GHSA-MW9P-H9XR-R672

Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32
VLAI
Details

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

firmware: arm_scmi: Drop handle on protocol bind failures

The SCMI bus notifier acquires an SCMI handle when the driver core emits BUS_NOTIFY_BIND_DRIVER, before invoking the protocol driver probe callback. The protocol probe path only checks whether sdev->handle is set.

If device_link_add() fails after the handle has been acquired, the protocol device can still bind with a valid handle but without the dependency link to the SCMI parent. A concurrent parent unbind can then miss the child and tear down the SCMI instance while the child still holds a handle into it.

If the protocol driver probe later fails, for example with -EPROBE_DEFER, the driver core emits BUS_NOTIFY_DRIVER_NOT_BOUND rather than BUS_NOTIFY_UNBOUND_DRIVER. The SCMI notifier only released the handle on BUS_NOTIFY_UNBOUND_DRIVER, so each failed protocol-device bind leaked the SCMI instance users refcount and left sdev->handle set after the failed probe.

Make the link helper report failure and drop the acquired handle if the link cannot be created. Also handle BUS_NOTIFY_DRIVER_NOT_BOUND in the same cleanup path used for unbind so failed probes balance the earlier BUS_NOTIFY_BIND_DRIVER acquisition.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-93084"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:18:02Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfirmware: arm_scmi: Drop handle on protocol bind failures\n\nThe SCMI bus notifier acquires an SCMI handle when the driver core emits\nBUS_NOTIFY_BIND_DRIVER, before invoking the protocol driver probe\ncallback. The protocol probe path only checks whether sdev-\u003ehandle is\nset.\n\nIf device_link_add() fails after the handle has been acquired, the\nprotocol device can still bind with a valid handle but without the\ndependency link to the SCMI parent. A concurrent parent unbind can then\nmiss the child and tear down the SCMI instance while the child still\nholds a handle into it.\n\nIf the protocol driver probe later fails, for example with\n-EPROBE_DEFER, the driver core emits BUS_NOTIFY_DRIVER_NOT_BOUND rather\nthan BUS_NOTIFY_UNBOUND_DRIVER. The SCMI notifier only released the\nhandle on BUS_NOTIFY_UNBOUND_DRIVER, so each failed protocol-device bind\nleaked the SCMI instance users refcount and left sdev-\u003ehandle set after\nthe failed probe.\n\nMake the link helper report failure and drop the acquired handle if the\nlink cannot be created. Also handle BUS_NOTIFY_DRIVER_NOT_BOUND in the\nsame cleanup path used for unbind so failed probes balance the earlier\nBUS_NOTIFY_BIND_DRIVER acquisition.",
  "id": "GHSA-mw9p-h9xr-r672",
  "modified": "2026-09-17T18:32:09Z",
  "published": "2026-09-17T18:32:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93084"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0f860db24ee95e5da4866303a35e55098b9641b3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/77d2985d1e80e67f32026fc03e975c4c83cc543d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a54dc23e8bd2246c28eafffa60b4634f0d1a11cc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/df273eced7cec550465fd1bb82a5d2c3c7d3c437"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e3a5c30d233ca5d3e799a80da806554c703bda13"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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