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

[Christoph Hellwig]

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
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