null_blk: register configfs subsystem after creating default devices

{
  "id": "b319351745bf66565adeca09e8cdfa32c6bc8c2bb4c7322f3bedfbd6bb11400e",
  "url": "https://osv.dev/vulnerability/CVE-2026-90189",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "null_blk: register configfs subsystem after creating default devices",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: null_blk: register configfs subsystem after creating default devices In null_init(), configfs_register_subsystem() currently runs before register_blkdev(), so when null_blk is built as a module, a racing mkdir() + poweron from userspace can reach null_add_dev() while null_major is still 0. __add_disk() then hits WARN_ON(disk->minors) (major=0 with minors!=0) and fails: [root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0, [ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib [ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full) ...... [ 2366.547251] Call Trace: [ 2366.547575] [ 2366.547831] ? _raw_spin_lock+0x84/0xe0 [ 2366.548260] add_disk_fwnode+0x114/0x560 [ 2366.548739] null_add_dev+0x102d/0x1b80 [null_blk] [ 2366.549310] ? __pfx_null_add_dev+0x10/0x10 [null_blk] [ 2366.549906] ? mutex_lock+0xde/0x1c0 [ 2366.550361] ? __pfx_mutex_lock+0x10/0x10 [ 2366.550827] nullb_device_power_store+0x1e7/0x280 [null_blk] [ 2366.551499] ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk] [ 2366.552177] ? __kmalloc_cache_noprof+0x1f5/0x470 [ 2366.552748] ? configfs_write_iter+0x35c/0x4e0 [ 2366.553242] configfs_write_iter+0x286/0x4e0 [ 2366.553787] vfs_write+0x52d/0xd00 [ 2366.554169] ? __pfx_vfs_write+0x10/0x10 [ 2366.554679] ? __pfx___css_rstat_updated+0x10/0x10 [ 2366.555196] ? fdget_pos+0x1cf/0x4c0 [ 2366.55564",
    "evidence": "osv:CVE-2026-90189",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.188",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.157",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.110",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.52",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-90189",
      "aliases": [
        "CVE-2026-90189"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa"
                },
                {
                  "fixed": "2679b11e9256bd70a5ef41783bab6ad6c34a3db1"
                },
                {
                  "fixed": "dbcedbe4819ae21274ea77469e61e46a878b9943"
                },
                {
                  "fixed": "57debc907aef66319d244009d3370dcd97388d37"
                },
                {
                  "fixed": "d761be1b8f2bbabc41252deb79a426d3f0d4fa10"
                },
                {
                  "fixed": "cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36"
                },
                {
                  "fixed": "c9d293d6bb0575fcb1f3408129453187e2a28a4e"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90189.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.14.0"
                },
                {
                  "fixed": "6.1.188"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.157"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.110"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.52"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90189.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:44.283097473Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2679b11e9256bd70a5ef41783bab6ad6c34a3db1",
        "https://git.kernel.org/stable/c/57debc907aef66319d244009d3370dcd97388d37",
        "https://git.kernel.org/stable/c/c9d293d6bb0575fcb1f3408129453187e2a28a4e",
        "https://git.kernel.org/stable/c/cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36",
        "https://git.kernel.org/stable/c/d761be1b8f2bbabc41252deb79a426d3f0d4fa10",
        "https://git.kernel.org/stable/c/dbcedbe4819ae21274ea77469e61e46a878b9943",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90189.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-90189",
        "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/2026/90xxx/CVE-2026-90189.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-90189",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 512394,
  "published_at": "2026-09-17T16:07:10.992+00:00"
}