CVE-2026-74568: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gxv2-5vpw-rgjq",
  "modified" : "2026-10-15T12:30:43Z",
  "published" : "2026-08-15T15:30:36Z",
  "aliases" : [ "CVE-2026-74568" ],
  "details" : "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's reference count and\nevicting that structure from the LPI xarray.\n\nLPI structures are maintained in the VGIC LPI xarray (dist->lpi_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's 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 -->  __xa_store(.., intid, ..)\n                                              xa_unlock_irqrestore()\n  xa_lock_irqsave();\n  vgic_release_lpi_locked()\n      __xa_erase(.., irq->intid)   <-- 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->pending_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 --> __xa_store(.., intid, ..)\n                                              xa_unlock_irqrestore()\n\n  vgic_release_deleted_lpis()\n      xa_lock_irqsave()\n      xa_for_each() { .. } <-- 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-74568"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/292e80a159aa88635bf668a7212cfdf526b8bd52"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/cbfe2b24a1ea9de35032dbdd100fdc700f5be92d"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/f8e5715a37378ea1a140ee1162fa441e149c5142"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-15T13:18:02Z"
  }
}