net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()

{
  "id": "fe1ad8f8de0e07c8e14de101604232bb2aa71fe7c4e250a46cdabc913bd3a7ec",
  "url": "https://osv.dev/vulnerability/CVE-2026-80981",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link() smc_llc_srv_add_link() keeps add_llc pointing into the queue entry: add_llc = &qentry->msg.add_link; smc_llc.c:1482 ... smc_llc_save_add_link_info(link_new, add_llc); smc_llc.c:1494 smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); smc_llc.c:1495 ... u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ? (u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc; smc_llc.c:1504 smc_llc_save_add_link_rkeys(link, link_new, llc_msg); smc_llc.c:1506 smc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared v2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is already freed. Before the Fixes: commit that branch always used lgr->wr_rx_buf_v2 and add_llc was not used after the free. Reproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot and a link forced to max_recv_sge == 1: the entry is freed and read by the same call, and the freeing frame is smc_llc_srv_add_link() itself. [ 2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11 [ 2.523789] [ 2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy) [ 2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 2.523866] Workqueue: smc_hs_wq smc_listen_wo",
    "evidence": "osv:CVE-2026-80981",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.50",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-80981",
      "aliases": [
        "CVE-2026-80981"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "c52a998a223e7e84333306996edec096178d1e95"
                },
                {
                  "fixed": "adef84cc85d449ac28d2b4b4c49cf19619c56e27"
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                {
                  "fixed": "a42a459ef0e54cb0c4b3e43e21cb0e658e664f64"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80981.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.14.0"
                },
                {
                  "fixed": "6.18.50"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.4"
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              ]
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80981.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.153631660Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/a42a459ef0e54cb0c4b3e43e21cb0e658e664f64",
        "https://git.kernel.org/stable/c/adef84cc85d449ac28d2b4b4c49cf19619c56e27",
        "https://git.kernel.org/stable/c/c52a998a223e7e84333306996edec096178d1e95",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80981.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-80981",
        "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/2026/80xxx/CVE-2026-80981.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-80981",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517614,
  "published_at": "2026-09-11T19:42:41.543+00:00"
}