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

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Date:   Tue, 7 Mar 2023 14:12:30 +0100
From:   Jan Kara <jack@...e.cz>
To:     Yu Kuai <yukuai1@...weicloud.com>
Cc:     hch@....de, jack@...e.cz, julianr@...ux.ibm.com, axboe@...nel.dk,
        yukuai3@...wei.com, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
        yangerkun@...wei.com
Subject: Re: [PATCH] block: fix wrong mode for blkdev_put() from
 disk_scan_partitions()

On Tue 07-03-23 18:55:52, Yu Kuai wrote:
> 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>

Thanks for fixing this! Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  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
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR