Patch #1511317: don't crash on invalid hostname info

Modules/socketmodule.c

@@ -3041,6 +3041,8 @@ gethost_common(struct hostent *h, struct sockaddr *addr, int alen, int af)
 	if ((addr_list = PyList_New(0)) == NULL)
 		goto err;
 
+	/* SF #1511317: h_aliases can be NULL */
+	if (h->h_aliases) {
 		for (pch = h->h_aliases; *pch != NULL; pch++) {
 			int status;
 			tmp = PyString_FromString(*pch);
@@ -3053,6 +3055,7 @@ gethost_common(struct hostent *h, struct sockaddr *addr, int alen, int af)
 			if (status)
 				goto err;
 		}
+	}
 
 	for (pch = h->h_addr_list; *pch != NULL; pch++) {
 		int status;