NFSD: fix bad length checking for backchannel

the length for backchannel checking should be multiplied by sizeof(__be32).
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -1853,6 +1853,11 @@ static __be32 check_forechannel_attrs(struct nfsd4_channel_attrs *ca, struct nfs
 	return nfs_ok;
 }
 
+#define NFSD_CB_MAX_REQ_SZ	((NFS4_enc_cb_recall_sz + \
+				 RPC_MAX_HEADER_WITH_AUTH) * sizeof(__be32))
+#define NFSD_CB_MAX_RESP_SZ	((NFS4_dec_cb_recall_sz + \
+				 RPC_MAX_REPHEADER_WITH_AUTH) * sizeof(__be32))
+
 static __be32 check_backchannel_attrs(struct nfsd4_channel_attrs *ca)
 {
 	ca->headerpadsz = 0;
@@ -1863,9 +1868,9 @@ static __be32 check_backchannel_attrs(struct nfsd4_channel_attrs *ca)
 	 * less than 1k.  Tighten up this estimate in the unlikely event
 	 * it turns out to be a problem for some client:
 	 */
-	if (ca->maxreq_sz < NFS4_enc_cb_recall_sz + RPC_MAX_HEADER_WITH_AUTH)
+	if (ca->maxreq_sz < NFSD_CB_MAX_REQ_SZ)
 		return nfserr_toosmall;
-	if (ca->maxresp_sz < NFS4_dec_cb_recall_sz + RPC_MAX_REPHEADER_WITH_AUTH)
+	if (ca->maxresp_sz < NFSD_CB_MAX_RESP_SZ)
 		return nfserr_toosmall;
 	ca->maxresp_cached = 0;
 	if (ca->maxops < 2)