Commit 903d0f49 authored Nov 08, 2023 by Zhang Wensheng Committed by Li Nan Nov 07, 2023

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

stable inclusion
from stable-v5.10.170
commit 4311ad1e7654f9dd569a4d1b0059f838f474e9d3
category: bugfix
bugzilla: 188217

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4311ad1e7654f9dd569a4d1b0059f838f474e9d3



----------------------------------------

commit 858f1bf6 upstream.

When 'index' is a big numbers, it may become negative which forced
to 'int'. then 'index << part_shift' might overflow to a positive
value that is not greater than '0xfffff', then sysfs might complains
about duplicate creation. Because of this, move the 'index' judgment
to the front will fix it and be better.

Fixes: b0d9111a ("nbd: use an idr to keep track of nbd devices")
Fixes: 940c2649 ("nbd: fix possible overflow for 'first_minor' in nbd_dev_add()")
Signed-off-by: Zhang Wensheng <zhangwensheng5@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20220521073749.3146892-6-yukuai3@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Wen Yang <wenyang.linux@foxmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Signed-off-by: Li Nan <linan122@huawei.com>

parent 16699a73

drivers/block/nbd.c

+12 −11

Original line number	Diff line number	Diff line
		@@ -1875,17 +1875,7 @@ static int nbd_dev_add(int index)
		refcount_set(&nbd->refs, 1);
		INIT_LIST_HEAD(&nbd->list);
		disk->major = NBD_MAJOR;

		/* Too big first_minor can cause duplicate creation of
		* 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 < index \|\| disk->first_minor > MINORMASK) {
		err = -EINVAL;
		goto out_free_idr;
		}

		disk->fops = &nbd_fops;
		disk->private_data = nbd;
		sprintf(disk->disk_name, "nbd%d", index);
		@@ -1972,8 +1962,19 @@ static int nbd_genl_connect(struct sk_buff skb, struct genl_info info)
		if (!netlink_capable(skb, CAP_SYS_ADMIN))
		return -EPERM;

		if (info->attrs[NBD_ATTR_INDEX])
		if (info->attrs[NBD_ATTR_INDEX]) {
		index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);

		/*
		* Too big first_minor can cause duplicate creation of
		* sysfs files/links, since index << part_shift might overflow, or
		* MKDEV() expect that the max bits of first_minor is 20.
		*/
		if (index < 0 \|\| index > MINORMASK >> part_shift) {
		printk(KERN_ERR "nbd: illegal input index %d\n", index);
		return -EINVAL;
		}
		}
		if (!info->attrs[NBD_ATTR_SOCKETS]) {
		printk(KERN_ERR "nbd: must specify at least one socket\n");
		return -EINVAL;