Edit report at https://bugs.php.net/bug.php?id=78175&edit=1
ID: 78175
Comment by: nicolas dot grekas+php at gmail dot com
Reported by: nicolas dot grekas+php at gmail dot com
Summary: Preloading segfaults at preload time and at runtime
Status: Re-Opened
Type: Bug
Package: opcache
PHP Version: 7.4.0alpha1
Assigned To: dmitry
Block user comment: N
Private report: N
New Comment:
> Although, this is a bug, it's also an interesting unexpected side effect, that allow
> initialization and preloading of big arrays as static properties (e.g. application configuration)
While funny, that's not that interesting to keep: if one wants this, it's always possible
to generate a file with the array and load it. Preloading the default static value is what would be
the most expected, to me at least :)
Previous Comments:
------------------------------------------------------------------------
[2019-06-19 09:22:31] dmitry@php.net
The problem caused by assignment object to static property of preloaded class, and opcache
doesn't expect objects...
A simpler way to reproduce:
preload.php
-----------
<?php
class Loader {
static private $loader;
static function getLoader() {
if (null !== self::$loader) {
return self::$loader;
}
return self::$loader = new Loader();
}
}
Loader::getLoader();
?>
$ USE_ZEND_ALLOC=0 valgrind sapi/cli/php -dopcache.preload=preload.php -r
'var_dump(get_class(Loader::getLoader()));'
Although, this is a bug, it's also an interesting unexpected side effect, that allow
initialization and preloading of big arrays as static properties (e.g. application configuration)
------------------------------------------------------------------------
[2019-06-19 07:48:49] dmitry@php.net
I don't see crash, but got the following valgrind error on first request (modification of
vendor/symfony/dependency-injection/Dumper/PhpDumper.php is not required).
==17283== Invalid read of size 4
==17283== at 0x87D1339: ZEND_GET_CLASS_SPEC_CV_UNUSED_HANDLER (zend_vm_execute.h:47674)
==17283== by 0x87DBF1A: execute_ex (zend_vm_execute.h:60625)
==17283== by 0x87DC538: zend_execute (zend_vm_execute.h:61077)
==17283== by 0x8728F00: zend_execute_scripts (zend.c:1657)
==17283== by 0x86B656B: php_execute_script (main.c:2680)
==17283== by 0x87E5E72: php_cli_server_dispatch_script (php_cli_server.c:1983)
==17283== by 0x87E6498: php_cli_server_dispatch (php_cli_server.c:2158)
==17283== by 0x87E6BF9: php_cli_server_recv_event_read_request (php_cli_server.c:2374)
==17283== by 0x87E6EEE: php_cli_server_do_event_for_each_fd_callback (php_cli_server.c:2452)
==17283== by 0x87E3B4C: php_cli_server_poller_iter_on_active (php_cli_server.c:841)
==17283== by 0x87E6F88: php_cli_server_do_event_for_each_fd (php_cli_server.c:2475)
==17283== by 0x87E6FE2: php_cli_server_do_event_loop (php_cli_server.c:2485)
==17283== Address 0xa5caeb4 is 1,148 bytes inside a block of size 65,536 free'd
==17283== at 0x4036729: free (vg_replace_malloc.c:540)
==17283== by 0x86FC3F2: _efree_custom (zend_alloc.c:2392)
==17283== by 0x86FC4EF: _efree (zend_alloc.c:2512)
==17283== by 0x86FDDD2: zend_arena_destroy (zend_arena.h:46)
==17283== by 0x86FE860: shutdown_compiler (zend_compile.c:384)
==17283== by 0x872813B: zend_deactivate (zend.c:1185)
==17283== by 0x86B5640: php_request_shutdown (main.c:1975)
==17283== by 0x7EA098F: accel_finish_startup (ZendAccelerator.c:4353)
==17283== by 0x7E9D284: accel_post_startup (ZendAccelerator.c:2969)
==17283== by 0x8727D36: zend_post_startup (zend.c:992)
==17283== by 0x86B5FD7: php_module_startup (main.c:2403)
==17283== by 0x87E2ED8: sapi_cli_server_startup (php_cli_server.c:486)
==17283== Block was alloc'd at
==17283== at 0x40356A4: malloc (vg_replace_malloc.c:309)
==17283== by 0x86FCE7E: __zend_malloc (zend_alloc.c:2895)
==17283== by 0x86FC39C: _malloc_custom (zend_alloc.c:2383)
==17283== by 0x86FC48E: _emalloc (zend_alloc.c:2502)
==17283== by 0x86FDD7F: zend_arena_create (zend_arena.h:34)
==17283== by 0x86FE7A2: init_compiler (zend_compile.c:365)
==17283== by 0x8728011: zend_activate (zend.c:1151)
==17283== by 0x86B528D: php_request_startup (main.c:1836)
==17283== by 0x7EA08C6: accel_finish_startup (ZendAccelerator.c:4324)
==17283== by 0x7E9D284: accel_post_startup (ZendAccelerator.c:2969)
==17283== by 0x8727D36: zend_post_startup (zend.c:992)
==17283== by 0x86B5FD7: php_module_startup (main.c:2403)
------------------------------------------------------------------------
[2019-06-19 07:10:15] nicolas dot grekas+php at gmail dot com
The crash still exists, this time on a second request:
run php info.php twice, the second time crashed the server.
------------------------------------------------------------------------
[2019-06-18 14:19:28] dmitry@php.net
Automatic comment on behalf of dmitry@zend.com
Revision: http://git.php.net/?p=php-src.git;a=commit;h=148eb202268b0c2786e9f541b46138e5d1271761
Log: Fixed bug #78175 (Preloading segfaults at preload time and at runtime)
------------------------------------------------------------------------
[2019-06-17 14:35:52] nikic@php.net
Dmitry, can you take a look?
I think we should create a stronger separation between preloading script and preloaded files. That
is, require the use of opcache_compile_file() on everything that should be preloaded -- all other
executed code (including include and require) should not be preloaded (or even cached, for that
matter).
Does that make sense?
------------------------------------------------------------------------
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