CVE-2026-80784 (GCVE-0-2026-80784)
Vulnerability from cvelistv5
Published
2026-09-04 15:12
Modified
2026-09-04 15:12
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: fix memory leak from alloc-during-teardown race mptcp_pm_destroy() empties msk->pm.anno_list and msk->pm.userspace_pm_local_addr_list under msk->pm.lock during socket teardown, dropping the lock between the two. A concurrent userspace PM genl ANNOUNCE on the same msk holds a sock reference via mptcp_token_get_sock() and, in mptcp_pm_nl_announce_doit(), calls mptcp_userspace_pm_append_new_local_addr() and mptcp_pm_announced_alloc(). Both take msk->pm.lock briefly to add to their respective lists. Because the genl handler holds a sock reference, mptcp_pm_destroy() may run on the same msk via mptcp_disconnect(), which invokes mptcp_destroy_common() without dropping the sock refcount, before the handler completes. If the lock acquisitions interleave such that mptcp_pm_destroy() empties a list first, the later alloc adds its entry to a list head that nothing else iterates for this msk, and the entry leaks. kmemleak reports both mptcp_pm_add_addr objects (from mptcp_pm_announced_alloc()) and mptcp_pm_addr_entry objects (from mptcp_userspace_pm_append_new_local_addr()) under sustained concurrent ANNOUNCE + close load against the userspace PM. Add an MPTCP_PM_DESTROYING bit in msk->pm.status, set by mptcp_pm_destroy() under pm.lock before the lists are emptied and checked under pm.lock by the alloc paths. Either the alloc takes pm.lock first, in which case its entry is on the list when mptcp_pm_destroy() frees it; or mptcp_pm_destroy() takes pm.lock first, in which case the later alloc observes the bit and refuses. Found by an MPTCP protocol-flow harness extending BRF (arXiv:2305.08782).
References
Impacted products
Vendor Product Version
Linux Linux Version: 9ab4807c84a4aacfc9b4f79cc81254035e0ec361
Version: 9ab4807c84a4aacfc9b4f79cc81254035e0ec361
Version: 9ab4807c84a4aacfc9b4f79cc81254035e0ec361
Version: 9ab4807c84a4aacfc9b4f79cc81254035e0ec361
Version: 9ab4807c84a4aacfc9b4f79cc81254035e0ec361
Version: 9ab4807c84a4aacfc9b4f79cc81254035e0ec361
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/pm.c",
            "net/mptcp/pm_userspace.c",
            "net/mptcp/protocol.h"
          ],
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/pm.c",
            "net/mptcp/pm_userspace.c",
            "net/mptcp/protocol.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "versionType": "semver"
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              "version": "6.12.106",
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              "version": "7.1.11",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.187",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
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              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: fix memory leak from alloc-during-teardown race\n\nmptcp_pm_destroy() empties msk-\u003epm.anno_list and\nmsk-\u003epm.userspace_pm_local_addr_list under msk-\u003epm.lock during socket\nteardown, dropping the lock between the two.\n\nA concurrent userspace PM genl ANNOUNCE on the same msk holds a sock\nreference via mptcp_token_get_sock() and, in\nmptcp_pm_nl_announce_doit(), calls\nmptcp_userspace_pm_append_new_local_addr() and\nmptcp_pm_announced_alloc(). Both take msk-\u003epm.lock briefly to add to\ntheir respective lists. Because the genl handler holds a sock reference,\nmptcp_pm_destroy() may run on the same msk via mptcp_disconnect(), which\ninvokes mptcp_destroy_common() without dropping the sock refcount,\nbefore the handler completes.\n\nIf the lock acquisitions interleave such that mptcp_pm_destroy() empties\na list first, the later alloc adds its entry to a list head that nothing\nelse iterates for this msk, and the entry leaks. kmemleak reports both\nmptcp_pm_add_addr objects (from mptcp_pm_announced_alloc()) and\nmptcp_pm_addr_entry objects (from\nmptcp_userspace_pm_append_new_local_addr()) under sustained concurrent\nANNOUNCE + close load against the userspace PM.\n\nAdd an MPTCP_PM_DESTROYING bit in msk-\u003epm.status, set by\nmptcp_pm_destroy() under pm.lock before the lists are emptied and\nchecked under pm.lock by the alloc paths. Either the alloc takes pm.lock\nfirst, in which case its entry is on the list when mptcp_pm_destroy()\nfrees it; or mptcp_pm_destroy() takes pm.lock first, in which case the\nlater alloc observes the bit and refuses.\n\nFound by an MPTCP protocol-flow harness extending BRF (arXiv:2305.08782)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T15:12:56.125Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f48341830e4202db3fe884b819b2db6740f0537d"
        },
        {
          "url": "https://git.kernel.org/stable/c/bb32e9a6a9a9f99eeda16c4efe443400f3e43892"
        },
        {
          "url": "https://git.kernel.org/stable/c/b2a0b55bf613bd3e81ed26a847b0f6b8e6b7f804"
        },
        {
          "url": "https://git.kernel.org/stable/c/9fe5eebb664ecdba88f3fde18062d94b1d1c465f"
        },
        {
          "url": "https://git.kernel.org/stable/c/6c290915a03fc8228b473641025cf762b256dbd2"
        },
        {
          "url": "https://git.kernel.org/stable/c/efc33b5102ff859bacd390a5f30112d8e0c084c0"
        }
      ],
      "title": "mptcp: pm: fix memory leak from alloc-during-teardown race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80784",
    "datePublished": "2026-09-04T15:12:56.125Z",
    "dateReserved": "2026-08-26T14:34:25.792Z",
    "dateUpdated": "2026-09-04T15:12:56.125Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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