[PATCH] btrfs: avoid overflow when sector_t is 32 bit

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From: Goffredo Baroncelli <kreijack@xxxxxxxxx>

Jean-Denis Girard noticed commit c821e7f3 "pass bytes to
btrfs_bio_alloc" (https://patchwork.kernel.org/patch/9763081/) introduces a
regression on 32 bit machines.
When CONFIG_LBDAF is _not_ defined (CONFIG_LBDAF == Support for large
(2TB+) block devices and files) sector_t is 32 bit on 32bit machines.

In the function submit_extent_page, 'sector' (which is sector_t type) is
multiplied by 512 to convert it from sectors to bytes, leading to an
overflow when the disk is bigger than 4GB (!).

I added a cast to u64 to avoid overflow.

Based on v4.14-rc3.


Signed-off-by: Goffredo Baroncelli <kreijack@xxxxxxxxx>
Tested-by: Jean-Denis Girard <jd.girard@xxxxxxxxx>

---
 fs/btrfs/extent_io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 12ab19a4b93e..970190cd347e 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2801,7 +2801,7 @@ static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
 		}
 	}
 
-	bio = btrfs_bio_alloc(bdev, sector << 9);
+	bio = btrfs_bio_alloc(bdev, (u64)sector << 9);
 	bio_add_page(bio, page, page_size, offset);
 	bio->bi_end_io = end_io_func;
 	bio->bi_private = tree;
-- 
2.14.2

--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5
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