Fix oss-fuzz #61712: assertion failure with error handler during binary op

Because the error handler is invoked after the property is updated,
the error handler has the opportunity to remove it before the property
is returned.

Switching the order around fixes this issue. The comments mention that
the current ordering prevents overwriting the EG(std_property_info)
field in the error handler. EG(std_property_info) no longer exists as it
was removed in 7471c21. Back then a global was used to store the
returned property info, but as this is no longer the case there is no
longer a need to protect against overwriting a global.

Closes GH-12062.

Author: nielsdos

NEWS

@@ -8,6 +8,8 @@ PHP                                                                        NEWS
     (Jakub Zelenka)
   . Fixed bug GH-11790 (On riscv64 require libatomic if actually needed).
     (Jeremie Courreges-Anglas)
+  . Fixed oss-fuzz #61712 (assertion failure with error handler during binary
+    op). (nielsdos)
 
 - DOM:
   . Fixed GH-11952 (Confusing warning when blocking entity loading via

Zend/tests/oss_fuzz_61712.phpt

@@ -0,0 +1,20 @@
+--TEST--
+OSS-Fuzz #61712 (assertion failure with error handler during binary op)
+--FILE--
+<?php
+#[AllowDynamicProperties]
+class C {
+    function error($_, $msg) {
+        echo $msg, "\n";
+        unset($this->a);
+    }
+}
+
+$c = new C;
+set_error_handler([$c, 'error']);
+$c->a %= 10;
+var_dump($c->a);
+?>
+--EXPECT--
+Undefined property: C::$a
+int(0)

Zend/zend_object_handlers.c

@@ -1160,12 +1160,10 @@ ZEND_API zval *zend_std_get_property_ptr_ptr(zend_object *zobj, zend_string *nam
 			if (UNEXPECTED(!zobj->properties)) {
 				rebuild_object_properties(zobj);
 			}
-			retval = zend_hash_update(zobj->properties, name, &EG(uninitialized_zval));
-			/* Notice is thrown after creation of the property, to avoid EG(std_property_info)
-			 * being overwritten in an error handler. */
 			if (UNEXPECTED(type == BP_VAR_RW || type == BP_VAR_R)) {
 				zend_error(E_WARNING, "Undefined property: %s::$%s", ZSTR_VAL(zobj->ce->name), ZSTR_VAL(name));
 			}
+			retval = zend_hash_update(zobj->properties, name, &EG(uninitialized_zval));
 		}
 	} else if (zobj->ce->__get == NULL) {
 		retval = &EG(error_zval);