php5 crashed with SIGSEGV in _Unwind_ForcedUnwind()

[Mikko Rantalainen]

Binary package hint: php5

This may be related to bug 259479.

Steps to reproduce (with command line php, see the attached file):
1) $ php test.php

Seems to be some kind of race condition because it only happens every now and then. Here's a backtrace from a core dump:

(gdb) bt
#0 0x00007f71213564ef in ?? () from /lib/libgcc_s.so.1
#1 0x00007f7121356e3b in ?? () from /lib/libgcc_s.so.1
#2 0x00007f7121356f43 in _Unwind_ForcedUnwind () from /lib/libgcc_s.so.1
#3 0x00007f71239bb710 in __pthread_unwind () from /lib/libpthread.so.0
#4 0x00007f71239b5b05 in pthread_exit () from /lib/libpthread.so.0
#5 0x00007f7120fa8f3b in ?? ()
#6 0x0000000000000000 in ?? ()

$ lsb_release -rd
Description: Ubuntu 9.04
Release: 9.04

$ apt-cache policy php5-cli
php5-cli:
  Installed: 5.2.6.dfsg.1-3ubuntu4.1
  Candidate: 5.2.6.dfsg.1-3ubuntu4.1
  Version table:
 *** 5.2.6.dfsg.1-3ubuntu4.1 0
        500 http://security.ubuntu.com jaunty-security/main Packages
        100 /var/lib/dpkg/status
     5.2.6.dfsg.1-3ubuntu4 0
        500 http://fi.archive.ubuntu.com jaunty/main Packages

$ uname -a
Linux semyol-329-b 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:58:03 UTC 2009 x86_64 GNU/Linux

I have a core dump (0.4 MB bzip2'd) if required.

[Mikko Rantalainen (mira)]

Probably related (or same as) http://bugs.mysql.com/bug.php?id=42850

That bug is caused by http://bugs.mysql.com/bug.php?id=24507 which is a (not so good) workaround for a glibc bug (http://sourceware.org/bugzilla/show_bug.cgi?id=2644). If the glibc bug is fixed in the currently distributed Ubuntu glibc, then the workaround for MySQL bug 24507 could be removed which in turn fixes the bug 42850.

[Mikko Rantalainen (mira)]

If this is related to http://bugs.mysql.com/bug.php?id=42850 then at least package php5-mysql must be installed. Here's the list of all php related packages I've installed:
dh-make-php
libapache2-mod-php5
php-pear
php-phpdocumentor
php-phpunit
php5-cli
php5-common
php5-mysql
php5-xcache
php5-xdebug

[Mikko Rantalainen (mira)]

I'm attaching the minimal test case (a php file that prints "test" and exists). This will also trigger the SIGSEGV.
Try following to test:

$ while true; do php test2.php; done

Hit CTRL+C when you see "Segmentation fault". Command "ulimit -c 100000" will allow dumping the core.
The core dump will have identical stack trace to first comment.

[Mikko Rantalainen (mira)]

If somebody can reproduce with php5-mysql installed and cannot reproduce without php5-mysql then this is highly probably the MySQL bug 42850.

[Mikko Rantalainen (mira)]

Probably a duplicate of bug 343870