FKIE_CVE-2026-64239

Vulnerability from fkie_nvd - Published: 2026-07-24 16:16 - Updated: 2026-11-06 17:18
Severity
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: mm/damon/sysfs-schemes: delete tried region in regions_rmdirs() DAMON sysfs maintains the DAMOS tried region directory objects via a linked list. When the user requests refresh of the directories, DAMON sysfs removes all the region directories first, and then generate updated regions directory on the empty space. The removal function (damon_sysfs_scheme_regions_rm_dirs()) only puts the kobj objects. Deletion of the container region object from the linked list is done inside the kobj release callback function. If somehow the callback invocation is delayed, the list will contain regions list that gonna be freed. If the updated region directories creation is started in this situation, the list can be corrupted and use-after-free can happen. Because the kobj objects are managed by only DAMON sysfs, the issue cannot happen in normal situation. But, such delays can be made on kernels that built with CONFIG_DEBUG_KOBJECT_RELEASE. On the kernel, the issue can indeed be reproduced like below. # damo start --damos_action stat # cd /sys/kernel/mm/damon/admin/kdamonds/0/ # for i in {1..10}; do echo update_schemes_tried_regions > state; done # dmesg | grep underflow [ 89.296152] refcount_t: underflow; use-after-free. Fix the issue by removing the region object from the list when decrementing the reference count. Also update damos_sysfs_populate_region_dir() to add the region object to the list only after the kobject_init_and_add() is success, so that fail of kobject_init_and_add() is not leaving the deallocated object on the list. The issue was discovered [1] by Sashiko.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0ba6c05156d9ff9fc6ca22b7690e2eec9eca66f7Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2c33177023c92e76806c535ddbffaa3d3fc37777Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/441f92f7d386b85bad16de49db95a307cba048a2Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a5fa42214de55e43d165144727ce9facb9fc6b08Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c0e37017a452addec873865c94cf7a665663a9b2Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/damon/sysfs-schemes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
            },
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              "versionType": "git"
            },
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              "version": "9277d0367ba18ef4bb98bafb1209e715844cdf7e",
              "versionType": "git"
            },
            {
              "lessThan": "2c33177023c92e76806c535ddbffaa3d3fc37777",
              "status": "affected",
              "version": "9277d0367ba18ef4bb98bafb1209e715844cdf7e",
              "versionType": "git"
            },
            {
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/damon/sysfs-schemes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.2"
            },
            {
              "lessThan": "6.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
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              "versionEndExcluding": "6.6.143",
              "versionStartIncluding": "6.2",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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          "negate": false,
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs-schemes: delete tried region in regions_rmdirs()\n\nDAMON sysfs maintains the DAMOS tried region directory objects via a\nlinked list.  When the user requests refresh of the directories, DAMON\nsysfs removes all the region directories first, and then generate updated\nregions directory on the empty space.  The removal function\n(damon_sysfs_scheme_regions_rm_dirs()) only puts the kobj objects. \nDeletion of the container region object from the linked list is done\ninside the kobj release callback function.\n\nIf somehow the callback invocation is delayed, the list will contain\nregions list that gonna be freed.  If the updated region directories\ncreation is started in this situation, the list can be corrupted and\nuse-after-free can happen.\n\nBecause the kobj objects are managed by only DAMON sysfs, the issue cannot\nhappen in normal situation.  But, such delays can be made on kernels that\nbuilt with CONFIG_DEBUG_KOBJECT_RELEASE.  On the kernel, the issue can\nindeed be reproduced like below.\n\n    # damo start --damos_action stat\n    # cd /sys/kernel/mm/damon/admin/kdamonds/0/\n    # for i in {1..10}; do echo update_schemes_tried_regions \u003e state; done\n    # dmesg | grep underflow\n    [   89.296152] refcount_t: underflow; use-after-free.\n\nFix the issue by removing the region object from the list when\ndecrementing the reference count.\n\nAlso update damos_sysfs_populate_region_dir() to add the region object to\nthe list only after the kobject_init_and_add() is success, so that fail of\nkobject_init_and_add() is not leaving the deallocated object on the list.\n\nThe issue was discovered [1] by Sashiko."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmm/damon/sysfs-schemes: eliminar regi\u00f3n probada en regions_rmdirs()\n\nDAMON sysfs mantiene los objetos de directorio de regi\u00f3n probada de DAMOS a trav\u00e9s de una lista enlazada. Cuando el usuario solicita la actualizaci\u00f3n de los directorios, DAMON sysfs elimina primero todos los directorios de regi\u00f3n y luego genera un directorio de regiones actualizado en el espacio vac\u00edo. La funci\u00f3n de eliminaci\u00f3n (damon_sysfs_scheme_regions_rm_dirs()) solo pone los objetos kobj. La eliminaci\u00f3n del objeto de regi\u00f3n contenedor de la lista enlazada se realiza dentro de la funci\u00f3n de devoluci\u00f3n de llamada de liberaci\u00f3n de kobj.\n\nSi de alguna manera la invocaci\u00f3n de la devoluci\u00f3n de llamada se retrasa, la lista contendr\u00e1 una lista de regiones que van a ser liberadas. Si la creaci\u00f3n de directorios de regi\u00f3n actualizados se inicia en esta situaci\u00f3n, la lista puede corromperse y puede ocurrir un uso despu\u00e9s de liberaci\u00f3n.\n\nDebido a que los objetos kobj son gestionados solo por DAMON sysfs, el problema no puede ocurrir en una situaci\u00f3n normal. Pero, tales retrasos pueden producirse en kernels que se construyeron con CONFIG_DEBUG_KOBJECT_RELEASE. En el kernel, el problema puede de hecho reproducirse como se muestra a continuaci\u00f3n.\n\n    # damo start --damos_action stat\n    # cd /sys/kernel/mm/damon/admin/kdamonds/0/\n    # for i in {1..10}; do echo update_schemes_tried_regions \u003e state; done\n    # dmesg | grep underflow\n    [   89.296152] refcount_t: underflow; use-after-free.\n\nSoluciona el problema eliminando el objeto de regi\u00f3n de la lista al decrementar el recuento de referencias.\n\nTambi\u00e9n actualiza damos_sysfs_populate_region_dir() para a\u00f1adir el objeto de regi\u00f3n a la lista solo despu\u00e9s de que kobject_init_and_add() sea exitoso, para que el fallo de kobject_init_and_add() no deje el objeto desasignado en la lista.\n\nEl problema fue descubierto [1] por Sashiko."
    }
  ],
  "id": "CVE-2026-64239",
  "lastModified": "2026-11-06T17:18:43.490",
  "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"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-64239",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-11-06T16:32:43.478120Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-24T16:16:53.193",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/0ba6c05156d9ff9fc6ca22b7690e2eec9eca66f7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/2c33177023c92e76806c535ddbffaa3d3fc37777"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/441f92f7d386b85bad16de49db95a307cba048a2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/a5fa42214de55e43d165144727ce9facb9fc6b08"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/c0e37017a452addec873865c94cf7a665663a9b2"
    }
  ],
  "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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