fkie_cve-2025-39759
Vulnerability from fkie_nvd
Published
2025-09-11 17:15
Modified
2025-09-15 15:22
Severity ?
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"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\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": "CVE-2025-39759",
"lastModified": "2025-09-15T15:22:38.297",
"metrics": {},
"published": "2025-09-11T17:15:39.827",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2fd0f5ceb997f90f4332ccbab6c7e907e6b2d0eb"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7cda0fdde5d9890976861421d207870500f9aace"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b172535ccba12f0cf7d23b3b840989de47fc104d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/c38028ce0d0045ca600b6a8345a0ff92bfb47b66"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/dd0b28d877b293b1d7f8727a7de08ae36b6b9ef0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e1249667750399a48cafcf5945761d39fa584edf"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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