[SCSI] scsi_transport_fc: Protect against overflow in dev_loss_tmo

The rport structure defines dev_loss_tmo as u32, which is
later multiplied with HZ to get the actual timeout value.
This might overflow for large dev_loss_tmo values. So we
should be better using u64 as intermediate variables here
to protect against overflow.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Acked-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/scsi_transport_fc.c

@@ -834,7 +834,7 @@ static ssize_t
 store_fc_rport_dev_loss_tmo(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t count)
 {
-	int val;
+	unsigned long val;
 	struct fc_rport *rport = transport_class_to_rport(dev);
 	struct Scsi_Host *shost = rport_to_shost(rport);
 	struct fc_internal *i = to_fc_internal(shost->transportt);
@@ -847,6 +847,12 @@ store_fc_rport_dev_loss_tmo(struct device *dev, struct device_attribute *attr,
 	if ((*cp && (*cp != '\n')) || (val < 0))
 		return -EINVAL;
 
+	/*
+	 * Check for overflow; dev_loss_tmo is u32
+	 */
+	if (val > UINT_MAX)
+		return -EINVAL;
+
 	/*
 	 * If fast_io_fail is off we have to cap
 	 * dev_loss_tmo at SCSI_DEVICE_BLOCK_MAX_TIMEOUT
@@ -2865,7 +2871,7 @@ void
 fc_remote_port_delete(struct fc_rport  *rport)
 {
 	struct Scsi_Host *shost = rport_to_shost(rport);
-	int timeout = rport->dev_loss_tmo;
+	unsigned long timeout = rport->dev_loss_tmo;
 	unsigned long flags;
 
 	/*