CVE-2024-35879: Missing Release of Memory after Effective Lifetime

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

of: dynamic: Synchronize of_changeset_destroy() with the devlink removals

In the following sequence: 1) of_platform_depopulate() 2) of_overlay_remove()

During the step 1, devices are destroyed and devlinks are removed. During the step 2, OF nodes are destroyed but __of_changeset_entry_destroy() can raise warnings related to missing of_node_put(): ERROR: memory leak, expected refcount 1 instead of 2 ...

Indeed, during the devlink removals performed at step 1, the removal itself releasing the device (and the attached of_node) is done by a job queued in a workqueue and so, it is done asynchronously with respect to function calls. When the warning is present, of_node_put() will be called but wrongly too late from the workqueue job.

In order to be sure that any ongoing devlink removals are done before the of_node destruction, synchronize the of_changeset_destroy() with the devlink removals.