Re: [PATCH nf] netfilter: nf_flow_table_ip: reset mac header before vlan push

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Mar 10, 2026 at 03:39:33PM +0100, Eric Woudstra wrote:
> With double vlan tagged packets in the fastpath, getting the error:
> 
> skb_vlan_push got skb with skb->data not at mac header (offset 18)
> 
> Call skb_reset_mac_header() before calling skb_vlan_push().

Fixes: c653d5a78f34 ("netfilter: flowtable: inline vlan encapsulation in xmit path")

> Signed-off-by: Eric Woudstra <ericwouds@gmail.com>

Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

> ---
> 
> This patch replaces:
> 
> "netfilter: nf_flow_table_ip: Introduce nf_flow_vlan_push()"
> 
>  net/netfilter/nf_flow_table_ip.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
> index 3fdb10d9bf7f..fd56d663cb5b 100644
> --- a/net/netfilter/nf_flow_table_ip.c
> +++ b/net/netfilter/nf_flow_table_ip.c
> @@ -738,6 +738,7 @@ static int nf_flow_encap_push(struct sk_buff *skb,
>  		switch (tuple->encap[i].proto) {
>  		case htons(ETH_P_8021Q):
>  		case htons(ETH_P_8021AD):
> +			skb_reset_mac_header(skb);
>  			if (skb_vlan_push(skb, tuple->encap[i].proto,
>  					  tuple->encap[i].id) < 0)
>  				return -1;
> -- 
> 2.53.0
>