CVE-2026-92508 (GCVE-0-2026-92508)
Vulnerability from cvelistv5
Published
2026-09-17 16:10
Modified
2026-10-19 09:04
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: RDMA/core: Fix potential use after free in ib_free_cq() When accessing a CQ via the netlink path the only synchronization mechanism for the said CQ is rdma_restrack_get(). Currently, rdma_restrack_del() is invoked at the end of ib_free_cq(), which is too late, since by that point vendor-specific resources associated with the CQ might already be freed. This can leave a short window where the CQ remains accessible through restrack, leading to a potential use-after-free. Fix this by moving the rdma_restrack_del() call to be before the freeing of the vendor-specific resources ensuring that the CQ is removed from restrack before its internal resources are released. This guarantees that no new users hold references to a CQ that is in the process of destruction.
References
Impacted products
Vendor Product Version
Linux Linux Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 43d781b9fa562f0c6e50f62c870fbfeb9dc85213
Version: 7ac277a01f9017fcde4f3f81670c995992945433
Version: 093f87dda065e0f618dd577985eccbe85efb9b54
Version: 5.8.17   ≤
Version: 5.9.2   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/core/cq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "5.8.17",
              "versionType": "semver"
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              "status": "affected",
              "version": "5.9.2",
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/core/cq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.10"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.221",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "6.1.188",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "6.12.110",
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.8.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.9.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/core: Fix potential use after free in ib_free_cq()\n\nWhen accessing a CQ via the netlink path the only synchronization\nmechanism for the said CQ is rdma_restrack_get().\nCurrently, rdma_restrack_del() is invoked at the end of\nib_free_cq(), which is too late, since by that point\nvendor-specific resources associated with the CQ might already be\nfreed. This can leave a short window where the CQ remains accessible\nthrough restrack, leading to a potential use-after-free.\n\nFix this by moving the rdma_restrack_del() call to be before the freeing\nof the vendor-specific resources ensuring that the CQ is removed from\nrestrack before its internal resources are released.\nThis guarantees that no new users hold references to a CQ that is in\nthe process of destruction."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The use side is a local NETLINK_RDMA RDMA_NLDEV_CMD_RES_CQ_GET handled by nldev_res_get_cq_doit/dumpit \u2192 res_get_common_doit/dumpit, which rdma_restrack_get()s a CQ still in the xarray while ib_free_cq() is destroying it. No remote protocol message carries the lookup; the accessor is a netlink syscall.\nAC:L - The attacker drives both sides of the race: one thread loops RDMA_NLDEV_CMD_RES_CQ_GET while another opens and drops kernel-ULP RDMA connections so ib_free_cq() runs (svc_rdma_free() or smbdirect_connection_destroy_qp()). That is not a victim-only timing window.\nPR:L - RDMA_NLDEV_CMD_RES_CQ_GET in nldev_cb_table has no RDMA_NL_ADMIN_PERM, and NETLINK_RDMA is created with NL_CFG_F_NONROOT_RECV, so an ordinary user can dump CQs. Kernel CQ teardown via /dev/infiniband/rdma_cm (ucma_misc mode 0666) also does not need init-namespace root.\nUI:N - The attacker sends the RDMA_NLDEV_CMD_RES_CQ_GET dumps and tears down their own kernel-ULP RDMA connections; no other user must mount a volume, open a device, or confirm an action.\nS:U - The UAF is of host-kernel CQ vendor state (ib_cq buffers freed in destroy_cq/pre_destroy_cq) and stays inside the same kernel authority; it is not a VM escape, IOMMU bypass, or guest-to-host boundary cross.\nC:H - c4iw_destroy_cq() \u2192 destroy_cq() dma_free_coherent()s chp-\u003ecq.queue before rdma_restrack_del(); a concurrent fill_res_cq_entry \u2192 c4iw_fill_res_cq_entry still indexes that queue, so the UAF reads freed CQ-ring memory.\nI:H - The same ib_free_cq() window lets fill_res_cq_entry use vendor CQ resources already released by destroy_cq/pre_destroy_cq (Chelsio queue pages; mlx5 destroy_cq_kernel CQ buffers). Reclaiming that heap object yields an arbitrary write and control-flow hijack.\nA:H - fill_res_cq_entry walking a CQ whose queue or HW context was already freed in ib_free_cq() (after pre_destroy_cq/destroy_cq, before rdma_restrack_del) oopses or panics the kernel even without a crafted exploit."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:04:14.344Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a804b162f9bc2b38b2ed1b4752eea9faadb1645b"
        },
        {
          "url": "https://git.kernel.org/stable/c/91f8a17a22ab615a03743120e19935e731f28fb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/76f2cb4f721815c3b6262a6dc2151de88646924c"
        },
        {
          "url": "https://git.kernel.org/stable/c/b8dcca427096fc9c50f1b376847fea72bc842d31"
        },
        {
          "url": "https://git.kernel.org/stable/c/9abea37942534eeb049335476178696b654b000c"
        },
        {
          "url": "https://git.kernel.org/stable/c/43403fe45379c64fa6276e5a8ede44493e5d2d3d"
        },
        {
          "url": "https://git.kernel.org/stable/c/29dc2f8e1c97372c2871a70088707933515fbd5b"
        }
      ],
      "title": "RDMA/core: Fix potential use after free in ib_free_cq()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-92508",
    "datePublished": "2026-09-17T16:10:19.443Z",
    "dateReserved": "2026-09-16T12:21:13.872Z",
    "dateUpdated": "2026-10-19T09:04:14.344Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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