[PATCH 4.14 22/30] dm-verity: align struct dm_verity_fec_io properly

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Mikulas Patocka <mpatocka@redhat.com>

commit 38bc1ab135db87577695816b190e7d6d8ec75879 upstream.

dm_verity_fec_io is placed after the end of two hash digests. If the hash
digest has unaligned length, struct dm_verity_fec_io could be unaligned.

This commit fixes the placement of struct dm_verity_fec_io, so that it's
aligned.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Fixes: a739ff3f543a ("dm verity: add support for forward error correction")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/md/dm-verity-fec.c |    3 ++-
 drivers/md/dm-verity.h     |    6 ------
 2 files changed, 2 insertions(+), 7 deletions(-)

--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -28,7 +28,8 @@ bool verity_fec_is_enabled(struct dm_ver
  */
 static inline struct dm_verity_fec_io *fec_io(struct dm_verity_io *io)
 {
-	return (struct dm_verity_fec_io *) verity_io_digest_end(io->v, io);
+	return (struct dm_verity_fec_io *)
+		((char *)io + io->v->ti->per_io_data_size - sizeof(struct dm_verity_fec_io));
 }
 
 /*
--- a/drivers/md/dm-verity.h
+++ b/drivers/md/dm-verity.h
@@ -113,12 +113,6 @@ static inline u8 *verity_io_want_digest(
 	return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
 }
 
-static inline u8 *verity_io_digest_end(struct dm_verity *v,
-				       struct dm_verity_io *io)
-{
-	return verity_io_want_digest(v, io) + v->digest_size;
-}
-
 extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 			       struct bvec_iter *iter,
 			       int (*process)(struct dm_verity *v,