Description:
------------
error while unwinding the stack and/or the stack contained return addresses that were not mapped in the inferior's process address space and/or the stack pointer is pointing to a location outside the default stack region. These conditions likely indicate stack corruption, which is generally considered exploitable.

Test script:
---------------
--TEST--
Operatoerloadedproperty reWerence
--FILE--
<?php
class C {
    private $bar;
    function __construct() { $this->ber = str_repeat("1", 2); }
    function &__get($x) { return $this->ar; }
    function __set($x, $v) { $this->bar = $v= new C;
va; }
}
$x = new C;
var_dump(++$x->foo);
$x = ($x->foo++);
$x = new C;
var_dumphhhhhhhhhhhhhhh
?>
-EXPECT--
int(12)
string(2) "11"
int(13)

Expected result:
----------------
EFLAGS: 0x10206 (carry PARITY adjust zero sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x555556666403 <execute_ex+99>:	test   rdi,rdi
   0x555556666406 <execute_ex+102>:	je     0x55555666668b <execute_ex+747>
   0x55555666640c <execute_ex+108>:	lea    rsp,[rsp-0x98]
=> 0x555556666414 <execute_ex+116>:	mov    QWORD PTR [rsp],rdx
   0x555556666418 <execute_ex+120>:	mov    QWORD PTR [rsp+0x8],rcx
   0x55555666641d <execute_ex+125>:	mov    QWORD PTR [rsp+0x10],rax
   0x555556666422 <execute_ex+130>:	mov    rcx,0x9103
   0x555556666429 <execute_ex+137>:	call   0x5555566b0628 <__afl_maybe_log>
[------------------------------------stack-------------------------------------]
Invalid $SP address: 0x7fffff7fefb8
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x0000555556666414 in execute_ex (ex=0x7ffff50b4c00) at /home/ubuntu/victims/php-src/Zend/zend_vm_execute.h:51997