NFSv4.1: integer overflow in decode_cb_sequence_args()

This seems like it could overflow on 32 bits.  Use kmalloc_array() which
has overflow protection built in.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/callback_xdr.c

@@ -455,9 +455,9 @@ static __be32 decode_cb_sequence_args(struct svc_rqst *rqstp,
 	args->csa_nrclists = ntohl(*p++);
 	args->csa_rclists = NULL;
 	if (args->csa_nrclists) {
-		args->csa_rclists = kmalloc(args->csa_nrclists *
-					    sizeof(*args->csa_rclists),
-					    GFP_KERNEL);
+		args->csa_rclists = kmalloc_array(args->csa_nrclists,
+						  sizeof(*args->csa_rclists),
+						  GFP_KERNEL);
 		if (unlikely(args->csa_rclists == NULL))
 			goto out;