HID: provide a helper for validating hid reports

kees · toddpoynor · commit d1e485f2f0a5 · 2014-08-13T19:54:35.000-07:00
Many drivers need to validate the characteristics of their HID report
during initialization to avoid misusing the reports. This adds a common
helper to perform validation of the report exisitng, the field existing,
and the expected number of values within the field.

Change-Id: I572af2301180ba9b260112e147ae80149f39e6a3
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: stable@vger.kernel.org
Reviewed-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
@@ -796,17 +796,7 @@ struct hid_report *hid_validate_values(struct hid_device *hid,
 	 * ->numbered being checked, which may not always be the case when
 	 * drivers go to access report values.
 	 */
-	if (id == 0) {
-		/*
-		 * Validating on id 0 means we should examine the first
-		 * report in the list.
-		 */
-		report = list_entry(
-				hid->report_enum[type].report_list.next,
-				struct hid_report, list);
-	} else {
-		report = hid->report_enum[type].report_id_hash[id];
-	}
+	report = hid->report_enum[type].report_id_hash[id];
 	if (!report) {
 		hid_err(hid, "missing %s %u\n", hid_report_names[type], id);
 		return NULL;
