CVE-2026-89840 (GCVE-0-2026-89840)
Vulnerability from cvelistv5
Published
2026-09-16 10:31
Modified
2026-10-21 12:49
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate MOVE_RANGE destination size F2FS_IOC_MOVE_RANGE checks the source range, but not the destination end before updating i_size. A source hole can expose this: __clone_blkaddrs() skips NULL_ADDR entries and returns success, so the caller can still extend the destination inode with unchecked pos_out + len. Reject destination overflow and use inode_newsize_ok() before extending the destination inode.
References
Impacted products
Vendor Product Version
Linux Linux Version: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b
Version: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b
Version: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b
Version: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b
Version: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/file.c"
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          "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": "4.8"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
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                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: validate MOVE_RANGE destination size\n\nF2FS_IOC_MOVE_RANGE checks the source range, but not the destination end\nbefore updating i_size. A source hole can expose this: __clone_blkaddrs()\nskips NULL_ADDR entries and returns success, so the caller can still extend\nthe destination inode with unchecked pos_out + len.\n\nReject destination overflow and use inode_newsize_ok() before extending\nthe destination inode."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - F2FS_IOC_MOVE_RANGE is a local ioctl (f2fs_ioctl \u2192 f2fs_ioc_move_range \u2192 f2fs_move_file_range) on f2fs file descriptors. f2fs has no remap_file_range, so nfsd/ksmbd copy_file_range cannot reach this path.\nAC:L - The attacker fully controls pos_out and len and can ftruncate a sparse source so __clone_blkaddrs skips NULL_ADDR holes and returns success, making the unchecked destination i_size update deterministic with no race or uncontrollable layout.\nPR:L - f2fs_ioc_move_range has no capable() check; it only needs FMODE_READ|FMODE_WRITE on the source and FMODE_WRITE on the destination. Any unprivileged user with files on mounted f2fs (Android /data, embedded userdata) can trigger it.\nUI:N - The attacker opens their own files on an already-mounted f2fs volume and issues F2FS_IOC_MOVE_RANGE; no separate victim action such as mounting a filesystem or opening a crafted file is required.\nS:U - Impact is corruption of f2fs inode size metadata and subsequent filesystem/kernel state on the local host, a standard kernel compromise within the same security authority with no VM escape or IOMMU bypass.\nC:N - The bug writes an oversized or overflowed i_size; reads of the resulting sparse file return zeros or EOF (negative i_size makes pos \u003e= i_size), and lookups beyond max_file_blocks fail with -E2BIG, so there is no kernel-memory or cross-file disclosure primitive.\nI:H - Missing overflow and inode_newsize_ok() checks let the attacker set destination i_size past s_maxbytes or wrap size_t into a negative loff_t, persisting corrupt on-disk inode size and poisoning later paths (fallocate COLLAPSE nrpages, __exchange_data_block ALLOC_NODE) that trust i_size for block-tree updates.\nA:H - A poisoned i_size enables unbounded node-tree walks and block-exchange loops (SEEK_DATA/HOLE, fallocate COLLAPSE via DIV_ROUND_UP(i_size)), can hang the kernel or exhaust node space, and leaves durable filesystem corruption on shared f2fs userdata."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:49:02.980Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/54c587f3f95ce2d6932a16566db83f73cc4313e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/bca61ee5192ea47003722486ae9588a2a4bb47b6"
        },
        {
          "url": "https://git.kernel.org/stable/c/db13064669526494cd78ba3a4394063b740e940c"
        },
        {
          "url": "https://git.kernel.org/stable/c/dcae1eeda53149f219dd6af93b3083b7271c1c63"
        },
        {
          "url": "https://git.kernel.org/stable/c/e533889fc26aea0cd83c90327063f272061dd820"
        }
      ],
      "title": "f2fs: validate MOVE_RANGE destination size",
      "x_generator": {
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      }
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89840",
    "datePublished": "2026-09-16T10:31:14.646Z",
    "dateReserved": "2026-09-11T19:38:34.769Z",
    "dateUpdated": "2026-10-21T12:49:02.980Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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