net/sched: sch_ets: don't peek at classes beyond 'nbands' in Kernel
Summary
GSD-2021-1002542: net/sched: sch_ets: don't peek at classes beyond 'nbands'. Affects Kernel versions >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33, < e25bdbc7e951ae5728fee1f4c09485df113d013c. No fix is published. How to fix ↓
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Background
The Kernel is a crucial component of the Linux operating system that manages system resources and facilitates communication between hardware and software. It provides essential functionalities for process management, memory management, device drivers, and more. The sch_ets module in the Kernel is responsible for implementing the Enhanced Transmission Selection (ETS) algorithm for packet scheduling. ETS allows for bandwidth allocation among different traffic classes in a network. However, a vulnerability has been discovered in the sch_ets module that could potentially lead to security issues.
Vulnerability Detail
The vulnerability in the sch_ets module allows an attacker to access classes beyond the specified 'nbands' parameter. This can result in unauthorized access to sensitive information or the execution of arbitrary code. The issue was introduced in version v5.6 of the Linux Kernel and has been fixed in version v5.15.6. The impact and attack plausibility of this vulnerability have not been proven yet.
How To Fix
No fixed version is published for this vulnerability.
To fix this vulnerability, it is recommended to update the Linux Kernel to version v5.15.6 or later. This can be done by downloading the latest stable version of the Kernel from the official Git repository (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/) and following the installation instructions provided. It is important to ensure that the new Kernel version is compatible with the system configuration and that all necessary dependencies are met.
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Workaround
As a temporary workaround, users can limit the 'nbands' parameter to a safe value to prevent unauthorized access to classes beyond the specified limit. This can be done by modifying the relevant configuration files or using command-line options during Kernel initialization. Here is an example of how to set the 'nbands' parameter to a safe value:
# Set nbands to 8
echo 8 > /sys/class/net/<interface>/queues/sch_ets/nbands
Please note that this workaround may affect the performance or functionality of the ETS algorithm.
Conclusion
The vulnerability in the sch_ets module of the Kernel can potentially lead to unauthorized access or code execution. It is crucial to update the Linux Kernel to version v5.15.6 or later to mitigate this vulnerability. Alternatively, users can apply the temporary workaround of limiting the 'nbands' parameter to a safe value. For further support and assistance in vulnerability remediation, please contact DevNack.com.
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FAQ
The sch_ets module is responsible for implementing the Enhanced Transmission Selection (ETS) algorithm for packet scheduling in the Linux Kernel. It allows for bandwidth allocation among different traffic classes in a network.
The vulnerability in sch_ets allows an attacker to access classes beyond the specified 'nbands' parameter. This can lead to unauthorized access to sensitive information or the execution of arbitrary code, potentially compromising system security.
The vulnerability was introduced in version v5.6 of the Linux Kernel. All versions between v5.6 and v5.15.5 (inclusive) are affected. The issue has been fixed in version v5.15.6.
No, the impact and attack plausibility of this vulnerability have not been proven yet. However, it is recommended to apply the fix or workaround as a precautionary measure.
You can find more information about this vulnerability, including the fix commit and the source of this information, in the GSD-2021-1002542.json file available on the GitHub repository of the Cloud Security Alliance's GSD database (https://github.com/cloudsecurityalliance/gsd-database).
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