Hi Javier, On Sun, Oct 01, 2023 at 05:35:54PM +0200, Javier Carrasco wrote: > syzbot has found a use-after-free bug [1] in the powermate driver. This > happens when the device is disconnected, which leads to a memory free > from the powermate_device struct. > When an asynchronous control message completes after the kfree and its > callback is invoked, the lock does not exist anymore and hence the bug. > > Use usb_kill_urb() on pm->config to cancel any in-progress requests upon > device disconnection. Given that this action is already done on pm->irq, > reorder the code to have both calls after the call to > input_unregister_device(), which is the most common approach. > > [1] https://syzkaller.appspot.com/bug?extid=0434ac83f907a1dbdd1e > > Signed-off-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx> > Reported-by: syzbot+0434ac83f907a1dbdd1e@xxxxxxxxxxxxxxxxxxxxxxxxx > --- > Changes in v2: > - Use usb_kill_urb() on pm->config upon device disconnection. > - Link to v1: https://lore.kernel.org/r/20230916-topic-powermate_use_after_free-v1-1-2ffa46652869@xxxxxxxxx > --- > drivers/input/misc/powermate.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/input/misc/powermate.c b/drivers/input/misc/powermate.c > index c1c733a9cb89..c0aea75eb087 100644 > --- a/drivers/input/misc/powermate.c > +++ b/drivers/input/misc/powermate.c > @@ -423,8 +423,9 @@ static void powermate_disconnect(struct usb_interface *intf) > usb_set_intfdata(intf, NULL); > if (pm) { > pm->requires_update = 0; > - usb_kill_urb(pm->irq); No, you do not want interrupts coming in while input device is being destroyed, this one needs to stay where it is. > input_unregister_device(pm->input); > + usb_kill_urb(pm->irq); > + usb_kill_urb(pm->config); > usb_free_urb(pm->irq); > usb_free_urb(pm->config); > powermate_free_buffers(interface_to_usbdev(intf), pm); Thanks. -- Dmitry
