bpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg()

{
  "id": "06d8e8c1e4218a0acfe2b5b774a57faa0419d74bb040f694280039016be23108",
  "url": "https://osv.dev/vulnerability/CVE-2026-68284",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg() tcp_bpf_sendmsg() keeps msg_tx across sk_stream_wait_memory(), which drops and reacquires the socket lock. Its error path tries to decide whether msg_tx names the local temporary message by comparing it with the current value of psock->cork. This comparison is unsafe when two threads send on the same socket: Thread A Thread B msg_tx = psock->cork sk_msg_alloc() fails sk_stream_wait_memory() releases the socket lock acquires the socket lock completes the cork psock->cork = NULL frees the cork reacquires the socket lock msg_tx != psock->cork sk_msg_free(msg_tx) The stale cork is therefore mistaken for the local temporary message and freed again. KASAN reported: BUG: KASAN: slab-use-after-free in sk_msg_free+0x49/0x50 Read of size 4 at addr ffff88810c908800 by task poc/90 Call Trace: sk_msg_free+0x49/0x50 tcp_bpf_sendmsg+0x14f5/0x1cc0 __sys_sendto+0x32c/0x3a0 __x64_sys_sendto+0xdb/0x1b0 Allocated by task 89: __kasan_kmalloc+0x8f/0xa0 tcp_bpf_sendmsg+0x16b3/0x1cc0 Freed by task 91: __kasan_slab_free+0x43/0x70 kfree+0x131/0x3c0 tcp_bpf_sendmsg+0xec3/0x1cc0 msg_tx can only name the stack-local tmp or the shared cork. Check for tmp directly so a changed psock->cork cannot turn a shared message into an apparent local one.",
    "evidence": "osv:CVE-2026-68284",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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    "severity": "high",
    "structured": {
      "id": "CVE-2026-68284",
      "aliases": [
        "CVE-2026-68284"
      ],
      "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": "2026-10-28T02:30:39.820776652Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0688e6fe599d2d39147ae9ece97944c6e1815ebf",
        "https://git.kernel.org/stable/c/2d66a033864e27ab8d5e44cb36f31d9d2413bee4",
        "https://git.kernel.org/stable/c/54be47e7cbb936429c3bbdfc526ea943954aaf80",
        "https://git.kernel.org/stable/c/752b1159ed5d0c48fe169a3721b96660a9822aa1",
        "https://git.kernel.org/stable/c/786d690257ec7a0c839f8710456e444ce3f1348b",
        "https://git.kernel.org/stable/c/b2bcbeabfd843d47468fa095b1bd08ddb90cf616",
        "https://git.kernel.org/stable/c/cde4d6bcd9b73073c66498f6723c7b364c4dbc18",
        "https://git.kernel.org/stable/c/ee762f684eefa59de34d9ed93cab08336e834f47",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68284.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-68284",
        "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/2026/68xxx/CVE-2026-68284.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-68284",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 507318,
  "published_at": "2026-08-10T12:02:16.572+00:00"
}