[SCSI] iscsi_tcp: check for valid session before accessing

Check that the session is setup before accessing its
connection. This fixes a oops where userspace tries
to get the ip address before the session is bound to
a host.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/iscsi_tcp.c

@@ -759,6 +759,9 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,
 
 	switch (param) {
 	case ISCSI_HOST_PARAM_IPADDRESS:
+		if (!session)
+			return -ENOTCONN;
+
 		spin_lock_bh(&session->frwd_lock);
 		conn = session->leadconn;
 		if (!conn) {