From: Yu Kuai <yukuai3@huawei.com>
Date: Tue, 2 Nov 2021 01:52:35 +0000 (+0800)
Subject: nbd: fix possible overflow for 'first_minor' in nbd_dev_add()
X-Git-Tag: accepted/tizen/unified/20230118.172025~5306
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e99270d7f2731f532831923b9dd35b7be79158fe;p=platform%2Fkernel%2Flinux-rpi.git

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

[ Upstream commit 940c264984fd1457918393c49674f6b39ee16506 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 0d820c4..577c7db 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1749,11 +1749,11 @@ 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;
 	}