Vulnerability-Lookup

FKIE_CVE-2025-38579

Vulnerability from fkie_nvd - Published: 2025-08-19 17:15 - Updated: 2026-07-30 06:23

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix KMSAN uninit-value in extent_info usage KMSAN reported a use of uninitialized value in `__is_extent_mergeable()` and `__is_back_mergeable()` via the read extent tree path. The root cause is that `get_read_extent_info()` only initializes three fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the remaining fields uninitialized. This leads to undefined behavior when those fields are accessed later, especially during extent merging. Fix it by zero-initializing the `extent_info` struct before population.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/01b6f5955e0008af6bc3a181310d2744bb349800	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/08e8ab00a6d20d5544c932ee85a297d833895141	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/154467f4ad033473e5c903a03e7b9bca7df9a0fa	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/44a79437309e0ee2276ac17aaedc71253af253a8	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/cc1615d5aba4f396cf412579928539a2b124c8a0	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/dabfa3952c8e6bfe6414dbf32e8b6c5f349dc898	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e68b751ec2b15d866967812c57cfdfc1eba6a269	Patch
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html	Mailing List, Third Party Advisory

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
debian	debian_linux	11.0

JSON

To clipboard

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    },
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      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: f2fs: correcci\u00f3n del valor no inicializado de KMSAN en el uso de extent_info. KMSAN inform\u00f3 del uso de un valor no inicializado en `__is_extent_mergeable()` y `__is_back_mergeable()` mediante la ruta de lectura del \u00e1rbol de extensiones. La causa principal es que `get_read_extent_info()` solo inicializa tres campos (`fofs`, `blk`, `len`) de `struct extent_info`, dejando los campos restantes sin inicializar. Esto provoca un comportamiento indefinido al acceder a dichos campos posteriormente, especialmente durante la fusi\u00f3n de extensiones. Para solucionarlo, inicialice a cero la estructura `extent_info` antes de rellenarla."
    }
  ],
  "id": "CVE-2025-38579",
  "lastModified": "2026-07-30T06:23:28.233",
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}

CVE-2025-38579 (GCVE-0-2025-38579)

Vulnerability from cvelistv5 – Published: 2025-08-19 17:03 – Updated: 2026-08-05 12:03

Title

f2fs: fix KMSAN uninit-value in extent_info usage

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root Scorecard

References

8 references

URL	Tags
https://git.kernel.org/stable/c/08e8ab00a6d20d554…
https://git.kernel.org/stable/c/e68b751ec2b15d866…
https://git.kernel.org/stable/c/dabfa3952c8e6bfe6…
https://git.kernel.org/stable/c/44a79437309e0ee22…
https://git.kernel.org/stable/c/cc1615d5aba4f396c…
https://git.kernel.org/stable/c/01b6f5955e0008af6…
https://git.kernel.org/stable/c/154467f4ad033473e…
https://lists.debian.org/debian-lts-announce/2025…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < 08e8ab00a6d20d5544c932ee85a297d833895141 (git) Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < e68b751ec2b15d866967812c57cfdfc1eba6a269 (git) Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < dabfa3952c8e6bfe6414dbf32e8b6c5f349dc898 (git) Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < 44a79437309e0ee2276ac17aaedc71253af253a8 (git) Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < cc1615d5aba4f396cf412579928539a2b124c8a0 (git) Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < 01b6f5955e0008af6bc3a181310d2744bb349800 (git) Affected: 94afd6d6e5253179c9b891d02081cc8355a11768 , < 154467f4ad033473e5c903a03e7b9bca7df9a0fa (git)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 5.15.190 , ≤ 5.15.* (semver) Unaffected: 6.1.148 , ≤ 6.1.* (semver) Unaffected: 6.6.102 , ≤ 6.6.* (semver) Unaffected: 6.12.42 , ≤ 6.12.* (semver) Unaffected: 6.15.10 , ≤ 6.15.* (semver) Unaffected: 6.16.1 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
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        "providerMetadata": {
          "dateUpdated": "2025-11-03T17:40:08.639Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
          }
        ],
        "title": "CVE Program Container"
      }
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                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix KMSAN uninit-value in extent_info usage\n\nKMSAN reported a use of uninitialized value in `__is_extent_mergeable()`\n and `__is_back_mergeable()` via the read extent tree path.\n\nThe root cause is that `get_read_extent_info()` only initializes three\nfields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the\nremaining fields uninitialized. This leads to undefined behavior\nwhen those fields are accessed later, especially during\nextent merging.\n\nFix it by zero-initializing the `extent_info` struct before population."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - f2fs is a local block-device filesystem; the uninitialized `extent_info` is consumed in `do_read_inode()`/`f2fs_init_read_extent_tree()`, reached by ordinary local file access (open/stat/read) on a mounted f2fs volume or by mounting a crafted image. There is no network-facing consumer of this code path.\nAC:L - The defect is deterministic \u2014 every regular-file inode loaded on an f2fs mount with the default read extent cache runs `get_read_extent_info()` over a stack-resident `struct extent_info` whose union bytes are never written, and the attacker both grooms the kernel stack (a preceding syscall leaves chosen values at that frame depth) and triggers the read at will. No race and no condition outside the attacker\u0027s control.\nPR:L - Any unprivileged local user who can open a file on an f2fs filesystem reaches `f2fs_iget()`\u2192`do_read_inode()`\u2192`f2fs_init_read_extent_tree()`; no capability, no CAP_SYS_ADMIN and no mount privilege is checked on this path. f2fs is the default userdata filesystem on Android and is common on embedded/IoT rootfs, so unprivileged app access suffices.\nUI:N - No victim action is required \u2014 the filesystem is already mounted in the normal deployment, and the attacker triggers the uninitialized read itself by touching any regular file. Nothing must be opened, plugged in, or mounted by another user.\nS:U - The uninitialized data stays inside the kernel\u0027s own extent cache and page cache within the same security authority; no VM, hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - Uninitialized kernel stack bytes are persisted into the long-lived extent tree (`en-\u003eei`, `et-\u003elargest`) and are printed verbatim to the kernel log by `f2fs_err_ratelimited()` in `__insert_extent_tree()`, which formats `ei.age`/`ei.last_blocks` \u2014 direct aliases of the never-written union bytes, potentially containing kernel pointers or residual data. Worse, a garbage `c_len` corrupts the `__is_extent_mergeable()` decision so an extent\u0027s file-offset\u2192block mapping becomes wrong, causing `f2fs_read_multi_pages()` to fetch and decompress unrelated on-disk blocks (`ei.blk + i - 1`) into this file\u0027s page cache, disclosing other files\u0027 data to the reader.\nI:H - The corrupted merge decision and the bogus `nr_cpages` bound derived from the uninitialized `c_len` make the compressed read path read the wrong physical blocks and decompress them into the inode\u0027s page cache, so applications silently observe corrupted file contents; the same paths set `SBI_NEED_FSCK` and `FI_COMPRESS_CORRUPT`, corrupting filesystem state that later writeback and fsck act on.\nA:H - Over-long/overlapping extents produced by the bad merge reach the corrupted-extent branch of `__insert_extent_tree()`, which calls `f2fs_bug_on(sbi, 1)` \u2014 a hard `BUG_ON()` panic with `CONFIG_F2FS_CHECK_FS` and a `WARN_ON()` (panic under `panic_on_warn`) otherwise \u2014 and the mismatched compressed-block count trips `f2fs_handle_error(sbi, ERROR_FAIL_DECOMPRESSION)` with `-EFSCORRUPTED`/EIO, denying access to file data."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:03:06.641Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/08e8ab00a6d20d5544c932ee85a297d833895141"
        },
        {
          "url": "https://git.kernel.org/stable/c/e68b751ec2b15d866967812c57cfdfc1eba6a269"
        },
        {
          "url": "https://git.kernel.org/stable/c/dabfa3952c8e6bfe6414dbf32e8b6c5f349dc898"
        },
        {
          "url": "https://git.kernel.org/stable/c/44a79437309e0ee2276ac17aaedc71253af253a8"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc1615d5aba4f396cf412579928539a2b124c8a0"
        },
        {
          "url": "https://git.kernel.org/stable/c/01b6f5955e0008af6bc3a181310d2744bb349800"
        },
        {
          "url": "https://git.kernel.org/stable/c/154467f4ad033473e5c903a03e7b9bca7df9a0fa"
        }
      ],
      "title": "f2fs: fix KMSAN uninit-value in extent_info usage",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38579",
    "datePublished": "2025-08-19T17:03:02.308Z",
    "dateReserved": "2025-04-16T04:51:24.026Z",
    "dateUpdated": "2026-08-05T12:03:06.641Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

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FKIE_CVE-2025-38579

CVE-2025-38579 (GCVE-0-2025-38579)

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