usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop

{
  "id": "7fdef1c68d7dd9a7521e733385e8274df72f74bf4d5843728c218683bdeffb55",
  "url": "https://osv.dev/vulnerability/CVE-2026-31728",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop A race condition between gether_disconnect() and eth_stop() leads to a NULL pointer dereference. Specifically, if eth_stop() is triggered concurrently while gether_disconnect() is tearing down the endpoints, eth_stop() attempts to access the cleared endpoint descriptor, causing the following NPE: Unable to handle kernel NULL pointer dereference Call trace: __dwc3_gadget_ep_enable+0x60/0x788 dwc3_gadget_ep_enable+0x70/0xe4 usb_ep_enable+0x60/0x15c eth_stop+0xb8/0x108 Because eth_stop() crashes while holding the dev->lock, the thread running gether_disconnect() fails to acquire the same lock and spins forever, resulting in a hardlockup: Core - Debugging Information for Hardlockup core(7) Call trace: queued_spin_lock_slowpath+0x94/0x488 _raw_spin_lock+0x64/0x6c gether_disconnect+0x19c/0x1e8 ncm_set_alt+0x68/0x1a0 composite_setup+0x6a0/0xc50 The root cause is that the clearing of dev->port_usb in gether_disconnect() is delayed until the end of the function. Move the clearing of dev->port_usb to the very beginning of gether_disconnect() while holding dev->lock. This cuts off the link immediately, ensuring eth_stop() will see dev->port_usb as NULL and safely bail out.",
    "evidence": "osv:CVE-2026-31728",
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    "severity": "unknown",
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      "modified": "2026-10-28T02:30:40.406384231Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/6ad77458637b78ec655e3da5f112c862e6690a9d",
        "https://git.kernel.org/stable/c/8ff689edfeceb5e3ec1623e09af2b2aa0f1098a8",
        "https://git.kernel.org/stable/c/a259ba0bce3b192c04334499690372a250f7d0b1",
        "https://git.kernel.org/stable/c/bbb09bb89ffa571475f66daca9482b974cd29d6a",
        "https://git.kernel.org/stable/c/e1e7a66584bf0aff3becb73c19fa31527889fc9e",
        "https://git.kernel.org/stable/c/e1eabb072c75681f78312c484ccfffb7430f206e",
        "https://git.kernel.org/stable/c/f02980594deef751e42133714aee25228f1494c6",
        "https://git.kernel.org/stable/c/f6813c2b2ae78def76b69e0f9d72f80e4a1c4aca",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31728.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-31728",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
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        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31728.json"
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        "value": "CVE-2026-31728",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
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  "source_id": "core-osv",
  "document_id": 507851,
  "published_at": "2026-05-01T14:14:28.231+00:00"
}