[PATCH 3.16 054/134] [media] digitv: limit messages to buffer size

[Ben Hutchings]

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

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

From: Alyssa Milburn <amilb...@zall.org>

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 <amilb...@zall.org>
Signed-off-by: Mauro Carvalho Chehab <mche...@s-opensource.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
--- a/drivers/media/usb/dvb-usb/digitv.c
+++ b/drivers/media/usb/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;