[PATCH] xfs: sanitize sb_inopblock in xfs_mount_validate_sb

[Jeff Liu]

On 01/29 2014 12:28 AM, Eric Sandeen wrote:
> xfs_mount_validate_sb doesn't check sb_inopblock for sanity
> (as does its xfs_repair counterpart, FWIW).
> 
> If it's out of bounds, we can go off the rails in i.e.
> xfs_inode_buf_verify(), which uses sb_inopblock as a loop
> limit when stepping through a metadata buffer.
> 
> The problem can be demonstrated easily by corrupting
> sb_inopblock with xfs_db and trying to mount the result:
> 
> # mkfs.xfs -dfile,name=fsfile,size=1g
> # xfs_db -x fsfile 
> xfs_db> sb 0
> xfs_db> write inopblock 512
> inopblock = 512
> xfs_db> quit
> 
> # mount -o loop fsfile  mnt
> and we blow up in xfs_inode_buf_verify().
> 
> With this patch, we get a (very noisy) corruption error,
> and fail the mount as we should.
> 
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>
> ---
> 
> diff --git a/fs/xfs/xfs_sb.c b/fs/xfs/xfs_sb.c
> index b7c9aea..511cce9 100644
> --- a/fs/xfs/xfs_sb.c
> +++ b/fs/xfs/xfs_sb.c
> @@ -288,6 +288,7 @@ xfs_mount_validate_sb(
>  	    sbp->sb_inodelog < XFS_DINODE_MIN_LOG			||
>  	    sbp->sb_inodelog > XFS_DINODE_MAX_LOG			||
>  	    sbp->sb_inodesize != (1 << sbp->sb_inodelog)		||
> +	    sbp->sb_inopblock != howmany(sbp->sb_blocksize,sbp->sb_inodesize) ||
>  	    (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)	||
>  	    (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)	||
>  	    (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)	||

Looks good to me.

Reviewed-by: Jie Liu <jeff.liu at oracle.com>


Thanks,
-Jeff