Re: [PATCH 1/8] xfs: check leaf attribute block freemap in verifier

[Brian Foster <bfoster@redhat.com>]

On Wed, Jul 18, 2018 at 08:50:34AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Check the leaf attribute freemap when we we're verifying the block.
> 

s/we//

> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_attr_leaf.c |   18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index 76e90046731c..b3c19339e1b5 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -244,6 +244,8 @@ xfs_attr3_leaf_verify(
>  	struct xfs_attr_leafblock	*leaf = bp->b_addr;
>  	struct xfs_perag		*pag = bp->b_pag;
>  	struct xfs_attr_leaf_entry	*entries;
> +	uint16_t			end;
> +	int				i;
>  
>  	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
>  
> @@ -289,6 +291,22 @@ xfs_attr3_leaf_verify(
>  	/* XXX: need to range check rest of attr header values */
>  	/* XXX: hash order check? */
>  
> +	for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
> +		if (ichdr.freemap[i].base > mp->m_attr_geo->blksize)
> +			return __this_address;
> +		if (ichdr.freemap[i].base & 0x3)
> +			return __this_address;

Same question as Carlos.. can you elaborate on the 0x3 magic number? (A
one-liner comment might be useful).

Brian

> +		if (ichdr.freemap[i].size > mp->m_attr_geo->blksize)
> +			return __this_address;
> +		if (ichdr.freemap[i].size & 0x3)
> +			return __this_address;
> +		end = ichdr.freemap[i].base + ichdr.freemap[i].size;
> +		if (end < ichdr.freemap[i].base)
> +			return __this_address;
> +		if (end > mp->m_attr_geo->blksize)
> +			return __this_address;
> +	}
> +
>  	return NULL;
>  }
>  
> 
> --
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