FKIE_CVE-2026-80895
Vulnerability from fkie_nvd - Published: 2026-09-04 18:17 - Updated: 2026-09-04 18:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
mshv: Order pt_vp_array publish against irqfd assertion path
mshv_partition_ioctl_create_vp() initialises a VP struct (allocations,
mutex_init, init_waitqueue_head, page mappings) and then publishes the
pointer into partition->pt_vp_array. Several ISR paths read this array
locklessly: the intercept ISR, the two scheduler ISRs, and
mshv_try_assert_irq_fast() on the irqfd fast path.
Of these, only mshv_try_assert_irq_fast() can structurally race the
publish. It runs from an eventfd waker without holding pt_mutex, and
MSHV_IRQFD does not require the target lapic_apic_id (== vp_index) to
refer to an existing VP at registration time. A user can therefore
register an irqfd targeting a yet-to-be-created VP, then trigger
mshv_try_assert_irq_fast() concurrently with MSHV_CREATE_VP for the
same index. On weakly-ordered architectures the reader can observe a
non-NULL pointer in pt_vp_array before the initialising stores to the
VP struct become visible, leading to use of partially-initialised
fields (e.g. vp_register_page).
The other ISR readers cannot reach this race: the hypervisor will not
generate intercept or scheduler messages for a VP that has never been
told to run, and the user can only call MSHV_RUN_VP on the VP fd
returned by MSHV_CREATE_VP, which by construction is returned after
the publish. Leave those readers as plain loads.
Use smp_store_release() in mshv_partition_ioctl_create_vp() to publish
the pointer, and pair it with smp_load_acquire() in
mshv_try_assert_irq_fast(). On x86 these compile to plain accesses
under TSO; on ARM64 they emit one-instruction acquire/release barriers,
acceptable on this fast path.
The destroy-side path (destroy_partition() clearing pt_vp_array[i] to
NULL after kfree(vp)) has a separate ordering and lifetime concern
that is out of scope here.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/hv/mshv_eventfd.c",
"drivers/hv/mshv_root_main.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9",
"status": "affected",
"version": "621191d709b14882270dfd8ea5d7d6cdfebe2c35",
"versionType": "git"
},
{
"lessThan": "eba2bf5daa7933f94c53ebbbf0f567d4274716df",
"status": "affected",
"version": "621191d709b14882270dfd8ea5d7d6cdfebe2c35",
"versionType": "git"
},
{
"lessThan": "b098dc869219c15dc49bf9cf63fb5fc1481d3373",
"status": "affected",
"version": "621191d709b14882270dfd8ea5d7d6cdfebe2c35",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/hv/mshv_eventfd.c",
"drivers/hv/mshv_root_main.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.15"
},
{
"lessThan": "6.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.44",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.8",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"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\nmshv: Order pt_vp_array publish against irqfd assertion path\n\nmshv_partition_ioctl_create_vp() initialises a VP struct (allocations,\nmutex_init, init_waitqueue_head, page mappings) and then publishes the\npointer into partition-\u003ept_vp_array. Several ISR paths read this array\nlocklessly: the intercept ISR, the two scheduler ISRs, and\nmshv_try_assert_irq_fast() on the irqfd fast path.\n\nOf these, only mshv_try_assert_irq_fast() can structurally race the\npublish. It runs from an eventfd waker without holding pt_mutex, and\nMSHV_IRQFD does not require the target lapic_apic_id (== vp_index) to\nrefer to an existing VP at registration time. A user can therefore\nregister an irqfd targeting a yet-to-be-created VP, then trigger\nmshv_try_assert_irq_fast() concurrently with MSHV_CREATE_VP for the\nsame index. On weakly-ordered architectures the reader can observe a\nnon-NULL pointer in pt_vp_array before the initialising stores to the\nVP struct become visible, leading to use of partially-initialised\nfields (e.g. vp_register_page).\n\nThe other ISR readers cannot reach this race: the hypervisor will not\ngenerate intercept or scheduler messages for a VP that has never been\ntold to run, and the user can only call MSHV_RUN_VP on the VP fd\nreturned by MSHV_CREATE_VP, which by construction is returned after\nthe publish. Leave those readers as plain loads.\n\nUse smp_store_release() in mshv_partition_ioctl_create_vp() to publish\nthe pointer, and pair it with smp_load_acquire() in\nmshv_try_assert_irq_fast(). On x86 these compile to plain accesses\nunder TSO; on ARM64 they emit one-instruction acquire/release barriers,\nacceptable on this fast path.\n\nThe destroy-side path (destroy_partition() clearing pt_vp_array[i] to\nNULL after kfree(vp)) has a separate ordering and lifetime concern\nthat is out of scope here."
}
],
"id": "CVE-2026-80895",
"lastModified": "2026-09-04T18:17:57.727",
"metrics": {},
"published": "2026-09-04T18:17:57.727",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b098dc869219c15dc49bf9cf63fb5fc1481d3373"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/eba2bf5daa7933f94c53ebbbf0f567d4274716df"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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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.
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.
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