In the Linux kernel, the following vulnerability has been resolved:

HID: magicmouse: Do not crash on missing msc->input

Fake USB devices can send their own report descriptors for which the inputmapping() hook does not get called. In this case, msc->input stays NULL, leading to a crash at a later time.

Detect this condition in the inputconfigured() hook and reject the device.

This is not supposed to happen with actual magic mouse devices, but can be provoked by imposing as a magic mouse USB device.