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); 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); --- base-commit: cefc06e4de1477dbdc3cb2a91d4b1873b7797a5c change-id: 20230916-topic-powermate_use_after_free-c703c7969c91 Best regards, -- Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx>
