net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock

{
  "id": "b5216239ad97edb7ae48e27280a55c00c2783cb75dcecde22014883a21b15669",
  "url": "https://osv.dev/vulnerability/CVE-2025-40120",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock Prevent USB runtime PM (autosuspend) for AX88772* in bind. usbnet enables runtime PM (autosuspend) by default, so disabling it via the usb_driver flag is ineffective. On AX88772B, autosuspend shows no measurable power saving with current driver (no link partner, admin up/down). The ~0.453 W -> ~0.248 W drop on v6.1 comes from phylib powering the PHY off on admin-down, not from USB autosuspend. The real hazard is that with runtime PM enabled, ndo_open() (under RTNL) may synchronously trigger autoresume (usb_autopm_get_interface()) into asix_resume() while the USB PM lock is held. Resume paths then invoke phylink/phylib and MDIO, which also expect RTNL, leading to possible deadlocks or PM lock vs MDIO wake issues. To avoid this, keep the device runtime-PM active by taking a usage reference in ax88772_bind() and dropping it in unbind(). A non-zero PM usage count blocks runtime suspend regardless of userspace policy (.../power/control - pm_runtime_allow/forbid), making this approach robust against sysfs overrides. Holding a runtime-PM usage ref does not affect system-wide suspend; system sleep/resume callbacks continue to run as before.",
    "evidence": "osv:CVE-2025-40120",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.195",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.156",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.112",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.53",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.17.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-40120",
      "aliases": [
        "CVE-2025-40120"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "4a2c7217cd5a87e85ceb761e307b030fe6db4805"
                },
                {
                  "fixed": "71a0ba7fdaf8d035426912a4ed7bf1738a81010c"
                },
                {
                  "fixed": "3e96cd27ff1a004d84908c1b6cc68ac60913874e"
                },
                {
                  "fixed": "724a9db84188f80ef60b1f21cc7b4e9c84e0cb64"
                },
                {
                  "fixed": "1534517300e12f2930b6ff477b8820ff658afd11"
                },
                {
                  "fixed": "9d8bcaf6fae1bd82bc27ec09a2694497e6f6c4b4"
                },
                {
                  "fixed": "3d3c4cd5c62f24bb3cb4511b7a95df707635e00a"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40120.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.14.0"
                },
                {
                  "fixed": "5.15.195"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.156"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.112"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.53"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.17.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40120.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.653801265Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1534517300e12f2930b6ff477b8820ff658afd11",
        "https://git.kernel.org/stable/c/3d3c4cd5c62f24bb3cb4511b7a95df707635e00a",
        "https://git.kernel.org/stable/c/3e96cd27ff1a004d84908c1b6cc68ac60913874e",
        "https://git.kernel.org/stable/c/71a0ba7fdaf8d035426912a4ed7bf1738a81010c",
        "https://git.kernel.org/stable/c/724a9db84188f80ef60b1f21cc7b4e9c84e0cb64",
        "https://git.kernel.org/stable/c/9d8bcaf6fae1bd82bc27ec09a2694497e6f6c4b4",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40120.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-40120",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40120.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-40120",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 502061,
  "published_at": "2025-11-12T10:23:18.726+00:00"
}