CVE-2026-98841 (GCVE-0-2026-98841)
Vulnerability from cvelistv5
Published
2026-10-18 15:50
Modified
2026-10-19 09:26
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: virt: vmgenid: set driver_data before registering notification handlers Both probe paths register their notification handler before assigning driver_data, which the handler dereferences. In the devicetree path, the notification IRQ can fire as soon as devm_request_irq() registers the handler: the interrupt may already be pending at probe time, for example when a VMM injects the generation-changed notification while restoring a guest from a snapshot that was taken before the driver had probed (Firecracker does exactly this on snapshot restore). The IRQ is also requested with IRQF_SHARED, so another device sharing the line can trigger the handler just as early. The handler then calls vmgenid_notify(), which dereferences the still-NULL driver_data and panics: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.38+ #1 PREEMPT(none) Hardware name: linux,dummy-virt (DT) pc : vmgenid_notify.isra.0+0x24/0x8c lr : vmgenid_of_irq_handler+0x14/0x34 Call trace: vmgenid_notify.isra.0+0x24/0x8c (P) vmgenid_of_irq_handler+0x14/0x34 __handle_irq_event_percpu+0x44/0x1bc handle_irq_event+0x4c/0xb4 handle_fasteoi_irq+0xf8/0x1f8 The ACPI path has the same ordering problem: the handler is installed with acpi_install_notify_handler() before driver_data is assigned. ACPI notifications are dispatched asynchronously from a workqueue, so the window is narrow, but a notification arriving between the two calls hits the same NULL dereference. Assign driver_data before registering the handlers. The state is fully initialized at that point, so the handlers are safe to run. Should registration fail, the probe error path leaves no dangling pointer behind: the driver core clears driver_data in device_unbind_cleanup().
References
Impacted products
Vendor Product Version
Linux Linux Version: e07606713a908eee8099883c8c830ebe33aaf748
Version: e07606713a908eee8099883c8c830ebe33aaf748
Version: e07606713a908eee8099883c8c830ebe33aaf748
Version: e07606713a908eee8099883c8c830ebe33aaf748
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/virt/vmgenid.c"
          ],
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/virt/vmgenid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "6.10"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.113",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.56",
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                  "vulnerable": true
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                  "vulnerable": true
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                {
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                  "versionEndExcluding": "7.3",
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: vmgenid: set driver_data before registering notification handlers\n\nBoth probe paths register their notification handler before assigning\ndriver_data, which the handler dereferences.\n\nIn the devicetree path, the notification IRQ can fire as soon as\ndevm_request_irq() registers the handler: the interrupt may already be\npending at probe time, for example when a VMM injects the\ngeneration-changed notification while restoring a guest from a snapshot\nthat was taken before the driver had probed (Firecracker does exactly\nthis on snapshot restore). The IRQ is also requested with IRQF_SHARED,\nso another device sharing the line can trigger the handler just as\nearly. The handler then calls vmgenid_notify(), which dereferences the\nstill-NULL driver_data and panics:\n\n  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010\n  CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.38+ #1 PREEMPT(none)\n  Hardware name: linux,dummy-virt (DT)\n  pc : vmgenid_notify.isra.0+0x24/0x8c\n  lr : vmgenid_of_irq_handler+0x14/0x34\n  Call trace:\n   vmgenid_notify.isra.0+0x24/0x8c (P)\n   vmgenid_of_irq_handler+0x14/0x34\n   __handle_irq_event_percpu+0x44/0x1bc\n   handle_irq_event+0x4c/0xb4\n   handle_fasteoi_irq+0xf8/0x1f8\n\nThe ACPI path has the same ordering problem: the handler is installed\nwith acpi_install_notify_handler() before driver_data is assigned.\nACPI notifications are dispatched asynchronously from a workqueue, so\nthe window is narrow, but a notification arriving between the two calls\nhits the same NULL dereference.\n\nAssign driver_data before registering the handlers. The state is fully\ninitialized at that point, so the handlers are safe to run. Should\nregistration fail, the probe error path leaves no dangling pointer\nbehind: the driver core clears driver_data in device_unbind_cleanup()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:26:33.492Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/538fe5efaa9704ad820ba34b4f9df135ca873d79"
        },
        {
          "url": "https://git.kernel.org/stable/c/7a1e8daeaa466c6aaffa223e1afe9cfeece0dd47"
        },
        {
          "url": "https://git.kernel.org/stable/c/8f42954ad8bf9bdbf574f2c437ad30cb2601f401"
        },
        {
          "url": "https://git.kernel.org/stable/c/9f8139c6145cf17d690d6c414d43b4c0bef632fb"
        }
      ],
      "title": "virt: vmgenid: set driver_data before registering notification handlers",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98841",
    "datePublished": "2026-10-18T15:50:15.224Z",
    "dateReserved": "2026-09-25T10:25:14.373Z",
    "dateUpdated": "2026-10-19T09:26:33.492Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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