Re: [PATCH] nfs: fix bitmap decoder to handle a 3rd word

[Trond Myklebust <trondmy@hammerspace.com>]

On Wed, 2024-08-21 at 11:01 -0400, Jeff Layton wrote:
> On Wed, 2024-08-21 at 14:58 +0000, Trond Myklebust wrote:
> > On Wed, 2024-08-21 at 08:16 -0400, Jeff Layton wrote:
> > > It only decodes the first two words at this point. Have it decode
> > > the
> > > third word as well. Without this, the client doesn't send
> > > delegated
> > > timestamps in the CB_GETATTR response.
> > > 
> > > Fixes: 43df7110f4a9 ("NFSv4: Add CB_GETATTR support for delegated
> > > attributes")
> > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > ---
> > > Found this while working on the delstid patches for nfsd.
> > > ---
> > >  fs/nfs/callback_xdr.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
> > > index 29c49a7e5fe1..246470306172 100644
> > > --- a/fs/nfs/callback_xdr.c
> > > +++ b/fs/nfs/callback_xdr.c
> > > @@ -118,7 +118,9 @@ static __be32 decode_bitmap(struct xdr_stream
> > > *xdr, uint32_t *bitmap)
> > >  	if (likely(attrlen > 0))
> > >  		bitmap[0] = ntohl(*p++);
> > >  	if (attrlen > 1)
> > > -		bitmap[1] = ntohl(*p);
> > > +		bitmap[1] = ntohl(*p++);
> > > +	if (attrlen > 2)
> > > +		bitmap[2] = ntohl(*p);
> > >  	return 0;
> > >  }
> > >  
> > > 
> > > ---
> > > base-commit: b311c1b497e51a628aa89e7cb954481e5f9dced2
> > > change-id: 20240821-nfs-6-11-188bb4e1f1dd
> > > 
> > > Best regards,
> > 
> > Why do we need this? I'm not really understanding which callback
> > attributes we'd want to return in that range.
> > 
> 
> (note that there is a v2 that fixes a potential buffer overrun with
> this change. We'll want that one)
> 
> FATTR4_WORD2_TIME_DELEG_ACCESS and FATTR4_WORD2_TIME_DELEG_MODIFY. 
> 43df7110f4a90 added support for those, but the client doesn't see the
> server's request for them without this change.
> 

D'oh! Acked...

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com