CVE-2026-93100 (GCVE-0-2026-93100)
Vulnerability from cvelistv5 – Published: 2026-09-17 16:11 – Updated: 2026-09-17 16:11
VLAI
EPSS
VEX
Title
fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()
Summary
In the Linux kernel, the following vulnerability has been resolved:
fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()
A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that
need the structure to remain valid across a sleep (while waiting on acquiring
rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with
rdtgroup_kn_put().
The release path is intended to serve as the fallback freer: if the count
drops to zero and the group has already been marked RDT_DELETED,
rdtgroup_kn_put() frees the structure.
The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting
from a resctrl directory remove or resctrl fs unmount act as the primary
freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is
zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.
These two freers race. rdtgroup_kn_put() commits waitcount == 0 with
atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags.
Between those two operations a concurrent caller of free_all_child_rdtgrp()
or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via
atomic_read(), call rdtgroup_remove(), and kfree() the structure.
The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then
a use-after-free, and the structure may even be freed twice if the freed
memory happens to satisfy the RDT_DELETED flag check.
Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so
that the decrement-to-zero takes rdtgroup_mutex before the count becomes
globally visible. The inspection of rdtgroup::flags then runs under the same
mutex held by the bulk freers, making the two paths mutually exclusive.
The common case where the count does not reach zero remains lock-free. Defer
kernfs_unbreak_active_protection() until after the mutex is dropped since
kernfs active protections functionally wrap rdtgroup_mutex. Remove resource
group, which in turn drops its kernfs reference, after kernfs protection is
restored.
[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
b8511ccc75c033f6d54188ea4df7bf1e85778740 , < ae69f936e8ffed553d899ba4c02f8a7461a89e54
(git)
Affected: b8511ccc75c033f6d54188ea4df7bf1e85778740 , < 4c593c62c1499665baebbb41b70e2c9b7e947b86 (git) Affected: b8511ccc75c033f6d54188ea4df7bf1e85778740 , < f5bcf539484d2d604c2f2330e09487ea090b21c7 (git) Affected: d20edc0bca5577bab38acb5b190619c922ddebf8 (git) Affected: 1b006f8cbde9f3dabdfafe2ff7aa9f831ed5b625 (git) Affected: 40300f986e47dbc8f1d02e5080385f5cf9f85f70 (git) Affected: b5a4949897ebada8132d54c93208989482503103 (git) Affected: 4.14.170 , < 4.15 (semver) Affected: 4.19.102 , < 4.20 (semver) Affected: 5.4.18 , < 5.5 (semver) Affected: 5.5.2 , < 5.6 (semver) |
guessed | |
| Linux | Linux |
Affected:
5.6
Unaffected: 0 , < 5.6 (semver) Unaffected: 6.18.52 , ≤ 6.18.* (semver) Unaffected: 7.2.6 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/resctrl/rdtgroup.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "ae69f936e8ffed553d899ba4c02f8a7461a89e54",
"status": "affected",
"version": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
},
{
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"status": "affected",
"version": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"versionType": "git"
},
{
"status": "affected",
"version": "d20edc0bca5577bab38acb5b190619c922ddebf8",
"versionType": "git"
},
{
"status": "affected",
"version": "1b006f8cbde9f3dabdfafe2ff7aa9f831ed5b625",
"versionType": "git"
},
{
"status": "affected",
"version": "40300f986e47dbc8f1d02e5080385f5cf9f85f70",
"versionType": "git"
},
{
"status": "affected",
"version": "b5a4949897ebada8132d54c93208989482503103",
"versionType": "git"
},
{
"lessThan": "4.15",
"status": "affected",
"version": "4.14.170",
"versionType": "semver"
},
{
"lessThan": "4.20",
"status": "affected",
"version": "4.19.102",
"versionType": "semver"
},
{
"lessThan": "5.5",
"status": "affected",
"version": "5.4.18",
"versionType": "semver"
},
{
"lessThan": "5.6",
"status": "affected",
"version": "5.5.2",
"versionType": "semver"
}
]
},
{
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"product": "Linux",
"programFiles": [
"fs/resctrl/rdtgroup.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.6"
},
{
"lessThan": "5.6",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.52",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.6",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3-rc1",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.14.170",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.19.102",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "5.4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "5.5.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/resctrl: Prevent use-after-free in rdtgroup_kn_put()\n\nA struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that\nneed the structure to remain valid across a sleep (while waiting on acquiring\nrdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with\nrdtgroup_kn_put().\n\nThe release path is intended to serve as the fallback freer: if the count\ndrops to zero and the group has already been marked RDT_DELETED,\nrdtgroup_kn_put() frees the structure.\n\nThe bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting\nfrom a resctrl directory remove or resctrl fs unmount act as the primary\nfreer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is\nzero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.\n\nThese two freers race. rdtgroup_kn_put() commits waitcount == 0 with\natomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags.\nBetween those two operations a concurrent caller of free_all_child_rdtgrp()\nor rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via\natomic_read(), call rdtgroup_remove(), and kfree() the structure.\n\nThe subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then\na use-after-free, and the structure may even be freed twice if the freed\nmemory happens to satisfy the RDT_DELETED flag check.\n\nReplace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so\nthat the decrement-to-zero takes rdtgroup_mutex before the count becomes\nglobally visible. The inspection of rdtgroup::flags then runs under the same\nmutex held by the bulk freers, making the two paths mutually exclusive.\n\nThe common case where the count does not reach zero remains lock-free. Defer\nkernfs_unbreak_active_protection() until after the mutex is dropped since\nkernfs active protections functionally wrap rdtgroup_mutex. Remove resource\ngroup, which in turn drops its kernfs reference, after kernfs protection is\nrestored.\n\n [ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]"
}
],
"providerMetadata": {
"dateUpdated": "2026-09-17T16:11:13.077Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/ae69f936e8ffed553d899ba4c02f8a7461a89e54"
},
{
"url": "https://git.kernel.org/stable/c/4c593c62c1499665baebbb41b70e2c9b7e947b86"
},
{
"url": "https://git.kernel.org/stable/c/f5bcf539484d2d604c2f2330e09487ea090b21c7"
}
],
"title": "fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()",
"x_generator": {
"engine": "bippy-1.2.0"
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}
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-93100",
"datePublished": "2026-09-17T16:11:13.077Z",
"dateReserved": "2026-09-17T16:02:15.085Z",
"dateUpdated": "2026-09-17T16:11:13.077Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
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"cve": {
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{
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"product": "Linux",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"versions": [
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"versionType": "git"
},
{
"status": "affected",
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"versionType": "git"
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{
"status": "affected",
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{
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"version": "40300f986e47dbc8f1d02e5080385f5cf9f85f70",
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},
{
"status": "affected",
"version": "b5a4949897ebada8132d54c93208989482503103",
"versionType": "git"
},
{
"lessThan": "4.15",
"status": "affected",
"version": "4.14.170",
"versionType": "semver"
},
{
"lessThan": "4.20",
"status": "affected",
"version": "4.19.102",
"versionType": "semver"
},
{
"lessThan": "5.5",
"status": "affected",
"version": "5.4.18",
"versionType": "semver"
},
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"lessThan": "5.6",
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"version": "5.5.2",
"versionType": "semver"
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]
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.6"
},
{
"lessThan": "5.6",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/resctrl: Prevent use-after-free in rdtgroup_kn_put()\n\nA struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that\nneed the structure to remain valid across a sleep (while waiting on acquiring\nrdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with\nrdtgroup_kn_put().\n\nThe release path is intended to serve as the fallback freer: if the count\ndrops to zero and the group has already been marked RDT_DELETED,\nrdtgroup_kn_put() frees the structure.\n\nThe bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting\nfrom a resctrl directory remove or resctrl fs unmount act as the primary\nfreer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is\nzero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.\n\nThese two freers race. rdtgroup_kn_put() commits waitcount == 0 with\natomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags.\nBetween those two operations a concurrent caller of free_all_child_rdtgrp()\nor rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via\natomic_read(), call rdtgroup_remove(), and kfree() the structure.\n\nThe subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then\na use-after-free, and the structure may even be freed twice if the freed\nmemory happens to satisfy the RDT_DELETED flag check.\n\nReplace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so\nthat the decrement-to-zero takes rdtgroup_mutex before the count becomes\nglobally visible. The inspection of rdtgroup::flags then runs under the same\nmutex held by the bulk freers, making the two paths mutually exclusive.\n\nThe common case where the count does not reach zero remains lock-free. Defer\nkernfs_unbreak_active_protection() until after the mutex is dropped since\nkernfs active protections functionally wrap rdtgroup_mutex. Remove resource\ngroup, which in turn drops its kernfs reference, after kernfs protection is\nrestored.\n\n [ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]"
}
],
"id": "CVE-2026-93100",
"lastModified": "2026-09-17T17:18:04.223",
"metrics": {},
"published": "2026-09-17T17:18:04.223",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/4c593c62c1499665baebbb41b70e2c9b7e947b86"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ae69f936e8ffed553d899ba4c02f8a7461a89e54"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f5bcf539484d2d604c2f2330e09487ea090b21c7"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"suse_vex": {
"aggregate_severity": "not set",
"current_release_date": "2026-09-18T00:12:07Z",
"cve": "CVE-2026-93100",
"id": "CVE-2026-93100",
"initial_release_date": "2026-09-18T00:12:07Z",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-93100",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-93100.json",
"version": "2"
}
}
}
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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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