Fix potential crash after unload of func_periodic_hook or test_message.

These modules save a pointer to the context they create on load, and
use that pointer to destroy the context at unload.  It is not safe
to save this pointer, it is replaced during load of pbx_config,
pbx_lua or pbx_ael.

This change causes the modules to pass NULL to ast_context_destroy,
a safer way to perform the unregistration since it does not use
a pointer that could become invalid.

ASTERISK-25085 #close
Reported by: Corey Farrell

Change-Id: I6a00ec8e38046058f97dc703e1adcde9bf517835

funcs/func_periodic_hook.c

@@ -446,13 +446,9 @@ static struct ast_custom_function hook_function = {
 	.write = hook_write,
 };
 
-static struct ast_context *func_periodic_hook_context;
-
 static int unload_module(void)
 {
-	if (func_periodic_hook_context) {
-		ast_context_destroy(func_periodic_hook_context, AST_MODULE);
-	}
+	ast_context_destroy(NULL, AST_MODULE);
 
 	return ast_custom_function_unregister(&hook_function);
 }
@@ -461,9 +457,7 @@ static int load_module(void)
 {
 	int res;
 
-	func_periodic_hook_context = ast_context_find_or_create(NULL, NULL,
-			context_name, AST_MODULE);
-	if (!func_periodic_hook_context) {
+	if (!ast_context_find_or_create(NULL, NULL, context_name, AST_MODULE)) {
 		ast_log(LOG_ERROR, "Failed to create %s dialplan context.\n", context_name);
 		return AST_MODULE_LOAD_DECLINE;
 	}

tests/test_message.c

@@ -51,8 +51,6 @@ ASTERISK_REGISTER_FILE()
 /*! \brief The number of user events we should get in a dialplan test */
 #define DEFAULT_EXPECTED_EVENTS 4
 
-static struct ast_context *test_message_context;
-
 /*! \brief The current number of received user events */
 static int received_user_events;
 
@@ -822,9 +820,7 @@ static int unload_module(void)
 	AST_TEST_UNREGISTER(test_message_has_destination_handler);
 	AST_TEST_UNREGISTER(test_message_msg_send);
 
-	if (test_message_context) {
-		ast_context_destroy(test_message_context, AST_MODULE);
-	}
+	ast_context_destroy(NULL, AST_MODULE);
 
 	ast_manager_unregister_hook(&user_event_hook);
 
@@ -835,8 +831,7 @@ static int create_test_dialplan(void)
 {
 	int res = 0;
 
-	test_message_context = ast_context_find_or_create(NULL, NULL, TEST_CONTEXT, AST_MODULE);
-	if (!test_message_context) {
+	if (!ast_context_find_or_create(NULL, NULL, TEST_CONTEXT, AST_MODULE)) {
 		return -1;
 	}