tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.

{
  "id": "32bddfb81392888f78ab9e130b31944069bb0aec10d31340d8ab7a51b308c41a",
  "url": "https://osv.dev/vulnerability/CVE-2023-53489",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp. syzkaller reported [0] memory leaks of an UDP socket and ZEROCOPY skbs. We can reproduce the problem with these sequences: sk = socket(AF_INET, SOCK_DGRAM, 0) sk.setsockopt(SOL_SOCKET, SO_TIMESTAMPING, SOF_TIMESTAMPING_TX_SOFTWARE) sk.setsockopt(SOL_SOCKET, SO_ZEROCOPY, 1) sk.sendto(b'', MSG_ZEROCOPY, ('127.0.0.1', 53)) sk.close() sendmsg() calls msg_zerocopy_alloc(), which allocates a skb, sets skb->cb->ubuf.refcnt to 1, and calls sock_hold(). Here, struct ubuf_info_msgzc indirectly holds a refcnt of the socket. When the skb is sent, __skb_tstamp_tx() clones it and puts the clone into the socket's error queue with the TX timestamp. When the original skb is received locally, skb_copy_ubufs() calls skb_unclone(), and pskb_expand_head() increments skb->cb->ubuf.refcnt. This additional count is decremented while freeing the skb, but struct ubuf_info_msgzc still has a refcnt, so __msg_zerocopy_callback() is not called. The last refcnt is not released unless we retrieve the TX timestamped skb by recvmsg(). Since we clear the error queue in inet_sock_destruct() after the socket's refcnt reaches 0, there is a circular dependency. If we close() the socket holding such skbs, we never call sock_put() and leak the count, sk, and skb. TCP has the same problem, and commit e0c8bccd40fc (\"net: stream: purge sk_error_queue in sk_stream_kill_queues()\") tried to ",
    "evidence": "osv:CVE-2023-53489",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.14.315",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "4.19.283",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.4.243",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.10.180",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.111",
            "evidence": "/affected/1/ranges"
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          {
            "value": "6.1.28",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.2.15",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.3.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-53489",
      "aliases": [
        "CVE-2023-53489"
      ],
      "affected": [
        {
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                  "fixed": "1f69c086b20e27763af28145981435423f088268"
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                {
                  "fixed": "602fa8af44fd55a58f9e94eb673e8adad2c6cc46"
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                {
                  "fixed": "230a5ed7d813fb516de81d23f09d7506753e41e9"
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                {
                  "fixed": "43e4197dd5f6b474a8b16f8b6a42cd45cf4f9d1a"
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                {
                  "fixed": "cb52e7f24c1d01a536a847dff0d1d95889cc3b5c"
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                {
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53489.json"
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        {
          "ranges": [
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              "type": "ECOSYSTEM",
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53489.json"
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      "modified": "2026-10-28T02:30:37.074195498Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1f69c086b20e27763af28145981435423f088268",
        "https://git.kernel.org/stable/c/230a5ed7d813fb516de81d23f09d7506753e41e9",
        "https://git.kernel.org/stable/c/281072fb2a7294cde7acbf5375b879f40a8001b7",
        "https://git.kernel.org/stable/c/30290f210ba7426ff7592fe2eb4114b1b5bad219",
        "https://git.kernel.org/stable/c/426384dd4980040651536fef5feac4dcc4d7ee4e",
        "https://git.kernel.org/stable/c/43e4197dd5f6b474a8b16f8b6a42cd45cf4f9d1a",
        "https://git.kernel.org/stable/c/50749f2dd6854a41830996ad302aef2ffaf011d8",
        "https://git.kernel.org/stable/c/602fa8af44fd55a58f9e94eb673e8adad2c6cc46",
        "https://git.kernel.org/stable/c/cb52e7f24c1d01a536a847dff0d1d95889cc3b5c",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53489.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-53489",
        "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-2023-53489.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-53489",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 504103,
  "published_at": "2025-10-01T11:45:41.304+00:00"
}