CVE-2026-97927 (GCVE-0-2026-97927)
Vulnerability from cvelistv5
Published
2026-09-25 10:22
Modified
2026-10-19 09:10
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ufs: create the root dentry after loading cylinder metadata ufs_fill_super() installed sb->s_root before it loaded the cylinder group structures for a writable mount: sb->s_root = d_make_root(inode); ... if (!sb_rdonly(sb)) if (!ufs_read_cylinder_structures(sb)) goto failed; When ufs_read_cylinder_structures() failed, the error path freed the in-core superblock information and set sb->s_fs_info to NULL while sb->s_root stayed installed. get_tree_bdev() then reached deactivate_locked_super(), and because s_root was present, generic_shutdown_super() called sync_filesystem() and the put_super operation. Both dereference UFS_SB(sb), which is now NULL, so a mount that fails only while reading the cylinder groups oopses during teardown. A crafted image whose first cylinder group cannot be read reaches this path. Load the cylinder group metadata first and create the root dentry last, so the superblock is published to the VFS only once it is fully set up. ufs_setup_cstotal() and ufs_read_cylinder_structures() take only the super_block and do not use the root inode, so the reordering is safe.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ufs/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.12"
            },
            {
              "lessThan": "2.6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nufs: create the root dentry after loading cylinder metadata\n\nufs_fill_super() installed sb-\u003es_root before it loaded the cylinder\ngroup structures for a writable mount:\n\n\tsb-\u003es_root = d_make_root(inode);\n\t...\n\tif (!sb_rdonly(sb))\n\t\tif (!ufs_read_cylinder_structures(sb))\n\t\t\tgoto failed;\n\nWhen ufs_read_cylinder_structures() failed, the error path freed the\nin-core superblock information and set sb-\u003es_fs_info to NULL while\nsb-\u003es_root stayed installed. get_tree_bdev() then reached\ndeactivate_locked_super(), and because s_root was present,\ngeneric_shutdown_super() called sync_filesystem() and the put_super\noperation. Both dereference UFS_SB(sb), which is now NULL, so a mount\nthat fails only while reading the cylinder groups oopses during\nteardown. A crafted image whose first cylinder group cannot be read\nreaches this path.\n\nLoad the cylinder group metadata first and create the root dentry last,\nso the superblock is published to the VFS only once it is fully set up.\nufs_setup_cstotal() and ufs_read_cylinder_structures() take only the\nsuper_block and do not use the root inode, so the reordering is safe."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:10:54.225Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e58db6c2dce6e453dca26c3a4953002425201880"
        },
        {
          "url": "https://git.kernel.org/stable/c/05360c6eb8388bb5adac3c439ffb1512de39550a"
        },
        {
          "url": "https://git.kernel.org/stable/c/5cc48633fb76196b596a449ba1f4f642ad6125ce"
        },
        {
          "url": "https://git.kernel.org/stable/c/cd21f1ff74b1c15077fa3b98e80da3b41055aae4"
        },
        {
          "url": "https://git.kernel.org/stable/c/a9804121d55aaa4319c1cac00b99794aa177dd6a"
        },
        {
          "url": "https://git.kernel.org/stable/c/785e523b6c1931d802cab9f85912f3e6c7028af1"
        },
        {
          "url": "https://git.kernel.org/stable/c/8173e051a8acbb4ae6547be0436727944119e0b5"
        },
        {
          "url": "https://git.kernel.org/stable/c/55a4c98abb9694b067c6a031d11501f06b6b523c"
        }
      ],
      "title": "ufs: create the root dentry after loading cylinder metadata",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97927",
    "datePublished": "2026-09-25T10:22:44.834Z",
    "dateReserved": "2026-09-25T10:18:58.203Z",
    "dateUpdated": "2026-10-19T09:10:54.225Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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