Re: [PATCH 10/12] xfs: check for buffer overruns when examining local/remote xattr entries

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

On Thu, Oct 08, 2026 at 05:03:38AM -0700, Christoph Hellwig wrote:
> On Wed, Oct 07, 2026 at 10:57:26PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > LOLLM noticed that the xattr scrub and repair code can walk off the end
> > of the buffer if the xattr entry record starts so close to the end of
> > the buffer that there's not even space for the entry structure itself.
> > Strengthen the bounds checking here.
> > 
> > Cc: <stable@vger.kernel.org> # v4.15
> > Fixes: 13791d3b833428 ("xfs: scrub extended attribute leaf space")
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > Assisted-by: LOLLM # finding obvious bugs
> > ---
> >  fs/xfs/scrub/attr.c        |   12 ++++++++++++
> >  fs/xfs/scrub/attr_repair.c |   16 ++++++++++++++--
> >  2 files changed, 26 insertions(+), 2 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
> > index 842d65834afbc9..4ce7299060fbba 100644
> > --- a/fs/xfs/scrub/attr.c
> > +++ b/fs/xfs/scrub/attr.c
> > @@ -335,6 +335,12 @@ xchk_xattr_entry(
> >  	/* Check the name information. */
> >  	if (ent->flags & XFS_ATTR_LOCAL) {
> >  		lentry = xfs_attr3_leaf_name_local(leaf, idx);
> > +		name_end = (char *)lentry +
> > +				offsetof(struct xfs_attr_leaf_name_local, nameval[0]);
> 
> Overly long line.
> 
> > +		if (name_end > buf_end) {
> > +			xchk_da_set_corrupt(ds, level);
> > +			return;
> > +		}
> >  		namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
> >  				be16_to_cpu(lentry->valuelen));
> >  		name_end = (char *)lentry + namesize;
> > @@ -342,6 +348,12 @@ xchk_xattr_entry(
> >  			xchk_da_set_corrupt(ds, level);
> >  	} else {
> >  		rentry = xfs_attr3_leaf_name_remote(leaf, idx);
> > +		name_end = (char *)rentry +
> > +				offsetof(struct xfs_attr_leaf_name_remote, name[0]);
> 
> Same here.
> 
> Can you split the local vs remote code into separate helpers as
> that would really help with readability here?

Will do, as a prep patch that comes before this one.

> Also for this long type names just using typeof might be nicer than
> spelling out the type.

Ooh, that works.  I'll fix that too.

--D