Re: [PATCH] null_blk: Fix zone size initialization

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Jan 04, 2021 at 09:11:47PM +0900, Damien Le Moal wrote:
> commit 0ebcdd702f49aeb0ad2e2d894f8c124a0acc6e23 upstream.
> 
> For a null_blk device with zoned mode enabled is currently initialized
> with a number of zones equal to the device capacity divided by the zone
> size, without considering if the device capacity is a multiple of the
> zone size. If the zone size is not a divisor of the capacity, the zones
> end up not covering the entire capacity, potentially resulting is out
> of bounds accesses to the zone array.
> 
> Fix this by adding one last smaller zone with a size equal to the
> remainder of the disk capacity divided by the zone size if the capacity
> is not a multiple of the zone size. For such smaller last zone, the zone
> capacity is also checked so that it does not exceed the smaller zone
> size.
> 
> Reported-by: Naohiro Aota <naohiro.aota@wdc.com>
> Fixes: ca4b2a011948 ("null_blk: add zone support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  drivers/block/null_blk_zoned.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)

That worked, thanks!

greg k-h