In the Linux kernel, the following vulnerability has been resolved:
net: fix NULL pointer dereference in l3mdev_l3_rcv
When delete l3s ipvlan:
ip link del link eth0 ipvlan1 type ipvlan mode l3s
This may cause a null pointer dereference:
Call trace:
ip_rcv_finish+0x48/0xd0
ip_rcv+0x5c/0x100
__netif_receive_skb_one_core+0x64/0xb0
__netif_receive_skb+0x20/0x80
process_backlog+0xb4/0x204
napi_poll+0xe8/0x294
net_rx_action+0xd8/0x22c
__do_softirq+0x12c/0x354
This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process like this:
(CPU1) | (CPU2)
l3mdev_l3_rcv() |
check dev->priv_flags: |
master = skb->dev; |
|
| ipvlan_l3s_unregister()
| set dev->priv_flags
| dev->l3mdev_ops = NULL;
|
visit master->l3mdev_ops |
To avoid this by do not set dev->l3mdev_ops when unregister l3s ipvlan.