在 2023/10/30 17:26, Yu Kuai 写道:
Hi,
在 2023/10/26 16:52, zhongjinghua 写道:
在 2023/10/25 18:06, Tetsuo Handa 写道:
On 2023/10/25 17:46, Zhong Jinghua wrote:
Checks added in patch:
commit e338924bd05d ("block: check minor range in device_add_disk()")
ignore the problem of first_minore < 0 and disk->minors < 0.
What is the problem of first_minor < 0 or disk->minors < 0 ?
Are negative values legal/illegal ?
These two values are used as the secondary device number and the
maximum number of partitions, which is illegal if negative. Then
first_minore and disk->minors are signed numbers, and the sum may be
less than MINORMASK to bypass the check.
Let me complement it, first_minor and minors can be set by driver, and
driver allow set them throuhh ioctl/sysfs from user parameters, for
example:
If user pass in -1, and each disk support 8 partitions, driver will
usually set:
disk->first_minor = -1 * 8 = -8;
disk->minors = 8;
Then first_minor + minors = 0, then the following condition can't detect
this case:
if (disk->first_minor + disk->minors > MINORMASK + 1)
By the way, we never limit how first_minor and minors is set by driver,
and it's illegal if driver set first_minor = -4, and minors = 8.
Thanks,
Kuai
.
Kuai, Thank for your explanation.
Jinghua
