ghsa-f7p4-h976-ch7q
Vulnerability from github
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.
{
"affected": [],
"aliases": [
"CVE-2025-39759"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-09-11T17:15:39Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: qgroup: fix race between quota disable and quota rescan ioctl\n\nThere\u0027s 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-\u003eqgroup_tree rbtree.\n\nThis happens as follows:\n\n1) Task A enters btrfs_ioctl_quota_rescan() -\u003e 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-\u003eqgroup_rescan_running is false (it wasn\u0027t set yet by\n task A);\n\n3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups\n from fs_info-\u003eqgroup_tree without taking the lock fs_info-\u003eqgroup_lock;\n\n4) Task A enters qgroup_rescan_zero_tracking() which starts iterating\n the fs_info-\u003eqgroup_tree tree while holding fs_info-\u003eqgroup_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-\u003eqgroup_lock at btrfs_free_qgroup_config().\nAlso at btrfs_qgroup_rescan() don\u0027t start the rescan worker if quotas\nwere already disabled.",
"id": "GHSA-f7p4-h976-ch7q",
"modified": "2025-11-03T18:31:40Z",
"published": "2025-09-11T18:35:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39759"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2fd0f5ceb997f90f4332ccbab6c7e907e6b2d0eb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7cda0fdde5d9890976861421d207870500f9aace"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b172535ccba12f0cf7d23b3b840989de47fc104d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c38028ce0d0045ca600b6a8345a0ff92bfb47b66"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dd0b28d877b293b1d7f8727a7de08ae36b6b9ef0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e1249667750399a48cafcf5945761d39fa584edf"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
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