CVE-2022-48985

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

net: mana: Fix race on per-CQ variable napi work_done

After calling napicompletedone(), the NAPIFSTATESCHED bit may be cleared, and another CPU can start napi thread and access per-CQ variable, cq->workdone. If the other thread (for example, from busypoll) sets it to a value >= budget, this thread will continue to run when it should stop, and cause memory corruption and panic.

To fix this issue, save the per-CQ workdone variable in a local variable before napicompletedone(), so it won't be corrupted by a possible concurrent thread after napicomplete_done().

Also, add a flag bit to advertise to the NIC firmware: the NAPI workdone variable race is fixed, so the driver is able to reliably support features like busypoll.