{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "bc08041b32abe6c9824f78735bac22018eabfc06"
            },
            {
              "fixed": "c3777d16bc3335c0ac4bdad0551c80d38c5d94cc"
            },
            {
              "fixed": "e5ac7ab78467b064f1da8b0f3042a63595fafcfd"
            },
            {
              "fixed": "81b39df5d701976cf20e52f33106c1fc1603b4cb"
            },
            {
              "fixed": "c7d34d17ea43ebc86b45d439ebb435e11ca44bca"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "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"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90400.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd: recheck spare changes before starting sync\n\nremove_spares() and remove_and_add_spares() modify the array's rdev\nconfiguration. These operations are only safe after the array has been\nsuspended.\n\nmd_start_sync() checks whether spare configuration changes are needed\nbefore taking reconfig_mutex. However, the rdev state can change before\nthe mutex is acquired, so the initial check can become stale. In that\ncase, md_choose_sync_action() may remove or replace rdevs while normal\nI/O is still accessing them.\n\nThe race can occur as follows:\n\nraid10d          Worker                      Normal IO\n____________     _______________________     ______________________\n\n                                             raid10_write_request()\n                                             wait_blocked_dev()\nset Blocked\nset Faulty\n                                             Skip Faulty rdev\n                                             rrdev-\u003enr_pending++\n                                             .repl_bio = bio\n                 removeable_rdev = false     .\n                 array not suspended         .\nlock mddev                                   goto err_handle\n                 lock mddev (wait)\n                 .\nupdate sb        .\nclear Blocked    .\n                 .\nunlock mddev     .\n                 lock mddev (acquires)\n                 remove_spares()\n                 removeable_rdev = true\n\n                 raid10_remove_disk()\n                 rdev = replacement\n                 replacement = NULL\n                                             rdev_dec_pending(NULL)\n                 unlock mddev                (NULL)-\u003enr_pending--\n\nIn this case, rdev_dec_pending() is called with a NULL pointer,\nresulting in a NULL pointer dereference when attempting to decrement\nnr_pending.\n\nFix this by suspending the array when spare configuration changes are\nneeded, including for non-read-write arrays, and checking again after\ntaking reconfig_mutex. If the array was not already suspended and a\nchange is now needed, release the mutex, suspend the array, and\nreacquire the mutex before continuing.",
  "id": "CVE-2026-90400",
  "modified": "2026-09-19T03:31:01.672712865Z",
  "published": "2026-09-17T16:09:30.915Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/81b39df5d701976cf20e52f33106c1fc1603b4cb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c3777d16bc3335c0ac4bdad0551c80d38c5d94cc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c7d34d17ea43ebc86b45d439ebb435e11ca44bca"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e5ac7ab78467b064f1da8b0f3042a63595fafcfd"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90400.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90400"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "md: recheck spare changes before starting sync"
}