nfsd: COPY and CLONE operations require the saved filehandle to be set

commit 01310bb7 upstream.

Make sure we have a saved filehandle, otherwise we'll oops with a null
pointer dereference in nfs4_preprocess_stateid_op().
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/nfsd/nfs4proc.c

@@ -1049,6 +1049,9 @@ nfsd4_verify_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 {
 	__be32 status;
 
+	if (!cstate->save_fh.fh_dentry)
+		return nfserr_nofilehandle;
+
 	status = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->save_fh,
 					    src_stateid, RD_STATE, src, NULL);
 	if (status) {