HID: make arrays usage and value to be the same

The HID subsystem allows an "HID report field" to have a different
number of "values" and "usages" when it is allocated. When a field
struct is created, the size of the usage array is guaranteed to be at
least as large as the values array, but it may be larger. This leads to
a potential out-of-bounds write in
__hidinput_change_resolution_multipliers() and an out-of-bounds read in
hidinput_count_leds().

To fix this, let's make sure that both the usage and value arrays are
the same size.

Cc: [e-mail]
Signed-off-by: Will McVicker <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/hid-core.c

···
  * Register a new field for this report.
  */
 
-static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)
+static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages)
 {
 	struct hid_field *field;
 
···
 
 	field = kzalloc((sizeof(struct hid_field) +
 			 usages * sizeof(struct hid_usage) +
-			 values * sizeof(unsigned)), GFP_KERNEL);
+			 usages * sizeof(unsigned)), GFP_KERNEL);
 	if (!field)
 		return NULL;
 
···
 	usages = max_t(unsigned, parser->local.usage_index,
 				 parser->global.report_count);
 
-	field = hid_register_field(report, usages, parser->global.report_count);
+	field = hid_register_field(report, usages);
 	if (!field)
 		return 0;