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! 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 In case of possible crash from other callers, fix this by always reserving VLAN_HLEN in hard_header_len even if the header_ops would not request it. Fixes: 029f5fc31cdb ("8021q: set hard_header_len when VLAN offload features are toggled") Signed-off-by: Chen Zhen --- net/8021q/vlan.c | 5 ----- net/8021q/vlan_dev.c | 8 +++----- 2 files changed, 3 insertions(+), 10 deletions(-) diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 2b74ed56eb16..a7b5da7f9999 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -323,11 +323,6 @@ 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; - #if IS_ENABLED(CONFIG_FCOE) vlandev->fcoe_ddp_xid = dev->fcoe_ddp_xid; #endif diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c index fbf296137b09..9e81669bffd6 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -572,13 +572,11 @@ 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->hard_header_len = real_dev->hard_header_len + VLAN_HLEN; + 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 { + else dev->header_ops = &vlan_header_ops; - dev->hard_header_len = real_dev->hard_header_len + VLAN_HLEN; - } dev->netdev_ops = &vlan_netdev_ops; -- 2.33.0