linux-kernel - [PATCH 4.13 137/160] btrfs: avoid overflow when sector

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Date:   Tue, 10 Oct 2017 21:51:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Goffredo Baroncelli <kreijack@...ind.it>,
        Jean-Denis Girard <jd.girard@...nux.pf>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 4.13 137/160] btrfs: avoid overflow when sector_t is 32 bit

4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Goffredo Baroncelli <kreijack@...ind.it>

commit 2d8ce70a08fe033c904115d59276ad86adeaa337 upstream.

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.

Fixes: c821e7f3 ("btrfs: pass bytes to btrfs_bio_alloc")
Signed-off-by: Goffredo Baroncelli <kreijack@...ind.it>
Tested-by: Jean-Denis Girard <jd.girard@...nux.pf>
Reviewed-by: David Sterba <dsterba@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2799,7 +2799,7 @@ static int submit_extent_page(int op, in
 		}
 	}

-	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;