btrfs: qgroup: fix race between quota disable and quota rescan ioctl

{
  "id": "1f49dbb1af9977cfa8b75bc70f81e4b9c71d99b04873d989eec3a91acc85022e",
  "url": "https://osv.dev/vulnerability/CVE-2025-39759",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "btrfs: qgroup: fix race between quota disable and quota rescan ioctl",
    "summary": "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.",
    "evidence": "osv:CVE-2025-39759",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
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            "value": "6.6.103",
            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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            "value": "6.15.11",
            "evidence": "/affected/1/ranges"
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            "value": "6.16.2",
            "evidence": "/affected/1/ranges"
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    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-39759",
      "aliases": [
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      "modified": "2026-10-28T02:30:49.687898275Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-032379.html",
        "https://git.kernel.org/stable/c/2fd0f5ceb997f90f4332ccbab6c7e907e6b2d0eb",
        "https://git.kernel.org/stable/c/7cda0fdde5d9890976861421d207870500f9aace",
        "https://git.kernel.org/stable/c/b172535ccba12f0cf7d23b3b840989de47fc104d",
        "https://git.kernel.org/stable/c/c38028ce0d0045ca600b6a8345a0ff92bfb47b66",
        "https://git.kernel.org/stable/c/dd0b28d877b293b1d7f8727a7de08ae36b6b9ef0",
        "https://git.kernel.org/stable/c/e1249667750399a48cafcf5945761d39fa584edf",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39759.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-39759",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
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      "provider_metadata": {
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    "security_relevant": true,
    "severity_evidence": null
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  "source_id": "core-osv",
  "document_id": 518132,
  "published_at": "2025-09-11T16:52:28.314+00:00"
}