GHSA-HHF3-44MR-39MW

Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-18 18:31
VLAI
Details

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

ALSA: seq: midi: Serialize input teardown with event_input

snd_midi_input_event() must not be running while a rawmidi substream is closing, since this can lead to the trigger state becoming out-of-step through this sequence in snd_rawmidi_input_trigger():

snd_rawmidi_input_trigger(up=0)
                snd_midi_input_event()
                 -> snd_rawmidi_kernel_read()
                     -> snd_rawmidi_input_trigger(up=1)
  -> cancel_work_sync()

which ends with the underlying device being active unexpectedly.

When this is called from close_substream(), further input can re-trigger the input event leaving it running after rawmidi_release_priv() has set rfile->rmidi to NULL which leads to:

Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b0
Call trace:
 snd_midi_input_event+0x3c/0x134 [snd_seq_midi] (P)
 snd_rawmidi_input_event_work+0x1c/0x2c
 process_one_work+0x150/0x3a4
 worker_thread+0x190/0x318

Apply a similar approach to commit ef7607ab1c8ad ("ALSA: seq: midi: Serialize output teardown with event_input") which fixed the same issue in the output direction, but updated to use RCU following Takashi Iwai's proposed follow-on patch [1].

With this change in place, midisynth_unsubscribe() clears the input file so snd_midi_input_event() will not re-trigger the stream and will be quiesced by the cancel_work_sync() in snd_rawmidi_input_trigger().

[1] https://lore.kernel.org/linux-sound/20260813144224.753399-1-tiwai@suse.de/

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-90207"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:17:15Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: midi: Serialize input teardown with event_input\n\nsnd_midi_input_event() must not be running while a rawmidi substream is\nclosing, since this can lead to the trigger state becoming out-of-step\nthrough this sequence in snd_rawmidi_input_trigger():\n\n\tsnd_rawmidi_input_trigger(up=0)\n\t\t\t\t\tsnd_midi_input_event()\n\t\t\t\t\t -\u003e snd_rawmidi_kernel_read()\n\t\t\t\t\t     -\u003e snd_rawmidi_input_trigger(up=1)\n\t  -\u003e cancel_work_sync()\n\nwhich ends with the underlying device being active unexpectedly.\n\nWhen this is called from close_substream(), further input can re-trigger\nthe input event leaving it running after rawmidi_release_priv() has set\nrfile-\u003ermidi to NULL which leads to:\n\n\tUnable to handle kernel NULL pointer dereference at virtual address 00000000000000b0\n\tCall trace:\n\t snd_midi_input_event+0x3c/0x134 [snd_seq_midi] (P)\n\t snd_rawmidi_input_event_work+0x1c/0x2c\n\t process_one_work+0x150/0x3a4\n\t worker_thread+0x190/0x318\n\nApply a similar approach to commit ef7607ab1c8ad (\"ALSA: seq: midi:\nSerialize output teardown with event_input\") which fixed the same issue\nin the output direction, but updated to use RCU following Takashi Iwai\u0027s\nproposed follow-on patch [1].\n\nWith this change in place, midisynth_unsubscribe() clears the input file\nso snd_midi_input_event() will not re-trigger the stream and will be\nquiesced by the cancel_work_sync() in snd_rawmidi_input_trigger().\n\n[1] https://lore.kernel.org/linux-sound/20260813144224.753399-1-tiwai@suse.de/",
  "id": "GHSA-hhf3-44mr-39mw",
  "modified": "2026-09-18T18:31:27Z",
  "published": "2026-09-17T18:31:55Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90207"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/210c193a9ef1312fab153948c6928e4cfaa1f03b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/282a3ef9e4b63b2f6823bbbb3c1a90b002cdaf12"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/403f7f3ad3808a0096d84cf228fab68dc253fd9d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6290afaae54c7a9fa3bca3b4d5433e6d83e8669d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/89d986897aff7275b42e075e556731b8353366af"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de76a2b47582cd6dba2e15f024681bf377ecc94a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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