!7804 v2 selinux: avoid dereference of garbage after mount failure

Merge Pull Request from: @ci-robot 
 
PR sync from: felix <fuzhen5@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/CBRCFUFQAVRX6RSUDB3GCWR47NZGX5AJ/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9QG73 
 
Link:https://gitee.com/openeuler/kernel/pulls/7804

 

Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>