Do not use realloc(seap_msg->attrs, 0) to free seap_msg->attrs

This is implementation dependent, frown upon and triggering
for sanitizers.

Author: evgenyz

src/OVAL/probes/SEAP/seap-packet.c

@@ -206,9 +206,14 @@ static int SEAP_packet_sexp2msg (SEXP_t *sexp_msg, SEAP_msg_t *seap_msg)
         _A(attr_i >= (SEXP_list_length (sexp_msg) - 4)/2);
 
         seap_msg->attrs_cnt = attr_i;
-        void *new_attrs = realloc(seap_msg->attrs, sizeof(SEAP_attr_t) * seap_msg->attrs_cnt);
-        if (new_attrs != NULL || seap_msg->attrs_cnt == 0)
+        if (seap_msg->attrs_cnt == 0) {
+                free(seap_msg->attrs);
+                seap_msg->attrs = NULL;
+        } else {
+                void *new_attrs = realloc(seap_msg->attrs, sizeof(SEAP_attr_t) * seap_msg->attrs_cnt);
                 seap_msg->attrs = new_attrs;
+        }
+
         seap_msg->sexp = SEXP_list_last (sexp_msg);
 
         return (0);