Commit 2ba5af42 authored Aug 21, 2014 by Jiri Benc Committed by David S. Miller Aug 22, 2014

openvswitch: fix panic with multiple vlan headers

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>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 793c3b40

net/openvswitch/actions.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -42,6 +42,9 @@ static int do_execute_actions(struct datapath dp, struct sk_buff skb,

		static int make_writable(struct sk_buff *skb, int write_len)
		{
		if (!pskb_may_pull(skb, write_len))
		return -ENOMEM;

		if (!skb_cloned(skb) \|\| skb_clone_writable(skb, write_len))
		return 0;

		@@ -70,6 +73,8 @@ static int __pop_vlan_tci(struct sk_buff skb, __be16 current_tci)

		vlan_set_encap_proto(skb, vhdr);
		skb->mac_header += VLAN_HLEN;
		if (skb_network_offset(skb) < ETH_HLEN)
		skb_set_network_header(skb, ETH_HLEN);
		skb_reset_mac_len(skb);

		return 0;