{"cve":"CVE-2026-90400","nvd":{"published":"2026-09-17T17:17:39.753","modified":"2026-10-19T09:19:34.123","status":"Received","description":"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->nr_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)->nr_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.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/81b39df5d701976cf20e52f33106c1fc1603b4cb","https://git.kernel.org/stable/c/c3777d16bc3335c0ac4bdad0551c80d38c5d94cc","https://git.kernel.org/stable/c/c7d34d17ea43ebc86b45d439ebb435e11ca44bca","https://git.kernel.org/stable/c/e5ac7ab78467b064f1da8b0f3042a63595fafcfd"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-90400","score":0.00168,"percentile":0.06014,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}