Re: [PATCH net] openvswitch: fix panic with multiple vlan headers

[David Miller <davem@davemloft.net>]

From: Jiri Benc <jbenc@redhat.com>
Date: Thu, 21 Aug 2014 21:33:44 +0200

> When there are multiple vlan headers present in a received frame, the first
> one is put into vlan_tci and protocol is set to ETH_P_8021Q. Anything in the
> skb beyond the VLAN TPID may be still non-linear, including the inner TCI
> and ethertype. While ovs_flow_extract takes care of IP and IPv6 headers, it
> does nothing with ETH_P_8021Q. Later, if OVS_ACTION_ATTR_POP_VLAN is
> executed, __pop_vlan_tci pulls the next vlan header into vlan_tci.
> 
> This leads to two things:
> 
> 1. Part of the resulting ethernet header is in the non-linear part of the
>    skb. When eth_type_trans is called later as the result of
>    OVS_ACTION_ATTR_OUTPUT, kernel BUGs in __skb_pull. Also, __pop_vlan_tci
>    is in fact accessing random data when it reads past the TPID.
> 
> 2. network_header points into the ethernet header instead of behind it.
>    mac_len is set to a wrong value (10), too.
> 
> Reported-by: Yulong Pei <ypei@redhat.com>
> Signed-off-by: Jiri Benc <jbenc@redhat.com>

Applied and queued up for -stable, thanks Jiri.