stable inclusion
from stable-v5.10.162
commit 0cf0ce8fb5b10d669072345ea855de112d0e0a43
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6BTWC

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.10.167&id=0cf0ce8fb5b10d669072345ea855de112d0e0a43

--------------------------------

[ Upstream commit 7d01ef75 ]

Initialize them in set_nameidata() and make sure that terminate_walk() clears them
once the pointers become potentially invalid (i.e. we leave RCU mode or drop them
in non-RCU one).  Currently we have "path_init() always initializes them and nobody
accesses them outside of path_init()/terminate_walk() segments", which is asking
for trouble.

With that change we would have nd->path.{mnt,dentry}
	1) always valid - NULL or pointing to currently allocated objects.
	2) non-NULL while we are successfully walking
	3) NULL when we are not walking at all
	4) contributing to refcounts whenever non-NULL outside of RCU mode.

Fixes: 6c6ec2b0 ("fs: add support for LOOKUP_CACHED")
Reported-by: syzbot+c88a7030da47945a3cc3@syzkaller.appspotmail.com
Tested-by: NChristian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflict：
	fs/namei.c
Signed-off-by: NLi Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Reviewed-by: NWang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>