CVE-2025-68292

/// Technical description

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 issu

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References