GHSA-F6VC-5CH2-5VXM
Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-07 09:32In the Linux kernel, the following vulnerability has been resolved:
KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()
kvmhv_emulate_tlbie_all_lpid() iterates the nested-guest IDR and drops mmu_lock before calling kvmhv_emulate_tlbie_lpid(), but does not hold a reference on the kvm_nested_guest pointer obtained from the IDR. A concurrent vCPU issuing a single-LPID tlbie (is=2, ric=2) can race through kvmhv_flush_nested() -> kvmhv_remove_nested() -> idr_remove / --refcnt -> kvmhv_release_nested() -> kfree(gp) in that window, leaving the iterating vCPU with a dangling pointer. The subsequent mutex_lock(&gp->tlb_lock) and accesses to gp->shadow_pgtable, gp->shadow_lpid and gp->l1_host all touch freed memory. The free path is fully L1-controlled.
Fix this by incrementing gp->refcnt inside the loop before dropping mmu_lock, mirroring what kvmhv_get_nested() does, and releasing the reference with kvmhv_put_nested() after the per-guest work completes. This is the same get/put discipline already used at every other call site that drops mmu_lock while holding a nested-guest pointer.
{
"affected": [],
"aliases": [
"CVE-2026-98283"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-06T09:18:18Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()\n\nkvmhv_emulate_tlbie_all_lpid() iterates the nested-guest IDR and drops\nmmu_lock before calling kvmhv_emulate_tlbie_lpid(), but does not hold a\nreference on the kvm_nested_guest pointer obtained from the IDR. A\nconcurrent vCPU issuing a single-LPID tlbie (is=2, ric=2) can race\nthrough kvmhv_flush_nested() -\u003e kvmhv_remove_nested() -\u003e idr_remove /\n--refcnt -\u003e kvmhv_release_nested() -\u003e kfree(gp) in that window, leaving\nthe iterating vCPU with a dangling pointer. The subsequent\nmutex_lock(\u0026gp-\u003etlb_lock) and accesses to gp-\u003eshadow_pgtable,\ngp-\u003eshadow_lpid and gp-\u003el1_host all touch freed memory. The free path\nis fully L1-controlled.\n\nFix this by incrementing gp-\u003erefcnt inside the loop before dropping\nmmu_lock, mirroring what kvmhv_get_nested() does, and releasing the\nreference with kvmhv_put_nested() after the per-guest work completes.\nThis is the same get/put discipline already used at every other\ncall site that drops mmu_lock while holding a nested-guest pointer.",
"id": "GHSA-f6vc-5ch2-5vxm",
"modified": "2026-10-07T09:32:15Z",
"published": "2026-10-06T09:31:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98283"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/24b634852413229bb8340d908b115c3365f3a247"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d8f7b1f586375df8bce23a0909566ad5e852259"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/51938dfa8a51a4f85328413fca9b6e21f9d2d088"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e37fba1ba69385cff2d0e60b371ee19e7d1852d1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ec2d7a52b3996ae81131617b4afc0af31583c1b4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fbf69b7d0555ee83c871f58750770f74b7179ad1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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.
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.
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.