block: fix integer overflow in __blkdev_sectors_to_bio_pages()

Fix possible integer overflow in __blkdev_sectors_to_bio_pages if sector_t is 32-bit. Signed-off-by: Mikulas Patocka <[email protected]> Fixes: 615d22a ("block: Fix __blkdev_issue_zeroout loop") Reviewed-by: Damien Le Moal <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
chewitt · Sep 11, 2017 · 09c2c35 · 09c2c35
1 parent dbec491
commit 09c2c35
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/block/blk-lib.c b/block/blk-lib.c
@@ -269,9 +269,9 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
  */
 static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
 {
-	sector_t bytes = (nr_sects << 9) + PAGE_SIZE - 1;
+	sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
 
-	return min(bytes >> PAGE_SHIFT, (sector_t)BIO_MAX_PAGES);
+	return min(pages, (sector_t)BIO_MAX_PAGES);
 }
 
 /**