CVE-2025-68292

About vulnerability

In the Linux kernel, the following vulnerability has been resolved: mm/memfd: fix information leak in hugetlb folios When allocating hugetlb folios for memfd, three initialization steps are missing:

1. Folios are not zeroed, leading to kernel memory disclosure to userspace
2. Folios are not marked uptodate before adding to page cache
3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache() The memfd allocation path bypasses the normal page fault handler (hugetlb_no_page) which would handle all of these initialization steps. This is problematic especially for udmabuf use cases where folios are pinned and directly accessed by userspace via DMA. Fix by matching the initialization pattern used in hugetlb_no_page():

• Zero the folio using folio_zero_user() which is optimized for huge pages
• Mark it uptodate with folio_mark_uptodate()
• Take hugetlb_fault_mutex before adding to page cache to prevent races The folio_zero_user() change also fixes a potential security issue where uninitialized kernel memory could be disclosed to userspace through read() or mmap() operations on the memfd. An information leak vulnerability was found in the Linux kernel’s memfd hugetlb folio allocation. Allocated hugetlb folios are not zeroed before use, allowing disclosure of stale kernel memory to userspace. This is particularly impactful for udmabuf use cases where folios are directly accessed via DMA.

Live-patch status from KernelCare for each operating system.