In the Linux kernel, the following vulnerability has been resolved: ovl: fix leaked dentry. Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock.
The CVSS score for this vulnerability is 5.5, indicating a medium severity level. This means organizations should address it in their priority patch cycle. Risk to organizations includes potential system availability issues during shutdowns, which can affect operational continuity.
The vulnerability was identified in the Linux kernel versions from 5.8 to below 5.10.35, from 5.11 to below 5.11.19, and from 5.12 to below 5.12.2. Organizations running these versions should take immediate action to patch their systems.
As of now, no public exploit or proof of concept has been confirmed. However, the potential impact on system availability necessitates prompt remediation. Organizations should prioritize patching immediately.
Details regarding the vulnerability can be found in the official Linux kernel commit logs, which address the specific issues leading to this vulnerability.
Vulnerability Details
In the Linux kernel, the following vulnerability has been resolved: ovl: fix leaked dentry. Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock.
This vulnerability is classified under CWE-401, which involves resource leaks. With a CVSS score of 5.5, it is categorized as medium severity. It is crucial to understand that the attack vector is local, requiring low attack complexity and low privileges.
Technical Analysis
The root cause of this vulnerability is the failure of overlayfs to properly manage temporary dentry during metacopy errors. This oversight can cause dentry leaks, particularly when the system attempts to shut down related superblocks. The issue arises during the unmounting of the overlay filesystem, leading to busy inodes that can hinder system shutdown processes.
The attack vector is local, meaning that an attacker must have access to the system where the kernel is running. The attack complexity is low, and only low privileges are required to exploit this vulnerability. Importantly, user interaction is not required for the exploitation to be successful.
Risk & Impact Analysis
Real-world deployment risk is significant as this vulnerability can lead to system availability issues. The potential for busy inodes after unmounting an overlay filesystem could disrupt normal operations. Organizations should be aware that failure to address this vulnerability may result in downtime or system instability.
The urgency for remediation is heightened due to the potential impact on operations. Given the medium severity level, organizations should address it in priority patch cycles.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of the Linux kernel include:
All versions from 5.8 to below 5.10.35, 5.11 to below 5.11.19, and 5.12 to below 5.12.2 are vulnerable.
Mitigation & Remediation
Organizations should prioritize patching immediately. The patches for this vulnerability have been released and are available in the following commits:
Linux kernel commit logs provide detailed information regarding the fixes.
If a patch is not available, organizations should consider implementing workarounds, such as disabling overlayfs.
Detection Guidance
Monitor logs for indicators of dentry leaks and busy inodes during unmount operations. Behavioral anomalies related to filesystem operations may also indicate potential exploitation of this vulnerability.
AppSecure Threat Intelligence Insight
The medium severity of this vulnerability signifies a manageable risk profile for organizations, but the potential for system disruption during shutdowns should not be underestimated.
Security teams should consider the long-term significance of similar vulnerabilities in kernel development, as these can represent patterns of oversight in resource management.
For strategic defensive takeaways, it is crucial to maintain an ongoing patch management program and to embed security practices into the software development lifecycle.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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