linux-kernel - [PATCH -next v4 2/4] nbd: fix possible overflow for 'first_minor' in nbd_dev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 2 Nov 2021 09:52:35 +0800
From:   Ye Bin <yebin10@...wei.com>
To:     <josef@...icpanda.com>, <axboe@...nel.dk>,
        <linux-block@...r.kernel.org>, <nbd@...er.debian.org>
CC:     <linux-kernel@...r.kernel.org>, Yu Kuai <yukuai3@...wei.com>
Subject: [PATCH -next v4 2/4] nbd: fix possible overflow for 'first_minor' in nbd_dev_add()

From: Yu Kuai <yukuai3@...wei.com>

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@...wei.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 678ee2688f63..cc32b5bc0f49 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1803,11 +1803,11 @@ 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;
 	}
-- 
2.31.1