{"cve":"CVE-2026-90184","nvd":{"published":"2026-09-17T17:17:12.833","modified":"2026-10-19T09:19:08.387","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: serialize configfs attribute updates with device setup\n\nThe attribute store methods generated with NULLB_DEVICE_ATTR() refuse to\nchange the configuration of a live device by testing\nNULLB_DEV_FL_CONFIGURED, but that flag is only set by\nnullb_device_power_store() after null_add_dev() has returned, and the\nstore methods take no lock at all. configfs only serializes writes to\nthe same open file (buffer->mutex), so a write to any attribute can run\nconcurrently with null_add_dev() and change the device configuration\nwhile it is being used.\n\nnull_add_dev() reads the configuration several times, e.g. dev->zoned is\nread once to set up the queue limits and once to initialize the zone\nresources:\n\n  CPU0: echo 1 > nullb0/power         CPU1: echo 1 > nullb0/zoned\n  nullb_device_power_store()\n    mutex_lock(&lock)\n    null_add_dev()\n      if (dev->zoned) -> false\n        /* no BLK_FEAT_ZONED */       nullb_device_zoned_store()\n                                        test_bit(FL_CONFIGURED) -> 0\n                                        dev->zoned = true\n      blk_mq_alloc_disk()\n        /* queue is not zoned */\n      if (nullb->dev->zoned) -> true\n        null_register_zoned_dev()\n          blk_revalidate_disk_zones()\n\nblk_revalidate_disk_zones() is then called for a queue that does not\nhave BLK_FEAT_ZONED set, which triggers its WARN_ON_ONCE() and fails the\ndevice setup with -EIO:\n\n  WARNING: CPU: 2 PID: 322 at block/blk-zoned.c:2357 blk_revalidate_disk_zones+0x4c/0x560\n\nClearing dev->zoned in the same window is worse: the queue is created\nwith BLK_FEAT_ZONED but the zone resources are never initialized, so\nadd_disk() succeeds for a zoned disk that has no zones. And a store that\nlands after the last dev->zoned test leaves dev->zoned set while\ndev->zones is still NULL, which null_process_zoned_cmd() dereferences on\nthe first write.\n\nFix this by taking the global lock, which nullb_device_power_store()\nalready holds across null_add_dev() and null_del_dev(), around both the\nNULLB_DEV_FL_CONFIGURED test and the update of the device configuration.\nThe submit_queues and poll_queues apply callbacks are now called with\nthat lock held, so remove the locking they did themselves.\n\nSince the store methods can run as soon as configfs_register_subsystem()\nreturns, that is, before null_init() gets to mutex_init(&lock), also\ninitialize the lock statically with DEFINE_MUTEX().","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/32456a85995579e56c60cc53c357cda75a9d4f7c","https://git.kernel.org/stable/c/4e1f23f9c33c156be7e313b40695af5a3a834739","https://git.kernel.org/stable/c/6352e7ead2d8111802a554eeb94886f5a9894bb9","https://git.kernel.org/stable/c/7de792b4c48fba02a36a8077032f7d5093c925e5","https://git.kernel.org/stable/c/aed8af338a09a64d63b068a803c4ecfc5701dd4c"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-90184","score":0.00206,"percentile":0.10493,"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."]}