ibmvscsi: Fix host config length field overflow

commit 225c5696 upstream.

The length field in the host config packet is only 16-bit long, so
passing it 0x10000 (64K which is our standard PAGE_SIZE) doesn't
work and result in an empty config from the server.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/scsi/ibmvscsi/ibmvscsi.c

@@ -1547,6 +1547,9 @@ static int ibmvscsi_do_host_config(struct ibmvscsi_host_data *hostdata,
 
 	host_config = &evt_struct->iu.mad.host_config;
 
+	/* The transport length field is only 16-bit */
+	length = min(0xffff, length);
+
 	/* Set up a lun reset SRP command */
 	memset(host_config, 0x00, sizeof(*host_config));
 	host_config->common.type = VIOSRP_HOST_CONFIG_TYPE;