On 2021/01/06 21:55, Pavel Machek wrote: > 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. Indeed. > > >> + 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? Yes, we can change to this to be more readable. Will send a cleanup patch. Thanks ! > > Best regards, > Pavel > -- Damien Le Moal Western Digital Research
