Memory Leak Vulnerability in Linux Kernel: PID Reference Count Issue
Summary
CVE-2021-46937: In the Linux kernel, the following vulnerability has been resolved: mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()' DAMON debugfs interface increases the reference counts of 'struct pid's for targets... Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing essential services for hardware management and system resources. It is known for its stability, performance, and extensive support for various hardware architectures. However, it is also susceptible to vulnerabilities that can affect system performance and security. This specific vulnerability involves the DAMON debugfs interface, which is responsible for monitoring memory access patterns. The issue arises from improper management of reference counts for 'struct pid' objects, leading to potential memory leaks.
Vulnerability Detail
In the Linux kernel, the DAMON debugfs interface increases the reference counts of 'struct pid' objects when writing to the 'target_ids' file. However, it fails to decrease these counts appropriately when the monitoring is not started or terminated correctly. This oversight can lead to memory leaks, as the memory allocated for these 'struct pid' objects cannot be freed, potentially exhausting system resources over time. The vulnerability is particularly concerning in scenarios where the 'target_ids' file is written to repeatedly without proper monitoring start/termination, leading to increased memory usage and possible system instability.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
Currently, there are no specific workarounds mentioned for this vulnerability other than applying the fix by updating the kernel. Users are advised to monitor their systems for unusual memory usage and consider temporarily stopping the use of the DAMON monitoring feature until the update is applied.
Conclusion
The CVE-2021-46937 vulnerability in the Linux kernel poses a significant risk due to improper reference count management, leading to potential memory leaks. Users are strongly advised to update their systems to the latest kernel version to mitigate this issue. Regular monitoring and updates are essential for maintaining system security and stability.
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FAQ
CVE-2021-46937 is a vulnerability in the Linux kernel related to improper management of reference counts for 'struct pid' objects, leading to potential memory leaks.
This vulnerability can lead to increased memory usage over time, potentially exhausting system resources and causing instability.
The vulnerability affects Linux kernel versions prior to 5.15.15-1 on Debian 12 and 13, and all versions on Debian 11.
You can use Vulert, which monitors open-source vulnerabilities in your software. By uploading your manifest file, you can check if your application is affected by this vulnerability.
The CVSS score for this vulnerability is 5.5, indicating a moderate level of severity.
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