CVE-2026-98467 (GCVE-0-2026-98467)
Vulnerability from cvelistv5
Published
2026-10-18 15:15
Modified
2026-10-19 09:20
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race Commit 7270cc9157f4 ("KVM: arm64: nv: Handle VNCR_EL2 invalidation from MMU notifiers") introduced VNCR_EL2 invalidation in both kvm_nested_s2_unmap() and kvm_nested_s2_wp(). However at the point of this being performed concurrent stage 2 teardown of a nested guest can cause kvm->arch.mmu.pgt to be set to NULL. This happens in kvm_flush_shadow_all() -> kvm_arch_flush_shadow_all() -> kvm_free_stage2_pgd() and is performed under the kvm->mmu_lock. Commit ec14c272408a ("KVM: arm64: nv: Unmap/flush shadow stage 2 page tables") introduced the teardown of the entire nested MMU range, which then invokes stage2_apply_range() with resched=true: mmu_notifier_invalidate_range_start() -> ... -> kvm_mmu_notifier_invalidate_range_start() -> kvm_mmu_unmap_gfn_range() -> kvm_unmap_gfn_range() -> kvm_nested_s2_unmap() -> kvm_stage2_unmap_range() -> __unmap_stage2_range() -> stage2_apply_range() This means that stage2_apply_range() can drop the kvm->mmu_lock and thus concurrent progress can be made in lockstep with kvm_arch_flush_shadow_all(). If kvm_arch_flush_shadow_all() advances ahead of stage2_apply_range() and completes its operation it guarantees a NULL pointer deref. Since kvm_free_stage2_pgd() is performed under the kvm->mmu_lock this will either be observed NULL or not and serialised against kvm_free_stage2_pgd(). Resolve the issue by abstracting the invalidation to a new function, kvm_invalidate_vncr_ipa_all(), and check that the pgt is non-NULL before dereferencing it.
References
Impacted products
Vendor Product Version
Linux Linux Version: 7270cc9157f474dfc46750a34c9d7defc686b2eb
Version: 7270cc9157f474dfc46750a34c9d7defc686b2eb
Version: 7270cc9157f474dfc46750a34c9d7defc686b2eb
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/nested.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "970de111c087488e53cadf5480b94e0f695db985",
              "status": "affected",
              "version": "7270cc9157f474dfc46750a34c9d7defc686b2eb",
              "versionType": "git"
            },
            {
              "lessThan": "3cefc1ab511fad6a0f708e7a4aee9f91346e9457",
              "status": "affected",
              "version": "7270cc9157f474dfc46750a34c9d7defc686b2eb",
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            {
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              "version": "7270cc9157f474dfc46750a34c9d7defc686b2eb",
              "versionType": "git"
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          ]
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/nested.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race\n\nCommit 7270cc9157f4 (\"KVM: arm64: nv: Handle VNCR_EL2 invalidation from MMU\nnotifiers\") introduced VNCR_EL2 invalidation in both kvm_nested_s2_unmap()\nand kvm_nested_s2_wp().\n\nHowever at the point of this being performed concurrent stage 2 teardown of\na nested guest can cause kvm-\u003earch.mmu.pgt to be set to NULL.\n\nThis happens in kvm_flush_shadow_all() -\u003e kvm_arch_flush_shadow_all() -\u003e\nkvm_free_stage2_pgd() and is performed under the kvm-\u003emmu_lock.\n\nCommit ec14c272408a (\"KVM: arm64: nv: Unmap/flush shadow stage 2 page\ntables\") introduced the teardown of the entire nested MMU range, which then\ninvokes stage2_apply_range() with resched=true:\n\nmmu_notifier_invalidate_range_start()\n  -\u003e ... -\u003e kvm_mmu_notifier_invalidate_range_start()\n    -\u003e kvm_mmu_unmap_gfn_range()\n      -\u003e kvm_unmap_gfn_range()\n        -\u003e kvm_nested_s2_unmap()\n          -\u003e kvm_stage2_unmap_range()\n            -\u003e __unmap_stage2_range()\n                -\u003e stage2_apply_range()\n\nThis means that stage2_apply_range() can drop the kvm-\u003emmu_lock and thus\nconcurrent progress can be made in lockstep with\nkvm_arch_flush_shadow_all().\n\nIf kvm_arch_flush_shadow_all() advances ahead of stage2_apply_range() and\ncompletes its operation it guarantees a NULL pointer deref.\n\nSince kvm_free_stage2_pgd() is performed under the kvm-\u003emmu_lock this will\neither be observed NULL or not and serialised against\nkvm_free_stage2_pgd().\n\nResolve the issue by abstracting the invalidation to a new function,\nkvm_invalidate_vncr_ipa_all(), and check that the pgt is non-NULL before\ndereferencing it."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:20:05.363Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/970de111c087488e53cadf5480b94e0f695db985"
        },
        {
          "url": "https://git.kernel.org/stable/c/3cefc1ab511fad6a0f708e7a4aee9f91346e9457"
        },
        {
          "url": "https://git.kernel.org/stable/c/4c74e233cdedd11592775fae2a6243e67ca3f891"
        }
      ],
      "title": "KVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98467",
    "datePublished": "2026-10-18T15:15:19.294Z",
    "dateReserved": "2026-09-25T10:25:14.351Z",
    "dateUpdated": "2026-10-19T09:20:05.363Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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