| Message ID | 1550484563-13217-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp (mailing list archive) |
|---|---|
| State | Rejected |
| Headers | show |
| Series | input : avoid too late kobject_uevent(KOBJ_REMOVE) call | expand |
Hi Tetsuo, On Mon, Feb 18, 2019 at 07:09:23PM +0900, Tetsuo Handa wrote: > 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 <syzbot+f648cfb7e0b52bf7ae32@syzkaller.appspotmail.com> > Analyzed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > Cc: Kay Sievers <kay@vrfy.org> > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > --- > 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)); Input has no business reaching into kobj internals. This should be solved in lib/kobject_uevent.c, not anywhere else. Thanks.
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)
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 <syzbot+f648cfb7e0b52bf7ae32@syzkaller.appspotmail.com> Analyzed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> --- drivers/input/input.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)