Messages in this thread | | | Date | Thu, 17 Mar 2022 21:05:11 +0800 | Subject | Re: [PATCH -next] nbd: fix possible overflow on 'first_minor' in nbd_dev_add() | From | "zhangwensheng (E)" <> |
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friendly ping...
在 2022/3/11 10:43, zhangwensheng (E) 写道: > friendly ping... > > 在 2022/3/10 17:32, Zhang Wensheng 写道: >> 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 <zhangwensheng5@huawei.com> >> --- >> drivers/block/nbd.c | 24 ++++++++++++------------ >> 1 file changed, 12 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c >> index 5a1f98494ddd..b3cdfc0ffb98 100644 >> --- a/drivers/block/nbd.c >> +++ b/drivers/block/nbd.c >> @@ -1800,17 +1800,6 @@ 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; >> @@ -1915,8 +1904,19 @@ 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; > .
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