CVE-2026-53154
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile — higher than 2% of all known CVEs
Summary
A vulnerability in the Linux kernel's hugetlb reservation management was found. During hugetlb folio copy operations (e.g., UFFDIO_COPY or fork), error handling fails to restore the VMA reservation, causing a leak that can lead to SIGBUS on previously reserved addresses.
Risk Assessment
The organization risks memory inconsistency in hugetlb pools, potentially causing unexpected process termination (SIGBUS) under pool pressure, especially with UFFDIO_COPY or fork involving pinned hugetlb anonymous pages.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit adding restore_reserve_on_error() before folio_put() in hugetlb copy error paths).
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: restore reservation on error in hugetlb folio copy paths Two sites in mm/hugetlb.c allocate a hugetlb folio via alloc_hugetlb_folio() (consuming a VMA reservation) and then call copy_user_large_folio(), which became int-returning in commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults") and can now fail (e.g. -EHWPOISON on a hwpoisoned source page). On the failure path, folio_put() restores the global hugetlb pool count through free_huge_folio(), but the per-VMA reservation map entry is left marked consumed: - hugetlb_mfill_atomic_pte() resubmission path (UFFDIO_COPY) - copy_hugetlb_page_range() fork-time CoW path when hugetlb_try_dup_anon_rmap() fails (rare: pinned hugetlb anon folio under fork) User-visible effect: on UFFDIO_COPY into a private hugetlb VMA where the resubmission copy fails, the reservation for that address is leaked from the VMA's reserve map. A subsequent fault at the same address takes the no-reservation path, and under hugetlb pool pressure the task is SIGBUSed at an address it had previously reserved. The fork-time CoW path leaks the same way in the child VMA's reserve map, though it requires the much rarer combination of pinned hugetlb anon page + hwpoisoned source. Add the missing restore_reserve_on_error() call before folio_put() on both error paths.