CVE-2023-52608

In the Linux kernel, the following vulnerability has been resolved:
firmware: arm_scmi: Check mailbox/SMT channel for consistency On reception
of a completion interrupt the shared memory area is accessed to retrieve
the message header at first and then, if the message sequence number
identifies a transaction which is still pending, the related payload is
fetched too. When an SCMI command times out the channel ownership remains
with the platform until eventually a late reply is received and, as a
consequence, any further transmission attempt remains pending, waiting for
the channel to be relinquished by the platform. Once that late reply is
received the channel ownership is given back to the agent and any pending
request is then allowed to proceed and overwrite the SMT area of the just
delivered late reply; then the wait for the reply to the new request
starts. It has been observed that the spurious IRQ related to the late
reply can be wrongly associated with the freshly enqueued request: when
that happens the SCMI stack in-flight lookup procedure is fooled by the
fact that the message header now present in the SMT area is related to the
new pending transaction, even though the real reply has still to arrive.
This race-condition on the A2P channel can be detected by looking at the
channel status bits: a genuine reply from the platform will have set the
channel free bit before triggering the completion IRQ. Add a consistency
check to validate such condition in the A2P ISR.

Notes