!9819 kdb: Fix buffer overflow during tab-complete

Merge Pull Request from: @ci-robot 
 
PR sync from: Tengda Wu <wutengda2@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/7LJPKMGPNHSJBRTJAXICOW4EXSQCOKJB/ 
 
https://gitee.com/src-openeuler/kernel/issues/IAB05N 
 
Link:https://gitee.com/openeuler/kernel/pulls/9819

 

Reviewed-by: Ye Weihua <yeweihua4@huawei.com>
Reviewed-by: Xu Kuohai <xukuohai@huawei.com>
Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>