CVE-2026-90184 (GCVE-0-2026-90184)
Vulnerability from cvelistv5
Published
2026-09-17 16:07
Modified
2026-10-19 08:59
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: null_blk: serialize configfs attribute updates with device setup The attribute store methods generated with NULLB_DEVICE_ATTR() refuse to change the configuration of a live device by testing NULLB_DEV_FL_CONFIGURED, but that flag is only set by nullb_device_power_store() after null_add_dev() has returned, and the store methods take no lock at all. configfs only serializes writes to the same open file (buffer->mutex), so a write to any attribute can run concurrently with null_add_dev() and change the device configuration while it is being used. null_add_dev() reads the configuration several times, e.g. dev->zoned is read once to set up the queue limits and once to initialize the zone resources: CPU0: echo 1 > nullb0/power CPU1: echo 1 > nullb0/zoned nullb_device_power_store() mutex_lock(&lock) null_add_dev() if (dev->zoned) -> false /* no BLK_FEAT_ZONED */ nullb_device_zoned_store() test_bit(FL_CONFIGURED) -> 0 dev->zoned = true blk_mq_alloc_disk() /* queue is not zoned */ if (nullb->dev->zoned) -> true null_register_zoned_dev() blk_revalidate_disk_zones() blk_revalidate_disk_zones() is then called for a queue that does not have BLK_FEAT_ZONED set, which triggers its WARN_ON_ONCE() and fails the device setup with -EIO: WARNING: CPU: 2 PID: 322 at block/blk-zoned.c:2357 blk_revalidate_disk_zones+0x4c/0x560 Clearing dev->zoned in the same window is worse: the queue is created with BLK_FEAT_ZONED but the zone resources are never initialized, so add_disk() succeeds for a zoned disk that has no zones. And a store that lands after the last dev->zoned test leaves dev->zoned set while dev->zones is still NULL, which null_process_zoned_cmd() dereferences on the first write. Fix this by taking the global lock, which nullb_device_power_store() already holds across null_add_dev() and null_del_dev(), around both the NULLB_DEV_FL_CONFIGURED test and the update of the device configuration. The submit_queues and poll_queues apply callbacks are now called with that lock held, so remove the locking they did themselves. Since the store methods can run as soon as configfs_register_subsystem() returns, that is, before null_init() gets to mutex_init(&lock), also initialize the lock statically with DEFINE_MUTEX().
References
Impacted products
Vendor Product Version
Linux Linux Version: 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
Version: 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
Version: 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
Version: 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
Version: 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
Version: 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/block/null_blk/main.c"
          ],
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "4.14"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.1.188",
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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-\u003emutex), 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-\u003ezoned is\nread once to set up the queue limits and once to initialize the zone\nresources:\n\n  CPU0: echo 1 \u003e nullb0/power         CPU1: echo 1 \u003e nullb0/zoned\n  nullb_device_power_store()\n    mutex_lock(\u0026lock)\n    null_add_dev()\n      if (dev-\u003ezoned) -\u003e false\n        /* no BLK_FEAT_ZONED */       nullb_device_zoned_store()\n                                        test_bit(FL_CONFIGURED) -\u003e 0\n                                        dev-\u003ezoned = true\n      blk_mq_alloc_disk()\n        /* queue is not zoned */\n      if (nullb-\u003edev-\u003ezoned) -\u003e 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-\u003ezoned 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-\u003ezoned test leaves dev-\u003ezoned set while\ndev-\u003ezones 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(\u0026lock), also\ninitialize the lock statically with DEFINE_MUTEX()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:59:21.103Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6352e7ead2d8111802a554eeb94886f5a9894bb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/7de792b4c48fba02a36a8077032f7d5093c925e5"
        },
        {
          "url": "https://git.kernel.org/stable/c/aed8af338a09a64d63b068a803c4ecfc5701dd4c"
        },
        {
          "url": "https://git.kernel.org/stable/c/32456a85995579e56c60cc53c357cda75a9d4f7c"
        },
        {
          "url": "https://git.kernel.org/stable/c/d3d35dd045a35991bf6fd13de5f293e6dd7bf3b3"
        },
        {
          "url": "https://git.kernel.org/stable/c/4e1f23f9c33c156be7e313b40695af5a3a834739"
        }
      ],
      "title": "null_blk: serialize configfs attribute updates with device setup",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90184",
    "datePublished": "2026-09-17T16:07:07.728Z",
    "dateReserved": "2026-09-11T19:38:34.791Z",
    "dateUpdated": "2026-10-19T08:59:21.103Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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