[PATCH net 0/5] net: reject short linear Ethernet headers from tc actions, tun and OVS

[Jamal Hadi Salim <jhs@mojatatu.com>]

A recent flurry of bug fixes for dealing with kernel crashes around
eth_type_trans() showed up on the list. The earliest attempt to fix
this came from Ren Wei <n05ec@lzu.edu.cn>. There are many others
(but i lost track of them). Ren Wei's latest attempt hit a roadblock
with a NACK from Eric[1] asking to fix at the "producers"

These producers can hand a packet to a shared consumer with less than a
full Ethernet header in the linear area.
This series identifies and fixes the following producers:

  1. act_vlan POP_ETH rejects a short linear Ethernet header at the tc
     action boundary.
  2. act_mpls POP does the same, standalone or chained after POP_ETH.
  3. tun keeps the no-offload copy hint safe (raising a short hint instead
     of rejecting a valid write) while guaranteeing a linear Ethernet
     header for the redirected consumer.
  4. OVS pop_mpls(ETH_P_TEB) pulls the inner Ethernet header before
     restoring MAC_PROTO_ETHERNET.
  5. OVS pop_nsh(TUN_P_ETHERNET) does the same for the NSH producer.

1: https://lore.kernel.org/netdev/e85fa16e-df3c-43dd-bb3a-9edca07200ea@kernel.org/
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>

Jamal Hadi Salim (5):
  net/sched: act_vlan: reject short linear Ethernet headers after POP_ETH
  net/sched: act_mpls: reject short linear Ethernet headers after pop
  net: tun: keep TUN short linear copy hints safe
  net: openvswitch: ensure a linear inner Ethernet header on TEB pop
  net: openvswitch: ensure a linear inner Ethernet header on NSH pop