CVE-2025-68292: mm/memfd: fix information leak in hugetlb folios
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. hugetlbfaultmutex is not taken before hugetlbaddtopagecache()
The memfd allocation path bypasses the normal page fault handler (hugetlbnopage) 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 hugetlbnopage(): - Zero the folio using foliozerouser() which is optimized for huge pages - Mark it uptodate with foliomarkuptodate() - Take hugetlbfaultmutex before adding to page cache to prevent races
The foliozerouser() change also fixes a potential security issue where uninitialized kernel memory could be disclosed to userspace through read() or mmap() operations on the memfd.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In the hugetlb folio allocation path for memfd, match the hugetlb_no_page() initialization pattern: take hugetlb_fault_mutex before hugetlb_add_to_page_cache(), zero the folio with folio_zero_user(), and mark it uptodate with folio_mark_uptodate().
Event History
Frequently Asked Questions
What is the severity of CVE-2025-68292?
CVE-2025-68292 has been classified with a severity rating that indicates a potential for kernel memory disclosure.
How do I fix CVE-2025-68292?
To fix CVE-2025-68292, ensure you apply the latest patches from the Linux kernel that address this vulnerability.
Which systems are affected by CVE-2025-68292?
CVE-2025-68292 affects systems running vulnerable versions of the Linux kernel using hugetlb folios for memfd.
What types of information are leaked in CVE-2025-68292?
CVE-2025-68292 can lead to kernel memory being disclosed to userspace, potentially exposing sensitive information.
When was CVE-2025-68292 announced or discovered?
CVE-2025-68292 was announced in the context of ongoing vulnerabilities in the Linux kernel, specifically related to memory management.