CVE-2026-99166 (GCVE-0-2026-99166)
Vulnerability from cvelistv5
Published
2026-10-28 10:35
Modified
2026-10-28 10:35
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net: rds: fix uninitialized trans dereference in CM event handler rds_rdma_cm_event_handler_cmn() assigns trans only when the RDMA device is an InfiniBand CA (RDMA_NODE_IB_CA). On any other device type, e.g. an iWARP RNIC such as siw, trans stays uninitialized, but the event switch dereferences it: unconditionally in the RDMA_CM_EVENT_CONNECT_REQUEST case via trans->cm_handle_connect(), and (with a connection context) in the ROUTE_RESOLVED and ESTABLISHED cases. An RDS listener on an iWARP device therefore crashes the kernel as soon as a connect request arrives: with CONFIG_INIT_STACK_ALL_ZERO the wild load becomes a NULL dereference at offset 0xa0 (&trans->cm_handle_connect) in the iw_cm_wq workqueue. GCC masks the bug in default builds by folding the uninitialized load into &rds_ib_transport; Clang-built kernels take the real uninitialized path and oops. The active side can land on a non-IB device too: the id that rds_ib_conn_path_connect() creates is not restricted to a node type, so rdma_resolve_addr() binds it to whichever device serves the local address, and an iWARP RNIC on the same netdev qualifies. The crash there is different: resolving a route on an iWARP id never fills in cm_id->route.path_rec, and the ROUTE_RESOLVED case writes path_rec[0].sl before it calls into the transport. The iWARP transport was dropped long ago and IB is the only transport left, so make that explicit: initialize trans to &rds_ib_transport at declaration, drop the conditional assignment, reject a connect request that arrives on a non-IB device, and drop a connection whose address resolved to one instead of resolving a route on it. The rejection is limited to RDMA_CM_EVENT_CONNECT_REQUEST on purpose: a non-zero return from the handler makes rdma_cm destroy the id the event was delivered on, which is right for the request's freshly created id but would free a connection id that RDS still owns for any other event. On the active side the id stays ic->i_cm_id and the connection's shutdown destroys it, so that case returns 0. [achender: reject only on RDMA_CM_EVENT_CONNECT_REQUEST instead of bailing out for every event on a non-IB device, so that rdma_cm does not destroy connection ids RDS still tracks; drop a connection whose address resolved to a non-IB device before a route is resolved on it; changelog adjusted]
References
Impacted products
Vendor Product Version
Linux Linux Version: dcdede0406d30e14a6ed727dce69dfac0518371d
Version: dcdede0406d30e14a6ed727dce69dfac0518371d
Version: dcdede0406d30e14a6ed727dce69dfac0518371d
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/rds/rdma_transport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "5f23e4e3a31dacfd82a8f56be253adc0910ee84f",
              "status": "affected",
              "version": "dcdede0406d30e14a6ed727dce69dfac0518371d",
              "versionType": "git"
            },
            {
              "lessThan": "ca14c289ed9ffed6cc64290d039e923e5720a8bf",
              "status": "affected",
              "version": "dcdede0406d30e14a6ed727dce69dfac0518371d",
              "versionType": "git"
            },
            {
              "lessThan": "492ba6ac1b1ffb8a06ff52db0825c1af2cdb28c8",
              "status": "affected",
              "version": "dcdede0406d30e14a6ed727dce69dfac0518371d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/rds/rdma_transport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.6"
            },
            {
              "lessThan": "4.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.59",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.13",
              "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": "6.18.59",
                  "versionStartIncluding": "4.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.13",
                  "versionStartIncluding": "4.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: rds: fix uninitialized trans dereference in CM event handler\n\nrds_rdma_cm_event_handler_cmn() assigns trans only when the RDMA\ndevice is an InfiniBand CA (RDMA_NODE_IB_CA).  On any other device\ntype, e.g. an iWARP RNIC such as siw, trans stays uninitialized, but\nthe event switch dereferences it: unconditionally in the\nRDMA_CM_EVENT_CONNECT_REQUEST case via trans-\u003ecm_handle_connect(),\nand (with a connection context) in the ROUTE_RESOLVED and\nESTABLISHED cases.\n\nAn RDS listener on an iWARP device therefore crashes the kernel as\nsoon as a connect request arrives: with CONFIG_INIT_STACK_ALL_ZERO\nthe wild load becomes a NULL dereference at offset 0xa0\n(\u0026trans-\u003ecm_handle_connect) in the iw_cm_wq workqueue.\n\nGCC masks the bug in default builds by folding the uninitialized\nload into \u0026rds_ib_transport; Clang-built kernels take the real\nuninitialized path and oops.\n\nThe active side can land on a non-IB device too: the id that\nrds_ib_conn_path_connect() creates is not restricted to a node type,\nso rdma_resolve_addr() binds it to whichever device serves the local\naddress, and an iWARP RNIC on the same netdev qualifies.  The crash\nthere is different: resolving a route on an iWARP id never fills in\ncm_id-\u003eroute.path_rec, and the ROUTE_RESOLVED case writes\npath_rec[0].sl before it calls into the transport.\n\nThe iWARP transport was dropped long ago and IB is the only\ntransport left, so make that explicit: initialize trans to\n\u0026rds_ib_transport at declaration, drop the conditional assignment,\nreject a connect request that arrives on a non-IB device, and drop a\nconnection whose address resolved to one instead of resolving a\nroute on it.  The rejection is limited to RDMA_CM_EVENT_CONNECT_REQUEST\non purpose: a non-zero return from the handler makes rdma_cm destroy\nthe id the event was delivered on, which is right for the request\u0027s\nfreshly created id but would free a connection id that RDS still owns\nfor any other event.  On the active side the id stays ic-\u003ei_cm_id and\nthe connection\u0027s shutdown destroys it, so that case returns 0.\n\n[achender: reject only on RDMA_CM_EVENT_CONNECT_REQUEST instead of\n bailing out for every event on a non-IB device, so that rdma_cm does\n not destroy connection ids RDS still tracks; drop a connection whose\n address resolved to a non-IB device before a route is resolved on it;\n changelog adjusted]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:35:18.050Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/5f23e4e3a31dacfd82a8f56be253adc0910ee84f"
        },
        {
          "url": "https://git.kernel.org/stable/c/ca14c289ed9ffed6cc64290d039e923e5720a8bf"
        },
        {
          "url": "https://git.kernel.org/stable/c/492ba6ac1b1ffb8a06ff52db0825c1af2cdb28c8"
        }
      ],
      "title": "net: rds: fix uninitialized trans dereference in CM event handler",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99166",
    "datePublished": "2026-10-28T10:35:18.050Z",
    "dateReserved": "2026-09-25T10:25:14.398Z",
    "dateUpdated": "2026-10-28T10:35:18.050Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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