CVE-2026-97927 (GCVE-0-2026-97927)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:22 – Updated: 2026-09-25 10:22
VLAI
Title
ufs: create the root dentry after loading cylinder metadata
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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < a9804121d55aaa4319c1cac00b99794aa177dd6a (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 785e523b6c1931d802cab9f85912f3e6c7028af1 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 8173e051a8acbb4ae6547be0436727944119e0b5 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 55a4c98abb9694b067c6a031d11501f06b6b523c (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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          "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."
        }
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    "datePublished": "2026-09-25T10:22:44.834Z",
    "dateReserved": "2026-09-25T10:18:58.203Z",
    "dateUpdated": "2026-09-25T10:22:44.834Z",
    "state": "PUBLISHED"
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            "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."
          }
        ],
        "id": "CVE-2026-97927",
        "lastModified": "2026-09-25T11:17:19.950",
        "metrics": {},
        "published": "2026-09-25T11:17:19.950",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.