Doc #63118 [Opn->Wfx]: mysql_real_escape_string doesn't always prepend backslashes

Edit report at https://bugs.php.net/bug.php?id=63118&edit=1 ID: 63118 Updated by: aharvey@php.net Reported by: mark at zedwood dot com Summary: mysql_real_escape_string doesn't always prepend backslashes -Status: Open +Status: Wont fix Type: Documentation Problem Package: Documentation problem PHP Version: Irrelevant Block user comment: N Private report: N New Comment: I think the wording on that is fine: the use of the word "character" is important there. At any rate, since you don't need to allocate a buffer in PHP, I think the reality is that mysql_real_escape_string() can basically be treated as a black box regardless (unsafe data goes in, safe data comes out). Previous Comments: ------------------------------------------------------------------------ [2012-09-19 16:39:37] mark at zedwood dot com Description: ------------ On: http://us3.php.net/manual/en/function.mysql-real-escape-string.php The documentation says: "mysql_real_escape_string() calls MySQL's library function mysql_real_escape_string, which prepends backslashes to the following characters: \x00, \n, \r, \, ', " and \x1a." This implies that "\x00" (1 char) escapes to "\\x00" (4 chars). This is not accurate, it should say "which escapes the following characters", because there are 2 cases where it doesn't just prepend a slash. For null and CTRL-Z, it turns "\x00" into '\0' and "\x1a" into '\Z'. If it didn't, it would be vulnerable to buffer overflow. The mysql C API documentation says, to allocate a buffer of input_length*2+1, implying that each escaped char can only ever escape to a max of 2 chars. http://dev.mysql.com/doc/refman/4.1/en/mysql-real-escape-string.html Test script: --------------- $db = mysql_connect($host, $user, $pass) or die("err: " . mysql_error()); mysql_select_db($dbname, $db) or die("err: " . mysql_error()); $a = mysql_real_escape_string("\x00\n\r\"'\x1a"); echo $a; Expected result: ---------------- //expected, based on current documentation: \x00\n\r\"\'\x1a Actual result: -------------- //actual: \0\n\r\"\'\Z ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=63118&edit=1