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

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

Posted by Yu Kuai 3 years, 1 month ago

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

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

Posted by Jens Axboe 3 years, 1 month ago

On Tue, 07 Mar 2023 18:55:52 +0800, Yu Kuai wrote:
> 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().
> 
> [...]

Applied, thanks!

[1/1] block: fix wrong mode for blkdev_put() from disk_scan_partitions()
      commit: 428913bce1e67ccb4dae317fd0332545bf8c9233

Best regards,
-- 
Jens Axboe

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

Posted by Jan Kara 3 years, 1 month ago

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

Thanks for fixing this! Feel free to add:

Reviewed-by: Jan Kara <jack@suse.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@suse.com>
SUSE Labs, CR