[PATCH 6.19 135/220] netfilter: nf_flow_table_ip: reset mac header before vlan push

Greg Kroah-Hartman
2026-03-23T13:56:17Z

From: Eric Woudstra <ericwouds@gmail.com>

[ Upstream commit a3aca98aec9a278ee56da4f8013bfa1dd1a1c298 ]

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>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 78883343e5d68..458895e9e1f85 100644
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -576,6 +576,7 @@ 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;
--
2.51.0