FKIE_CVE-2026-64541

Vulnerability from fkie_nvd - Published: 2026-07-27 21:17 - Updated: 2026-11-03 18:15
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket smc_cdc_rx_handler() looks up the connection by token under the link group's conns_lock, drops the lock, and then dereferences conn and the smc_sock derived from it, ending in sock_hold(&smc->sk) inside smc_cdc_msg_recv(). No reference is held across the lock release. The only reference pinning the socket while the connection is discoverable in the link group is taken in smc_lgr_register_conn() (sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both under conns_lock. Once the handler drops conns_lock, a concurrent close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn() can drop that reference and free the smc_sock, so the handler's later sock_hold() runs on freed memory: WARNING: lib/refcount.c:25 at refcount_warn_saturate Workqueue: rxe_wq do_work refcount_warn_saturate (lib/refcount.c:25) smc_cdc_msg_recv (net/smc/smc_cdc.c:430) smc_cdc_rx_handler (net/smc/smc_cdc.c:502) smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445) tasklet_action_common (kernel/softirq.c:938) handle_softirqs (kernel/softirq.c:622) Kernel panic - not syncing: panic_on_warn set Only SMC-R is affected. The SMC-D receive tasklet is stopped by tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection is unregistered, so it cannot run concurrently with the free. Take the socket reference while still holding conns_lock, so the registration reference can no longer be the last one, and drop it once the handler is done.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1951bffbc6493ec34cff3956b29d4bc6606904a6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/472e9d7c0d5b03be3ff91ff941f57da822b031bc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/647b19e5cc145a2f1f685ae8ff3805a17356888c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8145b432136285e01091815b48ceb2dae261f262
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8de4f665d0febfb92803dece377791a563fc7041
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9d160b35cc34a2ba8229d07651468a7848325135
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ce5aa8084329351086894aa34d77e40301d5bd3d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/smc/smc_cdc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8de4f665d0febfb92803dece377791a563fc7041",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "8145b432136285e01091815b48ceb2dae261f262",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "1951bffbc6493ec34cff3956b29d4bc6606904a6",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "647b19e5cc145a2f1f685ae8ff3805a17356888c",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "472e9d7c0d5b03be3ff91ff941f57da822b031bc",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "ce5aa8084329351086894aa34d77e40301d5bd3d",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            },
            {
              "lessThan": "9d160b35cc34a2ba8229d07651468a7848325135",
              "status": "affected",
              "version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/smc/smc_cdc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.18"
            },
            {
              "lessThan": "4.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket\n\nsmc_cdc_rx_handler() looks up the connection by token under the link\ngroup\u0027s conns_lock, drops the lock, and then dereferences conn and the\nsmc_sock derived from it, ending in sock_hold(\u0026smc-\u003esk) inside\nsmc_cdc_msg_recv(). No reference is held across the lock release.\n\nThe only reference pinning the socket while the connection is\ndiscoverable in the link group is taken in smc_lgr_register_conn()\n(sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both\nunder conns_lock. Once the handler drops conns_lock, a concurrent\nclose() -\u003e smc_release() -\u003e smc_conn_free() -\u003e smc_lgr_unregister_conn()\ncan drop that reference and free the smc_sock, so the handler\u0027s later\nsock_hold() runs on freed memory:\n\n  WARNING: lib/refcount.c:25 at refcount_warn_saturate\n  Workqueue: rxe_wq do_work\n   refcount_warn_saturate (lib/refcount.c:25)\n   smc_cdc_msg_recv (net/smc/smc_cdc.c:430)\n   smc_cdc_rx_handler (net/smc/smc_cdc.c:502)\n   smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445)\n   tasklet_action_common (kernel/softirq.c:938)\n   handle_softirqs (kernel/softirq.c:622)\n  Kernel panic - not syncing: panic_on_warn set\n\nOnly SMC-R is affected. The SMC-D receive tasklet is stopped by\ntasklet_kill(\u0026conn-\u003erx_tsklet) in smc_conn_free() before the connection\nis unregistered, so it cannot run concurrently with the free.\n\nTake the socket reference while still holding conns_lock, so the\nregistration reference can no longer be the last one, and drop it once\nthe handler is done."
    }
  ],
  "id": "CVE-2026-64541",
  "lastModified": "2026-11-03T18:15:39.353",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-64541",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T15:42:09.809089Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-27T21:17:06.570",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1951bffbc6493ec34cff3956b29d4bc6606904a6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/472e9d7c0d5b03be3ff91ff941f57da822b031bc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/647b19e5cc145a2f1f685ae8ff3805a17356888c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8145b432136285e01091815b48ceb2dae261f262"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8de4f665d0febfb92803dece377791a563fc7041"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9d160b35cc34a2ba8229d07651468a7848325135"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ce5aa8084329351086894aa34d77e40301d5bd3d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}



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