syzbot is hitting use-after-free bug in uinput module [1]. This is because
kobject_uevent(KOBJ_REMOVE) is called again due to commit 0f4dafc0563c6c49
("Kobject: auto-cleanup on final unref") after memory allocation fault
injection made kobject_uevent(KOBJ_REMOVE) from device_del() from
input_unregister_device() fail, while uinput_destroy_device() is expecting
that kobject_uevent(KOBJ_REMOVE) is not called after device_del() from
input_unregister_device() completed. Fix this problem by marking "remove"
event done regardless of result.[1] https://syzkaller.appspot.com/bug?id=8b17c134fe938bbddd75a45afaa9e68af43a362d Reported-by: syzbot <[email protected]> Analyzed-by: Dmitry Torokhov <[email protected]> Cc: Kay Sievers <[email protected]> Signed-off-by: Tetsuo Handa <[email protected]> --- lib/kobject_uevent.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index f058026..7ec4165 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -466,6 +466,13 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, int i = 0; int retval = 0; + /* + * Mark "remove" event done regardless of result, for some subsystems + * do not want to re-trigger "remove" event via automatic cleanup. + */ + if (action == KOBJ_REMOVE && kobj->state_add_uevent_sent) + kobj->state_remove_uevent_sent = 1; + pr_debug("kobject: '%s' (%p): %s\n", kobject_name(kobj), kobj, __func__); @@ -567,10 +574,6 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, kobj->state_add_uevent_sent = 1; break; - case KOBJ_REMOVE: - kobj->state_remove_uevent_sent = 1; - break; - case KOBJ_UNBIND: zap_modalias_env(env); break; -- 1.8.3.1
