In the Linux kernel, the following vulnerability has been resolved:

macsec: Fix use-after-free while sending the offloading packet

KASAN reports the following UAF. The metadata_dst, which is used to
store the SCI value for macsec offload, is already freed by
metadata_dst_free() in macsec_free_netdev(), while driver still use it
for sending the packet.

To fix this issue, dst_release() is used instead to release
metadata_dst. So it is not freed instantly in macsec_free_netdev() if
still referenced by skb.

 BUG: KASAN: slab-use-after-free in mlx5e_xmit+0x1e8f/0x4190 [mlx5_core]
 Read of size 2 at addr ffff88813e42e038 by task kworker/7:2/714
 [...]
 Workqueue: mld mld_ifc_work
 Call Trace:
  <TASK>
  dump_stack_lvl+0x51/0x60
  print_report+0xc1/0x600
  kasan_report+0xab/0xe0
  mlx5e_xmit+0x1e8f/0x4190 [mlx5_core]
  dev_hard_start_xmit+0x120/0x530
  sch_direct_xmit+0x149/0x11e0
  __qdisc_run+0x3ad/0x1730
  __dev_queue_xmit+0x1196/0x2ed0
  vlan_dev_hard_start_xmit+0x32e/0x510 [8021q]
  dev_hard_start_xmit+0x120/0x530
  __dev_queue_xmit+0x14a7/0x2ed0
  macsec_start_xmit+0x13e9/0x2340
  dev_hard_start_xmit+0x120/0x530
  __dev_queue_xmit+0x14a7/0x2ed0
  ip6_finish_output2+0x923/0x1a70
  ip6_finish_output+0x2d7/0x970
  ip6_output+0x1ce/0x3a0
  NF_HOOK.constprop.0+0x15f/0x190
  mld_sendpack+0x59a/0xbd0
  mld_ifc_work+0x48a/0xa80
  process_one_work+0x5aa/0xe50
  worker_thread+0x79c/0x1290
  kthread+0x28f/0x350
  ret_from_fork+0x2d/0x70
  ret_from_fork_asm+0x11/0x20
  </TASK>

 Allocated by task 3922:
  kasan_save_stack+0x20/0x40
  kasan_save_track+0x10/0x30
  __kasan_kmalloc+0x77/0x90
  __kmalloc_noprof+0x188/0x400
  metadata_dst_alloc+0x1f/0x4e0
  macsec_newlink+0x914/0x1410
  __rtnl_newlink+0xe08/0x15b0
  rtnl_newlink+0x5f/0x90
  rtnetlink_rcv_msg+0x667/0xa80
  netlink_rcv_skb+0x12c/0x360
  netlink_unicast+0x551/0x770
  netlink_sendmsg+0x72d/0xbd0
  __sock_sendmsg+0xc5/0x190
  ____sys_sendmsg+0x52e/0x6a0
  ___sys_sendmsg+0xeb/0x170
  __sys_sendmsg+0xb5/0x140
  do_syscall_64+0x4c/0x100
  entry_SYSCALL_64_after_hwframe+0x4b/0x53

 Freed by task 4011:
  kasan_save_stack+0x20/0x40
  kasan_save_track+0x10/0x30
  kasan_save_free_info+0x37/0x50
  poison_slab_object+0x10c/0x190
  __kasan_slab_free+0x11/0x30
  kfree+0xe0/0x290
  macsec_free_netdev+0x3f/0x140
  netdev_run_todo+0x450/0xc70
  rtnetlink_rcv_msg+0x66f/0xa80
  netlink_rcv_skb+0x12c/0x360
  netlink_unicast+0x551/0x770
  netlink_sendmsg+0x72d/0xbd0
  __sock_sendmsg+0xc5/0x190
  ____sys_sendmsg+0x52e/0x6a0
  ___sys_sendmsg+0xeb/0x170
  __sys_sendmsg+0xb5/0x140
  do_syscall_64+0x4c/0x100
  entry_SYSCALL_64_after_hwframe+0x4b/0x53