Re: [PATCH] null_blk: fix validation of block size

From: Damien Le Moal
Date: Sun Jun 02 2024 - 19:59:21 EST


On 6/2/24 19:57, John Garry wrote:
> On 01/06/2024 21:23, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
>>
>> Block size should be between 512
>
>
>> and 4096
>
> Or PAGE_SIZE?

PAGE_SIZE can be larger than 4096. But most drives are 512 or 4096 LBA-sized.

>
> and be a power of 2. The current
>> check does not validate this, so update the check.
>>
>> Without this patch, null_blk would Oops due to a null pointer deref when
>> loaded with bs=1536 [1].
>>
>> Link: https://urldefense.com/v3/__https://lore.kernel.org/all/87wmn8mocd.fsf@xxxxxxxxxxxx/__;!!ACWV5N9M2RV99hQ!OWXI3DGxeIAWvKfM5oVSiA5fTWmiRvUctIdVrcBcKnO_HF-vgkarVfd27jkvQ1-JjNgX5IFIvBWcsUttvg$
>>
>> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
>> ---
>> drivers/block/null_blk/main.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
>> index eb023d267369..6a26888c52bb 100644
>> --- a/drivers/block/null_blk/main.c
>> +++ b/drivers/block/null_blk/main.c
>> @@ -1823,8 +1823,10 @@ static int null_validate_conf(struct nullb_device *dev)
>> dev->queue_mode = NULL_Q_MQ;
>> }
>>
>> - dev->blocksize = round_down(dev->blocksize, 512);
>> - dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
>> + if ((dev->blocksize < 512 || dev->blocksize > 4096) ||
>> + ((dev->blocksize & (dev->blocksize - 1)) != 0)) {
>> + return -EINVAL;
>> + }
>
> Looks like blk_validate_block_size(), modulo PAGE_SIZE check

Not PAGE_SIZE...

>
>>
>> if (dev->use_per_node_hctx) {
>> if (dev->submit_queues != nr_online_nodes)
>>
>> base-commit: 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0
>
>

--
Damien Le Moal
Western Digital Research