CVE-2005-3107 in Linux
Summary
by MITRE
fs/exec.c in Linux 2.6, when one thread is tracing another thread that shares the same memory map, might allow local users to cause a denial of service (deadlock) by forcing a core dump when the traced thread is in the TASK_TRACED state.
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Analysis
by VulDB Data Team • 06/23/2019
The vulnerability described in CVE-2005-3107 represents a critical race condition and deadlock scenario within the Linux kernel's process tracing mechanisms. This flaw exists in the fs/exec.c file of Linux kernel version 2.6 and specifically affects systems where multiple threads share the same memory mapping while one thread is actively tracing another. The vulnerability arises from the improper handling of process states during core dump generation when tracing is involved, creating a situation where the kernel can become unresponsive due to circular dependency conditions between tracing and memory management subsystems.
The technical implementation of this vulnerability stems from the kernel's handling of the TASK_TRACED state, which occurs when a process is being traced by another process or thread. When a traced thread enters this state and a core dump is initiated, the kernel's memory management and process tracing subsystems can become entangled in a deadlock condition. This happens because the core dump mechanism attempts to access memory pages that are already locked or in a state that prevents proper cleanup, while the tracing mechanism itself is waiting for resources that are being held by the core dump process. The shared memory mapping between threads exacerbates this issue by creating additional synchronization points that can lead to circular waits, a classic deadlock scenario that violates fundamental operating system design principles.
The operational impact of this vulnerability is severe for local attackers who can exploit it to cause a denial of service condition on affected systems. By forcing a core dump while a thread is in the TASK_TRACED state, an attacker can effectively freeze the system's ability to manage processes, leading to complete system unresponsiveness. This vulnerability is particularly dangerous in multi-threaded environments or systems where process tracing is actively used, such as debugging environments, security monitoring systems, or applications that rely on ptrace for process control. The denial of service can persist until system reboot, making it a particularly insidious threat that can be exploited to disrupt critical services without requiring elevated privileges.
Mitigation strategies for this vulnerability require careful kernel patching and system hardening measures to prevent the conditions that lead to deadlock. The primary solution involves applying the official kernel patches that address the race condition in the fs/exec.c file by properly handling the TASK_TRACED state transitions and ensuring that core dump operations do not interfere with tracing mechanisms. System administrators should also consider implementing process tracing restrictions, particularly in environments where multiple threads share memory mappings, and monitor for unusual core dump patterns that might indicate exploitation attempts. From a security perspective, this vulnerability aligns with CWE-362, which describes concurrent execution using shared resource access issues, and relates to ATT&CK technique T1490, which covers execution through system binary modifications that could be used to exploit similar kernel-level race conditions. Organizations should also implement proper system monitoring to detect potential deadlock conditions and maintain regular kernel updates to address known vulnerabilities in their Linux environments.