CVE-2011-4132 in Linux
Summary
by MITRE
The cleanup_journal_tail function in the Journaling Block Device (JBD) functionality in the Linux kernel 2.6 allows local users to cause a denial of service (assertion error and kernel oops) via an ext3 or ext4 image with an "invalid log first block value."
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability identified as CVE-2011-4132 represents a critical flaw within the Linux kernel's Journaling Block Device subsystem that specifically affects the cleanup_journal_tail function. This issue resides in the JBD functionality that manages journaling operations for ext3 and ext4 filesystems, creating a pathway for local attackers to disrupt system operations through carefully crafted filesystem images. The vulnerability stems from inadequate validation of journal metadata, particularly the log first block value, which when set to invalid parameters triggers unexpected behavior in the kernel's journal management code.
The technical implementation of this vulnerability exploits a fundamental flaw in input validation within the kernel's journaling subsystem. When a filesystem image contains an invalid log first block value, the cleanup_journal_tail function fails to properly handle this malformed data, resulting in assertion errors that cause kernel oops conditions. This occurs because the function does not adequately check the validity of journal metadata before attempting to process it, leading to a situation where kernel execution flow encounters unexpected conditions that trigger system instability. The flaw operates at the kernel level where the journaling subsystem processes filesystem metadata, making it particularly dangerous as it can affect the stability of the entire operating system.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise system integrity and availability. Local users with access to create or modify filesystem images can exploit this weakness to force kernel panics or system crashes, effectively rendering the affected system unavailable to legitimate users. The assertion errors and kernel oops conditions generated by this exploit can lead to complete system shutdowns or require manual intervention to recover from the corrupted kernel state. This type of vulnerability is particularly concerning in production environments where system uptime and reliability are critical requirements, as it provides attackers with a mechanism to disrupt services without requiring elevated privileges or complex attack vectors.
Mitigation strategies for CVE-2011-4132 focus primarily on kernel updates and filesystem validation measures. System administrators should immediately apply the relevant kernel security patches that address this journaling validation issue, as the fix typically involves implementing proper bounds checking and validation of journal metadata before processing. Additionally, implementing filesystem integrity monitoring and regular validation of ext3/ext4 images can help detect and prevent exploitation attempts. Organizations should also consider restricting local user access to filesystem creation and modification capabilities where possible, as this vulnerability requires local access to craft malicious filesystem images. The remediation approach aligns with defensive programming principles and follows established security practices for kernel-level vulnerability management.
This vulnerability maps to CWE-129 Input Validation and CWE-248 Uncontrolled Format String, demonstrating the intersection of improper input validation with kernel-level execution flow control. From an ATT&CK perspective, this represents a privilege escalation vector through local system compromise, potentially enabling attackers to achieve persistent access or further exploit other system components. The vulnerability highlights the importance of robust kernel validation mechanisms and proper error handling in critical system subsystems, particularly those involved in storage and filesystem management operations that directly impact system stability and availability.