CVE-2026-72213 (GCVE-0-2026-72213)
Vulnerability from cvelistv5
Published
2026-08-15 05:54
Modified
2026-08-17 05:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
mm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch
In alloc_hugetlb_folio(), a single h_cg pointer is used for both the rsvd
and non-rsvd hugetlb cgroup charges. When map_chg is set,
hugetlb_cgroup_charge_cgroup_rsvd() stores the charged cgroup in h_cg, but
the immediately following hugetlb_cgroup_charge_cgroup() overwrites h_cg
with the non-rsvd cgroup pointer.
As a result, hugetlb_cgroup_commit_charge_rsvd() stores the wrong
(non-rsvd) cgroup pointer into the folio's rsvd slot.
When the folio is later freed, free_huge_folio() unconditionally calls
both hugetlb_cgroup_uncharge_folio() and
hugetlb_cgroup_uncharge_folio_rsvd(). The rsvd uncharge reads back the
wrong cgroup from the folio and decrements a counter that was never
charged for that cgroup, causing a page_counter underflow:
page_counter underflow: -512 nr_pages=512
WARNING: mm/page_counter.c:61 at page_counter_cancel
Fix this by introducing a separate h_cg_rsvd pointer exclusively for the
rsvd charge path, keeping the rsvd and non-rsvd charges fully independent
through their charge, commit, and error uncharge paths.
References
| URL | Tags | |
|---|---|---|
Impacted products
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"versions": [
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{
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"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.1.5",
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{
"lessThanOrEqual": "*",
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"version": "7.2",
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"cpeApplicability": [
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"vulnerable": true
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch\n\nIn alloc_hugetlb_folio(), a single h_cg pointer is used for both the rsvd\nand non-rsvd hugetlb cgroup charges. When map_chg is set,\nhugetlb_cgroup_charge_cgroup_rsvd() stores the charged cgroup in h_cg, but\nthe immediately following hugetlb_cgroup_charge_cgroup() overwrites h_cg\nwith the non-rsvd cgroup pointer.\n\nAs a result, hugetlb_cgroup_commit_charge_rsvd() stores the wrong\n(non-rsvd) cgroup pointer into the folio\u0027s rsvd slot.\n\nWhen the folio is later freed, free_huge_folio() unconditionally calls\nboth hugetlb_cgroup_uncharge_folio() and\nhugetlb_cgroup_uncharge_folio_rsvd(). The rsvd uncharge reads back the\nwrong cgroup from the folio and decrements a counter that was never\ncharged for that cgroup, causing a page_counter underflow:\n\n page_counter underflow: -512 nr_pages=512\n WARNING: mm/page_counter.c:61 at page_counter_cancel\n\nFix this by introducing a separate h_cg_rsvd pointer exclusively for the\nrsvd charge path, keeping the rsvd and non-rsvd charges fully independent\nthrough their charge, commit, and error uncharge paths."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is in alloc_hugetlb_folio()/free_huge_folio() and is reached only via local MM paths (mmap/munmap, hugetlb page faults, fallocate, memfd MFD_HUGETLB, MAP_HUGETLB) that syzbot triggered through hugetlbfs inode eviction, not via any network-facing kernel service.\nAC:L - An unprivileged attacker can reliably trigger the mismatch by creating hugetlbfs mappings without reservations (MAP_NORESERVE or fault-before-reserve), faulting in huge pages to run alloc_hugetlb_folio() with map_chg set, then closing/unmapping to free folios and hit the bad rsvd uncharge.\nPR:L - Triggering requires only an unprivileged local process that can use hugetlb memory (hugetlbfs/MAP_HUGETLB/memfd) under a hugetlb cgroup; no init-namespace root or special driver capabilities are needed, and cgroup hugetlb limits are controllable from user namespaces.\nUI:N - Exploitation is fully attacker-driven through normal syscalls (mmap, write/fault, close/unlink) and does not require any victim user action beyond the attacker operating on their own mappings.\nS:U - Impact is confined to kernel hugetlb/cgroup page_counter accounting within the same host kernel security domain; it does not cross VM, container runtime, or IOMMU boundaries.\nC:N - The flaw corrupts hugetlb cgroup reservation counters and emits a WARN on underflow; it does not read or disclose kernel memory, pointers, or other confidential data to the attacker.\nI:H - page_counter underflow forcibly resets hugetlb cgroup reservation usage to zero, corrupting kernel accounting so an attacker can bypass hugetlb.rsvd cgroup limits and consume hugepage resources beyond enforced quotas in multi-tenant/container deployments.\nA:H - free_huge_folio() unconditionally hits the bad rsvd uncharge and triggers a kernel WARNING/page_counter underflow during hugepage teardown; syzbot classified this as DoS and repeated alloc/free cycles can disrupt hugetlb availability for other workloads when limits are bypassed."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:41:39.361Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/5c32ae4a91fb5f4941328e0c1720a7fa4189c3bd"
},
{
"url": "https://git.kernel.org/stable/c/1697d253f51cf5e3825a3423ff49e128a3502ab2"
},
{
"url": "https://git.kernel.org/stable/c/b785f2bd9496facedc0a031be09cddcd1d3c84d3"
},
{
"url": "https://git.kernel.org/stable/c/15807d0ddde37407af72859426b654f3d1972b00"
}
],
"title": "mm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch",
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-72213",
"datePublished": "2026-08-15T05:54:07.854Z",
"dateReserved": "2026-08-09T03:40:39.912Z",
"dateUpdated": "2026-08-17T05:41:39.361Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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