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.

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Red Hat Enterprise Linux is not vulnerable to this flaw because the driver for the ADF7242 transceiver is not enabled or compiled in supported kernel packages. Triggering this race condition requires physical or emulated access to a system configured with this specialized IEEE 802.15.4 wireless transceiver during device unregistration. Consequently, standard Red Hat enterprise installations do not include the affected module and face no operational exposure.