EDAC/ghes: Fix Use after free in ghes_edac remove path
ghes_edac models a single logical memory controller, and uses a global ghes_init variable to ensure only the first ghes_edac_register() will do anything. ghes_edac is registered the first time a GHES entry in the HEST is probed. There may be multiple entries, so subsequent attempts to register ghes_edac are silently ignored as the work has already been done. When a GHES entry is unregistered, it calls ghes_edac_unregister(), which free()s the memory behind the global variables in ghes_edac. But there may be multiple GHES entries, the next call to ghes_edac_unregister() will dereference the free()d memory, and attempt to free it a second time. This may also be triggered on a platform with one GHES entry, if the driver is unbound/re-bound and unbound. The re-bind step will do nothing because of ghes_init, the second unbind will then do the same work as the first. Doing the unregister work on the first call is unsafe, as another CPU may be processin...
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