bpf: reject unhashed sockets in bpf_sk_assign

{
  "id": "ebd95a8c32b27ba23c4fa141e9bfcfe475a4c27bb2cbc61f202b87fc217e9180",
  "url": "https://osv.dev/vulnerability/CVE-2023-53585",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: reject unhashed sockets in bpf_sk_assign",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: reject unhashed sockets in bpf_sk_assign The semantics for bpf_sk_assign are as follows: sk = some_lookup_func() bpf_sk_assign(skb, sk) bpf_sk_release(sk) That is, the sk is not consumed by bpf_sk_assign. The function therefore needs to make sure that sk lives long enough to be consumed from __inet_lookup_skb. The path through the stack for a TCPv4 packet is roughly: netif_receive_skb_core: takes RCU read lock __netif_receive_skb_core: sch_handle_ingress: tcf_classify: bpf_sk_assign() deliver_ptype_list_skb: deliver_skb: ip_packet_type->func == ip_rcv: ip_rcv_core: ip_rcv_finish_core: dst_input: ip_local_deliver: ip_local_deliver_finish: ip_protocol_deliver_rcu: tcp_v4_rcv: __inet_lookup_skb: skb_steal_sock The existing helper takes advantage of the fact that everything happens in the same RCU critical section: for sockets with SOCK_RCU_FREE set bpf_sk_assign never takes a reference. skb_steal_sock then checks SOCK_RCU_FREE again and does sock_put if necessary. This approach assumes that SOCK_RCU_FREE is never set on a sk between bpf_sk_assign and skb_steal_sock, but this invariant is violated by unhashed UDP sockets. A new UDP socket is created in TCP_CLOSE state but without SOCK_RCU_FREE set. That flag is only added in udp_lib_get_port() which happens when a socket is bound. When bpf_sk_assign was added it wasn't possible to access unhashed UDP sockets from BPF, so this wasn't a problem. This changed i",
    "evidence": "osv:CVE-2023-53585",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.195",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.132",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.53",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.4.16",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.5.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-53585",
      "aliases": [
        "CVE-2023-53585"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449"
                },
                {
                  "fixed": "791a12102e5191dcb6ce0b3a99d71b5a2802d12a"
                },
                {
                  "fixed": "7dcbc0bb0e5cc1823923744befce59ac353135e6"
                },
                {
                  "fixed": "c0ce0fb76610d5fad31f56f2ca8241a2a6717a1b"
                },
                {
                  "fixed": "8aa43cfbb68b25119d2ced14ec717173e2901fa2"
                },
                {
                  "fixed": "3d4522f59fb748a54446846522941a4f09da63e9"
                },
                {
                  "fixed": "67312adc96b5a585970d03b62412847afe2c6b01"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53585.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.7.0"
                },
                {
                  "fixed": "5.10.195"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.132"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.53"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.4.16"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.5.0"
                },
                {
                  "fixed": "6.5.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53585.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:46.568217569Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3d4522f59fb748a54446846522941a4f09da63e9",
        "https://git.kernel.org/stable/c/67312adc96b5a585970d03b62412847afe2c6b01",
        "https://git.kernel.org/stable/c/791a12102e5191dcb6ce0b3a99d71b5a2802d12a",
        "https://git.kernel.org/stable/c/7dcbc0bb0e5cc1823923744befce59ac353135e6",
        "https://git.kernel.org/stable/c/8aa43cfbb68b25119d2ced14ec717173e2901fa2",
        "https://git.kernel.org/stable/c/c0ce0fb76610d5fad31f56f2ca8241a2a6717a1b",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53585.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-53585",
        "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/2023/53xxx/CVE-2023-53585.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-53585",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 514436,
  "published_at": "2025-10-04T15:44:01.022+00:00"
}