CVE-2006-2629 in Linux
Summary
by MITRE
Race condition in Linux kernel 2.6.15 to 2.6.17, when running on SMP platforms, allows local users to cause a denial of service (crash) by creating and exiting a large number of tasks, then accessing the /proc entry of a task that is exiting, which causes memory corruption that leads to a failure in the prune_dcache function or a BUG_ON error in include/linux/list.h.
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Analysis
by VulDB Data Team • 01/21/2025
This vulnerability represents a critical race condition within the Linux kernel's memory management subsystem that specifically affects versions 2.6.15 through 2.6.17 when operating on symmetric multiprocessing platforms. The flaw occurs during the interaction between process cleanup operations and the dynamic cache management system, creating a window where concurrent access patterns can lead to system instability. The vulnerability is particularly concerning because it allows local users to trigger a denial of service condition through relatively simple exploitation techniques that do not require elevated privileges.
The technical implementation of this vulnerability stems from improper synchronization mechanisms within the kernel's task management and memory cache subsystems. When a large number of processes are created and terminated rapidly, the kernel's dcache (directory cache) management functions become vulnerable to race conditions during the cleanup phase. Specifically, the prune_dcache function and the BUG_ON macro in include/linux/list.h become targets for memory corruption when accessing /proc entries of tasks that are in the process of exiting. This corruption occurs because the kernel fails to properly lock critical sections during the transition period between task creation and destruction, allowing concurrent access to already freed or partially freed memory structures.
The operational impact of this vulnerability extends beyond simple system crashes to potentially destabilize entire computing environments where multiple processes are actively created and destroyed. In production systems, this could manifest as unexpected system reboots, application failures, or complete service outages when the race condition is triggered through normal system operations or malicious exploitation. The vulnerability's local nature means that any user with access to the system can potentially trigger the condition, making it particularly dangerous in multi-user environments where privilege escalation is not required. The timing of the race condition makes detection difficult as it may not occur consistently under all system loads or configurations.
Mitigation strategies for this vulnerability require immediate kernel updates to versions that contain the appropriate fixes for the race condition. System administrators should prioritize patching affected systems and monitor for any signs of exploitation attempts. The fix typically involves implementing proper locking mechanisms around the dcache cleanup operations and ensuring that access to /proc entries of exiting processes is properly synchronized. Organizations should also consider implementing process monitoring and anomaly detection systems to identify unusual patterns of process creation and destruction that might indicate exploitation attempts. This vulnerability aligns with CWE-362 which describes race conditions in security-critical code sections, and represents a significant concern for the ATT&CK framework's privilege escalation and denial of service techniques, particularly in the context of kernel-level attacks that can compromise system availability and stability.