CVE-2026-90400 (GCVE-0-2026-90400)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:09 – Updated: 2026-10-19 09:03
VLAI
Title
md: recheck spare changes before starting sync
Summary
In the Linux kernel, the following vulnerability has been resolved: md: recheck spare changes before starting sync remove_spares() and remove_and_add_spares() modify the array's rdev configuration. These operations are only safe after the array has been suspended. md_start_sync() checks whether spare configuration changes are needed before taking reconfig_mutex. However, the rdev state can change before the mutex is acquired, so the initial check can become stale. In that case, md_choose_sync_action() may remove or replace rdevs while normal I/O is still accessing them. The race can occur as follows: raid10d Worker Normal IO ____________ _______________________ ______________________ raid10_write_request() wait_blocked_dev() set Blocked set Faulty Skip Faulty rdev rrdev->nr_pending++ .repl_bio = bio removeable_rdev = false . array not suspended . lock mddev goto err_handle lock mddev (wait) . update sb . clear Blocked . . unlock mddev . lock mddev (acquires) remove_spares() removeable_rdev = true raid10_remove_disk() rdev = replacement replacement = NULL rdev_dec_pending(NULL) unlock mddev (NULL)->nr_pending-- In this case, rdev_dec_pending() is called with a NULL pointer, resulting in a NULL pointer dereference when attempting to decrement nr_pending. Fix this by suspending the array when spare configuration changes are needed, including for non-read-write arrays, and checking again after taking reconfig_mutex. If the array was not already suspended and a change is now needed, release the mutex, suspend the array, and reacquire the mutex before continuing.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: bc08041b32abe6c9824f78735bac22018eabfc06 , < c3777d16bc3335c0ac4bdad0551c80d38c5d94cc (git)
Affected: bc08041b32abe6c9824f78735bac22018eabfc06 , < e5ac7ab78467b064f1da8b0f3042a63595fafcfd (git)
Affected: bc08041b32abe6c9824f78735bac22018eabfc06 , < 81b39df5d701976cf20e52f33106c1fc1603b4cb (git)
Affected: bc08041b32abe6c9824f78735bac22018eabfc06 , < c7d34d17ea43ebc86b45d439ebb435e11ca44bca (git)
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Linux Linux Affected: 6.7
Unaffected: 0 , < 6.7 (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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              "versionType": "semver"
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          "lang": "en",
          "value": "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\u0027s 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."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:03:04.317Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/c7d34d17ea43ebc86b45d439ebb435e11ca44bca"
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    "cveId": "CVE-2026-90400",
    "datePublished": "2026-09-17T16:09:30.915Z",
    "dateReserved": "2026-09-11T19:38:34.811Z",
    "dateUpdated": "2026-10-19T09:03:04.317Z",
    "state": "PUBLISHED"
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          {
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            "value": "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\u0027s 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",
        "lastModified": "2026-10-19T09:19:34.123",
        "metrics": {},
        "published": "2026-09-17T17:17:39.753",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
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      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-06T01:42:49+00:00",
      "cve": "CVE-2026-90400",
      "id": "CVE-2026-90400",
      "initial_release_date": "2026-09-17T00:00:00+00:00",
      "product_status:known_affected": "124",
      "product_status:known_not_affected": "79",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: md: recheck spare changes before starting sync",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90400.json",
      "version": "3"
    }
  }
}



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