null_blk: serialize configfs attribute updates with device setup

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-90184
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:12 UTC
Updated2026-09-17 17:17:12 UTC
DescriptionIn 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().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa 6352e7ead2d8111802a554eeb94886f5a9894bb9 git Not specified
CNA Linux Linux affected 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa 7de792b4c48fba02a36a8077032f7d5093c925e5 git Not specified
CNA Linux Linux affected 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa aed8af338a09a64d63b068a803c4ecfc5701dd4c git Not specified
CNA Linux Linux affected 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa 32456a85995579e56c60cc53c357cda75a9d4f7c git Not specified
CNA Linux Linux affected 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa d3d35dd045a35991bf6fd13de5f293e6dd7bf3b3 git Not specified
CNA Linux Linux affected 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa 4e1f23f9c33c156be7e313b40695af5a3a834739 git Not specified
CNA Linux Linux affected 4.14 Not specified
CNA Linux Linux unaffected 4.14 semver Not specified
CNA Linux Linux unaffected 6.1.188 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/7de792b4c48fba02a36a8077032f7d5093c925e5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d3d35dd045a35991bf6fd13de5f293e6dd7bf3b3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/32456a85995579e56c60cc53c357cda75a9d4f7c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4e1f23f9c33c156be7e313b40695af5a3a834739 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/aed8af338a09a64d63b068a803c4ecfc5701dd4c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6352e7ead2d8111802a554eeb94886f5a9894bb9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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