Commit 2ba5af42 authored by Jiri Benc's avatar Jiri Benc Committed by David S. Miller

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: default avatarYulong Pei <ypei@redhat.com>
Signed-off-by: default avatarJiri Benc <jbenc@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 793c3b40
...@@ -42,6 +42,9 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb, ...@@ -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) 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)) if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
return 0; return 0;
...@@ -70,6 +73,8 @@ static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci) ...@@ -70,6 +73,8 @@ static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
vlan_set_encap_proto(skb, vhdr); vlan_set_encap_proto(skb, vhdr);
skb->mac_header += VLAN_HLEN; skb->mac_header += VLAN_HLEN;
if (skb_network_offset(skb) < ETH_HLEN)
skb_set_network_header(skb, ETH_HLEN);
skb_reset_mac_len(skb); skb_reset_mac_len(skb);
return 0; return 0;
......
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