CVE-2026-31589 Linux内核释放后重用漏洞

/* * Conceptual PoC for CVE-2026-31589 * This demonstrates the vulnerable logic where mapping->a_ops is accessed * after the potential release of the mapping structure. */ #include <linux/mm.h> #include <linux/pagemap.h> // Vulnerable Logic Simulation void vulnerable_folio_unmap(struct folio *folio) { struct address_space *mapping = folio->mapping; // Simulate dropping the lock or reference // mapping might be freed here in a race condition // Unsafe access to mapping->a_ops after potential free if (mapping && mapping->a_ops->free_folio) { mapping->a_ops->free_folio(mapping, folio); } } // Fixed Logic Simulation void fixed_folio_unmap(struct folio *folio) { struct address_space *mapping = folio->mapping; void (*free_folio)(struct address_space *, struct folio *); // Load the function pointer BEFORE dropping the lock/unpinning free_folio = mapping->a_ops->free_folio; // Lock dropped / mapping potentially unpinned here // Use the cached pointer safely if (free_folio) { free_folio(mapping, folio); } }