8000 gh-131998: Fix `NULL` dereference when using an unbound method descri… · ZeroIntensity/cpython@ac3c439 · GitHub
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ZeroIntensitysobolevnvstinnermarkshannon
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pythongh-131998: Fix NULL dereference when using an unbound method descriptor in a specialized code path (python#132000)
Co-authored-by: sobolevn <mail@sobolevn.me> Co-authored-by: Victor Stinner <vstinner@python.org> Co-authored-by: Mark Shannon <mark@hotpy.org>
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‎Lib/test/test_types.py

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@@ -4,6 +4,7 @@
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run_with_locale, cpython_only, no_rerun,
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MISSING_C_DOCSTRINGS, EqualToForwardRef,
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)
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from test.support.script_helper import assert_python_ok
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from test.support.import_helper import import_fresh_module
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import collections.abc
@@ -672,6 +673,24 @@ def test_traceback_and_frame_types(self):
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def test_capsule_type(self):
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self.assertIsInstance(_datetime.datetime_CAPI, types.CapsuleType)
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def test_call_unbound_crash(self):
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# GH-131998: The specialized instruction would get tricked into dereferencing
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# a bound "self" that didn't exist if subsequently called unbound.
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code = """if True:
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def call(part):
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[] + ([] + [])
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part.pop()
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for _ in range(3):
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call(['a'])
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try:
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call(list)
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except TypeError:
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pass
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"""
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assert_python_ok("-c", code)
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class UnionTests(unittest.TestCase):
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‎Misc/NEWS.d/next/Core_and_Builtins/2025-04-01-22-24-19.gh-issue-131998.DvmZcT.rst

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Fix a crash when using an unbound method :term:`descriptor` object in a
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function where a bound method descriptor was used.

‎Python/bytecodes.c

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@@ -4300,12 +4300,14 @@ dummy_func(
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arguments--;
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total_args++;
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}
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EXIT_IF(total_args == 0);
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PyMethodDescrObject *method = (PyMethodDescrObject *)callable_o;
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EXIT_IF(!Py_IS_TYPE(method, &PyMethodDescr_Type));
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PyMethodDef *meth = method->d_method;
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EXIT_IF(meth->ml_flags != (METH_FASTCALL|METH_KEYWORDS));
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PyTypeObject *d_type = method->d_common.d_type;
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PyObject *self = PyStackRef_AsPyObjectBorrow(arguments[0]);
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assert(self != NULL);
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EXIT_IF(!Py_IS_TYPE(self, d_type));
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STAT_INC(CALL, hit);
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int nargs = total_args - 1;
@@ -4378,12 +4380,14 @@ dummy_func(
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arguments--;
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total_args++;
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}
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EXIT_IF(total_args == 0);
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PyMethodDescrObject *method = (PyMethodDescrObject *)callable_o;
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/* Builtin METH_FASTCALL methods, without keywords */
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EXIT_IF(!Py_IS_TYPE(method, &PyMethodDescr_Type));
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PyMethodDef *meth = method->d_method;
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EXIT_IF(meth->ml_flags != METH_FASTCALL);
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PyObject *self = PyStackRef_AsPyObjectBorrow(arguments[0]);
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assert(self != NULL);
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EXIT_IF(!Py_IS_TYPE(self, method->d_common.d_type));
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STAT_INC(CALL, hit);
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int nargs = total_args - 1;

‎Python/executor_cases.c.h

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‎Python/generated_cases.c.h

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