linux-kernel - Re: [PATCH] block: move capacity validation to blkpg_do

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Date: Tue, 5 Mar 2024 16:00:07 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Li Lingfeng <lilingfeng@...weicloud.com>, axboe@...nel.dk,
 min15.li@...sung.com
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, hch@....de,
 yangerkun@...wei.com, yukuai1@...weicloud.com, houtao1@...wei.com,
 yi.zhang@...wei.com
Subject: Re: [PATCH] block: move capacity validation to blkpg_do_ioctl()

On 3/5/24 15:24, Li Lingfeng wrote:
> 
> 在 2024/3/5 12:30, Damien Le Moal 写道:
>> On 3/5/24 12:21, Li Lingfeng wrote:
>>> From: Li Lingfeng <lilingfeng3@...wei.com>
>>>
>>> Commit 6d4e80db4ebe ("block: add capacity validation in
>>> bdev_add_partition()") add check of partition's start and end sectors to
>>> prevent exceeding the size of the disk when adding partitions. However,
>>> there is still no check for resizing partitions now.
>>> Move the check to blkpg_do_ioctl() to cover resizing partitions.
>>>
>>> Signed-off-by: Li Lingfeng <lilingfeng3@...wei.com>
>>> ---
>>>   block/ioctl.c           |  9 ++++++++-
>>>   block/partitions/core.c | 11 -----------
>>>   2 files changed, 8 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/block/ioctl.c b/block/ioctl.c
>>> index 438f79c564cf..de0cc0d215c6 100644
>>> --- a/block/ioctl.c
>>> +++ b/block/ioctl.c
>>> @@ -18,7 +18,7 @@ static int blkpg_do_ioctl(struct block_device *bdev,
>>>   {
>>>       struct gendisk *disk = bdev->bd_disk;
>>>       struct blkpg_partition p;
>>> -    sector_t start, length;
>>> +    sector_t start, length, capacity, end;
>>>         if (!capable(CAP_SYS_ADMIN))
>>>           return -EACCES;
>>> @@ -41,6 +41,13 @@ static int blkpg_do_ioctl(struct block_device *bdev,
>>>         start = p.start >> SECTOR_SHIFT;
>>>       length = p.length >> SECTOR_SHIFT;
>>> +    capacity = get_capacity(disk);
>>> +
>>> +    if (check_add_overflow(start, length, &end))
>>> +        return -EINVAL;
>>> +
>>> +    if (start >= capacity || end > capacity)
>>> +        return -EINVAL;
>>>         switch (op) {
>>>       case BLKPG_ADD_PARTITION:
>>> diff --git a/block/partitions/core.c b/block/partitions/core.c
>>> index 5f5ed5c75f04..b11e88c82c8c 100644
>>> --- a/block/partitions/core.c
>>> +++ b/block/partitions/core.c
>>> @@ -419,21 +419,10 @@ static bool partition_overlaps(struct gendisk *disk,
>>> sector_t start,
>>>   int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
>>>           sector_t length)
>>>   {
>>> -    sector_t capacity = get_capacity(disk), end;
>>>       struct block_device *part;
>>>       int ret;
>>>         mutex_lock(&disk->open_mutex);
>>> -    if (check_add_overflow(start, length, &end)) {
>>> -        ret = -EINVAL;
>>> -        goto out;
>>> -    }
>>> -
>>> -    if (start >= capacity || end > capacity) {
>>> -        ret = -EINVAL;
>>> -        goto out;
>>> -    }
>>> -
>> Why do you remove this ? The check will not be done when *existing* partitions
> I'm sorry, I didn't quite understand your point. The function
> bdev_add_partition() is only called within blkpg_do_ioctl(). I simply moved the
> check to a different location, but did not remove it entirely.

Oh ! My bad ! I got confused with blk_add_partition() which is the function
adding partitions when a new disk is scanned. So yes, your patch is fine. My
apologies for the noise.

>> are added. To do the check when *creating* a partition, make this code a helper
>> and call that helper function here and from blkpg_do_ioctl() as well.
> Do you mean call the helper function in blk_add_partition() and blkpg_do_ioctl()?
>>
>>>       if (!disk_live(disk)) {
>>>           ret = -ENXIO;
>>>           goto out;
> 
> 

-- 
Damien Le Moal
Western Digital Research