md: Put the right device in md_seq_next

commit c8870379a21fbd9ad14ca36204ccfbe9d25def43 upstream.

If there are multiple arrays in system and one mddevice is marked
with MD_DELETED and md_seq_next() is called in the middle of removal
then it _get()s proper device but it may _put() deleted one. As a result,
active counter may never be zeroed for mddevice and it cannot
be removed.

Put the device which has been _get with previous md_seq_next() call.

Cc: stable@vger.kernel.org
Fixes: 12a6caf27324 ("md: only delete entries from all_mddevs when the disk is freed")
Reported-by: AceLan Kao <acelan@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217798
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230914152416.10819-1-mariusz.tkaczyk@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 86b2acfba1a7fcc96d51c5001a4c4192b85b7e69..e87507d29895e772e12fc63b809d819b08e8d085 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8228,7 +8228,7 @@ static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
        spin_unlock(&all_mddevs_lock);
 
        if (to_put)
-               mddev_put(mddev);
+               mddev_put(to_put);
        return next_mddev;
 
 }