bpf: Silence a warning in btf_type_id_size()

{
  "id": "f5b841d3878dc60875af6fd858740349fe4d61112ab137bd1c7f9e4ba635c0c1",
  "url": "https://osv.dev/vulnerability/CVE-2023-54247",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Silence a warning in btf_type_id_size()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: Silence a warning in btf_type_id_size() syzbot reported a warning in [1] with the following stacktrace: WARNING: CPU: 0 PID: 5005 at kernel/bpf/btf.c:1988 btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988 ... RIP: 0010:btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988 ... Call Trace: map_check_btf kernel/bpf/syscall.c:1024 [inline] map_create+0x1157/0x1860 kernel/bpf/syscall.c:1198 __sys_bpf+0x127f/0x5420 kernel/bpf/syscall.c:5040 __do_sys_bpf kernel/bpf/syscall.c:5162 [inline] __se_sys_bpf kernel/bpf/syscall.c:5160 [inline] __x64_sys_bpf+0x79/0xc0 kernel/bpf/syscall.c:5160 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd With the following btf [1] DECL_TAG 'a' type_id=4 component_idx=-1 [2] PTR '(anon)' type_id=0 [3] TYPE_TAG 'a' type_id=2 [4] VAR 'a' type_id=3, linkage=static and when the bpf_attr.btf_key_type_id = 1 (DECL_TAG), the following WARN_ON_ONCE in btf_type_id_size() is triggered: if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) && !btf_type_is_var(size_type))) return NULL; Note that 'return NULL' is the correct behavior as we don't want a DECL_TAG type to be used as a btf_{key,value}_type_id even for the case like 'DECL_TAG -> STRUCT'. So there is no correctness issue here, we just want to silence warning. To silence the warning, I added DECL_TAG as one of kinds in btf_type_nosize() which will ca",
    "evidence": "osv:CVE-2023-54247",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.110",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.4.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-54247",
      "aliases": [
        "CVE-2023-54247"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "b5ea834dde6b6e7f75e51d5f66dac8cd7c97b5ef"
                },
                {
                  "fixed": "61f4bd46a03a81865aca3bcbad2f7b7032fb3160"
                },
                {
                  "fixed": "7c4f5ab63e7962812505cbd38cc765168a223acb"
                },
                {
                  "fixed": "e6c2f594ed961273479505b42040782820190305"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-54247.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.110"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.4.7"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-54247.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.352532679Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/61f4bd46a03a81865aca3bcbad2f7b7032fb3160",
        "https://git.kernel.org/stable/c/7c4f5ab63e7962812505cbd38cc765168a223acb",
        "https://git.kernel.org/stable/c/e6c2f594ed961273479505b42040782820190305",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/54xxx/CVE-2023-54247.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-54247",
        "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/2023/54xxx/CVE-2023-54247.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-54247",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 517697,
  "published_at": "2025-12-30T12:15:45.395+00:00"
}