php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login

go to bug id or search bugs for

Bug #63082 Segfault with libevent 2.0.20
Submitted: 2012-09-13 16:54 UTC Modified: 2012-11-16 19:35 UTC
From: evert at rooftopsolutions dot nl Assigned: tony2001 (profile)
Status: Closed Package: libevent (PECL)
PHP Version: 5.3.16 OS: OS/X 10.8
Private report: No CVE-ID: None
View Developer Edit
Welcome back! If you're the original bug submitter, here's where you can edit the bug or add additional notes.
If you forgot your password, you can retrieve your password here.
Password:
Status:
Package:
Bug Type:
Summary:
From: evert at rooftopsolutions dot nl
New email:
PHP Version: OS:

 

 [2012-09-13 16:54 UTC] evert at rooftopsolutions dot nl 
Description:
------------
I upgraded my libevent to 2.0.20, but this gave me "Segmentation fault 11" when using pecl/event.

Downgrading back to 2.0.19 seem to work. GDB indicated that the segmentation fault happened in event_pending(). The changelog seems to indicate a change did indeed happen there:

https://raw.github.com/libevent/libevent/release-2.0.20-stable/ChangeLog

Note that I did also recompile the pecl extension. Just in case there was an ABI break.

Test script:
---------------
Run : 

event_base_loop

with some events attached.

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2012-09-17 13:13 UTC] tony2001@php.net 
Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc. If the script requires a 
database to demonstrate the issue, please make sure it creates 
all necessary tables, stored procedures etc.

Please avoid embedding huge scripts into the report.
 [2012-09-17 13:13 UTC] tony2001@php.net
-Status: Open +Status: Feedback
 [2012-09-17 18:31 UTC] evert at rooftopsolutions dot nl
-Status: Feedback +Status: Open
 [2012-09-17 18:31 UTC] evert at rooftopsolutions dot nl 
Took me some time to get a very simple test case, and it also made me realize my bug is a lot more specific than I initially thought. Sorry about this, but here's the new information

This script will always throw the SIG11 with Libevent 2.0.20.

<?php
$buffer = event_buffer_new(
    STDIN,
    function() {
        echo "read\n";
    },  
    function() {
        echo "write\n";
    },  
    function() {
        echo "error\n";
    }   
);
event_buffer_timeout_set($buffer, 5, 5);
?>

I also came to the realization that event_buffer_timeout_set will not throw the segmentation fault, if it is called *after* event_buffer_base.

And just in case.. The SIG11 does not get thrown with libevent 2.0.19, so this is definitely a newly introduced bug.

Hope this helps! I have my workaround in any case.
 [2012-09-18 07:07 UTC] tony2001@php.net 
This is clearly a bug in libevent itself, so I reported it upstream: 
https://github.com/libevent/libevent/issues/19
I can think of a workaround in this particular case, but bufferevent_settimeout() is 
definitely not the only function that calls event_pending() and proper workaround 
would be to add a check to ALL the functions calling it, which kinda smells.
I'd suggest to wait for a fix in the libevent instead, fortunately it's extremely easy.
 [2012-09-18 07:07 UTC] tony2001@php.net
-Status: Open +Status: Feedback
 [2012-09-18 09:40 UTC] evert at rooftopsolutions dot nl
-Status: Feedback +Status: Open
 [2012-09-18 09:40 UTC] evert at rooftopsolutions dot nl 
Can't seem to leave a comment without putting it back to 'Open', but wanted to say thank you anyway :)
 [2012-09-19 07:59 UTC] tony2001@php.net
-Status: Open +Status: Assigned -Assigned To: +Assigned To: tony2001
 [2012-11-16 19:35 UTC] tony2001@php.net 
Fixed by 
https://github.com/libevent/libevent/commit/e3cccf380c23891089d7c3a4637cac5001
0a600d
 [2012-11-16 19:35 UTC] tony2001@php.net
-Status: Assigned +Status: Closed
 
PHP Copyright © 2001-2025 The PHP Group
All rights reserved. 		Last updated: Thu Mar 13 17:01:30 2025 UTC