'Re: Review Request: Fix a VLC crash by delaying object deletion to avoid invalid access by QtDBus'

[prev in list] [next in list] [prev in thread] [next in thread] 

List:       kde-core-devel
Subject:    Re: Review Request: Fix a VLC crash by delaying object deletion to avoid invalid access by QtDBus
From:       Cristian_Oneț <onet.cristian () gmail ! com>
Date:       2012-01-30 8:05:50
Message-ID: 20120130080550.538.66093 () vidsolbach ! de
[Download RAW message or body]

-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/100577/#review10221
-----------------------------------------------------------


I think this is the same crash that happens every time in kioslave.exe while closing \
a KDE on Windows application, since KDE 4.7.

- Cristian Oneț


On Jan. 30, 2012, 6:35 a.m., Dawit Alemayehu wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/100577/
> -----------------------------------------------------------
> 
> (Updated Jan. 30, 2012, 6:35 a.m.)
> 
> 
> Review request for kdelibs and Thiago Macieira.
> 
> 
> Description
> -------
> 
> As described in the bug report when opening the file dialog, canceling it and \
> exiting VLC causes the application to seg fault. The backtraces posted in the bug \
> report shows that the crash happens somewhere in QtDBus and I get a similar \
> backtrace when using v1.1.7 of this application.  
> When I looked into this issue what I discovered was that only KIO classes that \
> register themselves with QtDBus cause the crash. I only found that out because \
> fixing the crash in KIO::Scheduler by defering its deletion using deleteLater() did \
> not prevent the application from still crashing on exit. However, the crash had \
> moved to another location, KBookmarkManager. The only common thing between the \
> crash at KBookmarkmanager and KIO::Scheduler was that in both cases the backtrace \
> shows QtDBus attempting to invoke or access some method or slot in the object that \
> was just destroyed. At this point I decided to check how many other classes in KIO \
> register themselves with QtDBus and found only one more. I then applied the same \
> changes to all three,  defering the deletion of any object registered with QtDBus \
> using QObject::deleteLater, and the crashing went away. 
> Anyhow, I have no idea why the crashes are only seen with this application. I was \
> not able to duplicate the crash using the same sequences in another Qt only app, \
> Arora or any of the other KDE applications I tried. 
> 
> This addresses bug 234484.
> http://bugs.kde.org/show_bug.cgi?id=234484
> 
> 
> Diffs
> -----
> 
> kio/bookmarks/kbookmarkmanager.cc d8a9cb7 
> kio/kio/fileundomanager.cpp f580c29 
> kio/kio/scheduler.cpp 6b36d9d 
> 
> Diff: http://git.reviewboard.kde.org/r/100577/diff/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Dawit Alemayehu
> 
> 


[Attachment #3 (text/html)]

<html>
 <body>
  <div style="font-family: Verdana, Arial, Helvetica, Sans-Serif;">
   <table bgcolor="#f9f3c9" width="100%" cellpadding="8" style="border: 1px #c9c399 \
solid;">  <tr>
     <td>
      This is an automatically generated e-mail. To reply, visit:
      <a href="http://git.reviewboard.kde.org/r/100577/">http://git.reviewboard.kde.org/r/100577/</a>
  </td>
    </tr>
   </table>
   <br />





 <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">I think this is the same \
crash that happens every time in kioslave.exe while closing a KDE on Windows \
application, since KDE 4.7.</pre>  <br />







<p>- Cristian</p>


<br />
<p>On January 30th, 2012, 6:35 a.m., Dawit Alemayehu wrote:</p>






<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="8" \
style="background-image: \
url('http://git.reviewboard.kde.org/media/rb/images/review_request_box_top_bg.png'); \
background-position: left top; background-repeat: repeat-x; border: 1px black \
solid;">  <tr>
  <td>

<div>Review request for kdelibs and Thiago Macieira.</div>
<div>By Dawit Alemayehu.</div>


<p style="color: grey;"><i>Updated Jan. 30, 2012, 6:35 a.m.</i></p>






<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">As described in the bug report when opening the file dialog, canceling \
it and exiting VLC causes the application to seg fault. The backtraces posted in the \
bug report shows that the crash happens somewhere in QtDBus and I get a similar \
backtrace when using v1.1.7 of this application. 

When I looked into this issue what I discovered was that only KIO classes that \
register themselves with QtDBus cause the crash. I only found that out because fixing \
the crash in KIO::Scheduler by defering its deletion using deleteLater() did not \
prevent the application from still crashing on exit. However, the crash had moved to \
another location, KBookmarkManager. The only common thing between the crash at \
KBookmarkmanager and KIO::Scheduler was that in both cases the backtrace shows QtDBus \
attempting to invoke or access some method or slot in the object that was just \
destroyed. At this point I decided to check how many other classes in KIO register \
themselves with QtDBus and found only one more. I then applied the same changes to \
all three,  defering the deletion of any object registered with QtDBus using \
QObject::deleteLater, and the crashing went away.

Anyhow, I have no idea why the crashes are only seen with this application. I was not \
able to duplicate the crash using the same sequences in another Qt only app, Arora or \
any of the other KDE applications I tried.</pre>  </td>
 </tr>
</table>




<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>


 <a href="http://bugs.kde.org/show_bug.cgi?id=234484">234484</a>


</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>kio/bookmarks/kbookmarkmanager.cc <span style="color: \
grey">(d8a9cb7)</span></li>

 <li>kio/kio/fileundomanager.cpp <span style="color: grey">(f580c29)</span></li>

 <li>kio/kio/scheduler.cpp <span style="color: grey">(6b36d9d)</span></li>

</ul>

<p><a href="http://git.reviewboard.kde.org/r/100577/diff/" style="margin-left: \
3em;">View Diff</a></p>




  </td>
 </tr>
</table>








  </div>
 </body>
</html>



[prev in list] [next in list] [prev in thread] [next in thread]
Configure | About | News | Add a list | Sponsored by KoreLogic