Patch "ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()" has been added to the 4.9-stable tree

Patch "ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ieee802154-6lowpan-fix-possible-null-deref-in-lowpan_device_event.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Mar 28 20:16:33 CEST 2018
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 5 Mar 2018 08:51:03 -0800
Subject: ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit ca0edb131bdf1e6beaeb2b8289fd6b374b74147d ]

A tun device type can trivially be set to arbitrary value using
TUNSETLINK ioctl().

Therefore, lowpan_device_event() must really check that ieee802154_ptr
is not NULL.

Fixes: 2c88b5283f60d ("ieee802154: 6lowpan: remove check on null")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Aring <alex.aring@gmail.com>
Cc: Stefan Schmidt <stefan@osg.samsung.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ieee802154/6lowpan/core.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/net/ieee802154/6lowpan/core.c
+++ b/net/ieee802154/6lowpan/core.c
@@ -204,9 +204,13 @@ static inline void lowpan_netlink_fini(v
 static int lowpan_device_event(struct notifier_block *unused,
 			       unsigned long event, void *ptr)
 {
-	struct net_device *wdev = netdev_notifier_info_to_dev(ptr);
+	struct net_device *ndev = netdev_notifier_info_to_dev(ptr);
+	struct wpan_dev *wpan_dev;
 
-	if (wdev->type != ARPHRD_IEEE802154)
+	if (ndev->type != ARPHRD_IEEE802154)
+		return NOTIFY_DONE;
+	wpan_dev = ndev->ieee802154_ptr;
+	if (!wpan_dev)
 		return NOTIFY_DONE;
 
 	switch (event) {
@@ -215,8 +219,8 @@ static int lowpan_device_event(struct no
 		 * also delete possible lowpan interfaces which belongs
 		 * to the wpan interface.
 		 */
-		if (wdev->ieee802154_ptr->lowpan_dev)
-			lowpan_dellink(wdev->ieee802154_ptr->lowpan_dev, NULL);
+		if (wpan_dev->lowpan_dev)
+			lowpan_dellink(wpan_dev->lowpan_dev, NULL);
 		break;
 	default:
 		return NOTIFY_DONE;


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.9/ipv6-fix-access-to-non-linear-packet-in-ndisc_fill_redirect_hdr_option.patch
queue-4.9/skbuff-fix-not-waking-applications-when-errors-are-enqueued.patch
queue-4.9/l2tp-do-not-accept-arbitrary-sockets.patch
queue-4.9/net-use-skb_to_full_sk-in-skb_update_prio.patch
queue-4.9/ieee802154-6lowpan-fix-possible-null-deref-in-lowpan_device_event.patch