CVE-2023-54107 (GCVE-0-2023-54107)
Vulnerability from cvelistv5 – Published: 2025-12-24 13:06 – Updated: 2026-08-05 09:17
VLAI
EPSS
VEX
Title
blk-cgroup: dropping parent refcount after pd_free_fn() is done
Summary
In the Linux kernel, the following vulnerability has been resolved:
blk-cgroup: dropping parent refcount after pd_free_fn() is done
Some cgroup policies will access parent pd through child pd even
after pd_offline_fn() is done. If pd_free_fn() for parent is called
before child, then UAF can be triggered. Hence it's better to guarantee
the order of pd_free_fn().
Currently refcount of parent blkg is dropped in __blkg_release(), which
is before pd_free_fn() is called in blkg_free_work_fn() while
blkg_free_work_fn() is called asynchronously.
This patch make sure pd_free_fn() called from removing cgroup is ordered
by delaying dropping parent refcount after calling pd_free_fn() for
child.
BTW, pd_free_fn() will also be called from blkcg_deactivate_policy()
from deleting device, and following patches will guarantee the order.
Severity
7.8 (High)
Assigner
References
1 reference
Impacted products
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_free_fn() for parent is called\nbefore child, then UAF can be triggered. Hence it\u0027s better to guarantee\nthe order of pd_free_fn().\n\nCurrently refcount of parent blkg is dropped in __blkg_release(), which\nis before pd_free_fn() is called in blkg_free_work_fn() while\nblkg_free_work_fn() is called asynchronously.\n\nThis patch make sure pd_free_fn() called from removing cgroup is ordered\nby delaying dropping parent refcount after calling pd_free_fn() for\nchild.\n\nBTW, pd_free_fn() will also be called from blkcg_deactivate_policy()\nfrom deleting device, and following patches will guarantee the order."
}
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
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"value": "AV:L - Triggering requires local cgroup filesystem operations (mkdir/rmdir of nested cgroups, writes to io.max/io.weight/io.latency) plus block I/O to populate blkgs. There is no remote or adjacent-network path into blk-cgroup teardown.\nAC:L - Although the UAF arises from unordered asynchronous work items and timers, the attacker controls both sides \u2014 building the nested blkcg hierarchy, choosing the tear-down order and timing, looping thousands of create/destroy cycles, and loading system_wq to widen the window while pd_free_fn sleeps (hrtimer_cancel, blk_put_queue). The iocost/throttle timers also fire on their own, so the window recurs without any condition outside attacker influence.\nPR:L - An unprivileged local account with a delegated cgroup v2 subtree suffices \u2014 standard systemd user slices and rootless/OCI containers grant mkdir/rmdir plus ownership of the non-root io.max, io.weight and io.latency files in cgroups the user creates, and bfq/blk-throttle policies are active without any privileged setup. No real root in the initial namespace is needed.\nUI:N - The attacker performs the entire sequence \u2014 cgroup creation, I/O generation, and rmdir \u2014 in its own process with no action by any other user.\nS:U - The corruption is confined to kernel heap objects managed by the same kernel security authority; no VM, hypervisor, or IOMMU boundary is crossed.\nC:H - The freed parent ioc_gq/throtl_grp/bfq_group lives in a general kmalloc cache, and __propagate_weights()/current_hweight() read child_active_sum, child_inuse_sum, active and inuse straight out of the reclaimed slot, with results observable via io.stat and scheduling behaviour. Heap grooming turns this into a controllable kernel-memory disclosure primitive.\nI:H - __propagate_weights() performs read-modify-write arithmetic directly on the freed parent object (parent-\u003echild_active_sum += ..., parent-\u003echild_inuse_sum += ...) with deltas derived from attacker-chosen io.weight values, and throtl_rb_erase() writes rb-tree pointers into the freed parent service queue. Sprayed into an attacker-chosen reclaimed object, this is a write primitive leading to control-flow hijack and privilege escalation.\nA:H - Use-after-free access and modification of freed slab memory reliably produces KASAN splats, rb-tree/slab corruption, and kernel oops or panic, and the sequence can be repeated at will to crash the machine."
}
]
}
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"dateUpdated": "2026-08-05T09:17:19.939Z",
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"references": [
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"url": "https://git.kernel.org/stable/c/c7241babf0855d8a6180cd1743ff0ec34de40b4e"
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"title": "blk-cgroup: dropping parent refcount after pd_free_fn() is done",
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"cveId": "CVE-2023-54107",
"datePublished": "2025-12-24T13:06:31.505Z",
"dateReserved": "2025-12-24T13:02:52.517Z",
"dateUpdated": "2026-08-05T09:17:19.939Z",
"state": "PUBLISHED"
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"date": "2026-09-28",
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"vendor": "Linux",
"versions": [
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"status": "affected",
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"descriptions": [
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_free_fn() for parent is called\nbefore child, then UAF can be triggered. Hence it\u0027s better to guarantee\nthe order of pd_free_fn().\n\nCurrently refcount of parent blkg is dropped in __blkg_release(), which\nis before pd_free_fn() is called in blkg_free_work_fn() while\nblkg_free_work_fn() is called asynchronously.\n\nThis patch make sure pd_free_fn() called from removing cgroup is ordered\nby delaying dropping parent refcount after calling pd_free_fn() for\nchild.\n\nBTW, pd_free_fn() will also be called from blkcg_deactivate_policy()\nfrom deleting device, and following patches will guarantee the order."
}
],
"id": "CVE-2023-54107",
"lastModified": "2026-08-04T10:19:29.540",
"metrics": {
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{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
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"published": "2025-12-24T13:16:12.593",
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"url": "https://git.kernel.org/stable/c/c7241babf0855d8a6180cd1743ff0ec34de40b4e"
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
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"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-04T19:13:41+00:00",
"cve": "CVE-2023-54107",
"id": "CVE-2023-54107",
"initial_release_date": "2023-01-01T00:00:00+00:00",
"product_status:known_affected": "198",
"product_status:known_not_affected": "76",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: Linux kernel blk-cgroup: Use-after-free vulnerability leading to denial of service",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-54107.json",
"version": "3"
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"aggregate_severity": "moderate",
"current_release_date": "2026-08-29T02:03:53Z",
"cve": "CVE-2023-54107",
"id": "CVE-2023-54107",
"initial_release_date": "2025-12-25T00:55:28Z",
"product_status:known_affected": "374",
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"product_status:recommended": "87",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2023-54107",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2023-54107.json",
"version": "19"
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}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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