Re: [PATCH v2 10/9] xfs: don't accept inode buffers with suspicious unlinked chains

[Brian Foster <bfoster@redhat.com>]

On Wed, Mar 21, 2018 at 11:08:22PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> When we're verifying inode buffers, sanity-check the unlinked pointer.
> We don't want to run the risk of trying to purge something that's
> obviously broken.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: fix merge problems, hopefully; this accidentally landed in the wrong
> place in my patch stack
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_inode_buf.c |   10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> index cdd4c1d..f0cfcd79 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.c
> +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> @@ -93,20 +93,26 @@ xfs_inode_buf_verify(
>  	bool		readahead)
>  {
>  	struct xfs_mount *mp = bp->b_target->bt_mount;
> +	xfs_agnumber_t	agno;
>  	int		i;
>  	int		ni;
>  
>  	/*
>  	 * Validate the magic number and version of every inode in the buffer
>  	 */
> +	agno = xfs_daddr_to_agno(mp, XFS_BUF_ADDR(bp));
>  	ni = XFS_BB_TO_FSB(mp, bp->b_length) * mp->m_sb.sb_inopblock;
>  	for (i = 0; i < ni; i++) {
>  		int		di_ok;
>  		xfs_dinode_t	*dip;
> +		xfs_agino_t	unlinked_ino;
>  
>  		dip = xfs_buf_offset(bp, (i << mp->m_sb.sb_inodelog));
> +		unlinked_ino = be32_to_cpu(dip->di_next_unlinked);
>  		di_ok = dip->di_magic == cpu_to_be16(XFS_DINODE_MAGIC) &&
> -			xfs_dinode_good_version(mp, dip->di_version);
> +			xfs_dinode_good_version(mp, dip->di_version) &&
> +			(unlinked_ino == NULLAGINO ||
> +			 xfs_verify_agino(mp, agno, unlinked_ino));
>  		if (unlikely(XFS_TEST_ERROR(!di_ok, mp,
>  						XFS_ERRTAG_ITOBP_INOTOBP))) {
>  			if (readahead) {
> @@ -124,9 +130,9 @@ xfs_inode_buf_verify(
>  			xfs_buf_verifier_error(bp, -EFSCORRUPTED,
>  					__func__, dip, sizeof(*dip),
>  					NULL);
> +			return;
>  		}
>  	}
> -	xfs_inobp_check(mp, bp);
>  }
>  
>  
> --
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