media: winbond-cir: buffer overrun during transmit

We're reading beyond the buffer before checking its length.

BUG: KASAN: slab-out-of-bounds in wbcir_irq_tx
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/rc/winbond-cir.c

@@ -429,7 +429,7 @@ wbcir_irq_tx(struct wbcir_data *data)
 		bytes[used] = byte;
 	}
 
-	while (data->txbuf[data->txoff] == 0 && data->txoff != data->txlen)
+	while (data->txoff != data->txlen && data->txbuf[data->txoff] == 0)
 		data->txoff++;
 
 	if (used == 0) {