fs/resctrl: Fix use-after-free during unmount

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-72080
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:21:18 UTC
Updated2026-08-17 06:18:06 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001680000 probability, percentile 0.065830000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 2a65660385444e9d9deffe995c71ee20443ef76e 7b7bb07efe41bb646a93c4624aa2bb35df190342 git Not specified
CNA Linux Linux affected 2a65660385444e9d9deffe995c71ee20443ef76e 7d330a1d663381579b9d5dafa642b1b3158a0ce2 git Not specified
CNA Linux Linux affected 2a65660385444e9d9deffe995c71ee20443ef76e 52fce648607e0d6a76eeb443d78708c49df1c554 git Not specified
CNA Linux Linux affected 6.16 Not specified
CNA Linux Linux unaffected 6.16 semver Not specified
CNA Linux Linux unaffected 6.18.42 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/7d330a1d663381579b9d5dafa642b1b3158a0ce2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7b7bb07efe41bb646a93c4624aa2bb35df190342 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/52fce648607e0d6a76eeb443d78708c49df1c554 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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