CVE-2026-31575
mm/userfaultfd: fix hugetlb fault mutex hash calculation
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().
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3; < 5a525c43baaba0bf3063f86996ca3623b71e4172 (affected, git) ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3; < 574501ede47ac439afd67ba9812bc66722d500ba (affected, git) ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3; < 08282b1bf74c69fc8ecd25493e7fdb5460f01290 (affected, git) ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3; < f4689fc089765d36c026063fb22d23533e883eb6 (affected, git) ≥ a08c7193e4f18dc8508f2d07d0de2c5b94cb39a3; < 0217c7fb4de4a40cee667eb21901f3204effe5ac (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
6.7 (affected) ≥ 0; < 6.7 (unaffected, semver) ≥ 6.12.84; ≤ 6.12.* (unaffected, semver) ≥ 6.18.24; ≤ 6.18.* (unaffected, semver) ≥ 6.19.14; ≤ 6.19.* (unaffected, semver) ≥ 7.0.1; ≤ 7.0.* (unaffected, semver) ≥ 7.1; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/5a525c43baaba0bf3063f86996ca3623b71e4172CNA: Linux
- https://git.kernel.org/stable/c/574501ede47ac439afd67ba9812bc66722d500baCNA: Linux
- https://git.kernel.org/stable/c/08282b1bf74c69fc8ecd25493e7fdb5460f01290CNA: Linux
- https://git.kernel.org/stable/c/f4689fc089765d36c026063fb22d23533e883eb6CNA: Linux
- https://git.kernel.org/stable/c/0217c7fb4de4a40cee667eb21901f3204effe5acCNA: Linux
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