Fix GH-12215: Module entry being overwritten causes type errors in ext/dom (PHP 8.4)

When we try to load an extension multiple times, we still overwrite the
type, module number, and handle. If the module number is used to
indicate module boundaries (e.g. in reflection and in dom, see e.g.
dom_objects_set_class_ex), then all sorts of errors can happen.

In the case of ext/dom, OP's error happens because the following
happens:
- The property handler is set up incorrectly in
  dom_objects_set_class_ex() because the wrong module number is
  specified. The class highest in the hierarchy is DOMNode, so the
  property handler is incorrectly set to that of DOMNode instead of
  DOMDocument.
- The documentElement property doesn't exist on DOMNode, it only exists
  on DOMDocument, so it tries to read using zend_std_read_property().
  As there is no user property called documentElement, that read
  operation returns an undef value.
  However, the type is still checked, resulting in the strange exception.

Solve this by changing the API such that the data is only overwritten if
it's owned data.

Closes GH-12246.

Author: ndossche

UPGRADING.INTERNALS

@@ -14,6 +14,11 @@ PHP 8.4 INTERNALS UPGRADE NOTES
 1. Internal API changes
 ========================
 
+* zend_register_module_ex() now takes an additional int module_type argument.
+  This function will also assign the module number and type, there is no need
+  to do this at the call site anymore. Writing the handle should happen after
+  successful registration.
+
 ========================
 2. Build system changes
 ========================

Zend/zend_API.c

@@ -2446,7 +2446,7 @@ ZEND_API void zend_destroy_modules(void) /* {{{ */
 }
 /* }}} */
 
-ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module) /* {{{ */
+ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module, int module_type) /* {{{ */
 {
 	size_t name_len;
 	zend_string *lcname;
@@ -2483,9 +2483,11 @@ ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module) /
 	}
 
 	name_len = strlen(module->name);
-	lcname = zend_string_alloc(name_len, module->type == MODULE_PERSISTENT);
+	lcname = zend_string_alloc(name_len, module_type == MODULE_PERSISTENT);
 	zend_str_tolower_copy(ZSTR_VAL(lcname), module->name, name_len);
 
+	int module_number = zend_next_free_module();
+
 	lcname = zend_new_interned_string(lcname);
 	if ((module_ptr = zend_hash_add_ptr(&module_registry, lcname, module)) == NULL) {
 		zend_error(E_CORE_WARNING, "Module \"%s\" is already loaded", module->name);
@@ -2495,7 +2497,10 @@ ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module) /
 	module = module_ptr;
 	EG(current_module) = module;
 
-	if (module->functions && zend_register_functions(NULL, module->functions, NULL, module->type)==FAILURE) {
+	module->module_number = module_number;
+	module->type = module_type;
+
+	if (module->functions && zend_register_functions(NULL, module->functions, NULL, module_type)==FAILURE) {
 		zend_hash_del(&module_registry, lcname);
 		zend_string_release(lcname);
 		EG(current_module) = NULL;
@@ -2511,9 +2516,7 @@ ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module) /
 
 ZEND_API zend_module_entry* zend_register_internal_module(zend_module_entry *module) /* {{{ */
 {
-	module->module_number = zend_next_free_module();
-	module->type = MODULE_PERSISTENT;
-	return zend_register_module_ex(module);
+	return zend_register_module_ex(module, MODULE_PERSISTENT);
 }
 /* }}} */
 

Zend/zend_API.h

@@ -375,7 +375,7 @@ ZEND_API zend_result zend_register_functions(zend_class_entry *scope, const zend
 ZEND_API void zend_unregister_functions(const zend_function_entry *functions, int count, HashTable *function_table);
 ZEND_API zend_result zend_startup_module(zend_module_entry *module_entry);
 ZEND_API zend_module_entry* zend_register_internal_module(zend_module_entry *module_entry);
-ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module);
+ZEND_API zend_module_entry* zend_register_module_ex(zend_module_entry *module, int module_type);
 ZEND_API zend_result zend_startup_module_ex(zend_module_entry *module);
 ZEND_API void zend_startup_modules(void);
 ZEND_API void zend_collect_module_handlers(void);

Zend/zend_builtin_functions.c

@@ -59,9 +59,7 @@ zend_module_entry zend_builtin_module = { /* {{{ */
 
 zend_result zend_startup_builtin_functions(void) /* {{{ */
 {
-	zend_builtin_module.module_number = 0;
-	zend_builtin_module.type = MODULE_PERSISTENT;
-	return (EG(current_module) = zend_register_module_ex(&zend_builtin_module)) == NULL ? FAILURE : SUCCESS;
+	return (EG(current_module) = zend_register_module_ex(&zend_builtin_module, MODULE_PERSISTENT)) == NULL ? FAILURE : SUCCESS;
 }
 /* }}} */
 

ext/standard/dl.c

@@ -230,15 +230,14 @@ PHPAPI int php_load_extension(const char *filename, int type, int start_now)
 		DL_UNLOAD(handle);
 		return FAILURE;
 	}
-	module_entry->type = type;
-	module_entry->module_number = zend_next_free_module();
-	module_entry->handle = handle;
 
-	if ((module_entry = zend_register_module_ex(module_entry)) == NULL) {
+	if ((module_entry = zend_register_module_ex(module_entry, type)) == NULL) {
 		DL_UNLOAD(handle);
 		return FAILURE;
 	}
 
+	module_entry->handle = handle;
+
 	if ((type == MODULE_TEMPORARY || start_now) && zend_startup_module_ex(module_entry) == FAILURE) {
 		DL_UNLOAD(handle);
 		return FAILURE;

sapi/phpdbg/phpdbg_prompt.c

@@ -1314,16 +1314,14 @@ PHPDBG_API const char *phpdbg_load_module_or_extension(char **path, const char *
 			goto quit;
 		}
 
-		module_entry->type = MODULE_PERSISTENT;
-		module_entry->module_number = zend_next_free_module();
-		module_entry->handle = handle;
-
-		if ((module_entry = zend_register_module_ex(module_entry)) == NULL) {
+		if ((module_entry = zend_register_module_ex(module_entry, MODULE_PERSISTENT)) == NULL) {
 			phpdbg_error("Unable to register module %s", *name);
 
 			goto quit;
 		}
 
+		module_entry->handle = handle;
+
 		if (zend_startup_module_ex(module_entry) == FAILURE) {
 			phpdbg_error("Unable to startup module %s", module_entry->name);