From 09c2c359be546df45be0b158ea1d3cc8ea83c876 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Mon, 11 Sep 2017 09:46:49 -0600
Subject: [PATCH] block: fix integer overflow in __blkdev_sectors_to_bio_pages()
Git-commit: 09c2c359be546df45be0b158ea1d3cc8ea83c876
Patch-mainline: v4.14-rc1
References: fate#322738,fate#322919,fate#322950,fate#323773

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>
Signed-off-by: Coly Li <colyli@suse.de>
---
 block/blk-lib.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index e01adb5145b3..62240f8832ca 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);
 }
 
 /**
-- 
2.13.5