FAILED: patch "[PATCH] [media] digitv: limit messages to buffer size" failed to apply to 3.18-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 821117dc21083a99dd99174c10848d70ff43de29 Mon Sep 17 00:00:00 2001
From: Alyssa Milburn <amilburn@zall.org>
Date: Sat, 1 Apr 2017 14:33:42 -0300
Subject: [PATCH] [media] digitv: limit messages to buffer size

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@zall.org>
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/usb/dvb-usb/digitv.c b/drivers/media/usb/dvb-usb/digitv.c
index 4284f6984dc1..475a3c0cdee7 100644
--- a/drivers/media/usb/dvb-usb/digitv.c
+++ b/drivers/media/usb/dvb-usb/digitv.c
@@ -33,6 +33,9 @@ static int digitv_ctrl_msg(struct dvb_usb_device *d,
 
 	wo = (rbuf == NULL || rlen == 0); /* write-only */
 
+	if (wlen > 4 || rlen > 4)
+		return -EIO;
+
 	memset(st->sndbuf, 0, 7);
 	memset(st->rcvbuf, 0, 7);