[PATCH] block: fix wrong mode for blkdev_put() from disk_scan_partitions()

From: Yu Kuai <yukuai1@huaweicloud.com>
To: hch@lst.de, jack@suse.cz, julianr@linux.ibm.com, axboe@kernel.dk,
	yukuai3@huawei.com
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	yukuai1@huaweicloud.com, yi.zhang@huawei.com,
	yangerkun@huawei.com
Subject: [PATCH] block: fix wrong mode for blkdev_put() from disk_scan_partitions()
Date: Tue,  7 Mar 2023 18:55:52 +0800	[thread overview]
Message-ID: <20230307105552.1560439-1-yukuai1@huaweicloud.com> (raw)
In-Reply-To: <a3a4351375d51aa5e93e06bba212ba3637665885.camel@linux.ibm.com>

From: Yu Kuai <yukuai3@huawei.com>

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: e5cfefa97bcc ("block: fix scan partition for exclusively open device again")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 block/genhd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 3ee5577e1586..02d9cfb9e077 100644
--- 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);
-- 
2.31.1

