register_proc_table and unregister_proc_table didn't deal with the
possibility that the *table pointer could be NULL.  Check for this and
return if table is NULL.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
        int len;
        mode_t mode;
 
+       if (table == NULL)
+               return;
+
        for (; table->id; table++) {
                /* Can't do anything without a proc name. */
                if (!table->name)
        struct proc_dir_entry *de;
        struct nd_struct *tmp;
 
+       if (table == NULL)
+               return;
+
        list_for_each_entry(tmp, &nd_struct_list, list) {
                if ((table == dgrp_net_table) && (tmp->nd_net_de)) {
                        unregister_dgrp_device(tmp->nd_net_de);