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

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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: 2c88b5283f ("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>
This commit is contained in:
Eric Dumazet 2018-03-05 08:51:03 -08:00 committed by David S. Miller
parent 9f62c15f28
commit ca0edb131b
1 changed files with 8 additions and 4 deletions
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12
net/ieee802154/6lowpan/core.c
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@ -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;