[PATCH] null_blk: fix validation of block size

[PATCH] null_blk: fix validation of block size

[Andreas Hindborg]

From: Andreas Hindborg <a.hindborg@samsung.com>

Block size should be between 512 and 4096 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://lore.kernel.org/all/87wmn8mocd.fsf@metaspace.dk/

Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
---
 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;
+	}
 
 	if (dev->use_per_node_hctx) {
 		if (dev->submit_queues != nr_online_nodes)

base-commit: 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0
-- 
2.45.1

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

[John Garry]

On 01/06/2024 21:23, Andreas Hindborg wrote:
> From: Andreas Hindborg <a.hindborg@samsung.com>
> 
> Block size should be between 512


>and 4096

Or PAGE_SIZE?

  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@metaspace.dk/__;!!ACWV5N9M2RV99hQ!OWXI3DGxeIAWvKfM5oVSiA5fTWmiRvUctIdVrcBcKnO_HF-vgkarVfd27jkvQ1-JjNgX5IFIvBWcsUttvg$
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
> ---
>   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

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

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

[Damien Le Moal]

On 6/2/24 19:57, John Garry wrote:
> On 01/06/2024 21:23, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@samsung.com>
>>
>> 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@metaspace.dk/__;!!ACWV5N9M2RV99hQ!OWXI3DGxeIAWvKfM5oVSiA5fTWmiRvUctIdVrcBcKnO_HF-vgkarVfd27jkvQ1-JjNgX5IFIvBWcsUttvg$
>>
>> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
>> ---
>>   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

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

[Andreas Hindborg]

John Garry <john.g.garry@oracle.com> writes:

> On 01/06/2024 21:23, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@samsung.com>
>> Block size should be between 512
>
>
>>and 4096
>
> Or PAGE_SIZE?

Right 👍

>
>  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@metaspace.dk/__;!!ACWV5N9M2RV99hQ!OWXI3DGxeIAWvKfM5oVSiA5fTWmiRvUctIdVrcBcKnO_HF-vgkarVfd27jkvQ1-JjNgX5IFIvBWcsUttvg$
>> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
>> ---
>>   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

Cool, I will use that instead.


BR Andreas

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

[John Garry]

On 03/06/2024 00:59, Damien Le Moal wrote:
> On 6/2/24 19:57, John Garry wrote:
>> On 01/06/2024 21:23, Andreas Hindborg wrote:
>>> From: Andreas Hindborg<a.hindborg@samsung.com>
>>>
>>> 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.

Sure, but maybe someone wants larger than 4096, like the LBS support.

Having said that, is there LBS support for nullb? I don't think so. I 
assume that PAGE_SIZE or 4096 limit would need to go for that.

Cheers,
John

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

[Bart Van Assche]

On 6/1/24 13:23, Andreas Hindborg wrote:
> +	    ((dev->blocksize & (dev->blocksize - 1)) != 0)) {

Please use is_power_of_2() instead of open-coding it.

Bart.

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

[Bart Van Assche]

On 6/2/24 16:59, Damien Le Moal wrote:
> On 6/2/24 19:57, John Garry wrote:
>> On 01/06/2024 21:23, Andreas Hindborg wrote:
>>> From: Andreas Hindborg <a.hindborg@samsung.com>
>>>
>>> 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.

null_blk is not a physical device. Hence, why not to use 
blk_validate_block_size() here?

Thanks,

Bart.