CVE-2005-3106 in Linux
Summary
by MITRE
Race condition in Linux 2.6, when threads are sharing memory mapping via CLONE_VM (such as linuxthreads and vfork), might allow local users to cause a denial of service (deadlock) by triggering a core dump while waiting for a thread that has just performed an exec.
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Analysis
by VulDB Data Team • 01/16/2025
The vulnerability described in CVE-2005-3106 represents a critical race condition within the Linux kernel version 2.6 operating system that specifically affects thread synchronization mechanisms involving shared memory mappings. This flaw occurs when multiple threads utilize the CLONE_VM flag to share memory mappings, a feature commonly employed by threading libraries such as linuxthreads and the vfork system call. The race condition manifests during the execution of core dump operations when a process attempts to generate a memory dump while another thread is in the process of executing an exec system call, creating a scenario where the system enters a deadlock state that prevents normal operation.
The technical implementation of this vulnerability stems from the improper handling of memory management structures during the transition from one process state to another through the exec system call. When threads share memory mappings through CLONE_VM, they maintain references to the same virtual memory areas, which creates complex synchronization requirements during memory operations. The race condition occurs because the kernel does not properly coordinate between the thread that is about to execute exec and the thread that is attempting to trigger a core dump, leading to a circular dependency where each thread waits for the other to complete its operation. This situation is particularly dangerous because it can occur during normal system operations, making it difficult to predict or prevent the occurrence of the deadlock state.
The operational impact of this vulnerability extends beyond simple denial of service, as it can effectively compromise the stability and reliability of systems running affected kernel versions. Local users can exploit this condition to cause system-wide deadlocks that may require system reboot to resolve, potentially leading to extended downtime and service disruption. The vulnerability is particularly concerning in multi-threaded applications where vfork and CLONE_VM are commonly used, as these scenarios are prevalent in many system services and applications. The exploitability of this condition means that any process running on an affected system could potentially trigger the race condition, making it a significant threat to system availability and integrity.
Mitigation strategies for this vulnerability focus on kernel-level patches and system configuration adjustments to prevent the race condition from occurring. The most effective approach involves applying the official kernel patch that addresses the synchronization issue in the memory management subsystem, specifically targeting how the kernel handles the interaction between exec operations and core dump generation in multi-threaded environments. System administrators should also consider implementing process isolation measures and monitoring for unusual thread behavior that might indicate the race condition is occurring. Additionally, the vulnerability highlights the importance of proper thread synchronization practices in kernel development, aligning with best practices outlined in the Common Weakness Enumeration (CWE) category CWE-362 for concurrent execution issues. The ATT&CK framework would categorize this vulnerability under privilege escalation and denial of service techniques, as it allows local users to disrupt system operations and potentially gain unauthorized access to system resources through careful exploitation of the race condition.