PDO::quote() for SQL Server mis-quotes strings containing ASCII NUL

[MarkMaldaba]

I asked a question on StackOverflow and from the various responses it appears that perhaps this is a bug in the pdo_sqlsrv driver itself. I am therefore re-posting it here so that it can be investigated properly.

Here is the same question as posted on StackOverflow: https://stackoverflow.com/questions/46100518

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I'm trying to insert ASCII NUL characters (\0 aka U+0000) into an SQL Server database from PHP, using pdo_sqlsrv. This is a requirement for handling PHP serialized strings, which contain NUL characters to represent private/protected variables.

However, there is something about PDO::quote() which is breaking the strings.

Code to reproduce (replace DBNAME, USERNAME and PASSWORD with appropriate values):

<?php

try {
	$dsn = 'sqlsrv:Server=.\SQLEXPRESS;Database=DBNAME';
	$user = 'USERNAME';
	$pass = 'PASSWORD';

	$connection = new PDO($dsn, $user, $pass);
} catch (PDOException $e) {
	die("Connection error: " . $e->getMessage());
}

$str = "XX\0XX";

header("Content-Type: text/plain");

print("Original: " . str_replace("\0", "{NUL}", $str) . "\n");
$str = $connection->quote($str);
print("Quoted:   " . str_replace("\0", "{NUL}", $str) . "\n");

?>

Expected Output:

Original: XX{NUL}XX
Quoted:   'XX{NUL}XX'

Actual Output:

Original: XX{NUL}XX
Quoted:   'XX'{NUL}{NUL}a

Note that it appears that the final character is random, as on a subsequent run it was an e. This implies some form of memory access error, e.g. reading past the end of the string. Maybe a bug in the pdo_sqlsrv implementation?

[MarkMaldaba]

Oops - forgot to mention: the issue was experienced using php_pdo_sqlsrv_56_nts.dll (v3.2) on PHP 5.6.18.

[yukiwongky]

Hi @MarkMaldaba , we do not actively support PHP 5.6 anymore. Please get the latest PDO_SQLSRV driver from https://github.com/Microsoft/msphpsql/releases/tag/v5.0.0-preview. From your repo script and from the latest driver, the output that I get is:

'XX'{NUL}{NUL}{NUL}

This is a bug on the PDO_SQLSRV driver and we will investigate further.

[Hadis-Knj]

@MarkMaldaba we fixed the issue in the latest release, could you give it a try and confirm if it is fixed in your case?

[Hadis-Knj]

We believe this issue is fixed, feel free to reopen the issue if you face the issue