[PATCH net] net: bridge: fix corrupted ethernet header on multicast-to-unicast

[Felix Fietkau]

The change from skb_copy to pskb_copy unfortunately changed the data
copying to omit the ethernet header, since it was pulled before reaching
this point. Fix this by calling __skb_push/pull around pskb_copy.

Fixes: 59c878cbcdd8 ("net: bridge: fix multicast-to-unicast with fraglist GSO")
Signed-off-by: Felix Fietkau <n...@nbd.name>
---
 net/bridge/br_forward.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index d7c35f55bd69..d97064d460dc 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -258,6 +258,7 @@ static void maybe_deliver_addr(struct net_bridge_port *p, 
struct sk_buff *skb,
 {
        struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
        const unsigned char *src = eth_hdr(skb)->h_source;
+       struct sk_buff *nskb;
 
        if (!should_deliver(p, skb))
                return;
@@ -266,12 +267,16 @@ static void maybe_deliver_addr(struct net_bridge_port *p, 
struct sk_buff *skb,
        if (skb->dev == p->dev && ether_addr_equal(src, addr))
                return;
 
-       skb = pskb_copy(skb, GFP_ATOMIC);
-       if (!skb) {
+       __skb_push(skb, ETH_HLEN);
+       nskb = pskb_copy(skb, GFP_ATOMIC);
+       __skb_pull(skb, ETH_HLEN);
+       if (!nskb) {
                DEV_STATS_INC(dev, tx_dropped);
                return;
        }
 
+       skb = nskb;
+       __skb_pull(skb, ETH_HLEN);
        if (!is_broadcast_ether_addr(addr))
                memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
 
-- 
2.44.0