[PATCH net] macvlan: use skb_reset_mac_header() in macvlan_queue_xmit()

[PATCH net] macvlan: use skb_reset_mac_header() in macvlan_queue_xmit()

[Eric Dumazet]

I missed the fact that macvlan_broadcast() can be used both
in RX and TX.

skb_eth_hdr() makes only sense in TX paths, so we can not
use it blindly in macvlan_broadcast()

Fixes: 96cc4b69581d ("macvlan: do not assume mac_header is set in macvlan_broadcast()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jurgen Van Ham <juvanham@gmail.com>
---
 drivers/net/macvlan.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 747c0542a53c763676d491c91a5b704f0eb9848e..c5bf61565726b15aa1ea63590d7d8627b0c20d4a 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -259,7 +259,7 @@ static void macvlan_broadcast(struct sk_buff *skb,
 			      struct net_device *src,
 			      enum macvlan_mode mode)
 {
-	const struct ethhdr *eth = skb_eth_hdr(skb);
+	const struct ethhdr *eth = eth_hdr(skb);
 	const struct macvlan_dev *vlan;
 	struct sk_buff *nskb;
 	unsigned int i;
@@ -513,10 +513,11 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 	const struct macvlan_dev *dest;
 
 	if (vlan->mode == MACVLAN_MODE_BRIDGE) {
-		const struct ethhdr *eth = (void *)skb->data;
+		const struct ethhdr *eth = skb_eth_hdr(skb);
 
 		/* send to other bridge ports directly */
 		if (is_multicast_ether_addr(eth->h_dest)) {
+			skb_reset_mac_header(skb);
 			macvlan_broadcast(skb, port, dev, MACVLAN_MODE_BRIDGE);
 			goto xmit_world;
 		}
-- 
2.25.0.rc1.283.g88dfdc4193-goog

Re: [PATCH net] macvlan: use skb_reset_mac_header() in macvlan_queue_xmit()

[Matteo Croce]

On Tue, Jan 14, 2020 at 10:01 PM Eric Dumazet <edumazet@google.com> wrote:
>
> I missed the fact that macvlan_broadcast() can be used both
> in RX and TX.
>
> skb_eth_hdr() makes only sense in TX paths, so we can not
> use it blindly in macvlan_broadcast()
>
> Fixes: 96cc4b69581d ("macvlan: do not assume mac_header is set in macvlan_broadcast()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Jurgen Van Ham <juvanham@gmail.com>

Tested-by: Matteo Croce <mcroce@redhat.com>

-- 
Matteo Croce
per aspera ad upstream

Re: [PATCH net] macvlan: use skb_reset_mac_header() in macvlan_queue_xmit()

[David Miller]

From: Eric Dumazet <edumazet@google.com>
Date: Tue, 14 Jan 2020 13:00:35 -0800

> I missed the fact that macvlan_broadcast() can be used both
> in RX and TX.
> 
> skb_eth_hdr() makes only sense in TX paths, so we can not
> use it blindly in macvlan_broadcast()
> 
> Fixes: 96cc4b69581d ("macvlan: do not assume mac_header is set in macvlan_broadcast()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Jurgen Van Ham <juvanham@gmail.com>

Applied and queued up for -stable, thanks Eric.