ext4: Fix Use-After-Free Vulnerability When Remounting Read-Only MMP-Protected File System
Summary
GSD-2021-1001216: ext4: fix possible UAF when remounting r/o a mmp-protected file system. Affects Kernel versions < 7ed572cdf11081f8f9e07abd4bea56a3f2c4edbd. No fix is published. How to fix ↓
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Background
The ext4 package is a file system driver for the Linux kernel. It provides support for the fourth extended file system (ext4), which is the default file system for many Linux distributions. The ext4 file system offers improved performance, scalability, and reliability compared to its predecessors. However, a vulnerability has been discovered in the ext4 package that could lead to a use-after-free (UAF) condition when remounting a read-only file system protected by multi-mount protection (MMP).
Vulnerability Detail
The vulnerability arises when attempting to remount a read-only file system that is protected by multi-mount protection. Multi-mount protection is a feature in ext4 that prevents multiple instances of the file system from being mounted simultaneously. The issue occurs due to a use-after-free bug, which can result in a situation where a pointer to freed memory is still accessible. An attacker could potentially exploit this vulnerability to execute arbitrary code or cause a denial-of-service (DoS) condition. The impact and attack plausibility of this vulnerability have not been proven yet.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
There is no known workaround available for this vulnerability. It is recommended to apply the fix by updating the Linux Kernel to the patched version.
Conclusion
The ext4 package in the Linux Kernel is vulnerable to a use-after-free (UAF) condition when remounting a read-only file system protected by multi-mount protection (MMP). This vulnerability has been fixed in the Linux Kernel version v5.13.3. Users are advised to update their kernel to the patched version to mitigate the risk. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
ext4 is a file system driver for the Linux kernel that provides support for the fourth extended file system (ext4). It offers improved performance, scalability, and reliability compared to previous versions.
Multi-mount protection is a feature in ext4 that prevents multiple instances of the file system from being mounted simultaneously. It helps to avoid data corruption and other issues that can arise from concurrent mounts.
A use-after-free vulnerability occurs when a program continues to use a pointer to memory that has already been freed. This can lead to unpredictable behavior, including crashes, data corruption, or the execution of arbitrary code.
If exploited, this vulnerability could allow an attacker to execute arbitrary code or cause a denial-of-service (DoS) condition. However, the actual impact and attack plausibility have not been proven yet.
To fix this vulnerability, update your Linux Kernel to version v5.13.3 or later. Regularly updating the kernel is recommended to ensure the latest security patches are applied.
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