block: Limit allocation of zone descriptors for report zones

damien-lemoal · axboe · commit 2e85fbaff3a7 · 2018-10-25T11:17:40.000-06:00
There is no point in allocating more zone descriptors than the number of
zones a block device has for doing a zone report. Avoid doing that in
blkdev_report_zones_ioctl() by limiting the number of zone decriptors
allocated internally to process the user request.

Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Hannes Reinecke &lt;hare@suse.com&gt;
Signed-off-by: Damien Le Moal &lt;damien.lemoal@wdc.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
diff --git a/block/blk-zoned.c b/block/blk-zoned.c
@@ -355,8 +355,7 @@ int blkdev_report_zones_ioctl(struct block_device *bdev, fmode_t mode,
 	if (!rep.nr_zones)
 		return -EINVAL;
 
-	if (rep.nr_zones > INT_MAX / sizeof(struct blk_zone))
-		return -ERANGE;
+	rep.nr_zones = min(blkdev_nr_zones(bdev), rep.nr_zones);
 
 	zones = kvmalloc_array(rep.nr_zones, sizeof(struct blk_zone),
 			       GFP_KERNEL | __GFP_ZERO);
