bpf, sockmap: Fix af_unix null-ptr-deref in proto update

{
  "id": "1d978d60559d914b674e960ed3d58204d8ff452854a78a01cc739c999ddf9244",
  "url": "https://osv.dev/vulnerability/CVE-2026-53034",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf, sockmap: Fix af_unix null-ptr-deref in proto update",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix af_unix null-ptr-deref in proto update unix_stream_connect() sets sk_state (`WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED)`) _before_ it assigns a peer (`unix_peer(sk) = newsk`). sk_state == TCP_ESTABLISHED makes sock_map_sk_state_allowed() believe that socket is properly set up, which would include having a defined peer. IOW, there's a window when unix_stream_bpf_update_proto() can be called on socket which still has unix_peer(sk) == NULL. CPU0 bpf CPU1 connect -------- ------------ WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED) sock_map_sk_state_allowed(sk) ... sk_pair = unix_peer(sk) sock_hold(sk_pair) sock_hold(newsk) smp_mb__after_atomic() unix_peer(sk) = newsk BUG: kernel NULL pointer dereference, address: 0000000000000080 RIP: 0010:unix_stream_bpf_update_proto+0xa0/0x1b0 Call Trace: sock_map_link+0x564/0x8b0 sock_map_update_common+0x6e/0x340 sock_map_update_elem_sys+0x17d/0x240 __sys_bpf+0x26db/0x3250 __x64_sys_bpf+0x21/0x30 do_syscall_64+0x6b/0x3a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Initial idea was to move peer assignment _before_ the sk_state update[1], but that involved an additional memory barrier, and changing the hot path was rejected. Then a NULL check during proto update in unix_stream_bpf_update_proto() was considered[2], but the follow-up discussion[3] focused on the root cause, i.e. sockmap update taking a wrong lock. Or, more specifically, missing unix_state_lock()[4]. In th",
    "evidence": "osv:CVE-2026-53034",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.175",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.141",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.91",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.33",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-53034",
      "aliases": [
        "CVE-2026-53034"
      ],
      "affected": [
        {
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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                  "fixed": "a94d3dd78ee8b63e6b8ad629081c952c93ee5a10"
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                {
                  "fixed": "041eb6348d73ee5e15fc8161f1eac5a6e8289ca0"
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                {
                  "fixed": "37bfcd164161b47d00b1c3bd20adc816a6977ce0"
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                  "fixed": "dca38b7734d2ea00af4818ff3ae836fab33d5d5a"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53034.json"
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              "type": "ECOSYSTEM",
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            {
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              "events": [
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                {
                  "fixed": "6.6.141"
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
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                {
                  "fixed": "6.12.91"
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53034.json"
          }
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      ],
      "modified": "2026-10-28T02:30:34.177496406Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/041eb6348d73ee5e15fc8161f1eac5a6e8289ca0",
        "https://git.kernel.org/stable/c/37bfcd164161b47d00b1c3bd20adc816a6977ce0",
        "https://git.kernel.org/stable/c/4913c94a3adcdbb64c552110c0c243cb1fdbb317",
        "https://git.kernel.org/stable/c/75b7d3b3f8bd4e59eb3af1b11a43c64c0c2db6f4",
        "https://git.kernel.org/stable/c/a94d3dd78ee8b63e6b8ad629081c952c93ee5a10",
        "https://git.kernel.org/stable/c/dca38b7734d2ea00af4818ff3ae836fab33d5d5a",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53034.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-53034",
        "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/2026/53xxx/CVE-2026-53034.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-53034",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 501234,
  "published_at": "2026-06-24T16:29:41.676+00:00"
}