media: vp7045: do not read uninitialized values if usb transfer fails

It is not a fatal error if reading the mac address or the remote control
decoder state fails.

Reported-by: syzbot+ec869945d3dde5f33b43@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/usb/dvb-usb/vp7045.c

@@ -96,10 +96,14 @@ static int vp7045_power_ctrl(struct dvb_usb_device *d, int onoff)
 
 static int vp7045_rc_query(struct dvb_usb_device *d)
 {
+	int ret;
 	u8 key;
-	vp7045_usb_op(d,RC_VAL_READ,NULL,0,&key,1,20);
 
-	deb_rc("remote query key: %x %d\n",key,key);
+	ret = vp7045_usb_op(d, RC_VAL_READ, NULL, 0, &key, 1, 20);
+	if (ret)
+		return ret;
+
+	deb_rc("remote query key: %x\n", key);
 
 	if (key != 0x44) {
 		/*
@@ -115,15 +119,18 @@ static int vp7045_rc_query(struct dvb_usb_device *d)
 
 static int vp7045_read_eeprom(struct dvb_usb_device *d,u8 *buf, int len, int offset)
 {
-	int i = 0;
-	u8 v,br[2];
+	int i, ret;
+	u8 v, br[2];
 	for (i=0; i < len; i++) {
 		v = offset + i;
-		vp7045_usb_op(d,GET_EE_VALUE,&v,1,br,2,5);
+		ret = vp7045_usb_op(d, GET_EE_VALUE, &v, 1, br, 2, 5);
+		if (ret)
+			return ret;
+
 		buf[i] = br[1];
 	}
-	deb_info("VP7045 EEPROM read (offs: %d, len: %d) : ",offset, i);
-	debug_dump(buf,i,deb_info);
+	deb_info("VP7045 EEPROM read (offs: %d, len: %d) : ", offset, i);
+	debug_dump(buf, i, deb_info);
 	return 0;
 }