GHSA-3MX4-VRGG-R9XH
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
fs/resctrl: Fix use-after-free during unmount
During unmount or failure teardown all mon_data structures that contain monitoring event file private data are freed after which kernfs nodes are removed. However, the RDT_DELETED flag is never set for the statically allocated default resource group.
A concurrent reader of an event file associated with the default resource group may, after dropping kernfs active protection, block on rdtgroup_mutex while unmount proceeds to free the file private data and destroy the kernfs node without waiting for the reader.
When the mutex is released, the reader wakes up, observes that RDT_DELETED is not set for the default group, and dereferences the already-freed file private data.
The scenario can be depicted as follows: CPU0 CPU1 / * Default resource group's * monitoring data accessible via * kernfs file with kernfs_node::priv * pointing to a struct mon_data. * User opens the file for reading. / rdtgroup_mondata_show() / arch encounters fatal error / rdtgroup_kn_lock_live() resctrl_exit() atomic_inc(&rdtgroup_default.waitcount) cpus_read_lock() kernfs_break_active_protection(kn) mutex_lock(&rdtgroup_mutex) cpus_read_lock() resctrl_fs_teardown() mutex_lock(&rdtgroup_mutex) rmdir_all_sub() mon_put_kn_priv() / Delete all mon_data structures / rdtgroup_destroy_root() kernfs_destroy_root() rdtgroup_default.kn = NULL mutex_unlock(&rdtgroup_mutex) / * rdtgroup_default.flags is empty so * rdtgroup_kn_lock_live() returns * &rdtgroup_default / md = of->kn->priv;
/* md points to freed mon_data */
Set RDT_DELETED for the default group unconditionally since the flag does not lead to the freeing of this statically allocated group.
Do not allow a new resctrl mount if there are any waiters on default group of previous mount. A new mount will re-initialize the default group that would appear to waiters from previous mount as though the default group is accessible causing them to access the mon_data structures from the previous mount that have been removed.
{
"affected": [],
"aliases": [
"CVE-2026-72080"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:21:18Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/resctrl: Fix use-after-free during unmount\n\nDuring unmount or failure teardown all mon_data structures that contain\nmonitoring event file private data are freed after which kernfs nodes are\nremoved. However, the RDT_DELETED flag is never set for the statically\nallocated default resource group.\n\nA concurrent reader of an event file associated with the default resource\ngroup may, after dropping kernfs active protection, block on rdtgroup_mutex\nwhile unmount proceeds to free the file private data and destroy the kernfs\nnode without waiting for the reader.\n\nWhen the mutex is released, the reader wakes up, observes that RDT_DELETED\nis not set for the default group, and dereferences the already-freed\nfile private data.\n\nThe scenario can be depicted as follows:\n CPU0 CPU1\n /*\n * Default resource group\u0027s\n * monitoring data accessible via\n * kernfs file with kernfs_node::priv\n * pointing to a struct mon_data.\n * User opens the file for reading.\n */\n rdtgroup_mondata_show() /* arch encounters fatal error */\n rdtgroup_kn_lock_live() resctrl_exit()\n atomic_inc(\u0026rdtgroup_default.waitcount) cpus_read_lock()\n kernfs_break_active_protection(kn) mutex_lock(\u0026rdtgroup_mutex)\n cpus_read_lock() resctrl_fs_teardown()\n mutex_lock(\u0026rdtgroup_mutex) rmdir_all_sub()\n mon_put_kn_priv()\n /* Delete all mon_data structures */\n rdtgroup_destroy_root()\n kernfs_destroy_root()\n rdtgroup_default.kn = NULL\n mutex_unlock(\u0026rdtgroup_mutex)\n /*\n * rdtgroup_default.flags is empty so\n * rdtgroup_kn_lock_live() returns\n * \u0026rdtgroup_default\n */\n md = of-\u003ekn-\u003epriv;\n\n /* md points to freed mon_data */\n\nSet RDT_DELETED for the default group unconditionally since the flag does\nnot lead to the freeing of this statically allocated group.\n\nDo not allow a new resctrl mount if there are any waiters on default group\nof previous mount. A new mount will re-initialize the default group that\nwould appear to waiters from previous mount as though the default group is\naccessible causing them to access the mon_data structures from the previous\nmount that have been removed.",
"id": "GHSA-3mx4-vrgg-r9xh",
"modified": "2026-08-17T06:33:08Z",
"published": "2026-08-15T06:32:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72080"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/52fce648607e0d6a76eeb443d78708c49df1c554"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7b7bb07efe41bb646a93c4624aa2bb35df190342"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7d330a1d663381579b9d5dafa642b1b3158a0ce2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.