In the Linux kernel, the following vulnerability has been resolved: ieee802154: 6lowpan: fix NULL dereference in lowpan_newlink TUNSETLINK

In the Linux kernel, the following vulnerability has been resolved:

ieee802154: 6lowpan: fix NULL dereference in lowpan_newlink

TUNSETLINK allows a TUN device to change its link-layer type to
ARPHRD_IEEE802154 without initializing ieee802154_ptr. lowpan_newlink()
checks only the device type before dereferencing the pointer, so an
RTM_NEWLINK request can trigger a NULL pointer dereference.

Reject devices without ieee802154_ptr along with devices of the wrong type.