[PATCH v2 net 1/2] net: vlan: set header_ops to match hard_header_len when hw offload is toggled
From: Chen Zhen <hidden>
Date: 2026-01-07 03:24:13
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
When tx-vlan-hw-insert is toggled to on, vlan device hard_header_len
will be reduced to dev->hard_header_len since commit 029f5fc31cdb
("8021q: set hard_header_len when VLAN offload features are toggled"),
but the header_ops remains unchanged, ndisc skb will be allocated
with this len and filled in vlan hdr in vlan_dev_hard_header(), but
with reorder_hdr off, the skb room is not enough so it triggers
skb_panic() as below:
skbuff: skb_under_panic: text:ffffffffa0535126 len:90 put:14
head:ffff916c04232ec0 data:ffff916c04232ebe tail:0x58 end:0x180 dev:veth0.10
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:197!
<TASK>
skb_push+0x39/0x40 net/core/skbuff.c:207
eth_header+0x26/0xb0 net/ethernet/eth.c:90
vlan_dev_hard_header+0x58/0x130 net/8021q/vlan_dev.c:85 [8021q]
neigh_connected_output+0xae/0x100 net/core/neighbour.c:1589
ip6_finish_output2+0x2cc/0x650 net/ipv6/ip6_output.c:213
ip6_finish_output+0x27/0xd0 net/ipv6/ip6_output.c:246
ndisc_send_skb+0x1d0/0x370 net/ipv6/ndisc.c:516
ndisc_send_ns+0x5a/0xb0 net/ipv6/ndisc.c:672
addrconf_dad_work+0x2b5/0x380 net/ipv6/addrconf.c:4258
process_one_work+0x17f/0x320 kernel/workqueue.c:2743
Fix this by also setting header_ops of vlan dev when offload feature
is toggled.
Fixes: 029f5fc31cdb ("8021q: set hard_header_len when VLAN offload features are toggled")
Signed-off-by: Chen Zhen <redacted>
---
net/8021q/vlan.c | 5 +----
net/8021q/vlan.h | 3 +++
net/8021q/vlan_dev.c | 22 ++++++++++++++--------
3 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 2b74ed56eb16..84b3a3f67996 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c@@ -323,10 +323,7 @@ static void vlan_transfer_features(struct net_device *dev, netif_inherit_tso_max(vlandev, dev); - if (vlan_hw_offload_capable(dev->features, vlan->vlan_proto)) - vlandev->hard_header_len = dev->hard_header_len; - else - vlandev->hard_header_len = dev->hard_header_len + VLAN_HLEN; + vlan_dev_set_header_attributes(dev, vlandev, vlan->vlan_proto); #if IS_ENABLED(CONFIG_FCOE) vlandev->fcoe_ddp_xid = dev->fcoe_ddp_xid;
diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h
index c7ffe591d593..1d837814e061 100644
--- a/net/8021q/vlan.h
+++ b/net/8021q/vlan.h@@ -143,6 +143,9 @@ int register_vlan_dev(struct net_device *dev, struct netlink_ext_ack *extack); void unregister_vlan_dev(struct net_device *dev, struct list_head *head); bool vlan_dev_inherit_address(struct net_device *dev, struct net_device *real_dev); +void vlan_dev_set_header_attributes(struct net_device *dev, + struct net_device *vlan_dev, + __be16 proto); static inline u32 vlan_get_ingress_priority(struct net_device *dev, u16 vlan_tci)
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index fbf296137b09..1fe171748711 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c@@ -519,6 +519,19 @@ static const struct device_type vlan_type = { static const struct net_device_ops vlan_netdev_ops; +void vlan_dev_set_header_attributes(struct net_device *dev, + struct net_device *vlan_dev, + __be16 proto) +{ + if (vlan_hw_offload_capable(dev->features, proto)) { + vlan_dev->header_ops = &vlan_passthru_header_ops; + vlan_dev->hard_header_len = dev->hard_header_len; + } else { + vlan_dev->header_ops = &vlan_header_ops; + vlan_dev->hard_header_len = dev->hard_header_len + VLAN_HLEN; + } +} + static int vlan_dev_init(struct net_device *dev) { struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
@@ -572,14 +585,7 @@ static int vlan_dev_init(struct net_device *dev) #endif dev->needed_headroom = real_dev->needed_headroom; - if (vlan_hw_offload_capable(real_dev->features, vlan->vlan_proto)) { - dev->header_ops = &vlan_passthru_header_ops; - dev->hard_header_len = real_dev->hard_header_len; - } else { - dev->header_ops = &vlan_header_ops; - dev->hard_header_len = real_dev->hard_header_len + VLAN_HLEN; - } - + vlan_dev_set_header_attributes(real_dev, dev, vlan->vlan_proto); dev->netdev_ops = &vlan_netdev_ops; SET_NETDEV_DEVTYPE(dev, &vlan_type);
--
2.33.0