Commit 28c1382f authored by Yunjian Wang's avatar Yunjian Wang Committed by David S. Miller
Browse files

net: bridge: Fix ethernet header pointer before check skb forwardable

The skb header should be set to ethernet header before using
is_skb_forwardable. Because the ethernet header length has been
considered in is_skb_forwardable(including dev->hard_header_len

To reproduce the issue:
1, add 2 ports on linux bridge br using following commands:
$ brctl addbr br
$ brctl addif br eth0
$ brctl addif br eth1
2, the MTU of eth0 and eth1 is 1500
3, send a packet(Data 1480, UDP 8, IP 20, Ethernet 14, VLAN 4)
from eth0 to eth1

So the expect result is packet larger than 1500 cannot pass through
eth0 and eth1. But currently, the packet passes through success, it
means eth1's MTU limit doesn't take effect.

Fixes: f6367b46

 ("bridge: use is_skb_forwardable in forward path")
Cc: Nkolay Aleksandrov <>
Cc: Roopa Prabhu <>
Cc: Stephen Hemminger <>
Signed-off-by: default avatarYunjian Wang <>
Signed-off-by: default avatarDavid S. Miller <>
parent cc5e7107
......@@ -36,10 +36,10 @@ static inline int should_deliver(const struct net_bridge_port *p,
int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
skb_push(skb, ETH_HLEN);
if (!is_skb_forwardable(skb->dev, skb))
goto drop;
skb_push(skb, ETH_HLEN);
if (skb->ip_summed == CHECKSUM_PARTIAL &&
......@@ -98,12 +98,11 @@ static void __br_forward(const struct net_bridge_port *to,
net = dev_net(indev);
} else {
if (unlikely(netpoll_tx_running(to->br->dev))) {
if (!is_skb_forwardable(skb->dev, skb)) {
skb_push(skb, ETH_HLEN);
if (!is_skb_forwardable(skb->dev, skb))
} else {
skb_push(skb, ETH_HLEN);
br_netpoll_send_skb(to, skb);
br_hook = NF_BR_LOCAL_OUT;
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