tipc: Fix use-after-free in tipc_conn_close().

{
  "id": "dff803c0df4356ccf90703660b101e67951da5a5fd3629595582e1917921d8a0",
  "url": "https://osv.dev/vulnerability/CVE-2025-38464",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tipc: Fix use-after-free in tipc_conn_close().",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tipc: Fix use-after-free in tipc_conn_close(). syzbot reported a null-ptr-deref in tipc_conn_close() during netns dismantle. [0] tipc_topsrv_stop() iterates tipc_net(net)->topsrv->conn_idr and calls tipc_conn_close() for each tipc_conn. The problem is that tipc_conn_close() is called after releasing the IDR lock. At the same time, there might be tipc_conn_recv_work() running and it could call tipc_conn_close() for the same tipc_conn and release its last ->kref. Once we release the IDR lock in tipc_topsrv_stop(), there is no guarantee that the tipc_conn is alive. Let's hold the ref before releasing the lock and put the ref after tipc_conn_close() in tipc_topsrv_stop(). [0]: BUG: KASAN: use-after-free in tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165 Read of size 8 at addr ffff888099305a08 by task kworker/u4:3/435 CPU: 0 PID: 435 Comm: kworker/u4:3 Not tainted 4.19.204-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354 kasan_report mm/kasan/report.c:412 [inline] __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433 tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165 tipc_topsrv_stop net/tipc/topsrv.c:701 [inli",
    "evidence": "osv:CVE-2025-38464",
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      "modified": "2026-10-28T02:30:53.420661805Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/03dcdd2558e1e55bf843822fe4363dcb48743f2b",
        "https://git.kernel.org/stable/c/15a6f4971e2f157d57e09ea748d1fbc714277aa4",
        "https://git.kernel.org/stable/c/1dbf7cd2454a28b1da700085b99346b5445aeabb",
        "https://git.kernel.org/stable/c/3b89e17b2fd64012682bed158d9eb3d2e96dec42",
        "https://git.kernel.org/stable/c/50aa2d121bc2cfe2d825f8a331ea75dfaaab6a50",
        "https://git.kernel.org/stable/c/667eeab4999e981c96b447a4df5f20bdf5c26f13",
        "https://git.kernel.org/stable/c/be4b8392da7978294f2f368799d29dd509fb6c4d",
        "https://git.kernel.org/stable/c/dab8ded2e5ff41012a6ff400b44dbe76ccf3592a",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38464.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-38464",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
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    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 522013,
  "published_at": "2025-07-25T15:27:46.708+00:00"
}