CVE-2025-21695 Information

Description

In the Linux kernel the following vulnerability has been resolved:

platform/x86: dell-uart-backlight: fix serdev race

The dell_uart_bl_serdev_probe() function calls devm_serdev_device_open() before setting the client ops via serdev_device_set_client_ops(). This ordering can trigger a NULL pointer dereference in the serdev controller’s receive_buf handler as it assumes serdev->ops is valid when SERPORT_ACTIVE is set.

This is similar to the issue fixed in commit 5e700b384ec1 (\platform/chrome: cros_ec_uart: properly fix race condition) where devm_serdev_device_open() was called before fully initializing the device.

Fix the race by ensuring client ops are set before enabling the port via devm_serdev_device_open().

Note serdev_device_set_baudrate() and serdev_device_set_flow_control() calls should be after the devm_serdev_device_open() call.

Reference

https://git.kernel.org/stable/c/1b2128aa2d45ab20b22548dcf4b48906298ca7fd https://git.kernel.org/stable/c/d3a24d923333f75aaece9acb051d676edc0afb75