tcp: cdg: allow tcp_cdg_release() to be called multiple times

{
  "id": "76411e84798f18434d73ee3ff3954dd4f6662808be2d7ea461441448e1d0a9ab",
  "url": "https://osv.dev/vulnerability/CVE-2022-49775",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tcp: cdg: allow tcp_cdg_release() to be called multiple times",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tcp: cdg: allow tcp_cdg_release() to be called multiple times Apparently, mptcp is able to call tcp_disconnect() on an already disconnected flow. This is generally fine, unless current congestion control is CDG, because it might trigger a double-free [1] Instead of fixing MPTCP, and future bugs, we can make tcp_disconnect() more resilient. [1] BUG: KASAN: double-free in slab_free mm/slub.c:3539 [inline] BUG: KASAN: double-free in kfree+0xe2/0x580 mm/slub.c:4567 CPU: 0 PID: 3645 Comm: kworker/0:7 Not tainted 6.0.0-syzkaller-02734-g0326074ff465 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022 Workqueue: events mptcp_worker Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x719 mm/kasan/report.c:433 kasan_report_invalid_free+0x81/0x190 mm/kasan/report.c:462 ____kasan_slab_free+0x18b/0x1c0 mm/kasan/common.c:356 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1759 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1785 slab_free mm/slub.c:3539 [inline] kfree+0xe2/0x580 mm/slub.c:4567 tcp_disconnect+0x980/0x1e20 net/ipv4/tcp.c:3145 __mptcp_close_ssk+0x5ca/0x7e0 net/mptcp/protocol.c:2327 mptcp_do_fastclose net/mptcp/protocol.c:2592 [inline] mptcp_worker+0x78c/0xff0 net/mptcp/protocol.c:2627 process_one_work+0x99",
    "evidence": "osv:CVE-2022-49775",
    "products": [
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        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
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        "prerequisites": [],
        "fixed_versions": [
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    "severity": "high",
    "structured": {
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      "aliases": [
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
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      "modified": "2026-10-28T02:30:50.622104960Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0b19171439016a8e4c97eafe543670ac86e2b8fe",
        "https://git.kernel.org/stable/c/1b639be27cbf428a5ca01dcf8b5d654194c956f8",
        "https://git.kernel.org/stable/c/35309be06b6feded2ab2cafbc2bca8534c2fa41e",
        "https://git.kernel.org/stable/c/4026033907cc6186d86b48daa4a252c860db2536",
        "https://git.kernel.org/stable/c/72e560cb8c6f80fc2b4afc5d3634a32465e13a51",
        "https://git.kernel.org/stable/c/78be2ee0112409ae4e9ee9e326151e0559b3d239",
        "https://git.kernel.org/stable/c/9e481d87349d2282f400ee1d010a169c99f766b8",
        "https://git.kernel.org/stable/c/b49026d9c86f35a4c5bfb8d7345c9c4379828c6b",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49775.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49775",
        "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/2022/49xxx/CVE-2022-49775.json"
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        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519114,
  "published_at": "2025-05-01T14:09:11.827+00:00"
}