NFS: Potential NULL Dereference in nfs_get_client() in Linux Kernel
Summary
GSD-2021-1000882: NFS: Fix a potential NULL dereference in nfs_get_client(). Affects Kernel versions >= 31434f496abb9f3410b10f541462fe58613dd3ad, < 4b380a7d84ef2ce3f4f5bec5d8706ed937ac6502. No fix is published. How to fix ↓
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Background
The Linux Kernel is the core component of the Linux operating system, responsible for managing system resources and providing an interface for applications to interact with the hardware. NFS (Network File System) is a distributed file system protocol that allows remote file access over a network. The nfs_get_client() function in the Linux Kernel is responsible for retrieving the NFS client data structure associated with a given NFS client ID. This vulnerability in nfs_get_client() could lead to a NULL dereference, potentially resulting in a system crash or other security issues.
Vulnerability Detail
The vulnerability in nfs_get_client() arises from a potential NULL dereference. When the function is called with an invalid NFS client ID, it fails to handle the error condition properly, leading to a NULL pointer dereference. An attacker could exploit this vulnerability by sending a specially crafted request to the NFS server, causing the nfs_get_client() function to be called with an invalid client ID. This could result in a system crash or potentially allow the attacker to execute arbitrary code with kernel privileges. The vulnerability was introduced in version v3.17 of the Linux Kernel and has been fixed in version v4.19.195.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
If updating the Linux Kernel is not immediately feasible, a possible workaround is to disable the NFS functionality or restrict access to NFS services. This can be done by modifying the system configuration files to prevent the NFS modules from being loaded or by configuring firewall rules to block NFS traffic. However, it is important to note that these workarounds may impact the functionality of NFS-related services and should be carefully evaluated before implementation.
Conclusion
The vulnerability in nfs_get_client() in the Linux Kernel could lead to a NULL dereference, potentially resulting in a system crash or other security issues. It is recommended to update the Linux Kernel to version v4.19.195 or later to mitigate the risk. If immediate update is not possible, consider implementing the provided workaround. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
The vulnerability in nfs_get_client() could lead to a NULL dereference, potentially resulting in a system crash or other security issues. It could also allow an attacker to execute arbitrary code with kernel privileges.
You can use the Vulert Playground (https://vulert.com/scanner) to check if your system is affected by this vulnerability. Simply upload your package-lock.json file and Vulert will analyze it for any open-source vulnerabilities, including this specific vulnerability in the Linux Kernel.
Yes, this vulnerability has been fixed in version v4.19.195 of the Linux Kernel. It is recommended to update to this version or a later version to mitigate the risk.
At the time of this report, there are no known public exploits specifically targeting this vulnerability. However, it is always important to promptly apply security updates to mitigate the risk of potential exploits.
If updating the Linux Kernel is not immediately feasible, you can consider implementing the workaround mentioned in the 'workaround' section of this report. However, it is important to note that workarounds may have limitations and it is still recommended to update to the latest version of the Linux Kernel as soon as possible.
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