CVE-2026-74278 (GCVE-0-2026-74278)
Vulnerability from cvelistv5
Published
2026-08-15 05:57
Modified
2026-08-17 05:16
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix kernel heap address leak in bounce_error_event() The comment above bounce_error_event() documents that user clients should receive SNDRV_SEQ_EVENT_BOUNCE with the original event embedded as variable-length data, while kernel clients should receive SNDRV_SEQ_EVENT_KERNEL_ERROR with a quoted kernel pointer. However, the implementation unconditionally uses SNDRV_SEQ_EVENT_KERNEL_ERROR with data.quote.event set to the raw struct snd_seq_event pointer for all clients. When a bounce error event is delivered to a USER_CLIENT via snd_seq_read(), the kernel heap address in data.quote.event is exposed to userspace through copy_to_user() in the fixed-length branch. This is a distinct leak path from the one addressed by commit 705dd6dcbc0e ("ALSA: seq: Clear variable event pointer on read"), which sanitizes data.ext.ptr in the variable-length branch of snd_seq_read(). The bounce_error_event() leak uses fixed-length events that take the else branch where no sanitization occurs. Differentiate the bounce event by client type. For USER_CLIENT, send SNDRV_SEQ_EVENT_BOUNCE with SNDRV_SEQ_EVENT_LENGTH_VARIABLE and data.ext pointing to the original event. The variable-length path in snd_seq_event_dup() copies the event data into chained cells, and snd_seq_expand_var_event() copies only the content -- never the pointer -- to userspace. For KERNEL_CLIENT, keep the existing SNDRV_SEQ_EVENT_KERNEL_ERROR behavior with the quoted pointer.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/core/seq/seq_clientmgr.c"
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              "version": "0",
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              "version": "7.2",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: Fix kernel heap address leak in bounce_error_event()\n\nThe comment above bounce_error_event() documents that user clients\nshould receive SNDRV_SEQ_EVENT_BOUNCE with the original event embedded\nas variable-length data, while kernel clients should receive\nSNDRV_SEQ_EVENT_KERNEL_ERROR with a quoted kernel pointer.\n\nHowever, the implementation unconditionally uses\nSNDRV_SEQ_EVENT_KERNEL_ERROR with data.quote.event set to the raw\nstruct snd_seq_event pointer for all clients.  When a bounce error\nevent is delivered to a USER_CLIENT via snd_seq_read(), the kernel\nheap address in data.quote.event is exposed to userspace through\ncopy_to_user() in the fixed-length branch.\n\nThis is a distinct leak path from the one addressed by commit\n705dd6dcbc0e (\"ALSA: seq: Clear variable event pointer on read\"),\nwhich sanitizes data.ext.ptr in the variable-length branch of\nsnd_seq_read().  The bounce_error_event() leak uses fixed-length\nevents that take the else branch where no sanitization occurs.\n\nDifferentiate the bounce event by client type.  For USER_CLIENT,\nsend SNDRV_SEQ_EVENT_BOUNCE with SNDRV_SEQ_EVENT_LENGTH_VARIABLE\nand data.ext pointing to the original event.  The variable-length\npath in snd_seq_event_dup() copies the event data into chained\ncells, and snd_seq_expand_var_event() copies only the content --\nnever the pointer -- to userspace.  For KERNEL_CLIENT, keep the\nexisting SNDRV_SEQ_EVENT_KERNEL_ERROR behavior with the quoted\npointer."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:16:23.206Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/93d260ce43a81df579c98bee92b91316df9c1c57"
        },
        {
          "url": "https://git.kernel.org/stable/c/dae23c545eb5a2be3b27a82fd0f611894fb8ab69"
        },
        {
          "url": "https://git.kernel.org/stable/c/0527a56cb327021cb73167cfddf0e49efa043500"
        },
        {
          "url": "https://git.kernel.org/stable/c/efc86691e4d8083d9e380ea95042c2cf679f65fd"
        }
      ],
      "title": "ALSA: seq: Fix kernel heap address leak in bounce_error_event()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74278",
    "datePublished": "2026-08-15T05:57:49.475Z",
    "dateReserved": "2026-08-15T05:44:03.880Z",
    "dateUpdated": "2026-08-17T05:16:23.206Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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