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

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Jul 19, 2018 at 08:24:21AM -0400, Brian Foster wrote:
> 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//

Fixed.

> > 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).

/* Attribute data must be aligned to a multiple of four bytes. */

--D

> 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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