CVE-2014-9529 in Android
Summary
by MITRE
Race condition in the key_gc_unused_keys function in security/keys/gc.c in the Linux kernel through 3.18.2 allows local users to cause a denial of service (memory corruption or panic) or possibly have unspecified other impact via keyctl commands that trigger access to a key structure member during garbage collection of a key.
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Analysis
by VulDB Data Team • 09/15/2022
The vulnerability described in CVE-2014-9529 represents a critical race condition within the Linux kernel's key management subsystem, specifically affecting versions through 3.18.2. This flaw exists in the key_gc_unused_keys function located in security/keys/gc.c, where concurrent access patterns during key garbage collection create exploitable conditions that can lead to system instability and potential privilege escalation. The race condition manifests when local users execute keyctl commands that simultaneously access key structure members while the garbage collection process is actively processing key structures, creating a window where memory integrity can be compromised. This vulnerability operates at the kernel level and affects the fundamental security architecture that manages cryptographic keys and credentials within the Linux operating system.
The technical implementation of this race condition stems from insufficient synchronization mechanisms during key garbage collection operations. When multiple threads or processes attempt to access key structures while the garbage collector is in progress, the key_gc_unused_keys function fails to properly serialize access to shared key data structures. This lack of proper mutual exclusion allows for concurrent read and write operations on the same key metadata, potentially leading to memory corruption where key structure pointers become invalid or inconsistent. The vulnerability is particularly dangerous because it can be triggered through legitimate user-space keyctl commands, making exploitation straightforward and accessible to local attackers without requiring special privileges or complex attack vectors. The race condition creates a scenario where key structure members may be freed or reallocated while other processes are attempting to access them, resulting in unpredictable behavior that can manifest as system panics, memory corruption, or denial of service conditions.
The operational impact of CVE-2014-9529 extends beyond simple denial of service, as it can potentially enable more severe consequences including system crashes that require manual rebooting and recovery procedures. Local users who exploit this vulnerability can effectively disrupt system operations by causing kernel memory corruption that may lead to complete system panics or lockups. In certain scenarios, the memory corruption could potentially be leveraged to execute arbitrary code within kernel space, though this would require additional conditions and is not guaranteed by the race condition alone. The vulnerability affects the integrity of the kernel's key management system, which is critical for maintaining system security and credential handling across various security contexts including authentication, encryption, and access control mechanisms. This flaw directly impacts the reliability and security posture of Linux systems, particularly those running kernel versions within the affected range, and creates opportunities for attackers to disrupt normal system operations or potentially gain elevated privileges.
Mitigation strategies for CVE-2014-9529 primarily involve upgrading to patched kernel versions where the race condition has been resolved through proper synchronization mechanisms and mutex locking. System administrators should prioritize updating their kernel installations to versions that include the necessary fixes, typically found in kernel releases following 3.18.2. The fix implementation involves adding appropriate locking mechanisms to ensure that key structure access is properly serialized during garbage collection operations, preventing concurrent access patterns that lead to the race condition. Additional defensive measures include implementing proper system monitoring to detect unusual keyctl command usage patterns that might indicate exploitation attempts, as well as maintaining robust backup and recovery procedures to handle potential system crashes. Organizations should also consider implementing least privilege principles for keyctl usage and monitoring access to key management interfaces to minimize the attack surface. This vulnerability aligns with CWE-362, which describes race conditions in concurrent programming, and may map to ATT&CK techniques involving privilege escalation and system compromise through kernel-level vulnerabilities. Regular kernel updates and security audits remain the most effective long-term mitigation strategy to address this and similar vulnerabilities in the Linux kernel's security subsystem.