CVE-2005-3847 in Linux
Summary
by MITRE
The handle_stop_signal function in signal.c in Linux kernel 2.6.11 up to other versions before 2.6.13 and 2.6.12.6 allows local users to cause a denial of service (deadlock) by sending a SIGKILL to a real-time threaded process while it is performing a core dump.
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Analysis
by VulDB Data Team • 05/17/2025
The vulnerability described in CVE-2005-3847 represents a critical race condition and deadlock scenario within the Linux kernel's signal handling mechanism. This flaw exists in kernel versions between 2.6.11 and 2.6.12.6, specifically affecting the handle_stop_signal function located in the signal.c file. The vulnerability manifests when a local attacker sends a SIGKILL signal to a real-time threaded process that is in the midst of performing a core dump operation, creating a situation where the kernel becomes unresponsive due to circular locking dependencies. The technical implementation involves the kernel's inability to properly manage the interaction between signal processing and core dump operations, particularly when the process is already in a critical state of resource allocation and process termination.
The operational impact of this vulnerability extends beyond simple denial of service to encompass system stability and availability concerns. When exploited, the vulnerability creates a deadlock condition that prevents the kernel from properly terminating the targeted process, effectively rendering the system unresponsive to further signal processing operations. This occurs because the kernel's locking mechanisms become intertwined during the core dump process, with the SIGKILL signal attempting to acquire locks that are already held by the core dump operation, resulting in a circular wait condition. The vulnerability is particularly dangerous in multi-threaded environments where real-time processes are common, as it can cascade into broader system instability and prevent legitimate system administration tasks from completing successfully.
From a security perspective, this vulnerability aligns with CWE-362, which describes concurrent execution using shared resources with insufficient synchronization, and represents a classic example of a race condition in kernel space. The attack vector requires local access to the system, making it a privilege escalation concern rather than a remote exploit, though it can be leveraged to maintain persistent denial of service conditions. The vulnerability demonstrates the complexity of kernel-level signal handling and process management, where seemingly simple operations like core dumps can create intricate locking dependencies that are difficult to resolve without careful design considerations. The exploitability of this vulnerability is enhanced in real-time systems where process priority and threading behaviors are critical, as these environments often involve more complex locking scenarios that can be triggered by the specific sequence of events described.
The mitigation strategy for CVE-2005-3847 involves upgrading to kernel versions 2.6.13 or 2.6.12.6, which contain the necessary patches to resolve the locking dependencies in the handle_stop_signal function. System administrators should prioritize this update, particularly in environments where real-time processes are common or where system stability is paramount. Additionally, monitoring for processes that are frequently performing core dumps and may be vulnerable to this race condition can help identify potential exploitation attempts. The fix implemented by the kernel developers addresses the underlying synchronization issue by ensuring proper lock ordering and preventing the circular wait condition that led to the deadlock. This vulnerability serves as a reminder of the importance of careful kernel design and testing, particularly for systems that handle multiple concurrent operations and complex resource management scenarios. Organizations should implement regular kernel update policies and maintain awareness of security advisories related to kernel-level vulnerabilities, as these issues can have far-reaching impacts on system availability and overall security posture. The vulnerability also highlights the need for comprehensive testing of signal handling mechanisms in multi-threaded environments where process lifecycle management becomes increasingly complex.