[Python-Dev] Potential NULL pointer dereference in descrobject.c

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++