[PATCH 3.16.y-ckt 102/133] batman-adv: Fix potentially broken skb network header access

From: Luis Henriques
Date: Wed Sep 30 2015 - 06:11:05 EST

3.16.7-ckt18 -stable review patch. If anyone has any objections, please let me know.


From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@xxxxxxxxx>

commit 53cf037bf846417fd92dc92ddf97267f69b110f4 upstream.

The two commits noted below added calls to ip_hdr() and ipv6_hdr(). They
need a correctly set skb network header.

Unfortunately we cannot rely on the device drivers to set it for us.
Therefore setting it in the beginning of the according ndo_start_xmit

Fixes: 1d8ab8d3c176 ("batman-adv: Modified forwarding behaviour for multicast packets")
Fixes: ab49886e3da7 ("batman-adv: Add IPv4 link-local/IPv6-ll-all-nodes multicast support")
Signed-off-by: Linus LÃssing <linus.luessing@xxxxxxxxx>
Signed-off-by: Marek Lindner <mareklindner@xxxxxxxxxxxxx>
Signed-off-by: Antonio Quartulli <antonio@xxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
net/batman-adv/soft-interface.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 713498c378c7..3348eccf3e22 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -173,6 +173,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
int gw_mode;
enum batadv_forw_mode forw_mode;
struct batadv_orig_node *mcast_single_orig = NULL;
+ int network_offset = ETH_HLEN;

if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
goto dropped;
@@ -185,14 +186,18 @@ static int batadv_interface_tx(struct sk_buff *skb,
case ETH_P_8021Q:
vhdr = vlan_eth_hdr(skb);

- if (vhdr->h_vlan_encapsulated_proto != ethertype)
+ if (vhdr->h_vlan_encapsulated_proto != ethertype) {
+ network_offset += VLAN_HLEN;
+ }

/* fall through */
goto dropped;

+ skb_set_network_header(skb, network_offset);
if (batadv_bla_tx(bat_priv, skb, vid))
goto dropped;

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