net: Add rx_skb of kfree_skb to raw_tp_null_args[].

{
  "id": "6305f25fc205b3d55db0be6149d1a99a130f7b4edfb49d7ea1ad2c88f7a230f4",
  "url": "https://osv.dev/vulnerability/CVE-2025-21852",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: Add rx_skb of kfree_skb to raw_tp_null_args[].",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: Add rx_skb of kfree_skb to raw_tp_null_args[]. Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0] in trace_kfree_skb if the prog does not check if rx_sk is NULL. Commit c53795d48ee8 (\"net: add rx_sk to trace_kfree_skb\") added rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL. Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier validate such a prog and prevent the issue. Now we fail to load such a prog: libbpf: prog 'drop': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21 0: (79) r3 = *(u64 *)(r1 +24) func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock' 1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1) ; bpf_printk(\"sk: %d, %d\\n\", sk, sk->__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24 1: (69) r4 = *(u16 *)(r3 +16) R3 invalid mem access 'trusted_ptr_or_null_' processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 -- END PROG LOAD LOG -- Note this fix requires commit 838a10bd2ebf (\"bpf: Augment raw_tp arguments with PTR_MAYBE_NULL\"). [0]: BUG: kernel NULL pointer dereference, address: 0000000000000010 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 P4D 0 PREEMPT SMP RIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d Call Trace: ? __die+0x1f/0x60 ? page_fault_oops+0x148/0x420 ? search_bpf_ext",
    "evidence": "osv:CVE-2025-21852",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.17",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.13.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-21852",
      "aliases": [
        "CVE-2025-21852"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "c53795d48ee8f385c6a9e394651e7ee914baaeba"
                },
                {
                  "fixed": "f579afacd0a66971fc8481f30d2d377e230a8342"
                },
                {
                  "fixed": "4dba79c1e7aad6620bbb707b6c4459380fd90860"
                },
                {
                  "fixed": "5da7e15fb5a12e78de974d8908f348e279922ce9"
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              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21852.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.11.0"
                },
                {
                  "fixed": "6.12.17"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.13.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21852.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.393005732Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/4dba79c1e7aad6620bbb707b6c4459380fd90860",
        "https://git.kernel.org/stable/c/5da7e15fb5a12e78de974d8908f348e279922ce9",
        "https://git.kernel.org/stable/c/f579afacd0a66971fc8481f30d2d377e230a8342",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21852.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21852",
        "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/2025/21xxx/CVE-2025-21852.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-21852",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 501255,
  "published_at": "2025-03-12T09:42:07.175+00:00"
}