CVE-2026-93224 (GCVE-0-2026-93224)
Vulnerability from cvelistv5
Published
2026-09-24 15:21
Modified
2026-10-19 09:07
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: svcrdma: Fix unmatched rn_unregister on failed accept When svc_rdma_accept() takes the errout path before rpcrdma_rn_register() has succeeded, the existing cleanup block calls rpcrdma_rn_unregister(dev, &newxprt->sc_rn) unconditionally. svcxprt_rdma is kzalloc'd, so on that path sc_rn.rn_index is 0 and sc_rn.rn_done is NULL; the unregister therefore xa_erase()s another caller's slot 0 and performs an unmatched kref_put() on the rpcrdma_device's rd_kref. The same errout also brackets the cleanup with svc_xprt_get()/ svc_xprt_put() around the kref_init() birth reference. The kref goes 1 -> 2 -> 1 and never reaches 0, so the svcxprt_rdma (and the net/ns_tracker it pinned) is leaked on every failed accept. rpcrdma_rn_register() writes rn->rn_done last, only after xa_alloc() and kref_get() have both succeeded, so rn_done == NULL is a natural "never registered" sentinel. Guard rpcrdma_rn_unregister() with an early return when rn_done is NULL, and clear rn_done before the matching xa_erase() so a repeated unregister is also a no-op. With that guard in place, the accept errout drops the kref_init() birth reference via svc_xprt_put(), which dispatches svc_rdma_free(). Teardown of sc_qp, sc_sq_cq, sc_rq_cq, and sc_pd runs under existing IS_ERR/NULL guards in svc_rdma_free(); sc_rn is covered by the new rn_done sentinel; sc_cm_id is non-NULL on every errout path because svc_rdma_accept() dereferences it above the first goto errout. svc_xprt_free() drops the module reference associated with the freed transport, and svc_handle_xprt() drops its pre-acquired reference when ->xpo_accept() returns NULL. Take a replacement module reference before svc_xprt_put() so the two module_put()s remain balanced. The rn_done guard also covers svc_rdma_free()'s non-listener call to rpcrdma_rn_unregister() for transports whose register attempt failed or never ran.
References
Impacted products
Vendor Product Version
Linux Linux Version: cb3cba0ec372fa7c5f5f5c12990bef02e458ab86
Version: 8ac6fcae5dc0e801f1c82a83f5ae2c0a4db19932
Version: 8ac6fcae5dc0e801f1c82a83f5ae2c0a4db19932
Version: 8ac6fcae5dc0e801f1c82a83f5ae2c0a4db19932
Version: d310955106c358c8e1ea682defd8e21af44a6cba
Version: 6.12.35   ≤
Version: 6.15.4   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sunrpc/xprtrdma/ib_client.c",
            "net/sunrpc/xprtrdma/svc_rdma_transport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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              "versionType": "git"
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            {
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              "status": "affected",
              "version": "8ac6fcae5dc0e801f1c82a83f5ae2c0a4db19932",
              "versionType": "git"
            },
            {
              "lessThan": "26190394c64c9429481fc88a4738f70bb92fb352",
              "status": "affected",
              "version": "8ac6fcae5dc0e801f1c82a83f5ae2c0a4db19932",
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            },
            {
              "lessThan": "6.12.109",
              "status": "affected",
              "version": "6.12.35",
              "versionType": "semver"
            },
            {
              "lessThan": "6.16",
              "status": "affected",
              "version": "6.15.4",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sunrpc/xprtrdma/ib_client.c",
            "net/sunrpc/xprtrdma/svc_rdma_transport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "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": "6.12.109",
                  "versionStartIncluding": "6.12.35",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.15.4",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Fix unmatched rn_unregister on failed accept\n\nWhen svc_rdma_accept() takes the errout path before\nrpcrdma_rn_register() has succeeded, the existing cleanup block\ncalls rpcrdma_rn_unregister(dev, \u0026newxprt-\u003esc_rn) unconditionally.\nsvcxprt_rdma is kzalloc\u0027d, so on that path sc_rn.rn_index is 0 and\nsc_rn.rn_done is NULL; the unregister therefore xa_erase()s another\ncaller\u0027s slot 0 and performs an unmatched kref_put() on the\nrpcrdma_device\u0027s rd_kref.\n\nThe same errout also brackets the cleanup with svc_xprt_get()/\nsvc_xprt_put() around the kref_init() birth reference. The kref\ngoes 1 -\u003e 2 -\u003e 1 and never reaches 0, so the svcxprt_rdma (and the\nnet/ns_tracker it pinned) is leaked on every failed accept.\n\nrpcrdma_rn_register() writes rn-\u003ern_done last, only after xa_alloc()\nand kref_get() have both succeeded, so rn_done == NULL is a natural\n\"never registered\" sentinel. Guard rpcrdma_rn_unregister() with an\nearly return when rn_done is NULL, and clear rn_done before the\nmatching xa_erase() so a repeated unregister is also a no-op.\n\nWith that guard in place, the accept errout drops the kref_init()\nbirth reference via svc_xprt_put(), which dispatches svc_rdma_free().\nTeardown of sc_qp, sc_sq_cq, sc_rq_cq, and sc_pd runs under existing\nIS_ERR/NULL guards in svc_rdma_free(); sc_rn is covered by the new\nrn_done sentinel; sc_cm_id is non-NULL on every errout path because\nsvc_rdma_accept() dereferences it above the first goto errout.\n\nsvc_xprt_free() drops the module reference associated with the freed\ntransport, and svc_handle_xprt() drops its pre-acquired reference\nwhen -\u003expo_accept() returns NULL. Take a replacement module reference\nbefore svc_xprt_put() so the two module_put()s remain balanced.\n\nThe rn_done guard also covers svc_rdma_free()\u0027s non-listener call\nto rpcrdma_rn_unregister() for transports whose register attempt\nfailed or never ran."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - svcrdma is nfsd\u0027s RPC-over-RDMA server; a remote peer over routable RoCEv2 or iWARP sends RDMA_CM CONNECT_REQUEST to svc_rdma_listen_handler/handle_connect_req, which queues newxprt so svc_handle_xprt calls svc_rdma_accept, whose errout invokes the unguarded rpcrdma_rn_unregister.\nAC:H - The unmatched rpcrdma_rn_unregister in svc_rdma_accept errout runs only if rpcrdma_rn_register failed (RPCRDMA_RD_F_REMOVING or xa_alloc ENOMEM); a remote peer can send CONNECT_REQUEST but cannot unbind the IB device or force that GFP_KERNEL failure, and the UAF needs that in-progress rpcrdma_remove_one.\nPR:N - RDMA_CM CONNECT_REQUEST handling in svc_rdma_listen_handler, handle_connect_req, and svc_rdma_accept runs before svc_process/svc_authenticate; the CM handshake has no RPC or NFS credential check, so an unauthenticated peer can drive the failed-accept errout.\nUI:N - Sending CONNECT_REQUEST to an NFS/RDMA listener already created via nfsd portlist is enough to reach svc_rdma_accept; racing ib_unregister_device is attack complexity, not a victim mount, click, or other user action.\nS:U - The wrong-slot rd_xa erase, unmatched rd_kref put, and any use-after-free of rpcrdma_device or the victim svcxprt_rdma\u0027s IB objects stay in the host kernel that runs nfsd/svcrdma; this is not a VM, IOMMU, or sandbox escape.\nC:H - On pre-register errout, rpcrdma_rn_unregister xa_erase()s rd_xa index 0 (kzalloc\u0027d sc_rn.rn_index) of another transport and kref_put()s rd_kref while rpcrdma_remove_one may walk the same xarray; that transport\u0027s sc_cm_id/QP and the kfree\u0027d rpcrdma_device become reclaimable slab UAF reads.\nI:H - The extra kref_put can make rpcrdma_remove_one\u0027s refcount_dec_and_test skip wait_for_completion and kfree(rd) while a live transport later xa_erase/kref_put or QP/CM ops write through the freed rpcrdma_device or un-notified IB objects, a UAF write primitive.\nA:H - A concurrent rpcrdma_remove_one that proceeds after the unmatched kref_put, or later QP/CM use of a transport whose slot-0 notification was erased, dereferences freed IB or rpcrdma_device memory and oopses or panics; any UAF is availability High per kernel CVSS guidance."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:07:35.798Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0335800071a6dfdf7d21d729b5e7d8fa98936211"
        },
        {
          "url": "https://git.kernel.org/stable/c/5aabe070c00e5bdf4ab150fb5f72ad5f266d6241"
        },
        {
          "url": "https://git.kernel.org/stable/c/45a444a17240f4fa2235f0dfd4a96fc80f1eb2c2"
        },
        {
          "url": "https://git.kernel.org/stable/c/26190394c64c9429481fc88a4738f70bb92fb352"
        }
      ],
      "title": "svcrdma: Fix unmatched rn_unregister on failed accept",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93224",
    "datePublished": "2026-09-24T15:21:10.542Z",
    "dateReserved": "2026-09-17T16:02:15.094Z",
    "dateUpdated": "2026-10-19T09:07:35.798Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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