[PATCH 3/4] HID: fix LEDs when report is unnumbered

[Benjamin Tissoires <bentiss@kernel.org>]

Both usbhid and i2c-hid are expecting the first byte of the incoming
data to be the report ID. It should be set to 0 when the report ID is
not used. Currently, we are not enforcing this, which means that if we
enforce HID-BPF for LEDs, we will not be able to send them.

Note that the allocated buffer takes into account that extra byte, so
this is safe to shift the data buffer by one.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
 drivers/hid/hid-input.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index d5308adb2894..eb84f63c51b8 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1830,9 +1830,9 @@ static void hidinput_led_worker(struct work_struct *work)
 					      led_work);
 	struct hid_field *field;
 	struct hid_report *report;
+	__u8 *buf, *data;
 	int ret;
 	u32 len;
-	__u8 *buf;
 
 	field = hidinput_get_led_field(hid);
 	if (!field)
@@ -1863,7 +1863,14 @@ static void hidinput_led_worker(struct work_struct *work)
 	if (!buf)
 		return;
 
-	hid_output_report(report, buf);
+	data = buf;
+	if (!report->id) {
+		data = &buf[1];
+		len++;
+	}
+
+	hid_output_report(report, data);
+
 	/* synchronous output report */
 	ret = hid_hw_output_report(hid, buf, len);
 	if (ret == -ENOSYS)

-- 
2.52.0