bpo-37138: fix undefined behaviour with memcpy() on NULL array (GH-13867)
(cherry picked from commit 1f9531764cc0f8dbca1d8f429d162dc28282f4b4)
Co-authored-by: Jeroen Demeyer <J.Demeyer@UGent.be>
diff --git a/Objects/classobject.c b/Objects/classobject.c
index ffd3f87..2415ed1 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -71,7 +71,11 @@
}
/* use borrowed references */
newargs[0] = self;
- memcpy(newargs + 1, args, totalargs * sizeof(PyObject *));
+ if (totalargs) { /* bpo-37138: if totalargs == 0, then args may be
+ * NULL and calling memcpy() with a NULL pointer
+ * is undefined behaviour. */
+ memcpy(newargs + 1, args, totalargs * sizeof(PyObject *));
+ }
result = _PyObject_Vectorcall(func, newargs, nargs+1, kwnames);
PyMem_Free(newargs);
}