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GHSA-W77G-4C35-PRWP

Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-06-19 15:33
VLAI
Details

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

usb: gadget: f_ncm: Fix net_device lifecycle with device_move

The network device outlived its parent gadget device during disconnection, resulting in dangling sysfs links and null pointer dereference problems.

A prior attempt to solve this by removing SET_NETDEV_DEV entirely [1] was reverted due to power management ordering concerns and a NO-CARRIER regression.

A subsequent attempt to defer net_device allocation to bind [2] broke 1:1 mapping between function instance and network device, making it impossible for configfs to report the resolved interface name. This results in a regression where the DHCP server fails on pmOS.

Use device_move to reparent the net_device between the gadget device and /sys/devices/virtual/ across bind/unbind cycles. This preserves the network interface across USB reconnection, allowing the DHCP server to retain their binding.

Introduce gether_attach_gadget()/gether_detach_gadget() helpers and use __free(detach_gadget) macro to undo attachment on bind failure. The bind_count ensures device_move executes only on the first bind.

[1] https://lore.kernel.org/lkml/f2a4f9847617a0929d62025748384092e5f35cce.camel@crapouillou.net/ [2] https://lore.kernel.org/linux-usb/795ea759-7eaf-4f78-81f4-01ffbf2d7961@ixit.cz/

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-43421"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-08T15:16:54Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_ncm: Fix net_device lifecycle with device_move\n\nThe network device outlived its parent gadget device during\ndisconnection, resulting in dangling sysfs links and null pointer\ndereference problems.\n\nA prior attempt to solve this by removing SET_NETDEV_DEV entirely [1]\nwas reverted due to power management ordering concerns and a NO-CARRIER\nregression.\n\nA subsequent attempt to defer net_device allocation to bind [2] broke\n1:1 mapping between function instance and network device, making it\nimpossible for configfs to report the resolved interface name. This\nresults in a regression where the DHCP server fails on pmOS.\n\nUse device_move to reparent the net_device between the gadget device and\n/sys/devices/virtual/ across bind/unbind cycles. This preserves the\nnetwork interface across USB reconnection, allowing the DHCP server to\nretain their binding.\n\nIntroduce gether_attach_gadget()/gether_detach_gadget() helpers and use\n__free(detach_gadget) macro to undo attachment on bind failure. The\nbind_count ensures device_move executes only on the first bind.\n\n[1] https://lore.kernel.org/lkml/f2a4f9847617a0929d62025748384092e5f35cce.camel@crapouillou.net/\n[2] https://lore.kernel.org/linux-usb/795ea759-7eaf-4f78-81f4-01ffbf2d7961@ixit.cz/",
  "id": "GHSA-w77g-4c35-prwp",
  "modified": "2026-06-19T15:33:10Z",
  "published": "2026-05-08T15:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43421"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36c41e9724c9a7a7cda37f5a4e9d94f25c8031c4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7c97366f5dac5255e60a317ffe3a5b18f3745547"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/85acaba2f42b557499bab3608307f17bf13beb69"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/93f116c3393a22acab96ad1bef12b2572eb80ca4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e584cb58a2ea7ff4d3a4bc43d5ca512ed3ecb77d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ec35c1969650e7cb6c8a91020e568ed46e3551b0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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