FKIE_CVE-2026-31652

Vulnerability from fkie_nvd - Published: 2026-04-24 15:16 - Updated: 2026-06-17 10:34
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/damon/stat: deallocate damon_call() failure leaking damon_ctx damon_stat_start() always allocates the module's damon_ctx object (damon_stat_context). Meanwhile, if damon_call() in the function fails, the damon_ctx object is not deallocated. Hence, if the damon_call() is failed, and the user writes Y to “enabled” again, the previously allocated damon_ctx object is leaked. This cannot simply be fixed by deallocating the damon_ctx object when damon_call() fails. That's because damon_call() failure doesn't guarantee the kdamond main function, which accesses the damon_ctx object, is completely finished. In other words, if damon_stat_start() deallocates the damon_ctx object after damon_call() failure, the not-yet-terminated kdamond could access the freed memory (use-after-free). Fix the leak while avoiding the use-after-free by keeping returning damon_stat_start() without deallocating the damon_ctx object after damon_call() failure, but deallocating it when the function is invoked again and the kdamond is completely terminated. If the kdamond is not yet terminated, simply return -EAGAIN, as the kdamond will soon be terminated. The issue was discovered [1] by sashiko.

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/damon/stat.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "447f8870b484f6596d7a7130e72bd0a3f1e037bb",
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              "versionType": "git"
            },
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              "versionType": "git"
            },
            {
              "lessThan": "4c04c6b47c361612b1d70cec8f7a60b1482d1400",
              "status": "affected",
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              "versionType": "git"
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/damon/stat.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.17"
            },
            {
              "lessThan": "6.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.23",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
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              "versionEndExcluding": "6.18.23",
              "versionStartIncluding": "6.17.1",
              "vulnerable": true
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/stat: deallocate damon_call() failure leaking damon_ctx\n\ndamon_stat_start() always allocates the module\u0027s damon_ctx object\n(damon_stat_context).  Meanwhile, if damon_call() in the function fails,\nthe damon_ctx object is not deallocated.  Hence, if the damon_call() is\nfailed, and the user writes Y to \u201cenabled\u201d again, the previously\nallocated damon_ctx object is leaked.\n\nThis cannot simply be fixed by deallocating the damon_ctx object when\ndamon_call() fails.  That\u0027s because damon_call() failure doesn\u0027t guarantee\nthe kdamond main function, which accesses the damon_ctx object, is\ncompletely finished.  In other words, if damon_stat_start() deallocates\nthe damon_ctx object after damon_call() failure, the not-yet-terminated\nkdamond could access the freed memory (use-after-free).\n\nFix the leak while avoiding the use-after-free by keeping returning\ndamon_stat_start() without deallocating the damon_ctx object after\ndamon_call() failure, but deallocating it when the function is invoked\nagain and the kdamond is completely terminated.  If the kdamond is not yet\nterminated, simply return -EAGAIN, as the kdamond will soon be terminated.\n\nThe issue was discovered [1] by sashiko."
    }
  ],
  "id": "CVE-2026-31652",
  "lastModified": "2026-06-17T10:34:10.147",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-04-24T15:16:44.697",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/16c92e9bf55fa049ddb5e894dc0623dacd46a620"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
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    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/4c04c6b47c361612b1d70cec8f7a60b1482d1400"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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