#22117 [Opn]: Session vars inappropriately created as references
ID: 22117
User updated by: phpbugs@brianmertens.com
Reported By: phpbugs@brianmertens.com
Status: Open
Bug Type: Session related
Operating System: Win NT 4
PHP Version: 4.3.0
New Comment:
A colleague points out that this script also
produces the buggy behaviour.
<?php
session_start();
$var1 = "INITIALIZED";
$var2 = $var1;
session_register("var1","var2");
$var2 = "CHANGED";
echo $var1."<br>";
echo $var2."<br>";
?>
Previous Comments:
------------------------------------------------------------------------
[2003-02-09 16:36:48] phpbugs@brianmertens.com
Further searching makes me think that this may be
related to Bug #20583 :
http://bugs.php.net/bug.php?id=20583
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[2003-02-09 16:33:11] phpbugs@brianmertens.com
Actually, I have created a simpler test case,
which produces the behaviour in one script,
and BEFORE serialization:
<?php
// bug3.php
session_start();
$var1 = $var2 = "INITIALIZED";
session_register("var1","var2");
$var2 = "CHANGED";
echo $var1."<br>";
echo $var2."<br>";
?>
Actual Output in 4.3.0:
CHANGED
CHANGED
Session data after execution
var1|s:7:"CHANGED";var2|R:1;
So it seems that $var2 is a reference of $var1,
but only if the session_start and session_register
functions are called.
Notes:
The bug occurs even if the "session_start();" and the "$var1 = $var2 =
"INITIALIZED";" lines are swapped.
The buggy behaviour disappears if I move the line
"$var2 = "CHANGED"" above the session_register() call.
------------------------------------------------------------------------
[2003-02-09 16:07:53] phpbugs@brianmertens.com
Here's the contents of the session file,
immediately after execution of my first
test script test_bug1.php, from versions
4.2.2 and 4.3.0:
session file from 4.2.2:
var1|s:11:"INITIALIZED";var2|s:11:"INITIALIZED";
session file from 4.3.0:
var1|s:11:"INITIALIZED";var2|R:1;
------------------------------------------------------------------------
[2003-02-07 17:41:24] phpbugs@brianmertens.com
It took me a while to track this down...
we noticed that when we upgraded a develpment box
from 4.2.3 to 4.3.0, that one of our session vars
was being over-written by another.
It turns out that one was being serialized
to the session as a reference to the other,
but only if the vars were intialized like this:
$var1 = $var2 = "some value";
Consider two scripts, test_bug1.php and test_bug2.php
If you run test_bug1, and then test_bug2, surprisingly,
the output of test_bug2 will be:
BEFORE:
var1 = 'INITIALIZED'
var2 = 'INITIALIZED'
AFTER:
var1 = 'CHANGED'
var2 = 'CHANGED'
<?php
// test_bug1.php
session_start();
$var1 = $var2 = "INITIALIZED";
session_register("var1","var2");
echo "INIT:<br>\n";
echo "var1 = '$var1'<br>";
echo "var2 = '$var2'<br><p>";
echo "<a href='test_bug2.php'>test_bug2.php</a>";
?>
<?php
// test_bug2.php
session_start();
echo "BEFORE:<br>\n";
echo "var1 = '$var1'<br>\n";
echo "var2 = '$var2'<br><p>\n";
$var2 = "CHANGED";
echo "AFTER:<br>\n";
echo "var1 = '$var1'<br>\n";
echo "var2 = '$var2'<br><p>\n";
$var2 = "EXIT";
?>
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