Skip to content
Heist/ feed
Back to feed
UnratedFix available

RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency Commit 51976c6cd786 ("RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages") introduced disassociation_lock to protect new mmap registrations against uverbs_user_mmap_disassociate(), but created an ABBA deadlock: Thread A (mmap / fork): mmap_lock -> disassociation_lock Thread B (disassociate): disassociation_lock -> mmap_lock Fix by removing disassociation_lock entirely and using the pre-existing hw_destroy_rwsem instead. hw_destroy_rwsem already provides the same protection: rdma_umap_open() and ib_uverbs_mmap() both use down_read_trylock() before registering a new VMA, so holding hw_destroy_rwsem in uverbs_user_mmap_disassociate() is sufficient to block new registrations. trylock is used in both mmap paths (not blocking down_read) because mmap_lock is already held on entry, and uverbs_user_mmap_disassociate() acquires mmap_lock internally — a blocking read would recreate the same deadlock. The only caller that was not taking hw_destroy_rwsem for write was rdma_user_mmap_disassociate(). Fix it to take the rwsem per-ufile while iterating under lists_mutex. This is safe because ib_uverbs_close() releases hw_destroy_rwsem entirely before acquiring lists_mutex, so the two locks are never held simultaneously. lockdep warning: [ 776.654252] ====================================================== [ 776.655214] WARNING: possible

Products
Kernel
Affected versions
Not specified
Fixed versions
7.2.8
CVEs
CVE-2026-98431
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 11:32 UTC · Revision 1

Source evidence

RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency

core-osv · Original source

Published 14 Oct 2026, 13:27 UTC

In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency Commit 51976c6cd786 ("RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages") introduced disassociation_lock to protect new mmap registrations against uverbs_user_mmap_disassociate(), but created an ABBA deadlock: Thread A (mmap / fork): mmap_lock -> disassociation_lock Thread B (disassociate): disassociation_lock -> mmap_lock Fix by removing disassociation_lock entirely and using the pre-existing hw_destroy_rwsem instead. hw_destroy_rwsem already provides the same protection: rdma_umap_open() and ib_uverbs_mmap() both use down_read_trylock() before registering a new VMA, so holding hw_destroy_rwsem in uverbs_user_mmap_disassociate() is sufficient to block new registrations. trylock is used in both mmap paths (not blocking down_read) because mmap_lock is already held on entry, and uverbs_user_mmap_disassociate() acquires mmap_lock internally — a blocking read would recreate the same deadlock. The only caller that was not taking hw_destroy_rwsem for write was rdma_user_mmap_disassociate(). Fix it to take the rwsem per-ufile while iterating under lists_mutex. This is safe because ib_uverbs_close() releases hw_destroy_rwsem entirely before acquiring lists_mutex, so the two locks are never held simultaneously. lockdep warning: [ 776.654252] ====================================================== [ 776.655214] WARNING: possible

osv:CVE-2026-98431

Kernel

Fixed versions: 7.2.8

Complete source record
{
  "id": "022a1098f71555a0605578ee285728ad5ec41364e1947f335236cb73c98d8cb4",
  "url": "https://osv.dev/vulnerability/CVE-2026-98431",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency Commit 51976c6cd786 (\"RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages\") introduced disassociation_lock to protect new mmap registrations against uverbs_user_mmap_disassociate(), but created an ABBA deadlock: Thread A (mmap / fork): mmap_lock -> disassociation_lock Thread B (disassociate): disassociation_lock -> mmap_lock Fix by removing disassociation_lock entirely and using the pre-existing hw_destroy_rwsem instead. hw_destroy_rwsem already provides the same protection: rdma_umap_open() and ib_uverbs_mmap() both use down_read_trylock() before registering a new VMA, so holding hw_destroy_rwsem in uverbs_user_mmap_disassociate() is sufficient to block new registrations. trylock is used in both mmap paths (not blocking down_read) because mmap_lock is already held on entry, and uverbs_user_mmap_disassociate() acquires mmap_lock internally — a blocking read would recreate the same deadlock. The only caller that was not taking hw_destroy_rwsem for write was rdma_user_mmap_disassociate(). Fix it to take the rwsem per-ufile while iterating under lists_mutex. This is safe because ib_uverbs_close() releases hw_destroy_rwsem entirely before acquiring lists_mutex, so the two locks are never held simultaneously. lockdep warning: [ 776.654252] ====================================================== [ 776.655214] WARNING: possible",
    "evidence": "osv:CVE-2026-98431",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98431",
      "aliases": [
        "CVE-2026-98431"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "51976c6cd786151b6a1bdf8b8b3334beac0ba99c"
                },
                {
                  "fixed": "426f54f20b79c5b164a0472ad3f6ba36afcd08c6"
                },
                {
                  "fixed": "a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6.11.11"
                },
                {
                  "fixed": "6.12"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6.12.2"
                },
                {
                  "fixed": "6.13"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0598914a950ddfa694f410e482453cdbb9265515"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "86092a4e46d161d24f8106df082e24b8efe87382"
                }
              ]
            }
          ],
          "versions": [
            "v6.11.11",
            "v6.12.114",
            "v6.12.113",
            "v6.12.112",
            "v6.12.111",
            "v6.12.110",
            "v6.12.109",
            "v6.12.108",
            "v6.12.107",
            "v6.12.106",
            "v6.12.105",
            "v6.12.104",
            "v6.12.103",
            "v6.12.102",
            "v6.12.101",
            "v6.12.100",
            "v6.12.99",
            "v6.12.98",
            "v6.12.97",
            "v6.12.96",
            "v6.12.95",
            "v6.12.94",
            "v6.12.93",
            "v6.12.92",
            "v6.12.91",
            "v6.12.90",
            "v6.12.89",
            "v6.12.88",
            "v6.12.87",
            "v6.12.86",
            "v6.12.85",
            "v6.12.84",
            "v6.12.83",
            "v6.12.82",
            "v6.12.81",
            "v6.12.80",
            "v6.12.79",
            "v6.12.78",
            "v6.12.77",
            "v6.12.76",
            "v6.12.75",
            "v6.12.74",
            "v6.12.73",
            "v6.12.72",
            "v6.12.71",
            "v6.12.70",
            "v6.12.69",
            "v6.12.68",
            "v6.12.67",
            "v6.12.66",
            "v6.12.65",
            "v6.12.64",
            "v6.12.63",
            "v6.12.62",
            "v6.12.61",
            "v6.12.60",
            "v6.12.59",
            "v6.12.58",
            "v6.12.57",
            "v6.12.56",
            "v6.12.55",
            "v6.12.54",
            "v6.12.53",
            "v6.12.52",
            "v6.12.51",
            "v6.12.50",
            "v6.12.49",
            "v6.12.48",
            "v6.12.47",
            "v6.12.46",
            "v6.12.45",
            "v6.12.44",
            "v6.12.43",
            "v6.12.42",
            "v6.12.41",
            "v6.12.40",
            "v6.12.39",
            "v6.12.38",
            "v6.12.37",
            "v6.12.36",
            "v6.12.35",
            "v6.12.34",
            "v6.12.33",
            "v6.12.32",
            "v6.12.31",
            "v6.12.30",
            "v6.12.29",
            "v6.12.28",
            "v6.12.27",
            "v6.12.26",
            "v6.12.25",
            "v6.12.24",
            "v6.12.23",
            "v6.12.22",
            "v6.12.21",
            "v6.12.20",
            "v6.12.19",
            "v6.12.18",
            "v6.12.17",
            "v6.12.16",
            "v6.12.15",
            "v6.12.14",
            "v6.12.13",
            "v6.12.12",
            "v6.12.11",
            "v6.12.10",
            "v6.12.9",
            "v6.12.8",
            "v6.12.7",
            "v6.12.6",
            "v6.12.5",
            "v6.12.4",
            "v6.12.3",
            "v6.12.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98431.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "7.2.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98431.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.237690766Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/426f54f20b79c5b164a0472ad3f6ba36afcd08c6",
        "https://git.kernel.org/stable/c/a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98431.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98431",
        "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/2026/98xxx/CVE-2026-98431.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98431",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 494984,
  "published_at": "2026-10-14T13:27:56.162+00:00"
}