[New-bugs-announce] [issue29874] Need a look for return value checking [selectmodule.c]

[Alex CHEN]

New submission from Alex CHEN:

In file selectmodule.c

our static code scanner has reported the following case, function set2list is liable to return NULL (if PyTuple_New failed),  would any chance the NULL pointer be dereferenced (Py_DECREF(fdlist) after set2list) or it would just raise python exception to handle PyTuple_New error ?

static PyObject *
select_select(PyObject *self, PyObject *args)
{
    ......
    if (n < 0) {
        PyErr_SetFromErrno(SelectError);
    }
#endif
    else {
        /* any of these three calls can raise an exception.  it's more
           convenient to test for this after all three calls... but
           is that acceptable?
        */
        ifdlist = set2list(&ifdset, rfd2obj);          //   || <=====
        ofdlist = set2list(&ofdset, wfd2obj);          //   ||
        efdlist = set2list(&efdset, efd2obj);          //   ||
        if (PyErr_Occurred())
            ret = NULL;
        else
            ret = PyTuple_Pack(3, ifdlist, ofdlist, efdlist);

        Py_DECREF(ifdlist);
        Py_DECREF(ofdlist);
        Py_DECREF(efdlist);

----------
messages: 289967
nosy: alexc
priority: normal
severity: normal
status: open
title: Need a look for return value checking [selectmodule.c]

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue29874>
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