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CVE-2025-39759

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: qgroup: fix race between quota disable and quota rescan ioctl There's a race between a task disabling quotas and another running the rescan ioctl that can result in a use-after-free of qgroup records from the fs_info->qgroup_tree rbtree. This happens as follows: 1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan(); 2) Task B enters btrfs_quota_disable() and calls btrfs_qgroup_wait_for_completion(), which does nothing because at that point fs_info->qgroup_rescan_running is false (it wasn't set yet by task A); 3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock; 4) Task A enters qgroup_rescan_zero_tracking() which starts iterating the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock, but task B is freeing qgroup records from that tree without holding the lock, resulting in a use-after-free. Fix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config(). Also at btrfs_qgroup_rescan() don't start the rescan worker if quotas were already disabled.

Severity
HIGH
CVSS score
7.0 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-11 17:15:39.827000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON 
{
  "id": "CVE-2025-39759",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-09-11T17:15:39.827",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: qgroup: fix race between quota disable and quota rescan ioctl\n\nThere's a race between a task disabling quotas and another running the\nrescan ioctl that can result in a use-after-free of qgroup records from\nthe fs_info->qgroup_tree rbtree.\n\nThis happens as follows:\n\n1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan();\n\n2) Task B enters btrfs_quota_disable() and calls\n   btrfs_qgroup_wait_for_completion(), which does nothing because at that\n   point fs_info->qgroup_rescan_running is false (it wasn't set yet by\n   task A);\n\n3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups\n   from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock;\n\n4) Task A enters qgroup_rescan_zero_tracking() which starts iterating\n   the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock,\n   but task B is freeing qgroup records from that tree without holding\n   the lock, resulting in a use-after-free.\n\nFix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config().\nAlso at btrfs_qgroup_rescan() don't start the rescan worker if quotas\nwere already disabled."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nbtrfs: qgroup: solucionar condición de carrera entre la desactivación de cuotas y el ioctl de reescaneo de cuotas\n\nExiste una condición de carrera entre una tarea que desactiva las cuotas y otra que ejecuta el ioctl de reescaneo que puede resultar en un uso después de liberación de registros de qgroup del rbtree fs_info->qgroup_tree.\n\nEsto ocurre de la siguiente manera:\n\n1) La Tarea A entra en btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan();\n\n2) La Tarea B entra en btrfs_quota_disable() y llama a btrfs_qgroup_wait_for_completion(), lo cual no hace nada porque en ese momento fs_info->qgroup_rescan_running es falso (aún no había sido establecido por la Tarea A);\n\n3) La Tarea B llama a btrfs_free_qgroup_config() que comienza a liberar qgroups del fs_info->qgroup_tree sin tomar el bloqueo fs_info->qgroup_lock;\n\n4) La Tarea A entra en qgroup_rescan_zero_tracking() que comienza a iterar el árbol fs_info->qgroup_tree mientras mantiene el fs_info->qgroup_lock, pero la Tarea B está liberando registros de qgroup de ese árbol sin mantener el bloqueo, resultando en un uso después de liberación.\n\nSolucione esto tomando fs_info->qgroup_lock en btrfs_free_qgroup_config(). También en btrfs_qgroup_rescan() no inicie el trabajador de reescaneo si las cuotas ya estaban desactivadas."
    }
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      "affectedData": [
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          "product": "SIMATIC CN 4100",
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        "type": "Primary",
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          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 7.0,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "HIGH",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.0,
        "impactScore": 5.9
      }
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  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-362"
        }
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