block: move capacity validation to blkpg_do_ioctl()

Commit 6d4e80d ("block: add capacity validation in
bdev_add_partition()") add check of partition's start and end sectors to
prevent exceeding the size of the disk when adding partitions. However,
there is still no check for resizing partitions now.
Move the check to blkpg_do_ioctl() to cover resizing partitions.

Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240305032132.548958-1-lilingfeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/ioctl.c

@@ -18,7 +18,7 @@ static int blkpg_do_ioctl(struct block_device *bdev,
 {
 	struct gendisk *disk = bdev->bd_disk;
 	struct blkpg_partition p;
-	sector_t start, length;
+	sector_t start, length, capacity, end;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
@@ -41,6 +41,13 @@ static int blkpg_do_ioctl(struct block_device *bdev,
 
 	start = p.start >> SECTOR_SHIFT;
 	length = p.length >> SECTOR_SHIFT;
+	capacity = get_capacity(disk);
+
+	if (check_add_overflow(start, length, &end))
+		return -EINVAL;
+
+	if (start >= capacity || end > capacity)
+		return -EINVAL;
 
 	switch (op) {
 	case BLKPG_ADD_PARTITION:

block/partitions/core.c

@@ -419,21 +419,10 @@ static bool partition_overlaps(struct gendisk *disk, sector_t start,
 int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
 		sector_t length)
 {
-	sector_t capacity = get_capacity(disk), end;
 	struct block_device *part;
 	int ret;
 
 	mutex_lock(&disk->open_mutex);
-	if (check_add_overflow(start, length, &end)) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	if (start >= capacity || end > capacity) {
-		ret = -EINVAL;
-		goto out;
-	}
-
 	if (!disk_live(disk)) {
 		ret = -ENXIO;
 		goto out;