In the Linux kernel, the following vulnerability has been resolved: HID: wacom: fix OOB read in wacom_wac_pen_serial_enforce() The 'wacom_

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

HID: wacom: fix OOB read in wacom_wac_pen_serial_enforce()

The 'wacom_wac_pen_serial_enforce()' function may calculate and pass an
invalid offset to hid_field_extract(), resulting in memory reads at
incorrect addresses -- possibly beyond the end of the report. If a
field in the HID descriptor lists more usages than its Report Count
actually reserves space for, the function's inner 'j' will walk past
the end of the field:

 1for (i = 0; i < report->maxfield; i++) {
 2	for (j = 0; j < report->field[i]->maxusage; j++) {
 3		...
 4		value = hid_field_extract(hdev, raw_data + 1,
 5					  offset + j * size, size);

A descriptor listing 12288 usages against Report Count 1 has the loop
extract the usage at index 12287 from bit offset 98296 -- about 12 KB
past a 2-byte received report. The value is stored in
wacom_wac->serial[0] and can reach userspace as an MSC_SERIAL event,
making this an information disclosure.

Clamp the loop to field->report_count, the number of value slots the
report holds. Value slots past the last declared usage are still
scanned; they reuse that usage (HID 1.11, 6.2.2.8).

Verified on v6.12.105 with a UHID reproducer: a 2-byte report from
such a descriptor trips KASAN before the patch and not after it.