GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

FKIE_CVE-2026-74568

Vulnerability from fkie_nvd - Published: 2026-08-15 13:18 - Updated: 2026-08-17 06:19
Severity
9.3 (Critical) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: vgic: Fix race between LPI release and re-registration Fix a potential race between decrementing an LPI's reference count and evicting that structure from the LPI xarray. LPI structures are maintained in the VGIC LPI xarray (dist->lpi_xa). When the reference count of an LPI structure drops to zero, vgic_release_lpi_locked() removes the structure from the xarray and frees it under the xarray lock. However, the release of an LPI can race with a concurrent LPI re-registration with the same INTID via vgic_add_lpi() on another CPU, since the reference count drop and the xarray eviction are not performed in a single atomic step. This can happen e.g. if the guest issues a DISCARD while the LPI is still referenced from a vCPU's active-pending list (ap_list), and the same INTID is re-mapped via MAPTI. Particularly, vgic_release_lpi_locked() is called from two distinct paths: direct release via vgic_put_irq(), and deferred release via vgic_release_deleted_lpis(). During direct release, the issue can result in deleting a newly registered LPI from the xarray: CPU0 (Releasing LPI) CPU1 (Adding new LPI) ==================== ===================== vgic_put_irq() __vgic_put_irq() refcount_dec_and_test() vgic_add_lpi() xa_lock_irqsave() old_irq = xa_load(.., intid) vgic_try_get_irq_ref(old_irq) == false new IRQ inserted --> __xa_store(.., intid, ..) xa_unlock_irqrestore() xa_lock_irqsave(); vgic_release_lpi_locked() __xa_erase(.., irq->intid) <-- BUG: new IRQ is erased kfree_rcu(old_irq) During the deferred release path, the old IRQ can be leaked: CPU0 (Releasing LPI) CPU1 (Adding new LPI) ==================== ===================== vgic_put_irq_norelease() __vgic_put_irq() refcount_dec_and_test() irq->pending_release = true vgic_add_lpi() xa_lock_irqsave() old_irq = xa_load(.., intid) vgic_try_get_irq_ref(oldirq) == false BUG: old IRQ overwritten --> __xa_store(.., intid, ..) xa_unlock_irqrestore() vgic_release_deleted_lpis() xa_lock_irqsave() xa_for_each() { .. } <-- old IRQ with pending_release = true is gone, so it cannot be released To fix the direct release path, move the reference count drop inside the xarray lock, making sure that vgic_add_lpi() never encounters the to-be-released LPI. In the deferred release path, the refcount drop must happen under a raw spinlock, so the xarray lock cannot be grabbed, and the same solution does not work. Instead, update vgic_add_lpi(), so that if it evicts an LPI from the xarray, it takes on the responsibility of freeing it. Consequently, an LPI may now be freed concurrently after a deferred release drops the refcount, so accessing the pending_release field is no longer safe from use-after-free. Delete all uses of the flag, and update vgic_release_deleted_lpis() to identify orphaned LPIs purely based on their refcount.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/292e80a159aa88635bf668a7212cfdf526b8bd52
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cbfe2b24a1ea9de35032dbdd100fdc700f5be92d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/vgic/vgic-its.c",
            "arch/arm64/kvm/vgic/vgic.c",
            "include/kvm/arm_vgic.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "292e80a159aa88635bf668a7212cfdf526b8bd52",
              "status": "affected",
              "version": "3a08a6ca7c373198c84e2a8c025c395ee966ff8a",
              "versionType": "git"
            },
            {
              "lessThan": "cbfe2b24a1ea9de35032dbdd100fdc700f5be92d",
              "status": "affected",
              "version": "3a08a6ca7c373198c84e2a8c025c395ee966ff8a",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/vgic/vgic-its.c",
            "arch/arm64/kvm/vgic/vgic.c",
            "include/kvm/arm_vgic.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.17"
            },
            {
              "lessThan": "6.17",
              "status": "unaffected",
              "version": "0",
              "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\nKVM: arm64: vgic: Fix race between LPI release and re-registration\n\nFix a potential race between decrementing an LPI\u0027s reference count and\nevicting that structure from the LPI xarray.\n\nLPI structures are maintained in the VGIC LPI xarray (dist-\u003elpi_xa).\nWhen the reference count of an LPI structure drops to zero,\nvgic_release_lpi_locked() removes the structure from the xarray and\nfrees it under the xarray lock.\n\nHowever, the release of an LPI can race with a concurrent LPI\nre-registration with the same INTID via vgic_add_lpi() on another CPU,\nsince the reference count drop and the xarray eviction are not performed\nin a single atomic step. This can happen e.g. if the guest issues a\nDISCARD while the LPI is still referenced from a vCPU\u0027s active-pending\nlist (ap_list), and the same INTID is re-mapped via MAPTI.\n\nParticularly, vgic_release_lpi_locked() is called from two distinct\npaths: direct release via vgic_put_irq(), and deferred release via\nvgic_release_deleted_lpis(). During direct release, the issue can result\nin deleting a newly registered LPI from the xarray:\n\n  CPU0 (Releasing LPI)                    CPU1 (Adding new LPI)\n  ====================                    =====================\n  vgic_put_irq()\n      __vgic_put_irq()\n          refcount_dec_and_test()\n                                          vgic_add_lpi()\n                                              xa_lock_irqsave()\n                                              old_irq = xa_load(.., intid)\n                                              vgic_try_get_irq_ref(old_irq) == false\n                        new IRQ inserted --\u003e  __xa_store(.., intid, ..)\n                                              xa_unlock_irqrestore()\n  xa_lock_irqsave();\n  vgic_release_lpi_locked()\n      __xa_erase(.., irq-\u003eintid)   \u003c-- BUG: new IRQ is erased\n      kfree_rcu(old_irq)\n\nDuring the deferred release path, the old IRQ can be leaked:\n\n  CPU0 (Releasing LPI)                    CPU1 (Adding new LPI)\n  ====================                    =====================\n  vgic_put_irq_norelease()\n      __vgic_put_irq()\n          refcount_dec_and_test()\n      irq-\u003epending_release = true\n                                          vgic_add_lpi()\n                                              xa_lock_irqsave()\n                                              old_irq = xa_load(.., intid)\n                                              vgic_try_get_irq_ref(oldirq) == false\n                 BUG: old IRQ overwritten --\u003e __xa_store(.., intid, ..)\n                                              xa_unlock_irqrestore()\n\n  vgic_release_deleted_lpis()\n      xa_lock_irqsave()\n      xa_for_each() { .. } \u003c-- old IRQ with pending_release = true\n                               is gone, so it cannot be released\n\nTo fix the direct release path, move the reference count drop inside\nthe xarray lock, making sure that vgic_add_lpi() never encounters the\nto-be-released LPI.\n\nIn the deferred release path, the refcount drop must happen under a raw\nspinlock, so the xarray lock cannot be grabbed, and the same solution\ndoes not work. Instead, update vgic_add_lpi(), so that if it evicts\nan LPI from the xarray, it takes on the responsibility of freeing it.\nConsequently, an LPI may now be freed concurrently after a deferred\nrelease drops the refcount, so accessing the pending_release field is no\nlonger safe from use-after-free. Delete all uses of the flag, and update\nvgic_release_deleted_lpis() to identify orphaned LPIs purely based on\ntheir refcount."
    }
  ],
  "id": "CVE-2026-74568",
  "lastModified": "2026-08-17T06:19:55.053",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 9.3,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.5,
        "impactScore": 6.0,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T13:18:02.370",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/292e80a159aa88635bf668a7212cfdf526b8bd52"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cbfe2b24a1ea9de35032dbdd100fdc700f5be92d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.


Detection rules are retrieved from Rulezet.


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.