CVE-2026-90189
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: null_blk: register configfs subsystem after creating default devices In null_init(), configfs_register_subsystem() currently runs before register_blkdev(), so when null_blk is built as a module, a racing mkdir() + poweron from userspace can reach null_add_dev() while null_major is still 0. __add_disk() then hits WARN_ON(disk->minors) (major=0 with minors!=0) and fails: [root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0, [ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib [ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full) ...... [ 2366.547251] Call Trace: [ 2366.547575] <TASK> [ 2366.547831] ? _raw_spin_lock+0x84/0xe0 [ 2366.548260] add_disk_fwnode+0x114/0x560 [ 2366.548739] null_add_dev+0x102d/0x1b80 [null_blk] [ 2366.549310] ? __pfx_null_add_dev+0x10/0x10 [null_blk] [ 2366.549906] ? mutex_lock+0xde/0x1c0 [ 2366.550361] ? __pfx_mutex_lock+0x10/0x10 [ 2366.550827] nullb_device_power_store+0x1e7/0x280 [null_blk] [ 2366.551499] ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk] [ 2366.552177] ? __kmalloc_cache_noprof+0x1f5/0x470 [ 2366.552748] ? configfs_write_iter+0x35c/0x4e0 [ 2366.553242] configfs_write_iter+0x286/0x4e0 [ 2366.553787] vfs_write+0x52d/0xd00 [ 2366.554169] ? __pfx_vfs_write+0x10/0x10 [ 2366.554679] ? __pfx___css_rstat_updated+0x10/0x10 [ 2366.555196] ? fdget_pos+0x1cf/0x4c0 [ 2366.555649] ksys_write+0xfc/0x1d0 ...... Additionally, the err_dev path destroys all devices on nullb_list while configfs is still registered. If a racing mkdir() + poweron puts a user device on the list, null_destroy_dev()->null_free_dev() kfrees the user device's nullb_device but /sys/kernel/config/nullb/<name> is still reachable. Any userspace access to the item will trigger a UAF. For simplicity, move configfs_register_subsystem() to the end to solve the problems above.
View original CVE JSON
{
"id": "CVE-2026-90189",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-17T17:17:13.533",
"lastModified": "2026-10-19T09:19:08.907",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: register configfs subsystem after creating default devices\n\nIn null_init(), configfs_register_subsystem() currently runs before\nregister_blkdev(), so when null_blk is built as a module, a racing mkdir()\n+ poweron from userspace can reach null_add_dev() while null_major is still\n0. __add_disk() then hits WARN_ON(disk->minors) (major=0 with minors!=0)\nand fails:\n\n[root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0,\n[ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib\n[ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full)\n......\n[ 2366.547251] Call Trace:\n[ 2366.547575] <TASK>\n[ 2366.547831] ? _raw_spin_lock+0x84/0xe0\n[ 2366.548260] add_disk_fwnode+0x114/0x560\n[ 2366.548739] null_add_dev+0x102d/0x1b80 [null_blk]\n[ 2366.549310] ? __pfx_null_add_dev+0x10/0x10 [null_blk]\n[ 2366.549906] ? mutex_lock+0xde/0x1c0\n[ 2366.550361] ? __pfx_mutex_lock+0x10/0x10\n[ 2366.550827] nullb_device_power_store+0x1e7/0x280 [null_blk]\n[ 2366.551499] ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk]\n[ 2366.552177] ? __kmalloc_cache_noprof+0x1f5/0x470\n[ 2366.552748] ? configfs_write_iter+0x35c/0x4e0\n[ 2366.553242] configfs_write_iter+0x286/0x4e0\n[ 2366.553787] vfs_write+0x52d/0xd00\n[ 2366.554169] ? __pfx_vfs_write+0x10/0x10\n[ 2366.554679] ? __pfx___css_rstat_updated+0x10/0x10\n[ 2366.555196] ? fdget_pos+0x1cf/0x4c0\n[ 2366.555649] ksys_write+0xfc/0x1d0\n......\n\nAdditionally, the err_dev path destroys all devices on nullb_list while\nconfigfs is still registered. If a racing mkdir() + poweron puts a user\ndevice on the list, null_destroy_dev()->null_free_dev() kfrees the user\ndevice's nullb_device but /sys/kernel/config/nullb/<name> is still\nreachable. Any userspace access to the item will trigger a UAF.\n\nFor simplicity, move configfs_register_subsystem() to the end to solve\nthe problems above."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"drivers/block/null_blk/main.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa",
"lessThan": "2679b11e9256bd70a5ef41783bab6ad6c34a3db1",
"versionType": "git",
"status": "affected"
},
{
"version": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa",
"lessThan": "dbcedbe4819ae21274ea77469e61e46a878b9943",
"versionType": "git",
"status": "affected"
},
{
"version": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa",
"lessThan": "57debc907aef66319d244009d3370dcd97388d37",
"versionType": "git",
"status": "affected"
},
{
"version": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa",
"lessThan": "d761be1b8f2bbabc41252deb79a426d3f0d4fa10",
"versionType": "git",
"status": "affected"
},
{
"version": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa",
"lessThan": "cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36",
"versionType": "git",
"status": "affected"
},
{
"version": "3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa",
"lessThan": "c9d293d6bb0575fcb1f3408129453187e2a28a4e",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"drivers/block/null_blk/main.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "4.14",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.14",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.188",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.110",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.52",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.6",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/2679b11e9256bd70a5ef41783bab6ad6c34a3db1",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/57debc907aef66319d244009d3370dcd97388d37",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c9d293d6bb0575fcb1f3408129453187e2a28a4e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d761be1b8f2bbabc41252deb79a426d3f0d4fa10",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/dbcedbe4819ae21274ea77469e61e46a878b9943",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}