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

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

From: Daeho Jeong <daeho.je...@samsung.com>

commit 05ac5aa18abd7db341e54df4ae2b4c98ea0e43b7 upstream.

We've fixed the race condition problem in calculating ext4 checksum
value in commit b47820edd163 ("ext4: avoid modifying checksum fields
directly during checksum veficationon"). However, by this change,
when calculating the checksum value of inode whose i_extra_size is
less than 4, we couldn't calculate the checksum value in a proper way.
This problem was found and reported by Nix, Thank you.

Reported-by: Nix <n...@esperi.org.uk>
Signed-off-by: Daeho Jeong <daeho.je...@samsung.com>
Signed-off-by: Youngjin Gil <youngjin....@samsung.com>
Signed-off-by: Darrick J. Wong <darrick.w...@oracle.com>
Signed-off-by: Theodore Ts'o <ty...@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 fs/ext4/inode.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -71,10 +71,9 @@ static __u32 ext4_inode_csum(struct inod
                        csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
                                           csum_size);
                        offset += csum_size;
-                       csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
-                                          EXT4_INODE_SIZE(inode->i_sb) -
-                                          offset);
                }
+               csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
+                                  EXT4_INODE_SIZE(inode->i_sb) - offset);
        }
 
        return csum;


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