Hi! > 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.
> --- a/drivers/block/null_blk_zoned.c
> +++ b/drivers/block/null_blk_zoned.c
> @@ -1,9 +1,9 @@
> // SPDX-License-Identifier: GPL-2.0
> #include <linux/vmalloc.h>
> +#include <linux/sizes.h>
> #include "null_blk.h"
>
> -/* zone_size in MBs to sectors. */
> -#define ZONE_SIZE_SHIFT 11
> +#define MB_TO_SECTS(mb) (((sector_t)mb * SZ_1M) >> SECTOR_SHIFT)
This macro is quite dangerous. (mb) would help, but inline function
would be better.
> + dev->nr_zones = dev_capacity_sects >> ilog2(dev->zone_size_sects);
> + if (dev_capacity_sects & (dev->zone_size_sects - 1))
> + dev->nr_zones++;
Is this same as nr_zones = DIV_ROUND_UP(dev_capacity_sects,
dev->zone_size_sects)? Would that be faster, more readable and robust
against weird dev->zone_size_sects sizes?
Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek
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