GHSA-FGMP-3FCJ-WJ99

Vulnerability from github – Published: 2026-08-15 15:30 – Updated: 2026-08-15 15:30
VLAI
Details

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

ALSA: usb-audio: fix stack info leak in RME Digiface status

snd_rme_digiface_read_status() reads a four-word status block from the device into an uninitialised on-stack __le32 buf[4] and, whenever the vendor control-IN transfer does not return a negative error, copies all four words into the caller's status[].

snd_usb_ctl_msg() copies the full requested size back into the caller's buffer regardless of how many bytes the data stage actually delivered:

buf = kmemdup(data, size, GFP_KERNEL);
err = usb_control_msg(dev, pipe, request, requesttype,
              value, index, buf, size, timeout);
memcpy(data, buf, size);

usb_control_msg() returns the transferred length on a short control-IN, which is a non-negative value, and writes only that many bytes. The remainder of the copy back is the kmemdup()ed image of the caller's buffer, so a device answering with a short data stage leaves the trailing words of buf[] holding leftover kernel stack. The only guard in the caller is err < 0, so those words are stored into status[].

They then reach user space: snd_rme_digiface_get_status_val() selects a 16-bit halfword of status[] per the control's reg/mask, and the eight Digiface status controls together expose the whole 16-byte frame to an unprivileged reader of /dev/snd/controlC*.

Zero-initialise the buffer so a short read yields zeros instead of stack residue. This mirrors snd_rme_get_status1(), which already clears its output word before the same kind of vendor read.

Discovered by XBOW, triaged by Baul Lee baul.lee@xbow.com

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74500"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T13:17:54Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: fix stack info leak in RME Digiface status\n\nsnd_rme_digiface_read_status() reads a four-word status block from the\ndevice into an uninitialised on-stack __le32 buf[4] and, whenever the\nvendor control-IN transfer does not return a negative error, copies all\nfour words into the caller\u0027s status[].\n\nsnd_usb_ctl_msg() copies the full requested size back into the caller\u0027s\nbuffer regardless of how many bytes the data stage actually delivered:\n\n\tbuf = kmemdup(data, size, GFP_KERNEL);\n\terr = usb_control_msg(dev, pipe, request, requesttype,\n\t\t\t      value, index, buf, size, timeout);\n\tmemcpy(data, buf, size);\n\nusb_control_msg() returns the transferred length on a short control-IN,\nwhich is a non-negative value, and writes only that many bytes.  The\nremainder of the copy back is the kmemdup()ed image of the caller\u0027s\nbuffer, so a device answering with a short data stage leaves the\ntrailing words of buf[] holding leftover kernel stack.  The only guard\nin the caller is err \u003c 0, so those words are stored into status[].\n\nThey then reach user space: snd_rme_digiface_get_status_val() selects a\n16-bit halfword of status[] per the control\u0027s reg/mask, and the eight\nDigiface status controls together expose the whole 16-byte frame to an\nunprivileged reader of /dev/snd/controlC*.\n\nZero-initialise the buffer so a short read yields zeros instead of stack\nresidue.  This mirrors snd_rme_get_status1(), which already clears its\noutput word before the same kind of vendor read.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e",
  "id": "GHSA-fgmp-3fcj-wj99",
  "modified": "2026-08-15T15:30:34Z",
  "published": "2026-08-15T15:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74500"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/441aaad150c57edaf57ee482a79a3bf4c5b7e353"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ba01e0d3539d9cf0aef3e82938f1648147744cc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/98dbfbb38e297c25c5b0af4a9018d71ac25e8554"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b3a346d5c99dd73cf84711f2a43e42691990efd2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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