FKIE_CVE-2026-98764

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-30 13:21
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Fix NULL pointer dereference in FUNCTIONFS_ENDPOINT_DESC When user space sets up FunctionFS with only full-speed descriptors (e.g., flags = FUNCTIONFS_HAS_FS_DESC) and the gadget operates at a higher speed (such as USB_SPEED_HIGH or USB_SPEED_SUPER), config_ep_by_speed() detects that the function lacks descriptors for the current speed, logs a warning, and falls back to full-speed descriptors. The endpoint is then successfully enabled via usb_ep_enable(), and epfile->ep becomes valid. However, when user space subsequently issues the FUNCTIONFS_ENDPOINT_DESC ioctl to query the endpoint descriptor, ffs_epfile_ioctl() selects the descriptor index solely based on gadget->speed: switch (epfile->ffs->gadget->speed) { case USB_SPEED_SUPER: case USB_SPEED_SUPER_PLUS: desc_idx = 2; break; case USB_SPEED_HIGH: desc_idx = 1; break; default: desc_idx = 0; } desc = epfile->ep->descs[desc_idx]; memcpy(&desc1, desc, desc->bLength); Because user space only supplied full-speed descriptors, epfile->ep->descs[1] is NULL. Dereferencing desc->bLength triggers an immediate kernel NULL pointer dereference panic. Fix this by falling back through lower speed descriptors if the current speed descriptor was not supplied, matching the fallback logic in config_ep_by_speed() and historical f_fs behavior. If still missing, fall back to epfile->ep->ep->desc (the active descriptor), and return -EINVAL safely if no valid descriptor is found. In addition, mark desc as const to match struct usb_ep::desc and avoid discarding qualifiers.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/06ac8609d6d185ac18c1d6a6a8a9b99e398bd124
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/35ab269602e1f7c4c0fe6ea3477264bea77eced3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7811d8e26c77f8eea79e22d0d14c67ec0658b348
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7ef0ad5f462fa95bc4c6647d097d7c0384245b9c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9cd072788c76595529eb38f42bf94d23852f8534
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9d8761b3c133f6c6a6d3486839dac60e2cf4bfe3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c5f452e057df6ef89300523d13ad6833bfd199cd
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e5b9d6bb2a8906a1188c9a90cc8d102de3f07cad
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/gadget/function/f_fs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c5f452e057df6ef89300523d13ad6833bfd199cd",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "e5b9d6bb2a8906a1188c9a90cc8d102de3f07cad",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "7ef0ad5f462fa95bc4c6647d097d7c0384245b9c",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "06ac8609d6d185ac18c1d6a6a8a9b99e398bd124",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "9d8761b3c133f6c6a6d3486839dac60e2cf4bfe3",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "7811d8e26c77f8eea79e22d0d14c67ec0658b348",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "35ab269602e1f7c4c0fe6ea3477264bea77eced3",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            },
            {
              "lessThan": "9cd072788c76595529eb38f42bf94d23852f8534",
              "status": "affected",
              "version": "c559a353410939c0884e83bdb0e2420a986ac53b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/gadget/function/f_fs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.18"
            },
            {
              "lessThan": "3.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.273",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.224",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "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\nusb: gadget: f_fs: Fix NULL pointer dereference in FUNCTIONFS_ENDPOINT_DESC\n\nWhen user space sets up FunctionFS with only full-speed descriptors\n(e.g., flags = FUNCTIONFS_HAS_FS_DESC) and the gadget operates at a\nhigher speed (such as USB_SPEED_HIGH or USB_SPEED_SUPER),\nconfig_ep_by_speed() detects that the function lacks descriptors for\nthe current speed, logs a warning, and falls back to full-speed\ndescriptors. The endpoint is then successfully enabled via\nusb_ep_enable(), and epfile-\u003eep becomes valid.\n\nHowever, when user space subsequently issues the FUNCTIONFS_ENDPOINT_DESC\nioctl to query the endpoint descriptor, ffs_epfile_ioctl() selects the\ndescriptor index solely based on gadget-\u003espeed:\n\n\tswitch (epfile-\u003effs-\u003egadget-\u003espeed) {\n\tcase USB_SPEED_SUPER:\n\tcase USB_SPEED_SUPER_PLUS:\n\t\tdesc_idx = 2;\n\t\tbreak;\n\tcase USB_SPEED_HIGH:\n\t\tdesc_idx = 1;\n\t\tbreak;\n\tdefault:\n\t\tdesc_idx = 0;\n\t}\n\tdesc = epfile-\u003eep-\u003edescs[desc_idx];\n\tmemcpy(\u0026desc1, desc, desc-\u003ebLength);\n\nBecause user space only supplied full-speed descriptors,\nepfile-\u003eep-\u003edescs[1] is NULL. Dereferencing desc-\u003ebLength triggers an\nimmediate kernel NULL pointer dereference panic.\n\nFix this by falling back through lower speed descriptors if the current\nspeed descriptor was not supplied, matching the fallback logic in\nconfig_ep_by_speed() and historical f_fs behavior. If still missing,\nfall back to epfile-\u003eep-\u003eep-\u003edesc (the active descriptor), and return\n-EINVAL safely if no valid descriptor is found. In addition, mark desc\nas const to match struct usb_ep::desc and avoid discarding qualifiers."
    }
  ],
  "id": "CVE-2026-98764",
  "lastModified": "2026-10-30T13:21:25.903",
  "metrics": {},
  "published": "2026-10-18T16:17:30.217",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/06ac8609d6d185ac18c1d6a6a8a9b99e398bd124"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/35ab269602e1f7c4c0fe6ea3477264bea77eced3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7811d8e26c77f8eea79e22d0d14c67ec0658b348"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7ef0ad5f462fa95bc4c6647d097d7c0384245b9c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9cd072788c76595529eb38f42bf94d23852f8534"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9d8761b3c133f6c6a6d3486839dac60e2cf4bfe3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c5f452e057df6ef89300523d13ad6833bfd199cd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e5b9d6bb2a8906a1188c9a90cc8d102de3f07cad"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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