From ca0edb131bdf1e6beaeb2b8289fd6b374b74147d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 5 Mar 2018 08:51:03 -0800 Subject: [PATCH] ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event() 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 Cc: Alexander Aring Cc: Stefan Schmidt Reported-by: syzbot Acked-by: Stefan Schmidt Signed-off-by: David S. Miller --- net/ieee802154/6lowpan/core.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c index 974765b7d92a..e9f0489e4229 100644 --- a/net/ieee802154/6lowpan/core.c +++ b/net/ieee802154/6lowpan/core.c @@ -206,9 +206,13 @@ static inline void lowpan_netlink_fini(void) 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) { @@ -217,8 +221,8 @@ static int lowpan_device_event(struct notifier_block *unused, * 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; -- 2.30.2