block: fix wrong mode for blkdev_put() from disk_scan_partitions()

[ Upstream commit 828fe64cc7edb2e17d246f330c31bed38ffa29f9 ]

If disk_scan_partitions() is called with 'FMODE_EXCL',
blkdev_get_by_dev() will be called without 'FMODE_EXCL', however, follow
blkdev_put() is still called with 'FMODE_EXCL', which will cause
'bd_holders' counter to leak.

Fix the problem by using the right mode for blkdev_put().

Reported-by: syzbot+2bcc0d79e548c4f62a59@syzkaller.appspotmail.com
Link: https://lore.kernel.org/lkml/f9649d501bc8c3444769418f6c26263555d9d3be.camel@linux.ibm.com/T/
Tested-by: Julian Ruess <julianr@linux.ibm.com>
Fixes: 92ef14daac46 ("block: fix scan partition for exclusively open device again")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/block/genhd.c b/block/genhd.c
index 85ae755913e9e7d2e89c2fe5c8f4554f7b23bd98..0b6928e948f31d6397c2ce4df13f08b61a12aa68 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -385,7 +385,7 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode)
        if (IS_ERR(bdev))
                ret =  PTR_ERR(bdev);
        else
-               blkdev_put(bdev, mode);
+               blkdev_put(bdev, mode & ~FMODE_EXCL);
 
        if (!(mode & FMODE_EXCL))
                bd_abort_claiming(disk->part0, disk_scan_partitions);