From 858f1bf65d3d9c00b5e2d8ca87dc79ed88267c98 Mon Sep 17 00:00:00 2001 From: Zhang Wensheng Date: Sat, 21 May 2022 15:37:48 +0800 Subject: [PATCH] nbd: fix possible overflow on 'first_minor' in nbd_dev_add() 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: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices") Fixes: 940c264984fd ("nbd: fix possible overflow for 'first_minor' in nbd_dev_add()") Signed-off-by: Zhang Wensheng Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20220521073749.3146892-6-yukuai3@huawei.com Signed-off-by: Jens Axboe --- drivers/block/nbd.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index ec736cc52134..349bc3da878d 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1814,17 +1814,7 @@ 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; @@ -1929,8 +1919,19 @@ 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; -- 2.25.1