Apache crashes on module startup with SIGSEGV

[HeenaBansal2009]

Description

Apache configuration.

• CentOS Linux release 7.6.1810 (Core)
• Server version: Apache/2.4.6 (CentOS)
• PHP 7.3.15
  Server version: Apache/2.4.6 (CentOS)
  Server built: Jan 27 2023 17:36:29
  Server's Module Magic Number: 20120211:24
  Server loaded: APR 1.4.8, APR-UTIL 1.5.2
  Compiled using: APR 1.4.8, APR-UTIL 1.5.2
  Architecture: 64-bit
  Server MPM: worker
  threaded: yes (fixed thread count)
  forked: yes (variable process count)
  Server compiled with....
  -D APR_HAS_SENDFILE
  -D APR_HAS_MMAP
  -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
  -D APR_USE_SYSVSEM_SERIALIZE
  -D APR_USE_PTHREAD_SERIALIZE
  -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
  -D APR_HAS_OTHER_CHILD
  -D AP_HAVE_RELIABLE_PIPED_LOGS
  -D DYNAMIC_MODULE_LIMIT=256
  -D HTTPD_ROOT="/etc/httpd"
  -D SUEXEC_BIN="/usr/sbin/suexec"
  -D DEFAULT_PIDLOG="/run/httpd/httpd.pid"
  -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
  -D DEFAULT_ERRORLOG="logs/error_log"
  -D AP_TYPES_CONFIG_FILE="conf/mime.types"
  -D SERVER_CONFIG_FILE="conf/httpd.conf"

I am using mod_php with MPM worker and PHP 7.3 compiled with ZTS.

backtrace:

(gdb) bt
#0  0x00007f4cc79e1456 in zm_activate_xx (type=1, module_number=27) at xx.c :752
#1  0x00007f4cd49fe313 in zend_activate_modules () at /root/php-7.3.15/Zend/zend_API.c:2611
#2  0x00007f4cd4933773 in php_request_startup () at /root/php-7.3.15/main/main.c:1829
#3  0x00007f4cd4ad81ae in php_apache_request_ctor (r=0x7f4ca8002970, ctx=0x7f4ca8007730) at /root/php-7.3.15/sapi/apache2handler/sapi_apache2.c:534
#4  0x00007f4cd4ad89e2 in php_handler (r=0x7f4ca8002970) at /root/php-7.3.15/sapi/apache2handler/sapi_apache2.c:650
#5  0x0000557e762c3050 in ap_run_handler ()
#6  0x0000557e762c3599 in ap_invoke_handler ()
#7  0x0000557e762d851a in ap_process_async_request ()
#8  0x0000557e762d8802 in ap_process_request ()
#9  0x0000557e762d4662 in ap_process_http_connection ()
#10 0x0000557e762cc680 in ap_run_process_connection ()
#11 0x00007f4ccb30676b in worker_thread () from /etc/httpd/modules/mod_mpm_worker.so
#12 0x00007f4cd5ef2ea5 in start_thread (arg=0x7f4cc712f700) at pthread_create.c:307
#13 0x00007f4cd5a17b0d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

(gdb) f 1
#1  0x00007f4cd49fe313 in zend_activate_modules () at /root/php-7.3.15/Zend/zend_API.c:2611
2611			if (module->request_startup_func(module->type, module->module_number)==FAILURE) {
(gdb) list 
2606		zend_module_entry **p = module_request_startup_handlers;
2607	
2608		while (*p) {
2609			zend_module_entry *module = *p;
2610	
2611			if (module->request_startup_func(module->type, module->module_number)==FAILURE) {
2612				zend_error(E_WARNING, "request_startup() for %s module failed", module->name);
2613				exit(1);
2614			}
2615			p++;

FYI : Line 752 is first line of RINIT();

PHP Version

PHP 7.3.15

Operating System

CentOS

[HeenaBansal2009]

FYI, This is not happening when using same configuration with prefork mpm.
AS per latest apache 2.4 , worker and event mpm and mod_php DSO is valid and supported.

[nielsdos]

Looks like an extension you use is causing the issue, not php (xx.c is a file of the extension). Also your php version is pretty old, you should consider upgrading.

[HeenaBansal2009]

@nielsdos , Thanks for prompt response . Apache works fine with mod_php and prefork.

the issue is happening only with worker mpm and though the gdb is pointing to extension file. But 752 is the first line of RINT() method which seems doubtful .

[nielsdos]

Is this a custom extension? Gdb shows it fails there and the arguments passed to the request_startup_func look sane. Without more information it's gonna be difficult to give concrete help I'm afraid

[HeenaBansal2009]

I have built my extension with this configuration .

php-config
Usage: /usr/local/bin/php-config [OPTION]
Options:
  --prefix            [/usr/local]
  --includes          [-I/usr/local/include/php -I/usr/local/include/php/main -I/usr/local/include/php/TSRM -I/usr/local/include/php/Zend -I/usr/local/include/php/ext -I/usr/local/include/php/ext/date/lib]
  --ldflags           []
  --libs              [-lcrypt   -lresolv -lcrypt -lrt -lldap -llber -lz -lrt -lm -ldl -lnsl  -lpthread -lxml2 -lz -lm -ldl -lssl -lcrypto -lcurl -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lcrypt -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lssl -lcrypto -lcrypt ]
  --extension-dir     [/usr/local/php/modules]
  --include-dir       [/usr/local/include/php]
  --man-dir           [/usr/local/php/man]
  --php-binary        [/usr/local/bin/php]
  --php-sapis         [ cli embed fpm cgi]
  --configure-options [--prefix=/usr/local --with-config-file-path=/usr/local/etc/php --with-config-file-san-dir=/usr/local/etc/php/conf.d --disable-phpdbg --enable-json --enable-opcache --enable-mysqlnd --enable-pdo --enable-soap --enable-mbstring --enable-sockets --enable-fpm --enable-debug --enable-gcov --enable-embed --with-pdo-mysql=mysqlnd --with-pdo-sqlite --with-sqlite3 --with-mysqli=mysqlnd --with-curl --with-zlib --with-gnu-ld --with-openssl --with-phar --with-ldap --with-valgrind --with-pcre-valgrind --enable-zts --enable-maintainer-zts --disable-mbregex]
  --version           [7.3.29]
  --vernum            [70329]

And I am deploying the extension where php was build with below configuration:

Usage: /usr/bin/php-config [OPTION]
Options:

  --prefix            [/usr]
  --includes          [-I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib]
  --ldflags           []
  --libs              [-lcrypt   -lresolv -lcrypt -lrt -lrt -lm -ldl -lnsl  -lpthread -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lcrypt -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lxml2 -lz -lm -ldl -lcrypt ]
  --extension-dir     [/usr/lib/php/extensions/debug-zts-20180731]
  --include-dir       [/usr/include/php]
  --man-dir           [/usr/php/man]
  --php-binary        [/usr/bin/php]
  --php-sapis         [ apache2handler cli phpdbg cgi]
  --configure-options [--enable-debug --enable-maintainer-zts --prefix=/usr --with-config-file-path=/etc --with-apxs2]
  --version           [7.3.15]
  --vernum            [70315]

[HeenaBansal2009]

@nielsdos , Is anything related to pthreads needs to be enabled .
I am building my extension with above shared configuration. Am I missing something ?

[nielsdos]

Nothing stood out as weird in your configuration. From the information I have, I think the problem is in your extension code.

[HeenaBansal2009]

@nielsdos , Does Mod_php with MPM worker for ZTS enabled is supported by PHP ?
. I see the recommendation on PHP page
https://www.php.net/manual/en/install.unix.apache2.php.

Warning
We do not recommend using a threaded MPM in production with Apache 2. Use the prefork MPM, which is the default MPM with Apache 2.0 and 2.2. For information on why, read the related FAQ entry on using Apache2 with a threaded MPM

And my extension works fine with mod_php and prefork but not MPM worker. Any comments here.

[nielsdos]

It should work if all the components can handle the particular configuration. You might need to make modifications to your extension based on what I read in the comment. Although I'm not familiar enough with that particular configuration so it's best if someone else helps you further...

[HeenaBansal2009]

Thanks @nielsdos for inputs.
Can you please route this to someone who can help me on this.

I want to rule out the compatibly issues with PHP and MPM worker combination. As recommended by PHP , prefork is the best model to work with in case of ZTS.
https://www.php.net/manual/en/install.unix.apache2.php

However , I will be happy to work on extension modifications Once I figure out this is not PHP.

[HeenaBansal2009]

I was reading few of the posts on internet which says we should install pthreads using "pecl install pthreads" for zend extensions compiled with ZTS to work .

However , When I am installing "pecl install pthreads" getting compilation error. Can someone help here pls.

creating libtool
appending configuration tag "CXX" to libtool
configure: creating ./config.status
config.status: creating config.h
running: make
/bin/sh /tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/libtool --mode=compile cc -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -I. -I/tmp/pear/temp/pthreads -DPHP_ATOM_INC -I/tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/include -I/tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/main -I/tmp/pear/temp/pthreads -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib -I/tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/.  -DHAVE_CONFIG_H  -g -O2   -c /tmp/pear/temp/pthreads/php_pthreads.c -o php_pthreads.lo
mkdir .libs
 cc -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1 -I. -I/tmp/pear/temp/pthreads -DPHP_ATOM_INC -I/tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/include -I/tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/main -I/tmp/pear/temp/pthreads -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib -I/tmp/pear/temp/pear-build-rootglxvDf/pthreads-3.1.6/. -DHAVE_CONFIG_H -g -O2 -c /tmp/pear/temp/pthreads/php_pthreads.c  -fPIC -DPIC -o .libs/php_pthreads.o
In file included from /tmp/pear/temp/pthreads/php_pthreads.h:31:0,
                 from /tmp/pear/temp/pthreads/php_pthreads.c:26:
/tmp/pear/temp/pthreads/classes/threaded.h:89:84: error: macro "ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX" passed 6 arguments, but takes just 5
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(Threaded_isGarbage, 0, 0, _IS_BOOL, NULL, 0)
                                                                                    ^
In file included from /usr/include/php/main/php.h:37:0,
                 from /tmp/pear/temp/pthreads/src/pthreads.h:37,
                 from /tmp/pear/temp/pthreads/php_pthreads.c:22:
/usr/include/php/Zend/zend_API.h:125:30: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘}’ token
 #define ZEND_END_ARG_INFO()  };
                              ^
/tmp/pear/temp/pthreads/classes/threaded.h:90:1: note: in expansion of macro ‘ZEND_END_ARG_INFO’
 ZEND_END_ARG_INFO()
 ^
In file included from /tmp/pear/temp/pthreads/php_pthreads.h:39:0,
                 from /tmp/pear/temp/pthreads/php_pthreads.c:26:
/tmp/pear/temp/pthreads/classes/collectable.h:20:87: error: macro "ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX" passed 6 arguments, but takes just 5
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(Collectable_isGarbage, 0, 0, _IS_BOOL, NULL, 0)
                                                                                       ^
In file included from /usr/include/php/main/php.h:37:0,
                 from /tmp/pear/temp/pthreads/src/pthreads.h:37,
                 from /tmp/pear/temp/pthreads/php_pthreads.c:22:
/usr/include/php/Zend/zend_API.h:125:30: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘}’ token
 #define ZEND_END_ARG_INFO()  };
                              ^
/tmp/pear/temp/pthreads/classes/collectable.h:21:1: note: in expansion of macro ‘ZEND_END_ARG_INFO’
 ZEND_END_ARG_INFO()

[devnexen]

I m afraid pthreads has not been updated since this 3.1.6 release (2016) and is now deprecated.

[KapitanOczywisty]

There is updated fork for 7.4+ https://github.com/pmmp/pthreads However you're trying to compile for PHP 7.3, so you need compile from source this one: https://github.com/krakjoe/pthreads#unix-based-building-from-source

You also have multiple PHP versions installed, if you're trying to load extension compiled for wrong PHP version you might get SIGSEGV, so make sure you use correct phpize.