On Wed 2020-06-03 14:12:00, Cheng Jian wrote: > When lookup the symbols of module by module_kallsyms_lookup_name(), > the symbols address is visible only if the module's status isn't > MODULE_STATE_UNFORMED, This is problematic. > > When complete_formation is done, the state of the module is modified > to MODULE_STATE_COMING, and the symbol of module is visible to the > outside. > > At this time, the init function of the module has not been called, > so if the address of the function symbol has been found and called, > it may cause some exceptions. It is really handful that module symbols can be found already when the module is MODULE_STATE_COMING state. It is used by livepatching, ftrace, and maybe some other subsystems. The problem is that nobody is allowed to use (call) module symbols before mod->init() is called and the module is moved to MODULE_STATE_LIVE. By other words. Any code that calls module symbols before the module is fully initialized is buggy. The caller should get fixed, not the kallsyms side. Have you seen such a problem in the real life, please? Best Regards, Petr
