vlan: Set correct source MAC address with TX VLAN offload enabled

With TX VLAN offload enabled the source MAC address for frames sent using the VLAN interface is currently set to the address of the real interface. This is wrong since the VLAN interface may be configured with a different address.

The bug was introduced in commit 2205369a314e12fcec4781cc73ac9c08fc2b47de ("vlan: Fix header ops passthru when doing TX VLAN offload.").

This patch sets the source address before calling the create function of the real interface.

---
 net/8021q/vlan_dev.c | 3 +++
 1 file changed, 3 insertions(+)

index de51c48..4b65aa4 100644
@@ -538,6 +538,9 @@ static int vlan_passthru_hard_header(struct sk_buff *skb, struct net_device *dev
 	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
 	struct net_device *real_dev = vlan->real_dev;
 
+	if (saddr == NULL)
+		saddr = dev->dev_addr;
+
 	return dev_hard_header(skb, real_dev, type, daddr, saddr, len);
 }
 

From: Peter Boström <[email protected]>
Date: Mon, 10 Mar 2014 16:17:15 +0100

Good catch.

Applied and queued up for -stable, thanks!