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 pretending as if kobject_uevent(KOBJ_REMOVE) from device_del() from input_unregister_device() did not fail. [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]> --- drivers/input/input.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/input/input.c b/drivers/input/input.c index 3304aaaffe87..6df3c33ef3aa 100644 --- a/drivers/input/input.c +++ b/drivers/input/input.c @@ -2032,6 +2032,19 @@ static void __input_unregister_device(struct input_dev *dev) mutex_unlock(&input_mutex); device_del(&dev->dev); + /* + * Regarding input subsystem, we always take care of sending uevent at + * "unregister" time, and we do not expect to have uevent sent out at + * the final "put" time. Therefore, if we failed to send uevent at + * "unregister" time (due to e.g. fault injection), complain it and + * do not allow the final "put" time to send the remove uevent again. + */ + if (dev->dev.kobj.state_add_uevent_sent && + !dev->dev.kobj.state_remove_uevent_sent) { + dev->dev.kobj.state_remove_uevent_sent = 1; + pr_warn("Failed to send remove uevent for %s\n", + dev_name(&dev->dev)); + } } static void devm_input_device_unregister(struct device *dev, void *res) -- 2.17.1
