From: Mikulas Patocka <mpatocka@redhat.com>
Date: Mon, 11 Sep 2017 15:46:49 +0000 (-0600)
Subject: block: fix integer overflow in __blkdev_sectors_to_bio_pages()
X-Git-Tag: v4.14-rc1~42^2~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=09c2c359be546df45be0b158ea1d3cc8ea83c876;p=platform%2Fkernel%2Flinux-exynos.git

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 <mpatocka@redhat.com>
Fixes: 615d22a51c04 ("block: Fix __blkdev_issue_zeroout loop")
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-lib.c b/block/blk-lib.c
index e01adb5..62240f8 100644
--- 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);
 }
 
 /**