CVE-2022-49820

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

mctp i2c: don't count unused / invalid keys for flow release

We're currently hitting the WARNON in mctpi2cflowrelease:

if (midev->release_count > midev->i2c_lock_count) {
    WARN_ONCE(1, "release count overflow");

This may be hit if we expire a flow before sending the first packet it contains - as we will not be pairing the increment of release_count (performed on flow release) with the i2c lock operation (only performed on actual TX).

To fix this, only release a flow if we've encountered it previously (ie, devflowstate does not indicate NEW), as we will mark the flow as ACTIVE at the same time as accounting for the i2c lock operation. We also need to add an INVALID flow state, to indicate when we've done the release.