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CVE-2026-31575

Full vulnerability record from the local CVENow database.

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().

Severity
MEDIUM
CVSS score
5.5 (v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-04-24 15:16:32.123000
Last modified
2026-11-05 22:18:41.263000
View original CVE JSON 
{
  "id": "CVE-2026-31575",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-04-24T15:16:32.123",
  "lastModified": "2026-11-05T22:18:41.263",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/userfaultfd: fix hugetlb fault mutex hash calculation\n\nIn mfill_atomic_hugetlb(), linear_page_index() is used to calculate the\npage index for hugetlb_fault_mutex_hash().  However, linear_page_index()\nreturns the index in PAGE_SIZE units, while hugetlb_fault_mutex_hash()\nexpects the index in huge page units.  This mismatch means that different\naddresses within the same huge page can produce different hash values,\nleading to the use of different mutexes for the same huge page.  This can\ncause races between faulting threads, which can corrupt the reservation\nmap and trigger the BUG_ON in resv_map_release().\n\nFix this by introducing hugetlb_linear_page_index(), which returns the\npage index in huge page granularity, and using it in place of\nlinear_page_index()."
    }
  ],
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          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
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