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

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