Critical Race Condition in Linux Kernel: Dell UART Backlight Vulnerability
Summary
DEBIAN-CVE-2025-21695: 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 op... Affects linux versions < 6.12.11-1. Fixed in 6.12.11-1. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, providing essential services for hardware and software interaction. It is known for its robustness and versatility, supporting a wide range of devices and architectures. However, like any complex software, it is susceptible to vulnerabilities. This specific issue affects the Dell UART backlight functionality, which is responsible for managing the display backlight on Dell devices. The vulnerability arises from a race condition that can lead to system instability and potential crashes.
Vulnerability Detail
In the Linux kernel, a race condition exists in the dell_uart_bl_serdev_probe() function, where devm_serdev_device_open() is called before the client operations are set via serdev_device_set_client_ops(). This improper ordering can lead to a NULL pointer dereference in the serdev controller's receive_buf handler, as it assumes that serdev->ops is valid when SERPORT_ACTIVE is set. This vulnerability is similar to a previously fixed issue and can cause significant system errors if exploited.
How To Fix
Minimum fixed version
6.12.11-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
Currently, there are no specific workarounds provided for this vulnerability. It is recommended to apply the patch as soon as it is available to mitigate any risks.
Conclusion
The Dell UART backlight vulnerability in the Linux kernel represents a significant risk due to its potential to cause system instability. It is crucial for users to update their systems to the latest patched version to mitigate this risk. Utilizing tools like Vulert can help in monitoring and managing open-source vulnerabilities effectively.
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FAQ
The vulnerability is a race condition in the Linux kernel related to the Dell UART backlight functionality, which can lead to system crashes.
You can use Vulert, which monitors open-source vulnerabilities in your software. By uploading your manifest file like package-lock.json, you can check for vulnerabilities in real-time.
Exploitation of this vulnerability can lead to system instability, crashes, and potentially unauthorized access to system resources.
Yes, a patch is available in version 6.12.11-1 of the Linux package. It is recommended to update your system to this version.
Detailed information can be found in the Debian CVE database and through security advisories related to the Linux kernel.
References
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