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Bug #23732 Assignment to global variable overwrites session-value
Submitted: 2003-05-21 04:32 UTC Modified: 2003-05-21 06:06 UTC
From: daniel dot burckhardt at sur-gmbh dot ch Assigned:
Status: Not a bug Package: Session related
PHP Version: 4.3.1 OS: Linux
Private report: No CVE-ID: None
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From: daniel dot burckhardt at sur-gmbh dot ch
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 [2003-05-21 04:32 UTC] daniel dot burckhardt at sur-gmbh dot ch 
(this seems to be the same problem as in
Bug #20709  	Session variable getting mysteriously set
which has been closed)

When register_globals is On, the assignment
  $foo = 'bar';
has the side-effect of setting
  $_SESSION['foo'] = 'bar';

The following script shows this - enter a new value into the input-field and watch how $_SESSION['foo'] changes.

<?php
session_start();
if($_POST['submit'] != 'go') {
  if(empty($_SESSION['foo']))
    $_SESSION['foo'] = 'foo';
}
else
  $foo = $_POST['foo']; // This assignment overwrites $_SESSION['foo'] if and only if register_globals is on
?>
<html>
<body>
<?php echo 'Session:'.$_SESSION['foo']  ?>
<form action="session_test.php" method="post">
<input type="text" name="foo" />
<input type="submit" name="submit" value="go" />
</form>
</body>
</html>

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 [2003-05-21 06:06 UTC] mgf@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

This is expected behaviour: at version 4.3.0, a defect was corrected so that now the global variable and the $_SESSION[] entry always reference the same value.  (In versions 4.1 and 4.2 this was not the case, which could lead to unexpected and non-intuitive results.)
 
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