[Python-Dev] Potential NULL pointer dereference in descrobject.c (original) (raw)

Michael Mueller mmueller at vigilantsw.com
Sat Dec 17 10:55:55 CET 2011

Hi Guys,

We've been analyzing CPython with our static analysis tool (Sentry) and a NULL pointer dereference popped up the other day, in Objects/descrobject.c:

if (descr != NULL) {
    Py_XINCREF(type);
    descr->d_type = type;
    descr->d_name = PyUnicode_InternFromString(name);
    if (descr->d_name == NULL) {
        Py_DECREF(descr);
        descr = NULL;
    }
    descr->d_qualname = NULL; // Possible NULL pointer dereference
}

If the inner conditional block can be reached, descr will be set NULL and then dereferenced on the next line. The commented line above was added in this commit: http://hg.python.org/cpython/rev/73948#l4.92

Hopefully someone can take a look and determine the appropriate fix.

Best, Mike

-- Mike Mueller Phone: (401) 405-1525 Email: mmueller at vigilantsw.com

http://www.vigilantsw.com/ Static Analysis for C and C++

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