published September 4, 2026
In the Linux kernel, the following vulnerability has been resolved:
HID: pidff: fix OOB write when hid->inputs is empty
hid_pidff_init_with_quirks() derives its input_dev from
list_entry(hid->inputs.next, struct hid_input, list)
without first checking that hid->inputs is non-empty. The list member
of struct hid_input is at offset 0, so on an empty list list_entry()
yields &hid->inputs itself and the following hidinput->input load reads
an unrelated member of struct hid_device. dev is then a type-confused
pointer, and force-feedback init writes through it: each
set_bit(FF_*, dev->ffbit) stores 8 bytes at dev + 192, past the end of
the object dev actually aliases, and input_ff_create() adds further
writes of a heap pointer and two function pointers.
Until hid-universal-pidff the only caller was hid_pidff_init() from
usbhid, which runs under HID_CLAIMED_INPUT and therefore always has at
least one hid_input. universal_pidff_probe() starts the device with
HID_CONNECT_DEFAULT & ~HID_CONNECT_FF and then calls
hid_pidff_init_with_quirks() directly whenever the descriptor carries a
PID usage page, bypassing that gate. A report descriptor whose only
application collection is on HID_UP_PID leaves hid->inputs empty while
hid_connect() still succeeds through the hidraw claim, so probe reaches
the unguarded list_entry().
The write happens in the USB probe path, on the hotplug workqueue, so
plugging in a malicious device is enough to trigger it; no attacker
software and no logged-in user are required. KASAN reports an 8-byte
out-of-bounds write in hid_pidff_init_with_quirks() reached from
universal_pidff_probe().
Check for an empty list before deriving dev and return -ENODEV, as the
other HID force-feedback drivers already do. universal_pidff_probe()
propagates the error and unwinds.
Discovered by XBOW, triaged by Baul Lee <[email protected]>