Re: [PATCH v10 04/11] HID: asus: fortify keyboard handshake

Denis Benato
2025-11-26T20:09:40Z

On 11/22/25 12:00, Antheas Kapenekakis wrote:
> Handshaking with an Asus device involves sending it a feature report
> with the string "ASUS Tech.Inc." and then reading it back to verify the
> handshake was successful, under the feature ID the interaction will
> take place.
>
> Currently, the driver only does the first part. Add the readback to
> verify the handshake was successful. As this could cause breakages,
> allow the verification to fail with a dmesg error until we verify
> all devices work with it (they seem to).
>
> Since the response is more than 16 bytes, increase the buffer size
> to 64 as well to avoid overflow errors.
Reviewed-by: Denis Benato <benato.denis96@gmail.com>
> Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
> ---
> drivers/hid/hid-asus.c | 30 +++++++++++++++++++++++++++---
> 1 file changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
> index c1a36a8beb35..2a412e10f916 100644
> --- a/drivers/hid/hid-asus.c
> +++ b/drivers/hid/hid-asus.c
> @@ -49,7 +49,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
> #define FEATURE_REPORT_ID 0x0d
> #define INPUT_REPORT_ID 0x5d
> #define FEATURE_KBD_REPORT_ID 0x5a
> -#define FEATURE_KBD_REPORT_SIZE 16
> +#define FEATURE_KBD_REPORT_SIZE 64
> #define FEATURE_KBD_LED_REPORT_ID1 0x5d
> #define FEATURE_KBD_LED_REPORT_ID2 0x5e
>
> @@ -395,13 +395,37 @@ static int asus_kbd_set_report(struct hid_device *hdev, const u8 *buf, size_t bu
>
> static int asus_kbd_init(struct hid_device *hdev, u8 report_id)
> {
> + /*
> + * The handshake is first sent as a set_report, then retrieved
> + * from a get_report. They should be equal.
> + */
> const u8 buf[] = { report_id, 0x41, 0x53, 0x55, 0x53, 0x20, 0x54,
> 0x65, 0x63, 0x68, 0x2e, 0x49, 0x6e, 0x63, 0x2e, 0x00 };
> int ret;
>
> ret = asus_kbd_set_report(hdev, buf, sizeof(buf));
> - if (ret < 0)
> - hid_err(hdev, "Asus failed to send init command: %d\n", ret);
> + if (ret < 0) {
> + hid_err(hdev, "Asus failed to send handshake: %d\n", ret);
> + return ret;
> + }
> +
> + u8 *readbuf __free(kfree) = kzalloc(FEATURE_KBD_REPORT_SIZE, GFP_KERNEL);
> + if (!readbuf)
> + return -ENOMEM;
> +
> + ret = hid_hw_raw_request(hdev, report_id, readbuf,
> + FEATURE_KBD_REPORT_SIZE, HID_FEATURE_REPORT,
> + HID_REQ_GET_REPORT);
> + if (ret < 0) {
> + hid_err(hdev, "Asus failed to receive handshake ack: %d\n", ret);
> + } else if (memcmp(readbuf, buf, sizeof(buf)) != 0) {
> + hid_warn(hdev, "Asus handshake returned invalid response: %*ph\n",
> + FEATURE_KBD_REPORT_SIZE, readbuf);
> + /*
> + * Do not return error if handshake is wrong until this is
> + * verified to work for all devices.
> + */
> + }
>
> return ret;
> }