CVE-2022-49968

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

ieee802154/adf7242: defer destroy_workqueue call

There is a possible race condition (use-after-free) like below

(FREE) | (USE)

adf7242_remove | adf7242_channel

cancel_delayed_work_sync |

destroy_workqueue (1) | adf7242_cmd_rx

| mod_delayed_work (2)

|

The root cause for this race is that the upper layer (ieee802154) is

unaware of this detaching event and the function adf7242_channel can

be called without any checks.

To fix this, we can add a flag write at the beginning of adf7242_remove

and add flag check in adf7242_channel. Or we can just defer the

destructive operation like other commit 3e0588c291d6 ("hamradio: defer

ax25 kfree after unregister_netdev") which let the

ieee802154_unregister_hw() to handle the synchronization. This patch

takes the second option.

runs")