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

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