Skip to content
Heist/ feed
Back to feed
CriticalFix available

ext4: handle wraparound when searching for blocks for indirect mapped blocks

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().

Products
Kernel
Affected versions
Not specified
Fixed versions
6.1.168, 6.12.80, 6.18.21, 6.19.11, 6.6.134
CVEs
CVE-2026-43067
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 16:30 UTC · Revision 1

Source evidence

ext4: handle wraparound when searching for blocks for indirect mapped blocks

core-osv · Original source

Published 5 May 2026, 15:23 UTC

In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().

osv:CVE-2026-43067

Kernel

Fixed versions: 6.1.168, 6.6.134, 6.12.80, 6.18.21, 6.19.11

Complete source record
{
  "id": "514de60ba096a02c2e4f4d30346226f8854cd01ced938fc0c4d8ea844661270d",
  "url": "https://osv.dev/vulnerability/CVE-2026-43067",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ext4: handle wraparound when searching for blocks for indirect mapped blocks",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 (\"ext4: always allocate blocks only from groups inode can use\") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().",
    "evidence": "osv:CVE-2026-43067",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.168",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.134",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.80",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.21",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.19.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-43067",
      "aliases": [
        "CVE-2026-43067"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "9d89b9d55e25cb340c5b4b769876edc551b7a9ff"
                },
                {
                  "fixed": "f89bba144938921a2249237ad04a0183ff3f8930"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "1b0edd6022a3f44ce87fea9959a9310f4628fbea"
                },
                {
                  "fixed": "83170a05908b6cf2fb3235d3065bf613ff866f3c"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "9eea2f57d11b30049ff996ac3eff6e0dc8089e5f"
                },
                {
                  "fixed": "4bec4a498ce86314d470ae6144120461f2138c29"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "34c803edc0b3365a42efcf9815acab63b4cf54e0"
                },
                {
                  "fixed": "12624c5b724a81e14e532972b40d863b0de3b7d1"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "321ed8d559c951e71ad2d2d69a4cf0445644e865"
                },
                {
                  "fixed": "2a368ccddfc492a0aa951e2caef2985f20e96503"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "4865c768b563deff1b6a6384e74a62f143427b42"
                },
                {
                  "fixed": "bb81702370fad22c06ca12b6e1648754dbc37e0f"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "5.15.203"
                },
                {
                  "fixed": "5.16"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "16fce6b6c0b247258c6c217fce5a48abf50f6964"
                }
              ]
            }
          ],
          "versions": [
            "v6.1.167",
            "v6.6.133",
            "v6.6.132",
            "v6.6.131",
            "v6.6.130",
            "v6.12.79",
            "v6.12.78",
            "v6.12.77",
            "v6.18.20",
            "v6.18.19",
            "v6.18.18",
            "v6.18.17",
            "v6.18.16",
            "v6.18.15",
            "v6.18.14",
            "v6.19.10",
            "v6.19.9",
            "v6.19.8",
            "v6.19.7",
            "v6.19.6",
            "v6.19.5",
            "v6.19.4",
            "v5.15.223",
            "v5.15.222",
            "v5.15.221",
            "v5.15.220",
            "v5.15.219",
            "v5.15.218",
            "v5.15.217",
            "v5.15.216",
            "v5.15.215",
            "v5.15.214",
            "v5.15.213",
            "v5.15.212",
            "v5.15.211",
            "v5.15.210",
            "v5.15.209",
            "v5.15.208",
            "v5.15.207",
            "v5.15.206",
            "v5.15.205",
            "v5.15.204",
            "v5.15.203"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43067.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.1.167"
                },
                {
                  "fixed": "6.1.168"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.6.130"
                },
                {
                  "fixed": "6.6.134"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.12.77"
                },
                {
                  "fixed": "6.12.80"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.18.14"
                },
                {
                  "fixed": "6.18.21"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.4"
                },
                {
                  "fixed": "6.19.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43067.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.341053538Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1",
        "https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503",
        "https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29",
        "https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c",
        "https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f",
        "https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43067.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-43067",
        "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/2026/43xxx/CVE-2026-43067.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-43067",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497336,
  "published_at": "2026-05-05T15:23:26.717+00:00"
}