From: Felix Fietkau <nbd@nbd.name>
Date: Sun, 5 May 2024 20:36:56 +0200
Subject: [PATCH] net: bridge: fix corrupted ethernet header on
 multicast-to-unicast

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 <nbd@nbd.name>
---

--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -258,6 +258,7 @@ static void maybe_deliver_addr(struct ne
 {
 	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 ne
 	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);