FKIE_CVE-2026-98283

Vulnerability from fkie_nvd - Published: 2026-10-06 09:18 - Updated: 2026-10-07 07:17
Severity
8.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Summary
In 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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/24b634852413229bb8340d908b115c3365f3a247
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4d8f7b1f586375df8bce23a0909566ad5e852259
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/51938dfa8a51a4f85328413fca9b6e21f9d2d088
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e37fba1ba69385cff2d0e60b371ee19e7d1852d1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ec2d7a52b3996ae81131617b4afc0af31583c1b4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fbf69b7d0555ee83c871f58750770f74b7179ad1
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kvm/book3s_hv_nested.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "4d8f7b1f586375df8bce23a0909566ad5e852259",
              "status": "affected",
              "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49",
              "versionType": "git"
            },
            {
              "lessThan": "e37fba1ba69385cff2d0e60b371ee19e7d1852d1",
              "status": "affected",
              "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49",
              "versionType": "git"
            },
            {
              "lessThan": "24b634852413229bb8340d908b115c3365f3a247",
              "status": "affected",
              "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49",
              "versionType": "git"
            },
            {
              "lessThan": "fbf69b7d0555ee83c871f58750770f74b7179ad1",
              "status": "affected",
              "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49",
              "versionType": "git"
            },
            {
              "lessThan": "ec2d7a52b3996ae81131617b4afc0af31583c1b4",
              "status": "affected",
              "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49",
              "versionType": "git"
            },
            {
              "lessThan": "51938dfa8a51a4f85328413fca9b6e21f9d2d088",
              "status": "affected",
              "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kvm/book3s_hv_nested.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.20"
            },
            {
              "lessThan": "4.20",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "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\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": "CVE-2026-98283",
  "lastModified": "2026-10-07T07:17:08.070",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.0,
        "impactScore": 6.0,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-10-06T09:18:18.333",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/24b634852413229bb8340d908b115c3365f3a247"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4d8f7b1f586375df8bce23a0909566ad5e852259"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/51938dfa8a51a4f85328413fca9b6e21f9d2d088"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e37fba1ba69385cff2d0e60b371ee19e7d1852d1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ec2d7a52b3996ae81131617b4afc0af31583c1b4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fbf69b7d0555ee83c871f58750770f74b7179ad1"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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