[PATCH 6.6 190/301] net: bridge: fix corrupted ethernet header on multicast-to-unicast

Greg Kroah-Hartman
2024-05-14T11:17:32Z

From: Felix Fietkau <nbd@nbd.name>

[ Upstream commit 86b29d830ad69eecff25b22dc96c14c6573718e6 ]

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>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 d7c35f55bd69f..d97064d460dc7 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);

--
2.43.0