CVE-2025-68250 (GCVE-0-2025-68250)
Vulnerability from cvelistv5
Published
2025-12-16 14:32
Modified
2026-08-05 12:10
Severity ?
8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: hung_task: fix warnings caused by unaligned lock pointers The blocker tracking mechanism assumes that lock pointers are at least 4-byte aligned to use their lower bits for type encoding. However, as reported by Eero Tamminen, some architectures like m68k only guarantee 2-byte alignment of 32-bit values. This breaks the assumption and causes two related WARN_ON_ONCE checks to trigger. To fix this, the runtime checks are adjusted to silently ignore any lock that is not 4-byte aligned, effectively disabling the feature in such cases and avoiding the related warnings. Thanks to Geert Uytterhoeven for bisecting!
References
Impacted products
Vendor Product Version
Linux Linux Version: e711faaafbe54a884f33b53472434063d342f6d4
Version: e711faaafbe54a884f33b53472434063d342f6d4
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/hung_task.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c0e2dcbe54cb15ecdf9d8f4501c6720423243888",
              "status": "affected",
              "version": "e711faaafbe54a884f33b53472434063d342f6d4",
              "versionType": "git"
            },
            {
              "lessThan": "c97513cddcfc235f2522617980838e500af21d01",
              "status": "affected",
              "version": "e711faaafbe54a884f33b53472434063d342f6d4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/hung_task.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.6",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhung_task: fix warnings caused by unaligned lock pointers\n\nThe blocker tracking mechanism assumes that lock pointers are at least\n4-byte aligned to use their lower bits for type encoding.\n\nHowever, as reported by Eero Tamminen, some architectures like m68k\nonly guarantee 2-byte alignment of 32-bit values. This breaks the\nassumption and causes two related WARN_ON_ONCE checks to trigger.\n\nTo fix this, the runtime checks are adjusted to silently ignore any lock\nthat is not 4-byte aligned, effectively disabling the feature in such\ncases and avoiding the related warnings.\n\nThanks to Geert Uytterhoeven for bisecting!"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - On an affected m68k system running ksmbd, remote SMB2 IPC-pipe requests can contend on the unaligned session RPC rwsem and reach the vulnerable blocker tracking code over TCP/445.\nAC:L - The client can deterministically trigger the contemporaneous recursive-lock path or control concurrent requests against one session, so exploitation requires no uncontrollable race or memory-layout manipulation.\nPR:N - KSMBD permits passwordless guest sessions and allows restricted guest RPC operations, making the path reachable without credentials in a reasonable guest-enabled deployment.\nUI:N - Once the service is configured, attacker-supplied SMB requests trigger the vulnerable path without victim action.\nS:U - The warning, information exposure, and possible panic affect the same kernel and host security authority as the vulnerable code.\nC:L - The warning dumps kernel addresses and up to 48 raw m68k stack words, providing a bounded information disclosure where the kernel log or console is accessible.\nI:N - The rejected unaligned pointer is never stored or dereferenced, and the bug causes no memory corruption or attacker-controlled data modification.\nA:H - The warning immediately panics the kernel when panic_on_warn is enabled or the warning limit is reached, causing complete host unavailability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:10:27.999Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c0e2dcbe54cb15ecdf9d8f4501c6720423243888"
        },
        {
          "url": "https://git.kernel.org/stable/c/c97513cddcfc235f2522617980838e500af21d01"
        }
      ],
      "title": "hung_task: fix warnings caused by unaligned lock pointers",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68250",
    "datePublished": "2025-12-16T14:32:17.173Z",
    "dateReserved": "2025-12-16T13:41:40.266Z",
    "dateUpdated": "2026-08-05T12:10:27.999Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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