net/smc: reduce rtnl pressure in smc_pnet_create_pnetids_list()

{
  "id": "e8787f607e9a8823b25f5d38e00bf6ea4ebf488a74151a136408e5cb68c60262",
  "url": "https://osv.dev/vulnerability/CVE-2024-35934",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/smc: reduce rtnl pressure in smc_pnet_create_pnetids_list()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/smc: reduce rtnl pressure in smc_pnet_create_pnetids_list() Many syzbot reports show extreme rtnl pressure, and many of them hint that smc acquires rtnl in netns creation for no good reason [1] This patch returns early from smc_pnet_net_init() if there is no netdevice yet. I am not even sure why smc_pnet_create_pnetids_list() even exists, because smc_pnet_netdev_event() is also calling smc_pnet_add_base_pnetid() when handling NETDEV_UP event. [1] extract of typical syzbot reports 2 locks held by syz-executor.3/12252: #0: ffffffff8f369610 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x4c7/0x7b0 net/core/net_namespace.c:491 #1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_create_pnetids_list net/smc/smc_pnet.c:809 [inline] #1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_net_init+0x10a/0x1e0 net/smc/smc_pnet.c:878 2 locks held by syz-executor.4/12253: #0: ffffffff8f369610 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x4c7/0x7b0 net/core/net_namespace.c:491 #1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_create_pnetids_list net/smc/smc_pnet.c:809 [inline] #1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_net_init+0x10a/0x1e0 net/smc/smc_pnet.c:878 2 locks held by syz-executor.1/12257: #0: ffffffff8f369610 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x4c7/0x7b0 net/core/net_namespace.c:491 #1: ffffffff8f375b88 (rtnl_mutex){+.+.}-{3:3}, at: smc_pnet_create_",
    "evidence": "osv:CVE-2024-35934",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.215",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.155",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.86",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.27",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.8.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-35934",
      "aliases": [
        "CVE-2024-35934"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e888a2e8337c96dd785d204cf8ff775e79173add"
                },
                {
                  "fixed": "bc4d1ebca11b4f194e262326bd45938e857c59d2"
                },
                {
                  "fixed": "b9117dc783c0ab0a3866812f70e07bf2ea071ac4"
                },
                {
                  "fixed": "d7ee3bf0caf599c14db0bf4af7aacd6206ef8a23"
                },
                {
                  "fixed": "a2e6bffc0388526ed10406040279a693d62b36ec"
                },
                {
                  "fixed": "6e920422e7104928f760fc0e12b6d65ab097a2e7"
                },
                {
                  "fixed": "00af2aa93b76b1bade471ad0d0525d4d29ca5cc0"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35934.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.10.0"
                },
                {
                  "fixed": "5.10.215"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.155"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.86"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.27"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.8.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35934.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.792056935Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-265688.html",
        "https://git.kernel.org/stable/c/00af2aa93b76b1bade471ad0d0525d4d29ca5cc0",
        "https://git.kernel.org/stable/c/6e920422e7104928f760fc0e12b6d65ab097a2e7",
        "https://git.kernel.org/stable/c/a2e6bffc0388526ed10406040279a693d62b36ec",
        "https://git.kernel.org/stable/c/b9117dc783c0ab0a3866812f70e07bf2ea071ac4",
        "https://git.kernel.org/stable/c/bc4d1ebca11b4f194e262326bd45938e857c59d2",
        "https://git.kernel.org/stable/c/d7ee3bf0caf599c14db0bf4af7aacd6206ef8a23",
        "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35934.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-35934",
        "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/2024/35xxx/CVE-2024-35934.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-35934",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 495522,
  "published_at": "2024-05-19T10:10:41.668+00:00"
}