media: cec: cec_transmit_msg_fh: do sanity checks first

The code that fills in the CEC_MSG_CDC_MESSAGE physical address
is now done after the sanity checks. It also only does this if the
message length is >= 4 (i.e. there is room for the physical address).
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/cec/cec-adap.c

@@ -740,11 +740,6 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
 	else
 		msg->flags = 0;
 
-	if (msg->len > 1 && msg->msg[1] == CEC_MSG_CDC_MESSAGE) {
-		msg->msg[2] = adap->phys_addr >> 8;
-		msg->msg[3] = adap->phys_addr & 0xff;
-	}
-
 	/* Sanity checks */
 	if (msg->len == 0 || msg->len > CEC_MAX_MSG_SIZE) {
 		dprintk(1, "%s: invalid length %d\n", __func__, msg->len);
@@ -765,6 +760,12 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
 		dprintk(1, "%s: can't reply to poll msg\n", __func__);
 		return -EINVAL;
 	}
+
+	if (msg->len >= 4 && msg->msg[1] == CEC_MSG_CDC_MESSAGE) {
+		msg->msg[2] = adap->phys_addr >> 8;
+		msg->msg[3] = adap->phys_addr & 0xff;
+	}
+
 	if (msg->len == 1) {
 		if (cec_msg_destination(msg) == 0xf) {
 			dprintk(1, "%s: invalid poll message\n", __func__);