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[2016-09-23 20:03 UTC] ryan dot brothers at gmail dot com
Description:
------------
I am running into a few segmentation faults in PHP 7.0 and 7.1 when using Opcache. They seem to be very dependent on the code structure as minor updates to the code fix it - even just renaming a variable in some cases. It's tricky to generate small reproduce scripts, but I've been able to do one so far.
I am running on CentOS 7.
Create the below 3 files and run the script as:
php -n -d zend_extension=opcache.so -d opcache.enable_cli=1 file1.php
Test script:
---------------
file1.php:
-------
<?php
class a1
{
public function __call($name, $arguments)
{
require('file2.php');
}
}
$a1 = new a1;
$a1->file2();
-------
file2.php:
-------
<?php
$arguments = array();
require('file3.php');
class a2
{
public function __call($method_name, $arguments)
{
try
{
throw new \Exception('abc');
}
catch (\Exception $e)
{
try
{
test();
}
catch (\Error $e)
{
echo 'caught';
exit;
}
}
}
}
$a2 = new a2;
$a2->function2();
-------
file3.php:
-------
<?php
namespace test_aaaa;
function abc($row)
{
if (array_key_exists('a', $row) == true)
{
$a = ABC_ERROR_AAA__123_ERROR;
$a = ABC_ERROR_AAA__123_ERROR;
}
else
{
$a = ABC_ERROR_AAA__123_ERROR;
}
}
-------
Expected result:
----------------
caught
Actual result:
--------------
Segmentation fault
backtrace is:
Program received signal SIGSEGV, Segmentation fault.
zend_mm_alloc_small (size=56, bin_num=6, heap=0x7fffee200040) at /usr/local/src/php-7.1.0RC2/Zend/zend_alloc.c:1250
1250 heap->free_slot[bin_num] = p->next_free_slot;
(gdb) bt
#0 zend_mm_alloc_small (size=56, bin_num=6, heap=0x7fffee200040) at /usr/local/src/php-7.1.0RC2/Zend/zend_alloc.c:1250
#1 _emalloc_56 () at /usr/local/src/php-7.1.0RC2/Zend/zend_alloc.c:2325
#2 0x0000000000857300 in _array_init (arg=arg@entry=0x7fffffffab20, size=size@entry=2) at /usr/local/src/php-7.1.0RC2/Zend/zend_API.c:1060
#3 0x0000000000869baf in debug_backtrace_get_args (call=call@entry=0x7fffee2131a0, arg_array=arg_array@entry=0x7fffffffab20)
at /usr/local/src/php-7.1.0RC2/Zend/zend_builtin_functions.c:2271
#4 0x000000000086e446 in zend_fetch_debug_backtrace (return_value=return_value@entry=0x7fffffffaba0, skip_last=skip_last@entry=0, options=options@entry=0,
limit=limit@entry=0) at /usr/local/src/php-7.1.0RC2/Zend/zend_builtin_functions.c:2671
#5 0x0000000000874d9f in zend_default_exception_new_ex (class_type=0x1282820, skip_top_traces=0) at /usr/local/src/php-7.1.0RC2/Zend/zend_exceptions.c:214
#6 0x0000000000857abb in _object_and_properties_init (arg=arg@entry=0x7fffffffac10, class_type=class_type@entry=0x1282820, properties=properties@entry=0x0)
at /usr/local/src/php-7.1.0RC2/Zend/zend_API.c:1302
#7 0x0000000000857ba7 in _object_init_ex (arg=arg@entry=0x7fffffffac10, class_type=class_type@entry=0x1282820) at /usr/local/src/php-7.1.0RC2/Zend/zend_API.c:1310
#8 0x000000000044a403 in zend_throw_exception (exception_ce=exception_ce@entry=0x1282820, message=0x7fffee284000 "Call to undefined function test()",
code=code@entry=0) at /usr/local/src/php-7.1.0RC2/Zend/zend_exceptions.c:903
#9 0x0000000000449494 in zend_throw_error (exception_ce=0x1282820, exception_ce@entry=0x0, format=format@entry=0xe48ad8 "Call to undefined function %s()")
at /usr/local/src/php-7.1.0RC2/Zend/zend.c:1336
#10 0x00000000008e2589 in ZEND_INIT_FCALL_BY_NAME_SPEC_CONST_HANDLER () at /usr/local/src/php-7.1.0RC2/Zend/zend_vm_execute.h:2130
#11 0x0000000000899b8b in execute_ex (ex=<optimized out>) at /usr/local/src/php-7.1.0RC2/Zend/zend_vm_execute.h:429
#12 0x00000000008ec7c4 in zend_execute (op_array=0x7fffee27f0e0, op_array@entry=0x7fffe432a720, return_value=return_value@entry=0x7fffee2131a0)
at /usr/local/src/php-7.1.0RC2/Zend/zend_vm_execute.h:474
#13 0x0000000000855444 in zend_execute_scripts (type=type@entry=8, retval=0x7fffee2131a0, retval@entry=0x0, file_count=file_count@entry=3)
at /usr/local/src/php-7.1.0RC2/Zend/zend.c:1464
#14 0x00000000007f7140 in php_execute_script (primary_file=primary_file@entry=0x7fffffffd150) at /usr/local/src/php-7.1.0RC2/main/main.c:2533
#15 0x00000000008ee95f in do_cli (argc=7, argv=0x1202bd0) at /usr/local/src/php-7.1.0RC2/sapi/cli/php_cli.c:990
#16 0x000000000044dd50 in main (argc=7, argv=0x1202bd0) at /usr/local/src/php-7.1.0RC2/sapi/cli/php_cli.c:1378
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Last updated: Tue Oct 28 09:00:01 2025 UTC |
actually, this is not opcache issue, and also can be reproduced in 7.0, a simpler reproduce script is: <?php class A { public function __call($name, $args) { eval('$args = array(); var_dump(debug_backtrace());'); } } $a = new A(); $a->test("test"); ?> I don't see a easy fix for now howerver:<a fix could be: diff --git a/Zend/zend_execute_API.c b/Zend/zend_execute_API.c index 194f16d..1e68534 100644 --- a/Zend/zend_execute_API.c +++ b/Zend/zend_execute_API.c @@ -1527,7 +1527,9 @@ ZEND_API void zend_attach_symbol_table(zend_execute_data *execute_data) /* {{{ * if (zv) { if (Z_TYPE_P(zv) == IS_INDIRECT) { zval *val = Z_INDIRECT_P(zv); - + if (EXPECTED(Z_REFCOUNTED_P(zv) && (!Z_ISREF_P(val)))) { + ZVAL_NEW_REF(val, Z_INDIRECT_P(zv)); + } ZVAL_COPY_VALUE(var, val); } else { ZVAL_COPY_VALUE(var, zv);