HID: asus: do not abort probe when not necessary

[ Upstream commit 7253091 ]

In order to avoid dereferencing a NULL pointer asus_probe is aborted early
and control of some asus devices is transferred over hid-generic after
erroring out even when such NULL dereference cannot happen: only early
abort when the NULL dereference can happen.

Also make the code shorter and more adherent to coding standards
removing square brackets enclosing single-line if-else statements.

Fixes: d3af6ca ("HID: asus: fix UAF via HID_CLAIMED_INPUT validation")
Signed-off-by: Denis Benato <denis.benato@linux.dev>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: NeroReflex

drivers/hid/hid-asus.c

@@ -1223,22 +1223,17 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	 * were freed during registration due to no usages being mapped,
 	 * leaving drvdata->input pointing to freed memory.
 	 */
-	if (!drvdata->input || !(hdev->claimed & HID_CLAIMED_INPUT)) {
-		hid_err(hdev, "Asus input not registered\n");
-		ret = -ENOMEM;
-		goto err_stop_hw;
-	}
-
-	if (drvdata->tp) {
-		drvdata->input->name = "Asus TouchPad";
-	} else {
-		drvdata->input->name = "Asus Keyboard";
-	}
+	if (drvdata->input && (hdev->claimed & HID_CLAIMED_INPUT)) {
+		if (drvdata->tp)
+			drvdata->input->name = "Asus TouchPad";
+		else
+			drvdata->input->name = "Asus Keyboard";
 
-	if (drvdata->tp) {
-		ret = asus_start_multitouch(hdev);
-		if (ret)
-			goto err_stop_hw;
+		if (drvdata->tp) {
+			ret = asus_start_multitouch(hdev);
+			if (ret)
+				goto err_stop_hw;
+		}
 	}
 
 	return 0;