Messages in this thread Patch in this message |  | | Date | Wed, 19 Jun 2019 13:33:24 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH] module: Propagate MODULE_STATE_COMING notifier errors |
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On Wed, Jun 19, 2019 at 01:23:50PM +0200, Peter Zijlstra wrote: > On Wed, Jun 19, 2019 at 01:12:12PM +0200, Miroslav Benes wrote: > > > @@ -3780,7 +3781,7 @@ static int load_module(struct load_info *info, const char __user *uargs, > > > > > > err = prepare_coming_module(mod); > > > if (err) > > > - goto bug_cleanup; > > > + goto coming_cleanup; > > > > Not good. klp_module_going() is not prepared to be called without > > klp_module_coming() succeeding. "Funny" things might happen. > > Bah, I did look at that but failed to spot it :/ > > > So it calls for more fine-grained error handling. > > Another approach that I considered was trying to re-iterate the notifier > list up until the point we got, but that was fairly non-trivial and > needed changes to the notifier crud itself. > > I'll try again.
How's something like so:
diff --git a/kernel/module.c b/kernel/module.c index 80c7c09584cf..eba6560c89da 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3631,16 +3631,28 @@ static int complete_formation(struct module *mod, struct load_info *info) static int prepare_coming_module(struct module *mod) { - int err; + struct blocking_notifier_head *nh = &module_notify_list; + int err, nr; ftrace_module_enable(mod); err = klp_module_coming(mod); if (err) return err; - blocking_notifier_call_chain(&module_notify_list, - MODULE_STATE_COMING, mod); - return 0; + if (!rcu_access_pointer(nh->head)) + return 0; + + down_read(&nh->rwsem); + ret = notifier_call_chain(&nh->head, MODULE_STATE_COMING, mod, -1, &nr); + if (ret & NOTIFIER_STOP_MASK) + notifier_call_chain(&nh->head, MODULE_STATE_GOING, mod, nr, NULL); + up_read(&nh->rwsem); + + err = notifier_to_err(err); + if (err) + klp_module_going(mod); + + return err; } static int unknown_module_param_cb(char *param, char *val, const char *modname,
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