linux-kernel - [PATCH] block: fix wrong mode for blkdev_put() from disk_scan

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Message-Id: <20230307105552.1560439-1-yukuai1@huaweicloud.com>
Date:   Tue,  7 Mar 2023 18:55:52 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     hch@....de, jack@...e.cz, julianr@...ux.ibm.com, axboe@...nel.dk,
        yukuai3@...wei.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai1@...weicloud.com, yi.zhang@...wei.com, yangerkun@...wei.com
Subject: [PATCH] block: fix wrong mode for blkdev_put() from disk_scan_partitions()

From: Yu Kuai <yukuai3@...wei.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@...kaller.appspotmail.com
Link: https://lore.kernel.org/lkml/f9649d501bc8c3444769418f6c26263555d9d3be.camel@linux.ibm.com/T/
Tested-by: Julian Ruess <julianr@...ux.ibm.com>
Fixes: e5cfefa97bcc ("block: fix scan partition for exclusively open device again")
Signed-off-by: Yu Kuai <yukuai3@...wei.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