CVE-2025-21685: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: platform/x86: lenovo-yoga-tab2-pro-1380-fastcharger: fix serdev race The yt2_1380_fc_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.

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CVSS v3.1 Score

4.7

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.10 — 6.12.11
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/3f67e07873df3c6d9ce2582260b83732e1d3a40b https://git.kernel.org/stable/c/59616a91e5e74833b2008b56c66879857c616006

Frequently Asked Questions

What is CVE-2025-21685? +

In the Linux kernel, the following vulnerability has been resolved: platform/x86: lenovo-yoga-tab2-pro-1380-fastcharger: fix serdev race The yt2_1380_fc_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. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2025-21685? +

CVE-2025-21685 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21685? +

CVE-2025-21685 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21685? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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