CVE-2024-49964

mm/hugetlb: fix memfd_pin_folios free_huge_pages leak

Description

In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix memfd_pin_folios free_huge_pages leak memfd_pin_folios followed by unpin_folios fails to restore free_huge_pages if the pages were not already faulted in, because the folio refcount for pages created by memfd_alloc_folio never goes to 0. memfd_pin_folios needs another folio_put to undo the folio_try_get below: memfd_alloc_folio() alloc_hugetlb_folio_nodemask() dequeue_hugetlb_folio_nodemask() dequeue_hugetlb_folio_node_exact() folio_ref_unfreeze(folio, 1); ; adds 1 refcount folio_try_get() ; adds 1 refcount hugetlb_add_to_page_cache() ; adds 512 refcount (on x86) With the fix, after memfd_pin_folios + unpin_folios, the refcount for the (unfaulted) page is 512, which is correct, as the refcount for a faulted unpinned page is 513.

5.5

CVSS

Severity: Medium

CVSS 3.1 •

EPSS 0.03%

Affected: Linux Linux

References

Link	Tags
https://git.kernel.org/stable/c/59e081ff2e91bbf19b8c1ecb75b031f778858383	patch
https://git.kernel.org/stable/c/c56b6f3d801d7ec8965993342bdd9e2972b6cb8e	patch

Frequently Asked Questions

What is the severity of CVE-2024-49964?: CVE-2024-49964 has been scored as a medium severity vulnerability.
How to fix CVE-2024-49964?: To fix CVE-2024-49964, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2024-49964 being actively exploited in the wild?: As for now, there are no information to confirm that CVE-2024-49964 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2024-49964?: CVE-2024-49964 affects Linux Linux, Linux Linux.

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