Hello,
(This is my first time reporting a Linux bug; please accept my apologies for any mistakes in the process.)
When initializing a HID PID device, hid-pidff.c checks for eight required HID reports and five optional reports. If the eight required reports are present, the hid_pidff_init() function then attempts to find the necessary fields in each required or optional report, using the pidff_find_fields() function. However, if any of the five optional reports is not present, pidff_find_fields() will trigger a null-pointer dereference.
I recently implemented the descriptors for a USB HID device with PID force-feedback capability. After implementing the required report descriptors but not the optional ones, I got an OOPS from the pidff_find_fields function. I saved the OOPS from my Ubuntu installation, and have attached it here. I later reproduced the issue on 6.11.6.
I was able to work around the issue by having my device present all of the optional report descriptors as well as all of the required ones.
Thank you, Nolan Nicholson