请问一下为什么我这里设置了上传格式的限制然后也对应了然后为什

请问一下，为什么我这里设置了上传格式的限制，然后ID也对应了dr_ID 然后为什么我上传图片的时候比如jpg也还可以上传成功啊，。

表单代码：

<div class="layui-form-item layui-form-text">
<label class="layui-form-label col-md-2">*</label>
                        <div style="margin-left: 110px;text-align: left;" class="layui-upload">
                            <input type="hidden" name="data[jlsc]" lay-verify="head" id="dr_jlsc" value="">
                            <button type="button" class="layui-btn layui-btn-primary" id="upload">
                                <i class="layui-icon">&#xe608;</i> 请上传你的简历(仅支持pdf/doc/docx格式)
                            </button>
                        </div>
</div>

JS代码部分：

//layui触发上传按钮---简历上传//
upload.render({
                    elem: '#upload',
                    url: '/index.php?s=ltss&c=shangchuan&m=upload',
                    field: "file_data",
                    data: {
                        file_data: function(){
                            return $('#upload').val();
                        },
                {csrf_token()} : "{csrf_hash()}"
            },
                before: function(obj){
                    //预读本地文件示例，不支持ie8
                    obj.preview(function(index, file, result){
                    });
                },
                done: function(res){
                    if (!res.id){
                        return layer.msg('<span style="color: #fff">'+res.msg+'</span>');
                    }else {
                        if(res.code == 1){
                            $("#head").attr("value", res.id); 
                            return layer.msg('<span style="color: #fff">上传成功</span>');
                        }else{
                            return layer.msg('<span style="color: #fff">上传失败，请重试！</span>');
                        }
                    }
                },
                error: function(){
                    //请求异常回调
                }
            });

PHP代码部分：

<?php namespace Phpcmf\Controllers;
/**
 * 二次开发时可以修改本文件，不影响升级覆盖
 */
class Shangchuan extends \Phpcmf\Home\Module
{
public function upload() {
        $files = $this->request->getFiles();
        $p['exts'] = $files['file_data']->getClientExtension();
        $p['size'] = 100;

        // 验证上传权限
        $rt = \Phpcmf\Service::L('upload')->upload_file([
            'path' => '',
            'form_name' => 'file_data',
            'file_exts' => @explode(',', $p['exts']),
            'file_size' => (int)$p['size'] * 1024 * 1024,
            'attachment' => \Phpcmf\Service::M('Attachment')->get_attach_info(),
        ]);
        if (!$rt['code']) {
            exit(dr_array2string($rt));
        }

        // 附件归档
        $data = \Phpcmf\Service::M('Attachment')->save_data($rt['data']);
        if (!$data['code']) {
            exit(dr_array2string($data));
        }

        // 上传成功
        if (IS_API_HTTP) {
            $data['data'] = [
                'id' => $data['code'],
                'url' => $rt['data']['url'],
            ];
            exit(dr_array2string($data));
        } else {
            exit(dr_array2string(['code' => 1, 'msg' => dr_lang('上传成功'), 'id' => $data['code'], 'info' => $rt['data']]));
        }

    }
}

后台上传字段部分：