CVE-2025-21861 — Use After Free in Linux

In the Linux kernel, the following vulnerability has been resolved: mm/migrate_device: don't add folio to be freed to LRU in migrate_device_finalize() If migration succeeded, we called folio_migrate_flags()->mem_cgroup_migrate() to migrate the memcg from the old to the new folio. This will set memcg_data of the old folio to 0. Similarly, if migration failed, memcg_data of the dst folio is left unset. If we call folio_putback_lru() on such folios (memcg_data == 0), we will add the folio to be…