GHSA-X7MW-48GF-2RXM

Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-09-16 15:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

KVM: arm64: vgic-v3: take an LPI reference in vgic_v3_save_pending_tables

vgic_v3_save_pending_tables() iterates dist->lpi_xa using xa_for_each() and dereferences the returned struct vgic_irq in the loop body without holding a reference on the LPI.

The xarray iterator only provides temporary RCU coverage while looking up the current entry. That is not sufficient for this loop body, which reads fields from struct vgic_irq and performs guest memory accesses before the iteration completes.

A concurrent path can trigger this race: the irqfd cached injection path (vgic_its_inject_cached_translation) obtains a transient LPI reference via vgic_its_check_cache() without holding kvm->lock, vcpu->mutex, config_lock, or its_lock. If guest ITS DISCARD then drops the cache and ITE references under its_lock, the transient inject reference may become the final one. When vgic_put_irq() drops it, the LPI is erased from lpi_xa and freed via kfree_rcu(). Meanwhile, vgic_v3_save_pending_tables() may still hold a stale pointer obtained from the xarray iterator and dereference it after the RCU grace period completes.

Fix this by re-fetching each iterated LPI via vgic_get_irq(), which takes a stable reference, and dropping it with vgic_put_irq() on all paths. This matches the pattern already used by other lpi_xa iterators in the vgic ITS code.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-89913"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-16T11:17:00Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: vgic-v3: take an LPI reference in vgic_v3_save_pending_tables\n\nvgic_v3_save_pending_tables() iterates dist-\u003elpi_xa using xa_for_each()\nand dereferences the returned struct vgic_irq in the loop body without\nholding a reference on the LPI.\n\nThe xarray iterator only provides temporary RCU coverage while looking up\nthe current entry. That is not sufficient for this loop body, which reads\nfields from struct vgic_irq and performs guest memory accesses before the\niteration completes.\n\nA concurrent path can trigger this race: the irqfd cached injection path\n(vgic_its_inject_cached_translation) obtains a transient LPI reference\nvia vgic_its_check_cache() without holding kvm-\u003elock, vcpu-\u003emutex,\nconfig_lock, or its_lock. If guest ITS DISCARD then drops the cache and\nITE references under its_lock, the transient inject reference may become\nthe final one. When vgic_put_irq() drops it, the LPI is erased from\nlpi_xa and freed via kfree_rcu(). Meanwhile, vgic_v3_save_pending_tables()\nmay still hold a stale pointer obtained from the xarray iterator and\ndereference it after the RCU grace period completes.\n\nFix this by re-fetching each iterated LPI via vgic_get_irq(), which takes\na stable reference, and dropping it with vgic_put_irq() on all paths.\nThis matches the pattern already used by other lpi_xa iterators in the\nvgic ITS code.",
  "id": "GHSA-x7mw-48gf-2rxm",
  "modified": "2026-09-16T15:31:02Z",
  "published": "2026-09-16T12:30:41Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89913"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7631f95297560157d3a9283cb999e3be00103348"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d3a2d20b7248ea67465af1cf79c79f90ff70926c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f5b8f203bfc07a5a257dff859e66d2c500f9f509"
    }
  ],
  "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"
    }
  ]
}



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