scsi: target/iscsi: Make iscsit_ta_authentication() respect the output buffer size

Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/iscsi/iscsi_target_tpg.c

@@ -636,8 +636,7 @@ int iscsit_ta_authentication(struct iscsi_portal_group *tpg, u32 authentication)
 		none = strstr(buf1, NONE);
 		if (none)
 			goto out;
-		strncat(buf1, ",", strlen(","));
-		strncat(buf1, NONE, strlen(NONE));
+		strlcat(buf1, "," NONE, sizeof(buf1));
 		if (iscsi_update_param_value(param, buf1) < 0)
 			return -EINVAL;
 	}