block: Fix potential overflow in blk_report_zones()

For large values of the number of zones reported and/or large zone
sizes, the sector increment calculated with

blk_queue_zone_sectors(q) * n

in blk_report_zones() loop can overflow the unsigned int type used for
the calculation as both "n" and blk_queue_zone_sectors() value are
unsigned int. E.g. for a device with 256 MB zones (524288 sectors),
overflow happens with 8192 or more zones reported.

Changing the return type of blk_queue_zone_sectors() to sector_t, fixes
this problem and avoids overflow problem for all other callers of this
helper too. The same change is also applied to the bdev_zone_sectors()
helper.

Fixes: e76239a3748c ("block: add a report_zones method")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 1 insertions, 1 deletions

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index ae7e91bd0618..3249738242b4 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -70,7 +70,7 @@ EXPORT_SYMBOL_GPL(__blk_req_zone_write_unlock);
 static inline unsigned int __blkdev_nr_zones(struct request_queue *q,
 					     sector_t nr_sectors)
 {
-	unsigned long zone_sectors = blk_queue_zone_sectors(q);
+	sector_t zone_sectors = blk_queue_zone_sectors(q);
 
 	return (nr_sectors + zone_sectors - 1) >> ilog2(zone_sectors);
 }