CVE-2021-46969

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

bus: mhi: core: Fix invalid error returning in mhi_queue

mhi_queue returns an error when the doorbell is not accessible in

the current state. This can happen when the device is in non M0

state, like M3, and needs to be waken-up prior ringing the DB. This

case is managed earlier by triggering an asynchronous M3 exit via

controller resume/suspend callbacks, that in turn will cause M0

transition and DB update.

So, since it's not an error but just delaying of doorbell update, there

is no reason to return an error.

This also fixes a use after free error for skb case, indeed a caller

queuing skb will try to free the skb if the queueing fails, but in

that case queueing has been done.