2023-06-18 06:55:23

by Yu Kuai

Subject: [PATCH -next v2] block: fix wrong mode for blkdev_get_by_dev() from disk_scan_partitions()

From: Yu Kuai <[email protected]>

After commit 2736e8eeb0cc ("block: use the holder as indication for
exclusive opens"), blkdev_get_by_dev() will warn if holder is NULL and
mode contains 'FMODE_EXCL'.

holder from blkdev_get_by_dev() from disk_scan_partitions() is always NULL,
hence it should not use 'FMODE_EXCL', which is broben by the commit. For
consequence, WARN_ON_ONCE() will be triggered from blkdev_get_by_dev()
if user scan partitions with device opened exclusively.

Fix this problem by removing 'FMODE_EXCL' from disk_scan_partitions(),
as it used to be.

Reported-by: [email protected]
Link: https://syzkaller.appspot.com/bug?extid=00cd27751f78817f167b
Fixes: 2736e8eeb0cc ("block: use the holder as indication for exclusive opens")
Signed-off-by: Yu Kuai <[email protected]>
---

Changes in v2:
- fix a typo

block/genhd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 2c2f9a716822..d1e845ae1b32 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -365,7 +365,8 @@ int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode)
}

set_bit(GD_NEED_PART_SCAN, &disk->state);
- bdev = blkdev_get_by_dev(disk_devt(disk), mode, NULL, NULL);
+ bdev = blkdev_get_by_dev(disk_devt(disk), mode & ~FMODE_EXEC, NULL,
+ NULL);
if (IS_ERR(bdev))
ret = PTR_ERR(bdev);
else
--
2.39.2

2023-06-19 05:41:24

by Christoph Hellwig

Subject: Re: [PATCH -next v2] block: fix wrong mode for blkdev_get_by_dev() from disk_scan_partitions()

Looks good:

Reviewed-by: Christoph Hellwig <[email protected]>

2023-06-20 10:12:08

by Christian Brauner

Subject: Re: [PATCH -next v2] block: fix wrong mode for blkdev_get_by_dev() from disk_scan_partitions()

On Sun, Jun 18, 2023 at 10:04:02PM +0800, Yu Kuai wrote:
> From: Yu Kuai <[email protected]>
>
> After commit 2736e8eeb0cc ("block: use the holder as indication for
> exclusive opens"), blkdev_get_by_dev() will warn if holder is NULL and
> mode contains 'FMODE_EXCL'.
>
> holder from blkdev_get_by_dev() from disk_scan_partitions() is always NULL,
> hence it should not use 'FMODE_EXCL', which is broben by the commit. For
> consequence, WARN_ON_ONCE() will be triggered from blkdev_get_by_dev()
> if user scan partitions with device opened exclusively.
>
> Fix this problem by removing 'FMODE_EXCL' from disk_scan_partitions(),
> as it used to be.
>
> Reported-by: [email protected]
> Link: https://syzkaller.appspot.com/bug?extid=00cd27751f78817f167b
> Fixes: 2736e8eeb0cc ("block: use the holder as indication for exclusive opens")
> Signed-off-by: Yu Kuai <[email protected]>
> ---

Looks good to me,
Reviewed-by: Christian Brauner <[email protected]>

2023-06-20 13:39:07

by Jens Axboe

Subject: Re: [PATCH -next v2] block: fix wrong mode for blkdev_get_by_dev() from disk_scan_partitions()

On Sun, 18 Jun 2023 22:04:02 +0800, Yu Kuai wrote:
> After commit 2736e8eeb0cc ("block: use the holder as indication for
> exclusive opens"), blkdev_get_by_dev() will warn if holder is NULL and
> mode contains 'FMODE_EXCL'.
>
> holder from blkdev_get_by_dev() from disk_scan_partitions() is always NULL,
> hence it should not use 'FMODE_EXCL', which is broben by the commit. For
> consequence, WARN_ON_ONCE() will be triggered from blkdev_get_by_dev()
> if user scan partitions with device opened exclusively.
>
> [...]

Applied, thanks!

[1/1] block: fix wrong mode for blkdev_get_by_dev() from disk_scan_partitions()
commit: 985958b8584cc143555f1bd735e7ab5066c944a7

Best regards,
--
Jens Axboe