From 2ba5af42a7b59ef01f9081234d8855140738defd Mon Sep 17 00:00:00 2001 From: Jiri Benc Date: Thu, 21 Aug 2014 21:33:44 +0200 Subject: [PATCH] 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 Signed-off-by: Jiri Benc Signed-off-by: David S. Miller --- net/openvswitch/actions.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index fe5cda0deb39..5231652a95d9 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -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; -- 2.30.2