media: digitv: don't continue if remote control state can't be read

commit eecc70d2 upstream.

This results in an uninitialized variable read.

Reported-by: syzbot+6bf9606ee955b646c0e1@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/media/usb/dvb-usb/digitv.c

@@ -233,18 +233,22 @@ static struct rc_map_table rc_map_digitv_table[] = {
 
 static int digitv_rc_query(struct dvb_usb_device *d, u32 *event, int *state)
 {
-	int i;
+	int ret, i;
 	u8 key[5];
 	u8 b[4] = { 0 };
 
 	*event = 0;
 	*state = REMOTE_NO_KEY_PRESSED;
 
-	digitv_ctrl_msg(d,USB_READ_REMOTE,0,NULL,0,&key[1],4);
+	ret = digitv_ctrl_msg(d, USB_READ_REMOTE, 0, NULL, 0, &key[1], 4);
+	if (ret)
+		return ret;
 
 	/* Tell the device we've read the remote. Not sure how necessary
 	   this is, but the Nebula SDK does it. */
-	digitv_ctrl_msg(d,USB_WRITE_REMOTE,0,b,4,NULL,0);
+	ret = digitv_ctrl_msg(d, USB_WRITE_REMOTE, 0, b, 4, NULL, 0);
+	if (ret)
+		return ret;
 
 	/* if something is inside the buffer, simulate key press */
 	if (key[1] != 0)