CVE-2024-57881 mm/page_alloc: don't call pfn_to_page() on possibly non-existent PFN in split_large_buddy()

In the Linux kernel, the following vulnerability has been resolved: mm/pagealloc: don't call pfntopage on possibly non-existent PFN in splitlargebuddy In splitlargebuddy, we might call pfntopage on a PFN that might not exist. In corner cases, such as when freeing the highest pageblock in the last...