CVE-2023-53856: Undefined Security Weakness

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

of: overlay: Call of_changeset_init() early

When of_overlay_fdt_apply() fails, the changeset may be partially applied, and the caller is still expected to call of_overlay_remove() to clean up this partial state.

However, of_overlay_apply() calls of_resolve_phandles() before init_overlay_changeset(). Hence if the overlay fails to apply due to an unresolved symbol, the overlay_changeset.cset.entries list is still uninitialized, and cleanup will crash with a NULL-pointer dereference in overlay_removal_is_ok().

Fix this by moving the call to of_changeset_init() from init_overlay_changeset() to of_overlay_fdt_apply(), where all other early initialization is done.