tipc: fix NULL deref in cleanup_bearer()

{
  "id": "b9f3258df0e3b7c25d9e3e2f96df57fa63b5af1e2c9256a4a340faf2efb3fc82",
  "url": "https://osv.dev/vulnerability/CVE-2024-56661",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tipc: fix NULL deref in cleanup_bearer()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tipc: fix NULL deref in cleanup_bearer() syzbot found [1] that after blamed commit, ub->ubsock->sk was NULL when attempting the atomic_dec() : atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); Fix this by caching the tipc_net pointer. [1] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 0 UID: 0 PID: 5896 Comm: kworker/0:3 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events cleanup_bearer RIP: 0010:read_pnet include/net/net_namespace.h:387 [inline] RIP: 0010:sock_net include/net/sock.h:655 [inline] RIP: 0010:cleanup_bearer+0x1f7/0x280 net/tipc/udp_media.c:820 Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 3c f7 99 f6 48 8b 1b 48 83 c3 30 e8 f0 e4 60 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 1a f7 99 f6 49 83 c7 e8 48 8b 1b RSP: 0018:ffffc9000410fb70 EFLAGS: 00010206 RAX: 0000000000000006 RBX: 0000000000000030 RCX: ffff88802fe45a00 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000410f900 RBP: ffff88807e1f0908 R08: ffffc9000410f907 R09: 1ffff92000821f20 R10: dffffc0000000000 R11: fffff52000821f21 R12: ffff888031d19980 R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807e1f0918 FS: 0000000000000000(0000) GS:f",
    "evidence": "osv:CVE-2024-56661",
    "products": [
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          "value": "Kernel",
          "evidence": "/affected/1/package/name"
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        "prerequisites": [],
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    "severity": "medium",
    "structured": {
      "id": "CVE-2024-56661",
      "aliases": [
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
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            "ecosystem": "Linux"
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      "modified": "2026-10-28T02:30:49.005398549Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/07b569eda6fe6a1e83be5a587abee12d1303f95e",
        "https://git.kernel.org/stable/c/754ec823ee53422361da7958a8c8bf3275426912",
        "https://git.kernel.org/stable/c/89ecda492d0a37fd00aaffc4151f1f44c26d93ac",
        "https://git.kernel.org/stable/c/a771f349c95d3397636861a0a6462d4a7a7ecb25",
        "https://git.kernel.org/stable/c/a852c82eda4991e21610837aaa160965be71f5cc",
        "https://git.kernel.org/stable/c/b04d86fff66b15c07505d226431f808c15b1703c",
        "https://git.kernel.org/stable/c/d1d4dfb189a115734bff81c411bc58d9e348db7d",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56661.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-56661",
        "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/2024/56xxx/CVE-2024-56661.json"
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    "related_cves": [
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        "value": "CVE-2024-56661",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 517295,
  "published_at": "2024-12-27T15:06:23.928+00:00"
}