ext4: allow ext4_get_group_info() to fail

{
  "id": "d431f43c8292843ce9408031e55811e3ac7bafed4cc0a7194b90034da5bbaba5",
  "url": "https://osv.dev/vulnerability/CVE-2023-53503",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ext4: allow ext4_get_group_info() to fail",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ext4: allow ext4_get_group_info() to fail Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device. For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL. Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.",
    "evidence": "osv:CVE-2023-53503",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.181",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.113",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.30",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.3.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-53503",
      "aliases": [
        "CVE-2023-53503"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "2f2e09eb15849562aede80ed007658e4504ded26"
                },
                {
                  "fixed": "100c0ad6c04597fefeaaba2bb1827cc015d95067"
                },
                {
                  "fixed": "620a3c28221bb219b81bc0bffd065cc187494302"
                },
                {
                  "fixed": "b4319e457d6e3fb33e443efeaf4634fc36e8a9ed"
                },
                {
                  "fixed": "31668cebf45adfb6283e465e641c4f5a21b07afa"
                },
                {
                  "fixed": "5354b2af34064a4579be8bc0e2f15a7b70f14b5f"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53503.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "3.11.0"
                },
                {
                  "fixed": "5.10.181"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.113"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.30"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.3.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53503.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.645255378Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/100c0ad6c04597fefeaaba2bb1827cc015d95067",
        "https://git.kernel.org/stable/c/31668cebf45adfb6283e465e641c4f5a21b07afa",
        "https://git.kernel.org/stable/c/5354b2af34064a4579be8bc0e2f15a7b70f14b5f",
        "https://git.kernel.org/stable/c/620a3c28221bb219b81bc0bffd065cc187494302",
        "https://git.kernel.org/stable/c/b4319e457d6e3fb33e443efeaf4634fc36e8a9ed",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53503.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-53503",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53503.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-53503",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 517776,
  "published_at": "2025-10-01T11:45:54.052+00:00"
}