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nbd: fix possible overflow for 'first_minor' in nbd_dev_add()

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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: b0d9111a2d ("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>
This commit is contained in:
Yu Kuai 2021-11-02 09:52:35 +08:00 committed by Jens Axboe
parent e4c4871a73
commit 940c264984
1 changed files with 3 additions and 3 deletions
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6
drivers/block/nbd.c
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@ -1808,11 +1808,11 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
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;
}