{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e9b61f19858a5d6c42ce2298cf138279375d0d9b"
            },
            {
              "fixed": "426ee10711586617da869c8bb798214965337617"
            },
            {
              "fixed": "f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd"
            },
            {
              "fixed": "722cfaf6b31d31123439e67b5deac6b1261a3dea"
            },
            {
              "fixed": "7ddcf4a245c1c5a91fdd9698757e3d95179ffe41"
            },
            {
              "fixed": "b8c49ad888892ad7b77062b9c102b799a3e9b4f8"
            },
            {
              "fixed": "7ad1997b9bc8032603df8f091761114479285769"
            },
            {
              "fixed": "8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7"
            },
            {
              "fixed": "4c5e7f0fcd592801c9cc18f29f80fbee84eb8669"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.5.0"
            },
            {
              "fixed": "5.10.253"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.203"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.168"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.134"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.81"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.21"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31466.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softleaf_to_folio()\n\nOn arm64 server, we found folio that get from migration entry isn't locked\nin softleaf_to_folio().  This issue triggers when mTHP splitting and\nzap_nonpresent_ptes() races, and the root cause is lack of memory barrier\nin softleaf_to_folio().  The race is as follows:\n\n\tCPU0                                             CPU1\n\ndeferred_split_scan()                              zap_nonpresent_ptes()\n  lock folio\n  split_folio()\n    unmap_folio()\n      change ptes to migration entries\n    __split_folio_to_order()                         softleaf_to_folio()\n      set flags(including PG_locked) for tail pages    folio = pfn_folio(softleaf_to_pfn(entry))\n      smp_wmb()                                        VM_WARN_ON_ONCE(!folio_test_locked(folio))\n      prep_compound_page() for tail pages\n\nIn __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages\nare visible before the tail page becomes non-compound.  smp_wmb() should\nbe paired with smp_rmb() in softleaf_to_folio(), which is missed.  As a\nresult, if zap_nonpresent_ptes() accesses migration entry that stores tail\npfn, softleaf_to_folio() may see the updated compound_head of tail page\nbefore page-\u003eflags.\n\nThis issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()\nbecause of the race between folio split and zap_nonpresent_ptes()\nleading to a folio incorrectly undergoing modification without a folio\nlock being held.\n\nThis is a BUG_ON() before commit 93976a20345b (\"mm: eliminate further\nswapops predicates\"), which in merged in v6.19-rc1.\n\nTo fix it, add missing smp_rmb() if the softleaf entry is migration entry\nin softleaf_to_folio() and softleaf_to_page().\n\n[tujinjiang@huawei.com: update function name and comments]",
  "id": "CVE-2026-31466",
  "modified": "2026-07-08T05:39:28.600543606Z",
  "published": "2026-04-22T13:53:56.259Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31466.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31466"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "mm/huge_memory: fix folio isn't locked in softleaf_to_folio()"
}