Description:
------------
Seems to be the same problem as in #40039. In (very) specific circumstances, uksort() will lead to a segmentation fault.
The Reproduce code worked on two entirely different computers for me, I couldn't test on more.

php compiled with:

$ ./configure --disable-libxml --disable-dom --disable-simplexml --disable-xmlwriter --disable-xml --disable-xmlreader --without-pear --enable-debug

But bug obviously exists in other versions/configurations, too (with same trigger).

Reproduce code:
---------------
<?php
$data = array(
    'bar-bazbazbaz.' => 0,
    'bar-bazbazbaz-' => 0,
    'foo' => 0,
);
uksort($data, 'magic_sort_cmp');
print_r($data);

function magic_sort_cmp($a, $b) {
  $a = substr($a, 1);
  $b = substr($b, 1);
  if (!$a) return $b ? -1 : 0;
  if (!$b) return 1;
  return magic_sort_cmp($a, $b);
}

?>

Expected result:
----------------
The array is output in the same order as defined.

Actual result:
--------------
Segmentation fault

Backtrace:

#0  0x0824a33b in zend_call_function (fci=0xbf9e6f74, fci_cache=0x0)
    at ~/tmp/php/php-5.2.11/Zend/zend_execute_API.c:696
#1  0x0824b7b0 in call_user_function_ex (function_table=0x8488460, 
    object_pp=0x0, function_name=0x0, retval_ptr_ptr=0xbf9e6fd8, 
    param_count=2, params=0x851dbbc, no_separation=1, symbol_table=0x0)
    at ~/tmp/php/php-5.2.11/Zend/zend_execute_API.c:640
#2  0x0824b818 in call_user_function (function_table=0x8488460, object_pp=0x0, 
    function_name=0x0, retval_ptr=0xbf9e700c, param_count=2, params=0xbf9e701c)
    at ~/tmp/php/php-5.2.11/Zend/zend_execute_API.c:613
#3  0x081a2b3b in array_user_key_compare (a=0x851d520, b=0x851d518)
    at ~/tmp/php/php-5.2.11/ext/standard/array.c:797
#4  0x082684f8 in zend_qsort (base=0x851d518, nmemb=3, siz=4, 
    compare=0x81a2a60 <array_user_key_compare>)
    at ~/tmp/php/php-5.2.11/Zend/zend_qsort.c:86
#5  0x08261434 in zend_hash_sort (ht=0x851d434, 
    sort_func=0x8268390 <zend_qsort>, 
    compar=0x81a2a60 <array_user_key_compare>, renumber=0)
    at ~/tmp/php/php-5.2.11/Zend/zend_hash.c:1282
#6  0x081a5c31 in zif_uksort (ht=2, return_value=0x851d500, 
    return_value_ptr=0x0, this_ptr=0x0, return_value_used=0)
    at ~/tmp/php/php-5.2.11/ext/standard/array.c:837
#7  0x08289a6a in zend_do_fcall_common_helper_SPEC (execute_data=0xbf9e732c)
    at ~/tmp/php/php-5.2.11/Zend/zend_vm_execute.h:200
#8  0x08276870 in execute (op_array=0x851b598)
    at ~/tmp/php/php-5.2.11/Zend/zend_vm_execute.h:92
#9  0x08255442 in zend_execute_scripts (type=8, retval=0x0, file_count=3)
    at ~/tmp/php/php-5.2.11/Zend/zend.c:1134
#10 0x08212b19 in php_execute_script (primary_file=0xbf9e96d8)
    at ~/tmp/php/php-5.2.11/main/main.c:2020
#11 0x082c1fe1 in main (argc=2, argv=0xbf9e97f4)
    at ~/tmp/php/php-5.2.11/sapi/cli/php_cli.c:1162