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[2011-07-26 19:19 UTC] jstephens at qualtrics dot com
Description:
------------
usort and uksort (and possibly other related functions) will segfault with the given script. I believe it is related to Zend's internal array "copy-on-write".
Test script:
---------------
class X {
function __construct($v) { $this->v = $v; }
}
function sortIt(&$list) {
usort($list, function($a, $b) use ($list) {
return $a->v - $b->v;
});
}
$list = array();
for($i = 0; $i < 10; ++$i) $list[mt_rand()] = new X(mt_rand());
echo "Sort...";
sortIt($list);
gc_collect_cycles();//segfault
echo "pass.\n";
Expected result:
----------------
"Sort...pass."
Actual result:
--------------
"Sort...Segmentation fault"
[dev@box dev]$ php --version
PHP 5.3.6 (cli) (built: Mar 17 2011 19:14:03)
Copyright (c) 1997-2011 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies
with Xdebug v2.1.1, Copyright (c) 2002-2011, by Derick Rethans
[dev@box dev]$ gdb php
<snip>
Reading symbols from /usr/bin/php...(no debugging symbols found)...done.
(gdb) run usortCrash.php
Starting program: /usr/bin/php usortCrash.php
[Thread debugging using libthread_db enabled]
Sort...
Program received signal SIGSEGV, Segmentation fault.
0x00000000005db586 in ?? ()
(gdb) bt
#0 0x00000000005db586 in ?? ()
#1 0x00000000005db610 in ?? ()
#2 0x00000000005dbef5 in gc_collect_cycles ()
#3 0x00000000005cee1d in ?? ()
#4 0x00002aaaae139d0a in xdebug_execute_internal () from /usr/lib64/php/modules/xdebug.so
#5 0x00000000005e669d in ?? ()
#6 0x00000000005e5dcb in execute ()
#7 0x00002aaaae13998e in xdebug_execute () from /usr/lib64/php/modules/xdebug.so
#8 0x00000000005bf395 in zend_execute_scripts ()
#9 0x000000000056f628 in php_execute_script ()
#10 0x0000000000648ce0 in ?? ()
#11 0x00000033ad41d994 in __libc_start_main () from /lib64/libc.so.6
#12 0x0000000000422009 in _start ()
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Last updated: Sun Nov 23 10:00:01 2025 UTC |
I just downloaded and compiled 5.3.6 from the website using "./configure --enable-debug=yes" on a different machine (Ubuntu 11.04 x64) and was still able to reproduce it. Here's a better backtrace: (gdb) run uSortCrash.php Starting program: /home/jstephens/bin/php-5.3.6/sapi/cli/php uSortCrash.php [Thread debugging using libthread_db enabled] Sort... Program received signal SIGSEGV, Segmentation fault. 0x00000000007f8f2f in zval_mark_grey (pz=0xfd1ab8) at /home/jstephens/bin/php-5.3.6/Zend/zend_gc.c:372 372 pz = *(zval**)p->pData; (gdb) bt #0 0x00000000007f8f2f in zval_mark_grey (pz=0xfd1ab8) at /home/jstephens/bin/php-5.3.6/Zend/zend_gc.c:372 #1 0x00000000007f91d9 in gc_mark_roots () at /home/jstephens/bin/php-5.3.6/Zend/zend_gc.c:435 #2 0x00000000007f9a8c in gc_collect_cycles () at /home/jstephens/bin/php-5.3.6/Zend/zend_gc.c:664 #3 0x00000000007e751d in zif_gc_collect_cycles (ht=0, return_value=0xfd93e0, return_value_ptr=0x0, this_ptr=0x0, return_value_used=0) at /home/jstephens/bin/php-5.3.6/Zend/zend_builtin_functions.c:337 #4 0x000000000080751c in zend_do_fcall_common_helper_SPEC (execute_data=0x7ffff7ebe090) at /home/jstephens/bin/php-5.3.6/Zend/zend_vm_execute.h:316 #5 0x000000000080ba8b in ZEND_DO_FCALL_SPEC_CONST_HANDLER (execute_data=0x7ffff7ebe090) at /home/jstephens/bin/php-5.3.6/Zend/zend_vm_execute.h:1606 #6 0x0000000000806a1a in execute (op_array=0xff1800) at /home/jstephens/bin/php-5.3.6/Zend/zend_vm_execute.h:107 #7 0x00000000007d4053 in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/jstephens/bin/php-5.3.6/Zend/zend.c:1194 #8 0x000000000075e583 in php_execute_script (primary_file=0x7fffffffdf70) at /home/jstephens/bin/php-5.3.6/main/main.c:2268 #9 0x00000000008b47dd in main (argc=2, argv=0x7fffffffe1d8) at /home/jstephens/bin/php-5.3.6/sapi/cli/php_cli.c:1193