Re: [PATCH] NFS: change sign of nfs_fh length

[Trond Myklebust <trondmy@hammerspace.com>]

On Tue, 2018-10-23 at 08:40 -0700, Matthew Wilcox wrote:
> On Tue, Oct 23, 2018 at 10:34:57AM -0500, Frank Sorenson wrote:
> > 
> > The filehandle has a length which is defined as a 32-bit
> > "unsigned integer".  Change sign of the length appropriately.
> > 
> > Signed-off-by: Frank Sorenson <sorenson@redhat.com>
> 
> Is this a cleanup or does it fix a user-visible bug?

It fixes the following comparison:

                if (len > NFS4_FHSIZE)
                        return -EIO;

but in practice, the next line should always catch the buffer overflow
when len is negative:

                p = xdr_inline_decode(xdr, len);
                if (unlikely(!p))
                        goto out_overflow;

That said, it is nice to be redundant, so I'm happy to take the patch.

Frank, in  the future can you please Cc: the maintainers directly on
your patches? I missed this one completely because my mail filter
directed it to my 'linux-fsdevel' inbox rather than 'linux-nfs'...

Thanks,
  Trond

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