Re: KASAN: use-after-free Read in usbhid_close (3)

[Alan Stern]

linux-input people:

syzbot has found a bug related to USB/HID/input, and I have narrowed it
down to the wacom driver.  As far as I can tell, the problem is caused
the fact that drivers/hid/wacom_sys.c calls input_register_device()
in several places, but it never calls input_unregister_device().

I know very little about the input subsystem, but this certainly seems 
like a bug.

When the device is unplugged, the disconnect pathway doesn't call
hid_hw_close().  That routine doesn't get called until the user closes
the device file (which can be long after the device is gone and
hid_hw_stop() has run).  Then usbhid_close() gets a use-after-free
error when it tries to access data structures that were deallocated by
usbhid_stop().  No doubt there are other problems too, but this is
the one that syzbot found.

Can any of you help fix this?  Thanks.

Alan Stern