Re: [PATCH 2/3] xfs: validity check agbnos on the AGFL

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, May 29, 2023 at 10:08:24AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> If the agfl or the indexing in the AGF has been corrupted, getting a
> block form the AGFL could return an invalid block number. If this
> happens, bad things happen. Check the agbno we pull off the AGFL
> and return -EFSCORRUPTED if we find somethign bad.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>

This looks like a good addition to me,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_alloc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index fd3293a8c659..643d17877832 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2780,6 +2780,9 @@ xfs_alloc_get_freelist(
>  	 */
>  	agfl_bno = xfs_buf_to_agfl_bno(agflbp);
>  	bno = be32_to_cpu(agfl_bno[be32_to_cpu(agf->agf_flfirst)]);
> +	if (XFS_IS_CORRUPT(tp->t_mountp, !xfs_verify_agbno(pag, bno)))
> +		return -EFSCORRUPTED;
> +
>  	be32_add_cpu(&agf->agf_flfirst, 1);
>  	xfs_trans_brelse(tp, agflbp);
>  	if (be32_to_cpu(agf->agf_flfirst) == xfs_agfl_size(mp))
> -- 
> 2.40.1
>