Double fput() on failed usercopy in Linux Kernel
Summary
GSD-2022-1000501: misc: fastrpc: avoid double fput() on failed usercopy. Affects Kernel versions >= 6cffd79504ce040f460831030d3069fa1c99bb71, < 76f85c307ef9f10aa2cef1b1d5ee654c1f3345fc. 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. It is a critical piece of software that enables the functioning of various devices and services on Linux-based systems. The fastrpc module in the Linux Kernel is used for remote procedure calls (RPC) between different processes. RPC allows processes to communicate with each other over a network, enabling distributed computing. However, a vulnerability has been discovered in the fastrpc module that can lead to a double fput() on failed usercopy.
Vulnerability Detail
The vulnerability in the fastrpc module of the Linux Kernel arises from a double fput() call on a failed usercopy operation. Usercopy is a mechanism in the Linux Kernel that allows copying data between user space and kernel space. In this case, if the usercopy operation fails, the fastrpc module incorrectly calls fput() twice, leading to a reference count imbalance on the file object. This reference count imbalance can potentially be exploited by an attacker to trigger a use-after-free vulnerability or other memory corruption issues. The impact and attack plausibility of this vulnerability have not yet been proven.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
There is no specific workaround mentioned for this vulnerability.
Conclusion
The fastrpc module in the Linux Kernel is vulnerable to a double fput() on failed usercopy, which can potentially lead to memory corruption and other security issues. It is crucial to update the Linux Kernel to version v5.16.10 or later to mitigate this vulnerability. Regularly updating the Linux Kernel is recommended to ensure the latest security patches are applied. For further support on vulnerability remediation, you can reach out to DevNack.com.
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FAQ
The fastrpc module in the Linux Kernel is used for remote procedure calls (RPC) between different processes. It enables processes to communicate with each other over a network, facilitating distributed computing.
fput() is a function in the Linux Kernel that decreases the reference count of a file object. A double fput() call refers to calling this function twice on the same file object, which can lead to a reference count imbalance and potential memory corruption.
Usercopy is a mechanism in the Linux Kernel that allows copying data between user space and kernel space. It is used to ensure the safety and integrity of data transfers between these two domains.
A use-after-free vulnerability occurs when a program continues to use a memory region after it has been freed. This can lead to memory corruption and potentially be exploited by an attacker to execute arbitrary code or crash the system.
To update your Linux Kernel, you can follow the instructions provided by your Linux distribution or refer to the official documentation for your specific distribution. Typically, it involves using package management tools like apt, yum, or dnf to install the latest kernel updates.
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