From: Yu Kuai yukuai3@huawei.com

commit 940c264984fd1457918393c49674f6b39ee16506 upstream.

If 'part_shift' is not zero, then 'index << part_shift' might overflow to a value that is not greater than '0xfffff', then sysfs might complains about duplicate creation.

Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices") Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: Josef Bacik josef@toxicpanda.com Link: https://lore.kernel.org/r/20211102015237.2309763-3-yebin10@huawei.com Signed-off-by: Jens Axboe axboe@kernel.dk Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Wen Yang wenyang.linux@foxmail.com --- drivers/block/nbd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index bd05eaf04143..1ddae8f768d5 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1773,11 +1773,11 @@ static int nbd_dev_add(int index) disk->major = NBD_MAJOR;

/* Too big first_minor can cause duplicate creation of - * sysfs files/links, since MKDEV() expect that the max bits of - * first_minor is 20. + * sysfs files/links, since index << part_shift might overflow, or + * MKDEV() expect that the max bits of first_minor is 20. */ disk->first_minor = index << part_shift; - if (disk->first_minor > MINORMASK) { + if (disk->first_minor < index || disk->first_minor > MINORMASK) { err = -EINVAL; goto out_free_idr; }