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autofs: fix wait name hash calculation in autofs_wait() 

There's a mistake in commit 2be7828c9f ("get rid of autofs_getpath()")
that affects kernels from v5.13.0, basically missed because of me not
fully testing the change for Al.

The problem is that the hash calculation for the wait name qstr hasn't
been updated to account for the change to use dentry_path_raw(). This
prevents the correct matching an existing wait resulting in multiple
notifications being sent to the daemon for the same mount which must
not occur.

The problem wasn't discovered earlier because it only occurs when
multiple processes trigger a request for the same mount concurrently
so it only shows up in more aggressive testing.

Fixes: 2be7828c9f ("get rid of autofs_getpath()")
Cc: stable@vger.kernel.org
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Ian Kent 2021-09-23 15:13:39 +08:00 committed by Al Viro
parent 519d81956e
commit 25f54d08f1
1 changed files with 1 additions and 1 deletions
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2
fs/autofs/waitq.c
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@ -358,7 +358,7 @@ int autofs_wait(struct autofs_sb_info *sbi,
qstr.len = strlen(p);
offset = p - name;
}
qstr.hash = full_name_hash(dentry, name, qstr.len);
qstr.hash = full_name_hash(dentry, qstr.name, qstr.len);
if (mutex_lock_interruptible(&sbi->wq_mutex)) {
kfree(name);