FKIE_CVE-2026-64029

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-30 14:59
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: ALSA: seq: Serialize UMP output teardown with event_input seq_ump_process_event() borrows client->out_rfile.output without synchronizing with the first-open and last-close transition in seq_ump_client_open() and seq_ump_client_close(). The last output unuse can therefore drop opened[STR_OUT] to zero and release the rawmidi file while an in-flight event_input callback is still inside snd_rawmidi_kernel_write(). That leaves the rawmidi substream runtime exposed to teardown before the write path has taken its own buffer reference. Add a per-client rwlock for the event_input-visible output file. Publish a newly opened output file under the write side, and hold the read side from the output lookup through snd_rawmidi_kernel_write(). The last output close copies and clears the visible output file under the write side, then drops the lock and releases the saved rawmidi file. Use IRQ-safe rwlock guards because event_input can also be reached from atomic sequencer delivery. The buggy scenario involves two paths, with each column showing the order within that path: path A label: event_input path path B label: last unuse path 1. seq_ump_process_event() reads 1. seq_ump_client_close() client->out_rfile.output. drops opened[STR_OUT] to zero. 2. snd_rawmidi_kernel_write1() 2. snd_rawmidi_kernel_release() has not yet pinned runtime. closes the output file. 3. The writer continues using 3. close_substream() frees the borrowed substream. substream->runtime. This keeps the output substream and runtime alive for the full event_input write while keeping rawmidi release outside the rwlock. KASAN reproduced this as a slab-use-after-free in snd_rawmidi_kernel_write1(), with allocation through seq_ump_use()/snd_seq_port_connect() and free through seq_ump_unuse()/snd_seq_port_disconnect(). Validation reproduced this kernel report: KASAN slab-use-after-free in snd_rawmidi_kernel_write1+0x9d/0x400 RIP: 0033:0x7f5528af837f Read of size 8 Call trace: dump_stack_lvl+0x73/0xb0 (?:?) print_report+0xd1/0x650 (?:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x1a7/0x340 (?:?) kasan_complete_mode_report_info+0x64/0x200 (?:?) kasan_report+0xf7/0x130 (?:?) snd_rawmidi_kernel_write1+0x9d/0x400 (?:?) __asan_load8+0x82/0xb0 (?:?) update_stack_state+0x1ef/0x2d0 (?:?) snd_rawmidi_kernel_write+0x1a/0x20 (?:?) seq_ump_process_event+0xd4/0x120 (sound/core/seq/seq_ump_client.c:82) __snd_seq_deliver_single_event+0x8a/0xe0 (?:?) snd_seq_deliver_from_ump+0x2b2/0xd60 (?:?) lock_acquire+0x14e/0x2e0 (?:?) find_held_lock+0x31/0x90 (?:?) snd_seq_port_use_ptr+0xa6/0xe0 (?:?) __kasan_check_write+0x18/0x20 (?:?) do_raw_read_unlock+0x32/0xa0 (?:?) _raw_read_unlock+0x26/0x50 (?:?) snd_seq_deliver_single_event+0x45c/0x4b0 (?:?) snd_seq_deliver_event+0x10d/0x1b0 (?:?) snd_seq_client_enqueue_event+0x192/0x240 (?:?) snd_seq_write+0x2cd/0x450 (?:?) apparmor_file_permission+0x20/0x30 (?:?) security_file_permission+0x51/0x60 (?:?) vfs_write+0x1ce/0x850 (?:?) __fget_files+0x12b/0x220 (?:?) lock_release+0xc8/0x2a0 (?:?) __rcu_read_unlock+0x74/0x2d0 (?:?) __fget_files+0x135/0x220 (?:?) ksys_write+0x15a/0x180 (?:?) rcu_is_watching+0x24/0x60 (?:?) __x64_sys_write+0x46/0x60 (?:?) x64_sys_call+0x7d/0x20d0 (?:?) do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0cb1ad795570167558530d6194297ac2396a1991
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3aab4a58d23fb22dac5b558bbe5df1a8dad00b4b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/60a1969fae6209644698fca91c185d153674f631
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8ba1c4ddbb1c67d34bb440aecb9f5690ed3f64cb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ef46b616a4c219185bbf10ebcbacb571583fd0e4
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/core/seq/seq_ump_client.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8ba1c4ddbb1c67d34bb440aecb9f5690ed3f64cb",
              "status": "affected",
              "version": "81fd444aa371261cd33f31d4ffd80faeeeab0cc9",
              "versionType": "git"
            },
            {
              "lessThan": "0cb1ad795570167558530d6194297ac2396a1991",
              "status": "affected",
              "version": "81fd444aa371261cd33f31d4ffd80faeeeab0cc9",
              "versionType": "git"
            },
            {
              "lessThan": "3aab4a58d23fb22dac5b558bbe5df1a8dad00b4b",
              "status": "affected",
              "version": "81fd444aa371261cd33f31d4ffd80faeeeab0cc9",
              "versionType": "git"
            },
            {
              "lessThan": "ef46b616a4c219185bbf10ebcbacb571583fd0e4",
              "status": "affected",
              "version": "81fd444aa371261cd33f31d4ffd80faeeeab0cc9",
              "versionType": "git"
            },
            {
              "lessThan": "60a1969fae6209644698fca91c185d153674f631",
              "status": "affected",
              "version": "81fd444aa371261cd33f31d4ffd80faeeeab0cc9",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "sound/core/seq/seq_ump_client.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.142",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.92",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "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\nALSA: seq: Serialize UMP output teardown with event_input\n\nseq_ump_process_event() borrows client-\u003eout_rfile.output without\nsynchronizing with the first-open and last-close transition in\nseq_ump_client_open() and seq_ump_client_close().\n\nThe last output unuse can therefore drop opened[STR_OUT] to zero and\nrelease the rawmidi file while an in-flight event_input callback is still\ninside snd_rawmidi_kernel_write(). That leaves the rawmidi substream\nruntime exposed to teardown before the write path has taken its own\nbuffer reference.\n\nAdd a per-client rwlock for the event_input-visible output file. Publish\na newly opened output file under the write side, and hold the read side\nfrom the output lookup through snd_rawmidi_kernel_write(). The last\noutput close copies and clears the visible output file under the write\nside, then drops the lock and releases the saved rawmidi file. Use\nIRQ-safe rwlock guards because event_input can also be reached from\natomic sequencer delivery.\n\nThe buggy scenario involves two paths, with each column showing the\norder within that path:\n\npath A label: event_input path         path B label: last unuse path\n1. seq_ump_process_event() reads       1. seq_ump_client_close()\n   client-\u003eout_rfile.output.              drops opened[STR_OUT] to zero.\n2. snd_rawmidi_kernel_write1()         2. snd_rawmidi_kernel_release()\n   has not yet pinned runtime.            closes the output file.\n3. The writer continues using          3. close_substream() frees\n   the borrowed substream.                substream-\u003eruntime.\n\nThis keeps the output substream and runtime alive for the full\nevent_input write while keeping rawmidi release outside the rwlock.\n\nKASAN reproduced this as a slab-use-after-free in\nsnd_rawmidi_kernel_write1(), with allocation through\nseq_ump_use()/snd_seq_port_connect() and free through\nseq_ump_unuse()/snd_seq_port_disconnect().\n\n\nValidation reproduced this kernel report:\nKASAN slab-use-after-free in snd_rawmidi_kernel_write1+0x9d/0x400\nRIP: 0033:0x7f5528af837f\nRead of size 8\nCall trace:\n  dump_stack_lvl+0x73/0xb0 (?:?)\n  print_report+0xd1/0x650 (?:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x1a7/0x340 (?:?)\n  kasan_complete_mode_report_info+0x64/0x200 (?:?)\n  kasan_report+0xf7/0x130 (?:?)\n  snd_rawmidi_kernel_write1+0x9d/0x400 (?:?)\n  __asan_load8+0x82/0xb0 (?:?)\n  update_stack_state+0x1ef/0x2d0 (?:?)\n  snd_rawmidi_kernel_write+0x1a/0x20 (?:?)\n  seq_ump_process_event+0xd4/0x120 (sound/core/seq/seq_ump_client.c:82)\n  __snd_seq_deliver_single_event+0x8a/0xe0 (?:?)\n  snd_seq_deliver_from_ump+0x2b2/0xd60 (?:?)\n  lock_acquire+0x14e/0x2e0 (?:?)\n  find_held_lock+0x31/0x90 (?:?)\n  snd_seq_port_use_ptr+0xa6/0xe0 (?:?)\n  __kasan_check_write+0x18/0x20 (?:?)\n  do_raw_read_unlock+0x32/0xa0 (?:?)\n  _raw_read_unlock+0x26/0x50 (?:?)\n  snd_seq_deliver_single_event+0x45c/0x4b0 (?:?)\n  snd_seq_deliver_event+0x10d/0x1b0 (?:?)\n  snd_seq_client_enqueue_event+0x192/0x240 (?:?)\n  snd_seq_write+0x2cd/0x450 (?:?)\n  apparmor_file_permission+0x20/0x30 (?:?)\n  security_file_permission+0x51/0x60 (?:?)\n  vfs_write+0x1ce/0x850 (?:?)\n  __fget_files+0x12b/0x220 (?:?)\n  lock_release+0xc8/0x2a0 (?:?)\n  __rcu_read_unlock+0x74/0x2d0 (?:?)\n  __fget_files+0x135/0x220 (?:?)\n  ksys_write+0x15a/0x180 (?:?)\n  rcu_is_watching+0x24/0x60 (?:?)\n  __x64_sys_write+0x46/0x60 (?:?)\n  x64_sys_call+0x7d/0x20d0 (?:?)\n  do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)"
    }
  ],
  "id": "CVE-2026-64029",
  "lastModified": "2026-07-30T14:59:47.950",
  "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": "2026-07-19T16:17:42.997",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0cb1ad795570167558530d6194297ac2396a1991"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3aab4a58d23fb22dac5b558bbe5df1a8dad00b4b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/60a1969fae6209644698fca91c185d153674f631"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8ba1c4ddbb1c67d34bb440aecb9f5690ed3f64cb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ef46b616a4c219185bbf10ebcbacb571583fd0e4"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}



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