CVE-2025-39759 (GCVE-0-2025-39759)
Vulnerability from cvelistv5
Published
2025-09-11 16:52
Modified
2025-09-29 05:58
Severity ?
VLAI Severity ?
EPSS score ?
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 | |||||||
|---|---|---|---|---|---|---|---|---|---|
| ▼ | Linux | Linux |
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
||||||
|
|||||||||
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"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."
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{
"url": "https://git.kernel.org/stable/c/e1249667750399a48cafcf5945761d39fa584edf"
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],
"title": "btrfs: qgroup: fix race between quota disable and quota rescan ioctl",
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"datePublished": "2025-09-11T16:52:28.314Z",
"dateReserved": "2025-04-16T07:20:57.126Z",
"dateUpdated": "2025-09-29T05:58:50.124Z",
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