CVE-2026-31575
Description
In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: fix hugetlb fault mutex hash calculation In mfill_atomic_hugetlb(), linear_page_index() is used to calculate the page index for hugetlb_fault_mutex_hash(). However, linear_page_index() returns the index in PAGE_SIZE units, while hugetlb_fault_mutex_hash() expects the index in huge page units. This mismatch means that different addresses within the same huge page can produce different hash values, leading to the use of different mutexes for the same huge page. This can cause races between faulting threads, which can corrupt the reservation map and trigger the BUG_ON in resv_map_release(). Fix this by introducing hugetlb_linear_page_index(), which returns the page index in huge page granularity, and using it in place of linear_page_index().
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | fixed | 0 |
| debian | bullseye | fixed | 0 |
| debian | forky | fixed | 6.19.14-1 |
| debian | sid | fixed | 6.19.14-1 |
| debian | trixie | fixed | 6.12.85-1 |
| linux-kernel | affected | 6.12.84 |
References
- https://git.kernel.org/stable/c/0217c7fb4de4a40cee667eb21901f3204effe5ac
- https://git.kernel.org/stable/c/08282b1bf74c69fc8ecd25493e7fdb5460f01290
- https://git.kernel.org/stable/c/574501ede47ac439afd67ba9812bc66722d500ba
- https://git.kernel.org/stable/c/5a525c43baaba0bf3063f86996ca3623b71e4172
- https://git.kernel.org/stable/c/f4689fc089765d36c026063fb22d23533e883eb6
- https://www.suse.com/security/cve/CVE-2026-31575.html
- https://security-tracker.debian.org/tracker/CVE-2026-31575
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.