Bug report

There are multiple cases where PyList_SetItem does not check for -1 in termios module. We need to fix this. There are two options to fix this:

• < 0 check
• PyList_SET_ITEM usage

There are two possible errors that PyList_SetItem can produce:

    if (!PyList_Check(op)) {
        Py_XDECREF(newitem);
        PyErr_BadInternalCall();
        return -1;
    }
    if (!valid_index(i, Py_SIZE(op))) {
        Py_XDECREF(newitem);
        PyErr_SetString(PyExc_IndexError,
                        "list assignment index out of range");
        return -1;
    }

Each case needs an explanation.

Here cc is always a list and i goes from 0 to some other int value by i++, it is safe to use PyList_SET_ITEM.

Here cc is a list, but VMIN and VTIME are 3rd party constants from termios.h. I guess it is safer to use explicit error check.

Here we need to check for possibel PyLong_FromLong error, but we can use PyList_SET_ITEM.

Linked PRs

• gh-110260: Check for PyList_SetItem errors in termios module #110261