`PyObject_CallFunction` generates `MemoryError` when format string is `iy#` and buffer is on stack

[pkrn-ams-osram]

Bug report

Bug description:

Using Python 3.12.5 on Windows, the executable built from the following C code produces the output MemoryError:

#define PY_SSIZE_T_CLEAN
#include <Python.h>

int main(int argc, char *argv[])
{
    Py_Initialize();

    const char *python_code =
        "def func(*args):\n"
        "    print(args)\n";
    PyRun_SimpleString(python_code);

    PyObject *main_module = PyImport_AddModule("__main__");
    PyObject *main_dict = PyModule_GetDict(main_module);

    PyObject *func = PyDict_GetItemString(main_dict, "func");

    char data[10] = {0};
    PyObject *result = PyObject_CallFunction(func, "iy#", 1, data, 10);
    if (!result)
    {
        PyErr_Print();
    }

    Py_Finalize();

    return 0;
}

The error does not occur when the data variable is made a global variable. I am using GCC 13.10.0 (MinGW-Builds project) on x86-64 Windows 10. I cannot attach the binary to this issue due to GitHub file type restrictions, but please let me know if I should provide it to you via a different channel.

CPython versions tested on:

3.12

Operating systems tested on:

Windows

[vstinner]

Does it work if you replace the call with: PyObject *result = PyObject_CallFunction(func, "iy#", 1, data, (Py_ssize_t)10);?

[pkrn-ams-osram]

Good catch, this fixes the issue. Thank you!