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

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commit 858f1bf65d 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: b0d9111a2d ("nbd: use an idr to keep track of nbd devices")
Fixes: 940c264984 ("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>
This commit is contained in:
Zhang Wensheng
2022-05-21 15:37:48 +08:00
committed by Greg Kroah-Hartman
parent 2e0c3e43eb
commit 4311ad1e76
1 changed files with 12 additions and 11 deletions
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23
drivers/block/nbd.c
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@@ -1771,17 +1771,7 @@ 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);
@@ -1875,8 +1865,19 @@ 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;