CVE-2026-43271 (GCVE-0-2026-43271)
Vulnerability from cvelistv5
Published
2026-05-06 11:28
Modified
2026-05-11 22:21
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: md-cluster: fix NULL pointer dereference in process_metadata_update The function process_metadata_update() blindly dereferences the 'thread' pointer (acquired via rcu_dereference_protected) within the wait_event() macro. While the code comment states "daemon thread must exist", there is a valid race condition window during the MD array startup sequence (md_run): 1. bitmap_load() is called, which invokes md_cluster_ops->join(). 2. join() starts the "cluster_recv" thread (recv_daemon). 3. At this point, recv_daemon is active and processing messages. 4. However, mddev->thread (the main MD thread) is not initialized until later in md_run(). If a METADATA_UPDATED message is received from a remote node during this specific window, process_metadata_update() will be called while mddev->thread is still NULL, leading to a kernel panic. To fix this, we must validate the 'thread' pointer. If it is NULL, we release the held lock (no_new_dev_lockres) and return early, safely ignoring the update request as the array is not yet fully ready to process it.
References
Impacted products
Vendor Product Version
Linux Linux Version: 0ba959774e93911caff596de6391f085fb640ac4
Version: 0ba959774e93911caff596de6391f085fb640ac4
Version: 0ba959774e93911caff596de6391f085fb640ac4
Version: 0ba959774e93911caff596de6391f085fb640ac4
Version: 0ba959774e93911caff596de6391f085fb640ac4
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/md-cluster.c"
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              "version": "7.0",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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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\nmd-cluster: fix NULL pointer dereference in process_metadata_update\n\nThe function process_metadata_update() blindly dereferences the \u0027thread\u0027\npointer (acquired via rcu_dereference_protected) within the wait_event()\nmacro.\n\nWhile the code comment states \"daemon thread must exist\", there is a valid\nrace condition window during the MD array startup sequence (md_run):\n\n1. bitmap_load() is called, which invokes md_cluster_ops-\u003ejoin().\n2. join() starts the \"cluster_recv\" thread (recv_daemon).\n3. At this point, recv_daemon is active and processing messages.\n4. However, mddev-\u003ethread (the main MD thread) is not initialized until\n   later in md_run().\n\nIf a METADATA_UPDATED message is received from a remote node during this\nspecific window, process_metadata_update() will be called while\nmddev-\u003ethread is still NULL, leading to a kernel panic.\n\nTo fix this, we must validate the \u0027thread\u0027 pointer. If it is NULL, we\nrelease the held lock (no_new_dev_lockres) and return early, safely\nignoring the update request as the array is not yet fully ready to\nprocess it."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:21:19.841Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1"
        },
        {
          "url": "https://git.kernel.org/stable/c/dec123825c1ed74d98fd5fc7571a851dea4f46ff"
        },
        {
          "url": "https://git.kernel.org/stable/c/721599e837d3f4c0e6cc14da059612c017b6d3ec"
        },
        {
          "url": "https://git.kernel.org/stable/c/dceb5a843910004cb118148e267036104fc3ee43"
        },
        {
          "url": "https://git.kernel.org/stable/c/f150e753cb8dd756085f46e86f2c35ce472e0a3c"
        }
      ],
      "title": "md-cluster: fix NULL pointer dereference in process_metadata_update",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43271",
    "datePublished": "2026-05-06T11:28:55.507Z",
    "dateReserved": "2026-05-01T14:12:55.998Z",
    "dateUpdated": "2026-05-11T22:21:19.841Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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