[4.2.y-ckt stable] Patch "nl80211: check netlink protocol in socket release notification" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

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

    nl80211: check netlink protocol in socket release notification

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt9.

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

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 7cd57b4030afa44dbc536d8c139f4d3099e22f7a Mon Sep 17 00:00:00 2001
From: Dmitry Ivanov <dmitrijs.ivanovs at ubnt.com>
Date: Wed, 6 Apr 2016 17:23:18 +0300
Subject: nl80211: check netlink protocol in socket release notification

commit 8f815cdde3e550e10c2736990d791f60c2ce43eb upstream.

A non-privileged user can create a netlink socket with the same port_id as
used by an existing open nl80211 netlink socket (e.g. as used by a hostapd
process) with a different protocol number.

Closing this socket will then lead to the notification going to nl80211's
socket release notification handler, and possibly cause an action such as
removing a virtual interface.

Fix this issue by checking that the netlink protocol is NETLINK_GENERIC.
Since generic netlink has no notifier chain of its own, we can't fix the
problem more generically.

Fixes: 026331c4d9b5 ("cfg80211/mac80211: allow registering for and sending action frames")
Signed-off-by: Dmitry Ivanov <dima at ubnt.com>
[rewrite commit message]
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/wireless/nl80211.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d059cf3..517ecf1 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -12780,7 +12780,7 @@ static int nl80211_netlink_notify(struct notifier_block * nb,
 	struct wireless_dev *wdev;
 	struct cfg80211_beacon_registration *reg, *tmp;

-	if (state != NETLINK_URELEASE)
+	if (state != NETLINK_URELEASE || notify->protocol != NETLINK_GENERIC)
 		return NOTIFY_DONE;

 	rcu_read_lock();
--
2.7.4