Bug #77302 [Asn->Fbk]: Unserialize decode issue

From: Date: Mon, 14 Jan 2019 13:23:40 +0000
Subject: Bug #77302 [Asn->Fbk]: Unserialize decode issue
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=77302&edit=1

 ID:                 77302
 Updated by:         dmitry@php.net
 Reported by:        sh at analogic dot cz
 Summary:            Unserialize decode issue
-Status:             Assigned
+Status:             Feedback
 Type:               Bug
 Package:            Variables related
 PHP Version:        7.3.0
 Assigned To:        dmitry
 Block user comment: N
 Private report:     N

 New Comment:

The problem is caused by different order during serialisation and unserialization and therefore
different reference numbering. This only happens when Serializable objects call
serialize/unserialize functions few times.

function serialize() { 
    return serialize(array($this->data, parent::serialize())); 
}

function unserialize($data) { 
    list($this->$data, $parent_data) = unserialize($data); 
    parent::unserialize($parent_data); 
}

The problem can't be fixed without format change (e.g. we may use string position instead of
object number).

As a workaround, I propose avoiding nested serialization like parent::serialize() calls.


Previous Comments:
------------------------------------------------------------------------
[2019-01-03 10:26:02] nikic@php.net

@Sjon provided the following test case with a similar issue: https://3v4l.org/BEobu That one is an instance of bug #66052
though, where the stricter validation in 7.3 makes the unserialization fail rather than return bogus
data.

The case in this report looks different though, as you don't have any "C:" payloads
in the serialized data.

------------------------------------------------------------------------
[2018-12-25 13:43:03] php at famoser dot ch

I have managed to create an example to reliably reproduce the behaviour: https://github.com/mangelio/app/blob/php-bug-%2377302/README.BUG77302.md


The example is unfortunately not separated cleanly from the symfony framework and my specific
project; it is therefore still hard to tell how and why the bug is hit. I will try to isolate the
root cause further, but the example may already help others.

------------------------------------------------------------------------
[2018-12-23 10:36:18] me at famoser dot ch

The bug has an issue in the symfony repository on github: https://github.com/symfony/symfony/issues/29459
This PR shows how the serialize/unserialize calls were used: https://github.com/symfony/symfony/pull/29621/files

------------------------------------------------------------------------
[2018-12-19 23:57:43] nikic@php.net

Has the serialized string been produced by a vanilla serialize() call that is not
nested within a Serializable interface or similar? The r:6 reference looks off-by-one to me.

------------------------------------------------------------------------
[2018-12-15 20:02:43] kalle@php.net

Dmitry, can you please clarify?

------------------------------------------------------------------------


The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at

    https://bugs.php.net/bug.php?id=77302


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