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

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This reverts commit 6d35d04a9e.

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: Gabriel L. Somlo <somlo@cmu.edu>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-04-02 11:40:23 -06:00
parent 2651ee5ae4
commit 7198bfc201
1 changed files with 12 additions and 12 deletions
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24
drivers/block/nbd.c
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@ -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;