Vulnerability-Lookup

GHSA-X4CQ-72C3-QV9J

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32

Details

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

ALSA: FCP: do not copy out an uninitialised init response

fcp_ioctl_init() allocates its response buffer with kmalloc() and copies the whole buffer back to userspace:

buf_size = init.step0_resp_size + init.step2_resp_size;

void *resp __free(kfree) =
    kmalloc(buf_size, GFP_KERNEL);
...
if (copy_to_user(arg->resp, resp, buf_size))
    return -EFAULT;

Nothing clears the buffer, and the only writer of its leading step0_resp_size bytes is the step-0 control transfer:

err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0),
    FCP_USB_REQ_STEP0,
    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
    0, private->bInterfaceNumber,
    step0_resp, private->step0_resp_size);
if (err < 0)
    return err;

usb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or zero-length data stage completes with status 0 and snd_usb_ctl_msg() returns a small actual_length. The only check is err < 0, so a short transfer is accepted as success.

snd_usb_ctl_msg() copies the full size back unconditionally:

buf = kmemdup(data, size, GFP_KERNEL);
...
memcpy(data, buf, size);

Bytes the device never wrote are therefore restored into resp unchanged and copied to userspace. step0_resp_size and step2_resp_size are each validated only to 1..255, so the caller also picks the slab cache, from kmalloc-8 up to kmalloc-512.

On 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data stage, s0 = s2 = 255:

# init_on_alloc off, no spray step0 window [0,255): nonzero=94/255 000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01 010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff

# same kernel, kmalloc-512 pre-seeded with an 8-byte tag step0 window [0,255): nonzero=219/255 tagbytes=232

# identical run, init_on_alloc=1 step0 window [0,255): nonzero=0/255 tagbytes=0

# all three runs step2 window [255,510): device words matched=62/62

a8 c4 5f 80 00 80 ff ff is the little-endian kernel text address ffff8000805fc4a8. The step-2 window is unaffected, so the disclosure is exactly the step-0 region.

Zero the buffer, and require the step-0 transfer to deliver the full step0_resp_size bytes so a short data stage is reported as an error.

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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-80970"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:03Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: FCP: do not copy out an uninitialised init response\n\nfcp_ioctl_init() allocates its response buffer with kmalloc() and copies\nthe whole buffer back to userspace:\n\n\tbuf_size = init.step0_resp_size + init.step2_resp_size;\n\n\tvoid *resp __free(kfree) =\n\t\tkmalloc(buf_size, GFP_KERNEL);\n\t...\n\tif (copy_to_user(arg-\u003eresp, resp, buf_size))\n\t\treturn -EFAULT;\n\nNothing clears the buffer, and the only writer of its leading\nstep0_resp_size bytes is the step-0 control transfer:\n\n\terr = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0),\n\t\tFCP_USB_REQ_STEP0,\n\t\tUSB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,\n\t\t0, private-\u003ebInterfaceNumber,\n\t\tstep0_resp, private-\u003estep0_resp_size);\n\tif (err \u003c 0)\n\t\treturn err;\n\nusb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or\nzero-length data stage completes with status 0 and snd_usb_ctl_msg()\nreturns a small actual_length.  The only check is err \u003c 0, so a short\ntransfer is accepted as success.\n\nsnd_usb_ctl_msg() copies the full size back unconditionally:\n\n\tbuf = kmemdup(data, size, GFP_KERNEL);\n\t...\n\tmemcpy(data, buf, size);\n\nBytes the device never wrote are therefore restored into resp unchanged\nand copied to userspace.  step0_resp_size and step2_resp_size are each\nvalidated only to 1..255, so the caller also picks the slab cache, from\nkmalloc-8 up to kmalloc-512.\n\nOn 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data\nstage, s0 = s2 = 255:\n\n  # init_on_alloc off, no spray\n  step0 window [0,255): nonzero=94/255\n  000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01\n  010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff\n\n  # same kernel, kmalloc-512 pre-seeded with an 8-byte tag\n  step0 window [0,255): nonzero=219/255  tagbytes=232\n\n  # identical run, init_on_alloc=1\n  step0 window [0,255): nonzero=0/255  tagbytes=0\n\n  # all three runs\n  step2 window [255,510): device words matched=62/62\n\na8 c4 5f 80 00 80 ff ff is the little-endian kernel text address\nffff8000805fc4a8.  The step-2 window is unaffected, so the disclosure is\nexactly the step-0 region.\n\nZero the buffer, and require the step-0 transfer to deliver the full\nstep0_resp_size bytes so a short data stage is reported as an error.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e",
  "id": "GHSA-x4cq-72c3-qv9j",
  "modified": "2026-09-14T15:32:21Z",
  "published": "2026-09-11T21:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80970"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/29ab2df278ab4f1d238cd9c1c393ee00db175cba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4335e387786479889e6db691fe06d345e52ea536"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e9e52437120fb5f802152877ba20c4b406c9fa9e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-80970 (GCVE-0-2026-80970)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:42 – Updated: 2026-09-14 11:59

Title

ALSA: FCP: do not copy out an uninitialised init response

Summary

In the Linux kernel, the following vulnerability has been resolved: ALSA: FCP: do not copy out an uninitialised init response fcp_ioctl_init() allocates its response buffer with kmalloc() and copies the whole buffer back to userspace: buf_size = init.step0_resp_size + init.step2_resp_size; void *resp __free(kfree) = kmalloc(buf_size, GFP_KERNEL); ... if (copy_to_user(arg->resp, resp, buf_size)) return -EFAULT; Nothing clears the buffer, and the only writer of its leading step0_resp_size bytes is the step-0 control transfer: err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), FCP_USB_REQ_STEP0, USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN, 0, private->bInterfaceNumber, step0_resp, private->step0_resp_size); if (err < 0) return err; usb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or zero-length data stage completes with status 0 and snd_usb_ctl_msg() returns a small actual_length. The only check is err < 0, so a short transfer is accepted as success. snd_usb_ctl_msg() copies the full size back unconditionally: buf = kmemdup(data, size, GFP_KERNEL); ... memcpy(data, buf, size); Bytes the device never wrote are therefore restored into resp unchanged and copied to userspace. step0_resp_size and step2_resp_size are each validated only to 1..255, so the caller also picks the slab cache, from kmalloc-8 up to kmalloc-512. On 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data stage, s0 = s2 = 255: # init_on_alloc off, no spray step0 window [0,255): nonzero=94/255 000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01 010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff # same kernel, kmalloc-512 pre-seeded with an 8-byte tag step0 window [0,255): nonzero=219/255 tagbytes=232 # identical run, init_on_alloc=1 step0 window [0,255): nonzero=0/255 tagbytes=0 # all three runs step2 window [255,510): device words matched=62/62 a8 c4 5f 80 00 80 ff ff is the little-endian kernel text address ffff8000805fc4a8. The step-2 window is unaffected, so the disclosure is exactly the step-0 region. Zero the buffer, and require the step-0 transfer to deliver the full step0_resp_size bytes so a short data stage is reported as an error. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/e9e52437120fb5f80…
https://git.kernel.org/stable/c/29ab2df278ab4f1d2…
https://git.kernel.org/stable/c/4335e387786479889…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 46757a3e7d50dac923888e7fbe68377736f13c70 , < e9e52437120fb5f802152877ba20c4b406c9fa9e (git) Affected: 46757a3e7d50dac923888e7fbe68377736f13c70 , < 29ab2df278ab4f1d238cd9c1c393ee00db175cba (git) Affected: 46757a3e7d50dac923888e7fbe68377736f13c70 , < 4335e387786479889e6db691fe06d345e52ea536 (git)
Linux	Linux	Affected: 6.14 Unaffected: 0 , < 6.14 (semver) Unaffected: 6.18.52 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/usb/fcp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e9e52437120fb5f802152877ba20c4b406c9fa9e",
              "status": "affected",
              "version": "46757a3e7d50dac923888e7fbe68377736f13c70",
              "versionType": "git"
            },
            {
              "lessThan": "29ab2df278ab4f1d238cd9c1c393ee00db175cba",
              "status": "affected",
              "version": "46757a3e7d50dac923888e7fbe68377736f13c70",
              "versionType": "git"
            },
            {
              "lessThan": "4335e387786479889e6db691fe06d345e52ea536",
              "status": "affected",
              "version": "46757a3e7d50dac923888e7fbe68377736f13c70",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "sound/usb/fcp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: FCP: do not copy out an uninitialised init response\n\nfcp_ioctl_init() allocates its response buffer with kmalloc() and copies\nthe whole buffer back to userspace:\n\n\tbuf_size = init.step0_resp_size + init.step2_resp_size;\n\n\tvoid *resp __free(kfree) =\n\t\tkmalloc(buf_size, GFP_KERNEL);\n\t...\n\tif (copy_to_user(arg-\u003eresp, resp, buf_size))\n\t\treturn -EFAULT;\n\nNothing clears the buffer, and the only writer of its leading\nstep0_resp_size bytes is the step-0 control transfer:\n\n\terr = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0),\n\t\tFCP_USB_REQ_STEP0,\n\t\tUSB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,\n\t\t0, private-\u003ebInterfaceNumber,\n\t\tstep0_resp, private-\u003estep0_resp_size);\n\tif (err \u003c 0)\n\t\treturn err;\n\nusb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or\nzero-length data stage completes with status 0 and snd_usb_ctl_msg()\nreturns a small actual_length.  The only check is err \u003c 0, so a short\ntransfer is accepted as success.\n\nsnd_usb_ctl_msg() copies the full size back unconditionally:\n\n\tbuf = kmemdup(data, size, GFP_KERNEL);\n\t...\n\tmemcpy(data, buf, size);\n\nBytes the device never wrote are therefore restored into resp unchanged\nand copied to userspace.  step0_resp_size and step2_resp_size are each\nvalidated only to 1..255, so the caller also picks the slab cache, from\nkmalloc-8 up to kmalloc-512.\n\nOn 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data\nstage, s0 = s2 = 255:\n\n  # init_on_alloc off, no spray\n  step0 window [0,255): nonzero=94/255\n  000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01\n  010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff\n\n  # same kernel, kmalloc-512 pre-seeded with an 8-byte tag\n  step0 window [0,255): nonzero=219/255  tagbytes=232\n\n  # identical run, init_on_alloc=1\n  step0 window [0,255): nonzero=0/255  tagbytes=0\n\n  # all three runs\n  step2 window [255,510): device words matched=62/62\n\na8 c4 5f 80 00 80 ff ff is the little-endian kernel text address\nffff8000805fc4a8.  The step-2 window is unaffected, so the disclosure is\nexactly the step-0 region.\n\nZero the buffer, and require the step-0 transfer to deliver the full\nstep0_resp_size bytes so a short data stage is reported as an error.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T11:59:17.143Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e9e52437120fb5f802152877ba20c4b406c9fa9e"
        },
        {
          "url": "https://git.kernel.org/stable/c/29ab2df278ab4f1d238cd9c1c393ee00db175cba"
        },
        {
          "url": "https://git.kernel.org/stable/c/4335e387786479889e6db691fe06d345e52ea536"
        }
      ],
      "title": "ALSA: FCP: do not copy out an uninitialised init response",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80970",
    "datePublished": "2026-09-11T19:42:33.789Z",
    "dateReserved": "2026-08-26T14:34:25.810Z",
    "dateUpdated": "2026-09-14T11:59:17.143Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.