Merge branch 'fix-wrong-transport_header-when-sending-vlan-tagged-frames'

Wei Fang says:

====================
Fix wrong transport_header when sending VLAN-tagged frames

When sending a VLAN-tagged frame via AF_PACKET or tap, calling
skb_set_network_header() before skb_probe_transport_header() causes
the flow dissector to misinterpret the inner protocol header as a
VLAN header. As a result, transport_header is never set and remains
at its uninitialized sentinel value (~0U).

Move skb_probe_transport_header() to before skb_set_network_header()
so the flow dissector sees network_header still pointing to the VLAN
header and can correctly identify the transport layer.
====================

Link: https://patch.msgid.link/20260807063405.688780-1-wei.fang@oss.nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Paolo Abeni
2026-08-11 13:14:40 +02:00
2 changed files with 4 additions and 3 deletions

View File

@@ -1091,12 +1091,13 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
}
}
skb_probe_transport_header(skb);
/* Move network header to the right position for VLAN tagged packets */
if (eth_type_vlan(skb->protocol) &&
vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
skb_set_network_header(skb, depth);
skb_probe_transport_header(skb);
dev_queue_xmit(skb);
rcu_read_unlock();

View File

@@ -1943,13 +1943,13 @@ static void packet_parse_headers(struct sk_buff *skb, struct socket *sock)
sock->type == SOCK_RAW)
skb->protocol = dev_parse_header_protocol(skb);
skb_probe_transport_header(skb);
/* Move network header to the right position for VLAN tagged packets */
if (likely(skb->dev->type == ARPHRD_ETHER) &&
eth_type_vlan(skb->protocol) &&
vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
skb_set_network_header(skb, depth);
skb_probe_transport_header(skb);
}
/*