From: Toshiaki Makita <redacted>
Date: Thu, 29 Mar 2018 19:05:28 +0900

Eric Dumazet reported syzbot found a new bug which leads to underflow of
size argument of memmove(), causing crash[1]. This can be triggered by tun
devices.

The underflow happened because skb_vlan_untag() did not expect vlan packets
without ethernet headers, and tun can produce such packets.
I also checked vlan_insert_inner_tag() and found a similar bug.

This series fixes these problems.

[1] https://marc.info/?l=linux-netdev&m=152221753920510&w=2

Series applied, thank you.