[3.19.y-ckt stable] Patch "[media] si2168: Bounds check firmware" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    [media] si2168: Bounds check firmware

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 600edbcd809b9df2e5e6da68887a345cc5087dce Mon Sep 17 00:00:00 2001
From: Laura Abbott <labbott at fedoraproject.org>
Date: Tue, 29 Sep 2015 21:10:09 -0300
Subject: [PATCH 090/120] [media] si2168: Bounds check firmware

commit 47810b4341ac9d2f558894bc5995e6fa2a1298f9 upstream.

When reading the firmware and sending commands, the length must
be bounds checked to avoid overrunning the size of the command
buffer and smashing the stack if the firmware is not in the expected
format:

si2168 11-0064: found a 'Silicon Labs Si2168-B40'
si2168 11-0064: downloading firmware from file 'dvb-demod-si2168-b40-01.fw'
si2168 11-0064: firmware download failed -95
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ffffffffa085708f

Add the proper check.

Reported-by: Stuart Auchterlonie <sauchter at redhat.com>
Reviewed-by: Antti Palosaari <crope at iki.fi>
Signed-off-by: Laura Abbott <labbott at fedoraproject.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab at osg.samsung.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/media/dvb-frontends/si2168.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/media/dvb-frontends/si2168.c b/drivers/media/dvb-frontends/si2168.c
index acf0fc3..888cf2c 100644
--- a/drivers/media/dvb-frontends/si2168.c
+++ b/drivers/media/dvb-frontends/si2168.c
@@ -466,6 +466,10 @@ static int si2168_init(struct dvb_frontend *fe)
 		/* firmware is in the new format */
 		for (remaining = fw->size; remaining > 0; remaining -= 17) {
 			len = fw->data[fw->size - remaining];
+			if (len > SI2168_ARGLEN) {
+				ret = -EINVAL;
+				break;
+			}
 			memcpy(cmd.args, &fw->data[(fw->size - remaining) + 1], len);
 			cmd.wlen = len;
 			cmd.rlen = 1;
--
1.9.1