diff --git a/Include/internal/pycore_frame.h b/Include/internal/pycore_frame.h index ecc8346f5ef0b5..4866ea21b9989c 100644 --- a/Include/internal/pycore_frame.h +++ b/Include/internal/pycore_frame.h @@ -94,7 +94,10 @@ static inline void _PyFrame_StackPush(_PyInterpreterFrame *f, PyObject *value) { void _PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *dest); -/* Consumes reference to func */ +/* Consumes reference to func and locals. + Does not initialize frame->previous, which happens + when frame is linked into the frame stack. + */ static inline void _PyFrame_InitializeSpecials( _PyInterpreterFrame *frame, PyFunctionObject *func, diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py index 6cda91677054d7..db7a7741621979 100644 --- a/Lib/test/test_capi/test_misc.py +++ b/Lib/test/test_capi/test_misc.py @@ -1335,6 +1335,16 @@ def test_frame_get_generator(self): frame = next(gen) self.assertIs(gen, _testcapi.frame_getgenerator(frame)) + def test_frame_fback_api(self): + """Test that accessing `f_back` does not cause a segmentation fault on + a frame created with `PyFrame_New` (GH-99110).""" + def dummy(): + pass + + frame = _testcapi.frame_new(dummy.__code__, globals(), locals()) + # The following line should not cause a segmentation fault. + self.assertIsNone(frame.f_back) + SUFFICIENT_TO_DEOPT_AND_SPECIALIZE = 100 diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-12-12-01-05-16.gh-issue-99110.1JqtIg.rst b/Misc/NEWS.d/next/Core and Builtins/2022-12-12-01-05-16.gh-issue-99110.1JqtIg.rst new file mode 100644 index 00000000000000..175740dfca07ec --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2022-12-12-01-05-16.gh-issue-99110.1JqtIg.rst @@ -0,0 +1,2 @@ +Initialize frame->previous in frameobject.c to fix a segmentation fault when +accessing frames created by :c:func:`PyFrame_New`. diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c index 70242d78ab8c54..bb7de220a2db9a 100644 --- a/Modules/_testcapimodule.c +++ b/Modules/_testcapimodule.c @@ -22,6 +22,7 @@ #include "Python.h" #include "datetime.h" // PyDateTimeAPI +#include "frameobject.h" // PyFrame_New #include "marshal.h" // PyMarshal_WriteLongToFile #include "structmember.h" // PyMemberDef #include // FLT_MAX @@ -6000,6 +6001,22 @@ frame_getlasti(PyObject *self, PyObject *frame) return PyLong_FromLong(lasti); } +static PyObject * +frame_new(PyObject *self, PyObject *args) +{ + PyObject *code, *globals, *locals; + if (!PyArg_ParseTuple(args, "OOO", &code, &globals, &locals)) { + return NULL; + } + if (!PyCode_Check(code)) { + PyErr_SetString(PyExc_TypeError, "argument must be a code object"); + return NULL; + } + PyThreadState *tstate = PyThreadState_Get(); + + return (PyObject *)PyFrame_New(tstate, (PyCodeObject *)code, globals, locals); +} + static PyObject * eval_get_func_name(PyObject *self, PyObject *func) { @@ -6492,6 +6509,7 @@ static PyMethodDef TestMethods[] = { {"frame_getgenerator", frame_getgenerator, METH_O, NULL}, {"frame_getbuiltins", frame_getbuiltins, METH_O, NULL}, {"frame_getlasti", frame_getlasti, METH_O, NULL}, + {"frame_new", frame_new, METH_VARARGS, NULL}, {"eval_get_func_name", eval_get_func_name, METH_O, NULL}, {"eval_get_func_desc", eval_get_func_desc, METH_O, NULL}, {"get_feature_macros", get_feature_macros, METH_NOARGS, NULL}, diff --git a/Objects/frameobject.c b/Objects/frameobject.c index f77f5ed39392e2..1e6bdcfb592df5 100644 --- a/Objects/frameobject.c +++ b/Objects/frameobject.c @@ -1010,6 +1010,7 @@ init_frame(_PyInterpreterFrame *frame, PyFunctionObject *func, PyObject *locals) Py_INCREF(func); PyCodeObject *code = (PyCodeObject *)func->func_code; _PyFrame_InitializeSpecials(frame, func, locals, code->co_nlocalsplus); + frame->previous = NULL; for (Py_ssize_t i = 0; i < code->co_nlocalsplus; i++) { frame->localsplus[i] = NULL; }