NFS4: fix cb_recallany decode error

craa_type_mask is bitmap4 per RFC5661. We need to expect a length before
extracting bitmap value.

Cc: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: NPeng Tao <peng_tao@emc.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/callback_xdr.c

@@ -488,17 +488,18 @@ static __be32 decode_recallany_args(struct svc_rqst *rqstp,
 				      struct xdr_stream *xdr,
 				      struct cb_recallanyargs *args)
 {
-	__be32 *p;
+	uint32_t bitmap[2];
+	__be32 *p, status;
 
 	args->craa_addr = svc_addr(rqstp);
 	p = read_buf(xdr, 4);
 	if (unlikely(p == NULL))
 		return htonl(NFS4ERR_BADXDR);
 	args->craa_objs_to_keep = ntohl(*p++);
-	p = read_buf(xdr, 4);
-	if (unlikely(p == NULL))
-		return htonl(NFS4ERR_BADXDR);
-	args->craa_type_mask = ntohl(*p);
+	status = decode_bitmap(xdr, bitmap);
+	if (unlikely(status))
+		return status;
+	args->craa_type_mask = bitmap[0];
 
 	return 0;
 }