KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio
Summary
UVI-2021-1001346: KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio. Affects Kernel versions >= 7d1bc32d6477ff96a32695ea4be8144e4513ab2d, < f2ff9d03432fcb160e9f7d4be26174d89de2779a. No fix is published. How to fix ↓
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Background
The Kernel package is a crucial component of the Linux operating system. It provides the core functionality and interfaces for the system's hardware and software components. KVM (Kernel-based Virtual Machine) is a module within the Kernel package that enables the creation and management of virtual machines on Linux systems. It allows users to run multiple operating systems simultaneously on a single physical machine. The vulnerability in question affects the mmio (memory-mapped I/O) functionality of KVM. Memory-mapped I/O is a mechanism that allows devices to communicate directly with the CPU by mapping their memory addresses to the system's memory. This vulnerability can be exploited to trigger a use-after-free read, potentially leading to unauthorized access or denial of service.
Vulnerability Detail
The vulnerability arises from a use-after-free read in the kvm_vm_ioctl_unregister_coalesced_mmio function of the KVM mmio module. A use-after-free vulnerability occurs when a program continues to use a memory region after it has been freed, leading to unpredictable behavior. In this case, an attacker could exploit the vulnerability by unregistering a coalesced mmio region while it is still in use, causing a use-after-free read. The impact of this vulnerability could range from information disclosure to privilege escalation or system crashes. The vulnerability was introduced in version v5.4.119 of the Linux Kernel and has been fixed in version v5.4.134.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
There is no specific workaround available for this vulnerability. However, users can mitigate the risk by ensuring that their systems are running the latest version of the Linux Kernel and regularly applying security updates.
Conclusion
The KVM mmio vulnerability (UVI-2021-1001346) in the Linux Kernel can lead to a use-after-free read, potentially enabling unauthorized access or denial of service. It is crucial to update the Kernel package to version v5.4.134 or later to mitigate the risk. Regularly applying security updates and following best practices for system hardening are also recommended. For further support and assistance with vulnerability remediation, please contact DevNack.com.
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FAQ
The impact of this vulnerability can range from information disclosure to privilege escalation or system crashes. It could potentially allow an attacker to gain unauthorized access to sensitive data or disrupt the normal operation of the system.
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 known vulnerabilities, including this one.
Yes, a patch for this vulnerability has been included in version v5.4.134 of the Linux Kernel. It is recommended to update your system to this version or later to mitigate the risk.
At the time of this report, there are no known exploits for this vulnerability. However, it is important to apply the necessary updates and security patches to protect your system from potential future exploits.
This vulnerability can potentially be exploited remotely if an attacker can establish a connection to the affected system. However, the likelihood of remote exploitation depends on various factors, such as network configuration and access controls.
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