[PATCH] nvmet: fixup buffer overrun in nvmet_subsys_attr_serial()

[Hannes Reinecke]

On 9/1/21 2:22 PM, Christoph Hellwig wrote:
> On Fri, Aug 27, 2021 at 06:26:36PM +0200, Christoph Hellwig wrote:
>> On Fri, Aug 27, 2021 at 11:29:26AM +0200, Hannes Reinecke wrote:
>>> The serial number is copied into the buffer via memcpy_and_pad()
>>> with the length NVMET_SN_MAX_SIZE. So when printing out we also
>>> need to take just that length as anything beyond that will be
>>> uninitialized.
>>>
>>> Signed-off-by: Hannes Reinecke <hare at suse.de>
>>
>> The normal way to print a potentially unterminated fixed length string
>> would be something like:
> 
> Does this version still look ok to you?
> 
>>
>> diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
>> index f74485c705ff2..d784f3c200b4c 100644
>> --- a/drivers/nvme/target/configfs.c
>> +++ b/drivers/nvme/target/configfs.c
>> @@ -1067,7 +1067,8 @@ static ssize_t nvmet_subsys_attr_serial_show(struct config_item *item,
>>   {
>>   	struct nvmet_subsys *subsys = to_subsys(item);
>>   
>> -	return snprintf(page, PAGE_SIZE, "%s\n", subsys->serial);
>> +	return snprintf(page, PAGE_SIZE, "%*s\n",
>> +			NVMET_SN_MAX_SIZE, subsys->serial);
>>   }
>>   
>>   static ssize_t
> ---end quoted text---
> 
Yes, it does; will be sending an updated patch.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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