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Segmentation fault in PHP 7.0.3 (and earlier versions)

php.internals

Simon Svensson

10 years ago
Hi, I'm using Ondřej Surý's ppa which was recently upgraded to PHP 7.0.3. My test-suite is causing segmentation faults since 7.0.0 RC5, including the 7.0.3 release. I can reproduce this consistently by running my test-suite in PHPUnit. Identifying the tests executing when the fault occurs (using --debug) and rerunning them one-by-one does not reproduce the segmentation faults. I'm running this on Ubuntu 14.04.3 LTS. My application is built on with Laravel 5.1 and Doctrine 2.5. I'm using PHPUnit 4.8 and an in-memory sqlite database for the tests. (I'm mentioning this to convey what type of code is running.) My test-suite works on PHP 5.6 and HHVM. I've got a gist with a gdb backtrace, with and without opcache. (There's no difference.) With: https://gist.github.com/sisve/0f75be357e557d439c19 Without: https://gist.github.com/sisve/01542193a27fd9da2b7b I've verified that the opcache is disabled by '/usr/bin/php7.0 -i | grep "opcache.enable"' not returning anything, and '/usr/bin/php7.0 -m' does not contain any entry for opcache. (I'm unsure if this is enough.) I've got some older backtraces from my previous failures. These may be related, or related to something totally different. These have unknown opcache-status (probably enabled). PHP 7.0.2: https://gist.github.com/sisve/05b4c4075ef223c4ab52 PHP 7.0.0-RC?: https://gist.github.com/sisve/fe8e1b85b4cc488ff457 PHP 7.0.0-RC5: https://gist.github.com/sisve/7ce5980e05068972b8e6 PHP 7.0.0-RC5: https://gist.github.com/sisve/ad318ca820a38bdb8133 I've been whining some time on irc about this, and finally got my thumb out of my behind to write this email. I doubt that these traces are enough to identify and solve the problem. What can I do to gather more information and debug this further? // Simon

julien PAULI

10 years ago
On Fri, Feb 5, 2016 at 7:37 PM, Simon Svensson <sisve@devhost.se> wrote:
> Hi, > > I'm using Ondřej Surý's ppa which was recently upgraded to PHP 7.0.3. My > test-suite is causing segmentation faults since 7.0.0 RC5, including the > 7.0.3 release. > > I can reproduce this consistently by running my test-suite in PHPUnit. > Identifying the tests executing when the fault occurs (using --debug) > and rerunning them one-by-one does not reproduce the segmentation faults. > > I'm running this on Ubuntu 14.04.3 LTS. My application is built on with > Laravel 5.1 and Doctrine 2.5. I'm using PHPUnit 4.8 and an in-memory > sqlite database for the tests. (I'm mentioning this to convey what type > of code is running.) > > My test-suite works on PHP 5.6 and HHVM. > > I've got a gist with a gdb backtrace, with and without opcache. (There's > no difference.) > With: https://gist.github.com/sisve/0f75be357e557d439c19 > Without: https://gist.github.com/sisve/01542193a27fd9da2b7b > > I've verified that the opcache is disabled by '/usr/bin/php7.0 -i | grep > "opcache.enable"' not returning anything, and '/usr/bin/php7.0 -m' does > not contain any entry for opcache. (I'm unsure if this is enough.) > > I've got some older backtraces from my previous failures. These may be > related, or related to something totally different. These have unknown > opcache-status (probably enabled). > PHP 7.0.2: https://gist.github.com/sisve/05b4c4075ef223c4ab52 > PHP 7.0.0-RC?: https://gist.github.com/sisve/fe8e1b85b4cc488ff457 > PHP 7.0.0-RC5: https://gist.github.com/sisve/7ce5980e05068972b8e6 > PHP 7.0.0-RC5: https://gist.github.com/sisve/ad318ca820a38bdb8133 > > I've been whining some time on irc about this, and finally got my thumb > out of my behind to write this email. > > I doubt that these traces are enough to identify and solve the problem. > What can I do to gather more information and debug this further? >
Interesting. The traces tell us some really vague clue, we'd really need a reproducer. It seems to be involving generators triggered through reflection, faulting on a foreach() by value. However, can you confirm that you *don't* reproduce with a debug build of PHP ? (exact same reproducer) This is really weird. You may try -O0 -g only. Julien.Pauli

Simon Svensson

10 years ago
On 05/02/16 19:57, julien PAULI wrote:
> On Fri, Feb 5, 2016 at 7:37 PM, Simon Svensson <sisve@devhost.se> wrote: >> Hi, >> >> I'm using Ondřej Surý's ppa which was recently upgraded to PHP 7.0.3. My >> test-suite is causing segmentation faults since 7.0.0 RC5, including the >> 7.0.3 release. >> >> I can reproduce this consistently by running my test-suite in PHPUnit. >> Identifying the tests executing when the fault occurs (using --debug) >> and rerunning them one-by-one does not reproduce the segmentation faults. >> >> I'm running this on Ubuntu 14.04.3 LTS. My application is built on with >> Laravel 5.1 and Doctrine 2.5. I'm using PHPUnit 4.8 and an in-memory >> sqlite database for the tests. (I'm mentioning this to convey what type >> of code is running.) >> >> My test-suite works on PHP 5.6 and HHVM. >> >> I've got a gist with a gdb backtrace, with and without opcache. (There's >> no difference.) >> With: https://gist.github.com/sisve/0f75be357e557d439c19 >> Without: https://gist.github.com/sisve/01542193a27fd9da2b7b >> >> I've verified that the opcache is disabled by '/usr/bin/php7.0 -i | grep >> "opcache.enable"' not returning anything, and '/usr/bin/php7.0 -m' does >> not contain any entry for opcache. (I'm unsure if this is enough.) >> >> I've got some older backtraces from my previous failures. These may be >> related, or related to something totally different. These have unknown >> opcache-status (probably enabled). >> PHP 7.0.2: https://gist.github.com/sisve/05b4c4075ef223c4ab52 >> PHP 7.0.0-RC?: https://gist.github.com/sisve/fe8e1b85b4cc488ff457 >> PHP 7.0.0-RC5: https://gist.github.com/sisve/7ce5980e05068972b8e6 >> PHP 7.0.0-RC5: https://gist.github.com/sisve/ad318ca820a38bdb8133 >> >> I've been whining some time on irc about this, and finally got my thumb >> out of my behind to write this email. >> >> I doubt that these traces are enough to identify and solve the problem. >> What can I do to gather more information and debug this further? >> > > Interesting. > > The traces tell us some really vague clue, we'd really need a reproducer. > It seems to be involving generators triggered through reflection, > faulting on a foreach() by value. > > > However, can you confirm that you *don't* reproduce with a debug build > of PHP ? (exact same reproducer) > This is really weird. You may try -O0 -g only. > > > > Julien.Pauli >
Hi, At least the latest traces comes from the php7.0-dbg package. If I recall correctly the normal php7.0 package caused very hard-to-understand backtraces with memory addresses instead of proper function names. I've recompiled the latest from master on a vagrant machine (marcus/php7dev) that calls configure with --enable-debug. However, I do not speak configure-ish so I do not know if that's enough use the requested compilation flags. I am unable to reproduce the error with this recompiled source, both with the /usr/local/php70/bin/php and /usr/local/php70-debug/bin/php. This is the same experience I had with earlier releases, where I have been unable to reproduce the segmentation faults when recompiling (but always have them occur from the ppa). Is there any guide for compiling the source? I could attempt to setup a new virtual machine with Ubuntu 14.04 (instead of php7dev's Debian) to reproduce the error, but I do know know the steps needed to compile everything. The newly build, and working, versions: /usr/local/php70/bin/php --version: PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:14:08) ( NTS ) Copyright (c) 1997-2016 The PHP Group Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies /usr/local/php70-debug/bin/php --version: PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:19:10) ( NTS DEBUG ) Copyright (c) 1997-2016 The PHP Group Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies // Simon

Rasmus Lerdorf

10 years ago
On 02/05/2016 11:39 AM, Simon Svensson wrote:
> I am unable to reproduce the error with this recompiled source, both > with the /usr/local/php70/bin/php and /usr/local/php70-debug/bin/php. > This is the same experience I had with earlier releases, where I have > been unable to reproduce the segmentation faults when recompiling (but > always have them occur from the ppa). > > Is there any guide for compiling the source? I could attempt to setup a > new virtual machine with Ubuntu 14.04 (instead of php7dev's Debian) to > reproduce the error, but I do know know the steps needed to compile > everything. > > The newly build, and working, versions: > > /usr/local/php70/bin/php --version: > PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:14:08) ( NTS ) > Copyright (c) 1997-2016 The PHP Group > Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies > with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend > Technologies > > /usr/local/php70-debug/bin/php --version: > PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:19:10) ( NTS DEBUG ) > Copyright (c) 1997-2016 The PHP Group > Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies > with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend > Technologies
"php -i" will show you the configure flags that were used to build it, so you could try to match those to see if you can reproduce with sources from php.net. Otherwise, if it is something that only happens with the distro build then there isn't a while lot we can do to help you. -Rasmus

Simon Svensson

10 years ago
On 05/02/16 22:29, Rasmus Lerdorf wrote:
> On 02/05/2016 11:39 AM, Simon Svensson wrote: >> I am unable to reproduce the error with this recompiled source, both >> with the /usr/local/php70/bin/php and /usr/local/php70-debug/bin/php. >> This is the same experience I had with earlier releases, where I have >> been unable to reproduce the segmentation faults when recompiling (but >> always have them occur from the ppa). >> >> Is there any guide for compiling the source? I could attempt to setup a >> new virtual machine with Ubuntu 14.04 (instead of php7dev's Debian) to >> reproduce the error, but I do know know the steps needed to compile >> everything. >> >> The newly build, and working, versions: >> >> /usr/local/php70/bin/php --version: >> PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:14:08) ( NTS ) >> Copyright (c) 1997-2016 The PHP Group >> Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies >> with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend >> Technologies >> >> /usr/local/php70-debug/bin/php --version: >> PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:19:10) ( NTS DEBUG ) >> Copyright (c) 1997-2016 The PHP Group >> Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies >> with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend >> Technologies > > "php -i" will show you the configure flags that were used to build it, > so you could try to match those to see if you can reproduce with sources > from php.net. Otherwise, if it is something that only happens with the > distro build then there isn't a while lot we can do to help you. > > -Rasmus > >
An update to avoid leaving the thread hanging in suspense. I was in contact with Ondřej Surý, the author of the PPA I was using, and got help in grabbing build-logs so that I should be able to reproduce the compile locally, this time without all the optimization. However, since I still do not speak configure-ish I failed to resolve all packages/libraries needed for a complete build, but I managed to smash my keyboard enough to get a working configure & make. My test-suite now terminates like this: PHPUnit 4.8.21 by Sebastian Bergmann and contributors. Runtime: PHP 7.0.3 Configuration: /root/web/phpunit.xml ........................................... 43 / 1229 ( 3%) ........................................... 86 / 1229 ( 6%) ........................................... 129 / 1229 ( 10%) ........................................... 172 / 1229 ( 13%) ........................................... 215 / 1229 ( 17%) ...............R........................... 258 / 1229 ( 20%) ........................................... 301 / 1229 ( 24%) ........................................... 344 / 1229 ( 27%) .R.R.....................R................. 387 / 1229 ( 31%) ........................................... 430 / 1229 ( 34%) ........................................... 473 / 1229 ( 38%) ........................................... 516 / 1229 ( 41%) ........................................... 559 / 1229 ( 45%) ........................................... 602 / 1229 ( 48%) ........................................... 645 / 1229 ( 52%) .php: /root/php-src/Zend/zend_execute.h:275: zend_vm_stack_free_call_frame_ex: Assertion `(executor_globals.vm_stack_top) > (zval *) (executor_globals.vm_stack) && (executor_globals.vm_stack_end) > (zval *) (executor_globals.vm_stack) && (executor_globals.vm_stack_top) <= (executor_globals.vm_stack_end)' failed. Aborted (core dumped) The failed assertion and my backtrace matches exactly that of https://bugs.php.net/bug.php?id=71474 which was fixed a few days ago, and is not part of the 7.0.3 release. It's part of the PHP-7.0 branch, so I presume this will be fixed in the 7.0.4 release. I've recompiled using the PHP-7.0 branch, and my test-suite works there. I look forward to the 7.0.4 release! // Simon

Rasmus Lerdorf

10 years ago
On 02/06/2016 10:10 AM, Simon Svensson wrote:
> On 05/02/16 22:29, Rasmus Lerdorf wrote: >> On 02/05/2016 11:39 AM, Simon Svensson wrote: >>> I am unable to reproduce the error with this recompiled source, both >>> with the /usr/local/php70/bin/php and /usr/local/php70-debug/bin/php. >>> This is the same experience I had with earlier releases, where I have >>> been unable to reproduce the segmentation faults when recompiling (but >>> always have them occur from the ppa). >>> >>> Is there any guide for compiling the source? I could attempt to setup a >>> new virtual machine with Ubuntu 14.04 (instead of php7dev's Debian) to >>> reproduce the error, but I do know know the steps needed to compile >>> everything. >>> >>> The newly build, and working, versions: >>> >>> /usr/local/php70/bin/php --version: >>> PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:14:08) ( NTS ) >>> Copyright (c) 1997-2016 The PHP Group >>> Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies >>> with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend >>> Technologies >>> >>> /usr/local/php70-debug/bin/php --version: >>> PHP 7.0.4-dev (cli) (built: Feb 5 2016 19:19:10) ( NTS DEBUG ) >>> Copyright (c) 1997-2016 The PHP Group >>> Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies >>> with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend >>> Technologies >> >> "php -i" will show you the configure flags that were used to build it, >> so you could try to match those to see if you can reproduce with sources >> from php.net. Otherwise, if it is something that only happens with the >> distro build then there isn't a while lot we can do to help you. >> >> -Rasmus >> >> > > An update to avoid leaving the thread hanging in suspense. > > I was in contact with Ondřej Surý, the author of the PPA I was using, > and got help in grabbing build-logs so that I should be able to > reproduce the compile locally, this time without all the optimization. > However, since I still do not speak configure-ish I failed to resolve > all packages/libraries needed for a complete build, but I managed to > smash my keyboard enough to get a working configure & make. > > My test-suite now terminates like this: > > PHPUnit 4.8.21 by Sebastian Bergmann and contributors. > > Runtime: PHP 7.0.3 > Configuration: /root/web/phpunit.xml > > ........................................... 43 / 1229 ( 3%) > ........................................... 86 / 1229 ( 6%) > ........................................... 129 / 1229 ( 10%) > ........................................... 172 / 1229 ( 13%) > ........................................... 215 / 1229 ( 17%) > ...............R........................... 258 / 1229 ( 20%) > ........................................... 301 / 1229 ( 24%) > ........................................... 344 / 1229 ( 27%) > .R.R.....................R................. 387 / 1229 ( 31%) > ........................................... 430 / 1229 ( 34%) > ........................................... 473 / 1229 ( 38%) > ........................................... 516 / 1229 ( 41%) > ........................................... 559 / 1229 ( 45%) > ........................................... 602 / 1229 ( 48%) > ........................................... 645 / 1229 ( 52%) > .php: /root/php-src/Zend/zend_execute.h:275: > zend_vm_stack_free_call_frame_ex: Assertion > `(executor_globals.vm_stack_top) > (zval *) (executor_globals.vm_stack) > && (executor_globals.vm_stack_end) > (zval *) > (executor_globals.vm_stack) && (executor_globals.vm_stack_top) <= > (executor_globals.vm_stack_end)' failed. > Aborted (core dumped) > > The failed assertion and my backtrace matches exactly that of > https://bugs.php.net/bug.php?id=71474 which was fixed a few days ago, > and is not part of the 7.0.3 release. It's part of the PHP-7.0 branch, > so I presume this will be fixed in the 7.0.4 release. > > I've recompiled using the PHP-7.0 branch, and my test-suite works there. > I look forward to the 7.0.4 release!
Thank you very much for your persistence on this. It is motivating for us when people put a bit of effort into tracking down issues. And yes, that fix will be in 7.0.4. It came in too late to be part of 7.0.3. -Rasmus