btrfs: avoid overflow when sector_t is 32 bit

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@inwind.it>
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 0aff9b278c1990f55feb2693a9fff65d5bf693ed..4aa3d4c27dfea4a608d02e0e46e0ba7495e47783 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2799,7 +2799,7 @@ static int submit_extent_page(int op, int op_flags, 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;