FKIE_CVE-2026-64584

Vulnerability from fkie_nvd - Published: 2026-08-06 08:16 - Updated: 2026-08-08 15:16
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_midi: cancel pending IN work before freeing the midi object The f_midi driver embeds a work item (midi->work) whose handler, f_midi_in_work(), dereferences the enclosing struct f_midi through container_of(). This work is armed from two sites: f_midi_complete(), on a normal IN-endpoint completion, and f_midi_in_trigger(), on an ALSA rawmidi output-stream start. Neither f_midi_disable() nor f_midi_unbind() cancels midi->work. f_midi_disable() only disables the endpoints and drains the in_req_fifo; it does not synchronize the work item, and the sound card is released asynchronously to the final free of the midi object. The midi object is reference-counted (midi->free_ref) and is freed in f_midi_free() only once both the usb_function reference and the rawmidi private_data reference have been dropped. In f_midi_unbind(), f_midi_disable() runs before the sound card is released, so while the USB endpoints are already disabled the rawmidi device is still usable by an open substream. A concurrent userspace write on such a substream can reach f_midi_in_trigger() and queue midi->work again after f_midi_disable() has returned. A work item armed this way may still be pending when the last reference drops and f_midi_free() proceeds to kfree(midi), letting f_midi_in_work() dereference the struct after it has been freed, a use-after-free. For this reason cancelling midi->work in f_midi_disable() would not be sufficient: the ALSA trigger path can rearm the work after disable() returns. Cancelling at the refcount-zero free site is the boundary after which neither arming source can survive, because by then both references that keep the midi object alive have been dropped: the USB endpoints are already disabled and the rawmidi device has been released. Fix this by calling cancel_work_sync(&midi->work) in the refcount-zero block of f_midi_free(), before the embedded work_struct is freed along with the rest of the structure. opts->lock is a sleeping mutex, so calling cancel_work_sync() under it is permitted, and the handler takes midi->transmit_lock rather than opts->lock, so no self-deadlock can occur while it waits for a running instance of the work to finish. This issue was found by an in-house static analysis tool.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5650c18d93a1db7e27cb5a40b394747eb4686d5b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/87bc316dd6fc90072297c635e10b9aa6075ecda1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ac9a51d910bb7465c554c45320cb6c09f3d0b49d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f45089eaad0a083d71d84ff175741d7e157d9b69
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/gadget/function/f_midi.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9",
              "status": "affected",
              "version": "8653d71ce3763aedcf3d2331f59beda3fecd79e4",
              "versionType": "git"
            },
            {
              "lessThan": "87bc316dd6fc90072297c635e10b9aa6075ecda1",
              "status": "affected",
              "version": "8653d71ce3763aedcf3d2331f59beda3fecd79e4",
              "versionType": "git"
            },
            {
              "lessThan": "f45089eaad0a083d71d84ff175741d7e157d9b69",
              "status": "affected",
              "version": "8653d71ce3763aedcf3d2331f59beda3fecd79e4",
              "versionType": "git"
            },
            {
              "lessThan": "ac9a51d910bb7465c554c45320cb6c09f3d0b49d",
              "status": "affected",
              "version": "8653d71ce3763aedcf3d2331f59beda3fecd79e4",
              "versionType": "git"
            },
            {
              "lessThan": "5650c18d93a1db7e27cb5a40b394747eb4686d5b",
              "status": "affected",
              "version": "8653d71ce3763aedcf3d2331f59beda3fecd79e4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "89019ab7a64fcdf98a2ba7799e5c6aff58d4a05d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3635523e9b96213969693c320302d536774d8e9b",
              "versionType": "git"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.291",
              "versionType": "semver"
            },
            {
              "lessThan": "5.11",
              "status": "affected",
              "version": "5.10.235",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/gadget/function/f_midi.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.12"
            },
            {
              "lessThan": "5.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.148",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_midi: cancel pending IN work before freeing the midi object\n\nThe f_midi driver embeds a work item (midi-\u003ework) whose handler,\nf_midi_in_work(), dereferences the enclosing struct f_midi through\ncontainer_of().  This work is armed from two sites: f_midi_complete(),\non a normal IN-endpoint completion, and f_midi_in_trigger(), on an ALSA\nrawmidi output-stream start.\n\nNeither f_midi_disable() nor f_midi_unbind() cancels midi-\u003ework.\nf_midi_disable() only disables the endpoints and drains the in_req_fifo;\nit does not synchronize the work item, and the sound card is released\nasynchronously to the final free of the midi object.\n\nThe midi object is reference-counted (midi-\u003efree_ref) and is freed in\nf_midi_free() only once both the usb_function reference and the rawmidi\nprivate_data reference have been dropped.  In f_midi_unbind(),\nf_midi_disable() runs before the sound card is released, so while the\nUSB endpoints are already disabled the rawmidi device is still usable by\nan open substream.  A concurrent userspace write on such a substream can\nreach f_midi_in_trigger() and queue midi-\u003ework again after\nf_midi_disable() has returned.  A work item armed this way may still be\npending when the last reference drops and f_midi_free() proceeds to\nkfree(midi), letting f_midi_in_work() dereference the struct after it\nhas been freed, a use-after-free.\n\nFor this reason cancelling midi-\u003ework in f_midi_disable() would not be\nsufficient: the ALSA trigger path can rearm the work after disable()\nreturns.  Cancelling at the refcount-zero free site is the boundary\nafter which neither arming source can survive, because by then both\nreferences that keep the midi object alive have been dropped: the USB\nendpoints are already disabled and the rawmidi device has been released.\n\nFix this by calling cancel_work_sync(\u0026midi-\u003ework) in the refcount-zero\nblock of f_midi_free(), before the embedded work_struct is freed along\nwith the rest of the structure.  opts-\u003elock is a sleeping mutex, so\ncalling cancel_work_sync() under it is permitted, and the handler takes\nmidi-\u003etransmit_lock rather than opts-\u003elock, so no self-deadlock can\noccur while it waits for a running instance of the work to finish.\n\nThis issue was found by an in-house static analysis tool."
    }
  ],
  "id": "CVE-2026-64584",
  "lastModified": "2026-08-08T15:16:33.570",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-06T08:16:33.543",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5650c18d93a1db7e27cb5a40b394747eb4686d5b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/87bc316dd6fc90072297c635e10b9aa6075ecda1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ac9a51d910bb7465c554c45320cb6c09f3d0b49d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f45089eaad0a083d71d84ff175741d7e157d9b69"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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