u003coptimized out\u003e, function=\u003coptimized out\u003e) at ./assert/assert.c:118\n#6  0x00007ffff7c3c19f in __assert_fail (assertion=\u003coptimized out\u003e, file=\u003coptimized out\u003e, line=\u003coptimized out\u003e, function=\u003coptimized out\u003e) at ./assert/assert.c:127\n#7  0x00005555558cd986 in _Py_ext_module_loader_info_init_for_builtin (info=info@entry=0x7fffffffc228, name=name@entry=0x7ffff6d2f580) at ./Python/importdl.c:159\n#8  0x00005555558c6696 in create_builtin (tstate=tstate@entry=0x555555d988c0 \u003c_PyRuntime+358640\u003e, name=0x53465, name@entry=0x7ffff6d2f580, spec=0x6, spec@entry=0x7ffff6c222c0,\n    initfunc=0x7ffff7ca5fed \u003c__GI___pthread_kill+285\u003e, initfunc@entry=0x0) at Python/import.c:2405\n#9  0x00005555558cc023 in _imp_create_builtin (module=0x7ffff6d6e840, spec=0x7ffff6c222c0) at Python/import.c:4423\n#10 0x00005555557136f5 in cfunction_vectorcall_O (func=func@entry=0x7ffff6d8a2d0, args=args@entry=0x7fffffffc468, nargsf=nargsf@entry=9223372036854775809, kwnames=kwnames@entry=0x0)\n    at Objects/methodobject.c:536\n#11 0x0000555555698e0e in _PyObject_VectorcallTstate (tstate=0x555555d988c0 \u003c_PyRuntime+358640\u003e, callable=0x7ffff6d8a2d0, args=0x7fffffffc468, nargsf=9223372036854775809, kwnames=0x0)\n    at ./Include/internal/pycore_call.h:169\n```\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nLinux\n\n### Output from running 'python -VV' on the command line:\n\nPython 3.15.0a2+ (heads/main-dirty:bc9e63dd9d2, Nov 26 2025, 19:23:56) [Clang 21.1.2 (2ubuntu6)]\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-142033\n* gh-142054\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/devdanzin","@type":"Person","name":"devdanzin"},"datePublished":"2025-11-28T02:04:54.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/142029/cpython/issues/142029"}