MySQL paging negative SQL attack

1 Attack analysis

Clevercode's OPS colleague told me that when he looked at MySQL's error log, he found a lot of errors, so someone was attacking an address. A large number of this error occurs because MySQL does not support negative numbers at limit. Usually when we split the page, the URL is generally written as http://xxx.com?page=1&pageSize=20, that is, to get the first page of data. 20 rows per page. But if http://xxx.com?page=-1&pageSize=20 is passed in. The following error will occur.

2 Problematic PHP code

function Getuserloginlog ($page, $pageSize) {        //parameter Check    if (!is_int ($page) | |!is_int ($pageSize)) {        return;    }        $start = ($page-1) * $pageSize;     $SQLSTR = "SELECT * from User_login_log the ORDER by id desc limit $start, $pageSize";    Execute SQL statement    //...            .. If page=-1,pagesize=20, the above statement becomes    //$sqlStr = "SELECT * from User_login_log ORDER BY id desc limit-40,20";       

3 PHP code to prevent attacks

You only need to judge $page, $pageSize is a positive integer.

function Getuserloginlog ($page, $pageSize) {        //parameter Check    if (!is_int ($page) | |!is_int ($pageSize)) {        return;    }        //Positive integer check    if ($page < 1 | | $pageSize < 1) {        return;    }        $start = ($page-1) * $pageSize;     $SQLSTR = "SELECT * from User_login_log the ORDER by id desc limit $start, $pageSize";        Execute SQL statement    //...              }

Copyright Notice:

1) original works, from "Clevercode's blog" , please be sure to mention the following original address when reproduced , otherwise hold the copyright legal responsibility.

2) Original address : http://blog.csdn.net/clevercode/article/details/45935593 ( reprint must indicate this address ).

3) Category address: http://blog.csdn.net/clevercode/article/category/3262205 ( Blog continues to increase, concern please collection )

4) welcome everyone to pay attention to my blog more wonderful content: Http://blog.csdn.net/CleverCode.

MySQL paging negative SQL attack