CVE-2026-97478

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: virt: acrn: Fix irqfd use-after-free during eventfd shutdown acrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free the same struct hsm_irqfd: CPU0 CPU1 ---- ---- eventfd_release() wake_up_poll(EPOLLHUP) hsm_irqfd_wakeup() queue_work(&irqfd->shutdown) acrn_irqfd_deassign() hsm_irqfd_shutdown() list_del_init() eventfd_ctx_remove_wait_queue() eventfd_ctx_put() kfree(irqfd) hsm_irqfd_shutdown_work() container_of(work, ..., shutdown) irqfd->vm <-- use-after-free The deassign path freed the irqfd while a shutdown work item was already queued by EPOLLHUP (or vice versa), so the work item could resurrect a dangling pointer through container_of(). Switch to the lifetime model used by KVM irqfds: - Deassign/deinit only deactivate the irqfd: remove it from vm->irqfds under irqfds_lock and queue the cleanup work. - hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the eventfd waitqueue entry, drops the eventfd reference and frees the irqfd. - A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit() ensures the cleanup work is queued at most once, no matter how many of {EPOLLHUP, deassign, deinit} fire concurrently. This is safe to call from the waitqueue callback, which runs with wqh->lock held and IRQs disabled and therefore cannot take irqfds_lock. - acrn_irqfd_deassign() flushes vm->irqfd_wq before returning so the eventfd is fully detached on return. acrn_irqfd_deinit() deactivates every irqfd, flushes the workqueue and only then destroys it, so no path can queue_work() onto a torn-down workqueue. - acrn_irqfd_assign() now installs the eventfd waitqueue entry and publishes the irqfd to vm->irqfds under irqfds_lock, so the irqfd is never visible to deassign/deinit before its waitqueue entry is in place, and any EPOLLHUP that fires in the assign window queues cleanup work that blocks on irqfds_lock until publication is done.

Severity

HIGH

CVSS score

7.8 (v3.1)

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-09-24 17:17:25.183000

Last modified

2026-10-30 13:21:04.313000

View original CVE JSON

{
  "id": "CVE-2026-97478",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-24T17:17:25.183",
  "lastModified": "2026-10-30T13:21:04.313",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: acrn: Fix irqfd use-after-free during eventfd shutdown\n\nacrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free\nthe same struct hsm_irqfd:\n\n  CPU0                                 CPU1\n  ----                                 ----\n  eventfd_release()\n    wake_up_poll(EPOLLHUP)\n      hsm_irqfd_wakeup()\n        queue_work(&irqfd->shutdown)\n                                       acrn_irqfd_deassign()\n                                         hsm_irqfd_shutdown()\n                                           list_del_init()\n                                           eventfd_ctx_remove_wait_queue()\n                                           eventfd_ctx_put()\n                                         kfree(irqfd)\n  hsm_irqfd_shutdown_work()\n    container_of(work, ..., shutdown)\n    irqfd->vm                  <-- use-after-free\n\nThe deassign path freed the irqfd while a shutdown work item was\nalready queued by EPOLLHUP (or vice versa), so the work item could\nresurrect a dangling pointer through container_of().\n\nSwitch to the lifetime model used by KVM irqfds:\n\n - Deassign/deinit only deactivate the irqfd: remove it from vm->irqfds\n   under irqfds_lock and queue the cleanup work.\n - hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the\n   eventfd waitqueue entry, drops the eventfd reference and frees the\n   irqfd.\n - A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit()\n   ensures the cleanup work is queued at most once, no matter how many\n   of {EPOLLHUP, deassign, deinit} fire concurrently.  This is safe to\n   call from the waitqueue callback, which runs with wqh->lock held and\n   IRQs disabled and therefore cannot take irqfds_lock.\n - acrn_irqfd_deassign() flushes vm->irqfd_wq before returning so the\n   eventfd is fully detached on return.  acrn_irqfd_deinit() deactivates\n   every irqfd, flushes the workqueue and only then destroys it, so no\n   path can queue_work() onto a torn-down workqueue.\n - acrn_irqfd_assign() now installs the eventfd waitqueue entry and\n   publishes the irqfd to vm->irqfds under irqfds_lock, so the irqfd is\n   never visible to deassign/deinit before its waitqueue entry is in\n   place, and any EPOLLHUP that fires in the assign window queues\n   cleanup work that blocks on irqfds_lock until publication is done."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "drivers/virt/acrn/irqfd.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71",
              "lessThan": "dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71",
              "lessThan": "6e9e007ee1dfb54bc2d070550308077ec28dbaec",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71",
              "lessThan": "0e1152f689847b9db2f05454775d34610c1424c2",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71",
              "lessThan": "d8156aacfcabb81f52c20ef89094945434d08079",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "aa3b483ff1d71c50b33db154048dff9a8f08ac71",
              "lessThan": "666c7f9e07925aa0863348f960e09bb89f8f05a3",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "drivers/virt/acrn/irqfd.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "5.12",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.12",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.160",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.114",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.53",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0e1152f689847b9db2f05454775d34610c1424c2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/666c7f9e07925aa0863348f960e09bb89f8f05a3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6e9e007ee1dfb54bc2d070550308077ec28dbaec",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d8156aacfcabb81f52c20ef89094945434d08079",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/dccf23a72a6c5ec8d9eab2a7f98e186af6eaff48",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}