[PATCH 3.2 25/59] [media] digitv: limit messages to buffer size

[Ben Hutchings]

3.2.92-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Alyssa Milburn <amilburn@xxxxxxxx>

commit 821117dc21083a99dd99174c10848d70ff43de29 upstream.

Return an error rather than memcpy()ing beyond the end of the buffer.
Internal callers use appropriate sizes, but digitv_i2c_xfer may not.

Signed-off-by: Alyssa Milburn <amilburn@xxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/media/dvb/dvb-usb/digitv.c
+++ b/drivers/media/dvb/dvb-usb/digitv.c
@@ -30,6 +30,10 @@ static int digitv_ctrl_msg(struct dvb_us
 {
 	int wo = (rbuf == NULL || rlen == 0); /* write-only */
 	u8 sndbuf[7],rcvbuf[7];
+
+	if (wlen > 4 || rlen > 4)
+		return -EIO;
+
 	memset(sndbuf,0,7); memset(rcvbuf,0,7);
 
 	sndbuf[0] = cmd;