CVE-2025-21921 (GCVE-0-2025-21921)
Vulnerability from cvelistv5
Published
2025-04-01 15:40
Modified
2025-05-04 07:24
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device ethnl_req_get_phydev() is used to lookup a phy_device, in the case an ethtool netlink command targets a specific phydev within a netdev's topology. It takes as a parameter a const struct nlattr *header that's used for error handling : if (!phydev) { NL_SET_ERR_MSG_ATTR(extack, header, "no phy matching phyindex"); return ERR_PTR(-ENODEV); } In the notify path after a ->set operation however, there's no request attributes available. The typical callsite for the above function looks like: phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER], info->extack); So, when tb is NULL (such as in the ethnl notify path), we have a nice crash. It turns out that there's only the PLCA command that is in that case, as the other phydev-specific commands don't have a notification. This commit fixes the crash by passing the cmd index and the nlattr array separately, allowing NULL-checking it directly inside the helper.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1f458fa42c29144cef280e05bc49fc21b873d897
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/637399bf7e77797811adf340090b561a8f9d1213
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/639c70352958735addbba5ae7dd65985da96e061
Impacted products
Vendor Product Version
Linux Linux Version: c15e065b46dc4e19837275b826c1960d55564abd
Version: c15e065b46dc4e19837275b826c1960d55564abd
Version: c15e065b46dc4e19837275b826c1960d55564abd
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   Linux Linux Version: 6.12
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ethtool/cabletest.c",
            "net/ethtool/linkstate.c",
            "net/ethtool/netlink.c",
            "net/ethtool/netlink.h",
            "net/ethtool/phy.c",
            "net/ethtool/plca.c",
            "net/ethtool/pse-pd.c",
            "net/ethtool/stats.c",
            "net/ethtool/strset.c"
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            "net/ethtool/linkstate.c",
            "net/ethtool/netlink.c",
            "net/ethtool/netlink.h",
            "net/ethtool/phy.c",
            "net/ethtool/plca.c",
            "net/ethtool/pse-pd.c",
            "net/ethtool/stats.c",
            "net/ethtool/strset.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "6.12"
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              "version": "6.13.7",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "*",
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              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ethtool: netlink: Allow NULL nlattrs when getting a phy_device\n\nethnl_req_get_phydev() is used to lookup a phy_device, in the case an\nethtool netlink command targets a specific phydev within a netdev\u0027s\ntopology.\n\nIt takes as a parameter a const struct nlattr *header that\u0027s used for\nerror handling :\n\n       if (!phydev) {\n               NL_SET_ERR_MSG_ATTR(extack, header,\n                                   \"no phy matching phyindex\");\n               return ERR_PTR(-ENODEV);\n       }\n\nIn the notify path after a -\u003eset operation however, there\u0027s no request\nattributes available.\n\nThe typical callsite for the above function looks like:\n\n\tphydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER],\n\t\t\t\t      info-\u003eextack);\n\nSo, when tb is NULL (such as in the ethnl notify path), we have a nice\ncrash.\n\nIt turns out that there\u0027s only the PLCA command that is in that case, as\nthe other phydev-specific commands don\u0027t have a notification.\n\nThis commit fixes the crash by passing the cmd index and the nlattr\narray separately, allowing NULL-checking it directly inside the helper."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T07:24:36.169Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/639c70352958735addbba5ae7dd65985da96e061"
        },
        {
          "url": "https://git.kernel.org/stable/c/1f458fa42c29144cef280e05bc49fc21b873d897"
        },
        {
          "url": "https://git.kernel.org/stable/c/637399bf7e77797811adf340090b561a8f9d1213"
        }
      ],
      "title": "net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21921",
    "datePublished": "2025-04-01T15:40:55.110Z",
    "dateReserved": "2024-12-29T08:45:45.788Z",
    "dateUpdated": "2025-05-04T07:24:36.169Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21921\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-04-01T16:15:22.790\",\"lastModified\":\"2025-04-01T20:26:01.990\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet: ethtool: netlink: Allow NULL nlattrs when getting a phy_device\\n\\nethnl_req_get_phydev() is used to lookup a phy_device, in the case an\\nethtool netlink command targets a specific phydev within a netdev\u0027s\\ntopology.\\n\\nIt takes as a parameter a const struct nlattr *header that\u0027s used for\\nerror handling :\\n\\n       if (!phydev) {\\n               NL_SET_ERR_MSG_ATTR(extack, header,\\n                                   \\\"no phy matching phyindex\\\");\\n               return ERR_PTR(-ENODEV);\\n       }\\n\\nIn the notify path after a -\u003eset operation however, there\u0027s no request\\nattributes available.\\n\\nThe typical callsite for the above function looks like:\\n\\n\\tphydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER],\\n\\t\\t\\t\\t      info-\u003eextack);\\n\\nSo, when tb is NULL (such as in the ethnl notify path), we have a nice\\ncrash.\\n\\nIt turns out that there\u0027s only the PLCA command that is in that case, as\\nthe other phydev-specific commands don\u0027t have a notification.\\n\\nThis commit fixes the crash by passing the cmd index and the nlattr\\narray separately, allowing NULL-checking it directly inside the helper.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1f458fa42c29144cef280e05bc49fc21b873d897\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/637399bf7e77797811adf340090b561a8f9d1213\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/639c70352958735addbba5ae7dd65985da96e061\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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