Commit 7198bfc2 authored by Jens Axboe's avatar Jens Axboe
Browse files

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

This reverts commit 6d35d04a.

Both Gabriel and Borislav report that this commit casues a regression
with nbd:

sysfs: cannot create duplicate filename '/dev/block/43:0'

Revert it before 5.18-rc1 and we'll investigage this separately in
due time.

Link: https://lore.kernel.org/all/YkiJTnFOt9bTv6A2@zn.tnic/


Reported-by: default avatarGabriel L. Somlo <somlo@cmu.edu>
Reported-by: default avatarBorislav Petkov <bp@alien8.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2651ee5a

drivers/block/nbd.c

+12 −12
Original line number Diff line number Diff line
@@ -1800,6 +1800,17 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs) 
	refcount_set(&nbd->refs, 0);

	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_work;

	}



	disk->minors = 1 << part_shift;

	disk->fops = &nbd_fops;

	disk->private_data = nbd;
@@ -1904,19 +1915,8 @@ 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;