{"id":"CVE-2026-90400","title":"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","summary":"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 …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bc08041b32abe6c9824f78735bac22018eabfc06 < c3777d16bc3335c0ac4bdad0551c80d38c5d94cc","Linux >= bc08041b32abe6c9824f78735bac22018eabfc06 < e5ac7ab78467b064f1da8b0f3042a63595fafcfd","Linux >= bc08041b32abe6c9824f78735bac22018eabfc06 < 81b39df5d701976cf20e52f33106c1fc1603b4cb","Linux >= bc08041b32abe6c9824f78735bac22018eabfc06 < c7d34d17ea43ebc86b45d439ebb435e11ca44bca","Linux 6.7"],"published":"2026-09-17","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:17:39.753","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90400","references":[{"url":"https://git.kernel.org/stable/c/81b39df5d701976cf20e52f33106c1fc1603b4cb","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c3777d16bc3335c0ac4bdad0551c80d38c5d94cc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c7d34d17ea43ebc86b45d439ebb435e11ca44bca","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e5ac7ab78467b064f1da8b0f3042a63595fafcfd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-17T16:21:47.800Z","epss":0.00168,"epssPercentile":0.06486,"slug":"CVE-2026-90400","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}