mptcp: fix NULL pointer in can_accept_new_subflow

{
  "id": "ccc21e4688de4ff1f563a47227192bf6230442767225533a52418f86bb2e8098",
  "url": "https://osv.dev/vulnerability/CVE-2025-23145",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mptcp: fix NULL pointer in can_accept_new_subflow",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: mptcp: fix NULL pointer in can_accept_new_subflow When testing valkey benchmark tool with MPTCP, the kernel panics in 'mptcp_can_accept_new_subflow' because subflow_req->msk is NULL. Call trace: mptcp_can_accept_new_subflow (./net/mptcp/subflow.c:63 (discriminator 4)) (P) subflow_syn_recv_sock (./net/mptcp/subflow.c:854) tcp_check_req (./net/ipv4/tcp_minisocks.c:863) tcp_v4_rcv (./net/ipv4/tcp_ipv4.c:2268) ip_protocol_deliver_rcu (./net/ipv4/ip_input.c:207) ip_local_deliver_finish (./net/ipv4/ip_input.c:234) ip_local_deliver (./net/ipv4/ip_input.c:254) ip_rcv_finish (./net/ipv4/ip_input.c:449) ... According to the debug log, the same req received two SYN-ACK in a very short time, very likely because the client retransmits the syn ack due to multiple reasons. Even if the packets are transmitted with a relevant time interval, they can be processed by the server on different CPUs concurrently). The 'subflow_req->msk' ownership is transferred to the subflow the first, and there will be a risk of a null pointer dereference here. This patch fixes this issue by moving the 'subflow_req->msk' under the `own_req == true` conditional. Note that the !msk check in subflow_hmac_valid() can be dropped, because the same check already exists under the own_req mpj branch where the code has been moved to.",
    "evidence": "osv:CVE-2025-23145",
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      "modified": "2026-10-28T02:30:31.982373732Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/443041deb5ef6a1289a99ed95015ec7442f141dc",
        "https://git.kernel.org/stable/c/4b2649b9717678aeb097893cc49f59311a1ecab0",
        "https://git.kernel.org/stable/c/7f9ae060ed64aef8f174c5f1ea513825b1be9af1",
        "https://git.kernel.org/stable/c/855bf0aacd51fced11ea9aa0d5101ee0febaeadb",
        "https://git.kernel.org/stable/c/8cf7fef1bb2ffea7792bcbf71ca00216cecc725d",
        "https://git.kernel.org/stable/c/b3088bd2a6790c8efff139d86d7a9d0b1305977b",
        "https://git.kernel.org/stable/c/dc81e41a307df523072186b241fa8244fecd7803",
        "https://git.kernel.org/stable/c/efd58a8dd9e7a709a90ee486a4247c923d27296f",
        "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html",
        "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/23xxx/CVE-2025-23145.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-23145",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
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        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 498862,
  "published_at": "2025-05-01T12:55:34.622+00:00"
}