CVE-2013-3302 in Linux
Summary
by MITRE
Race condition in the smb_send_rqst function in fs/cifs/transport.c in the Linux kernel before 3.7.2 allows local users to cause a denial of service (NULL pointer dereference and OOPS) or possibly have unspecified other impact via vectors involving a reconnection event.
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Analysis
by VulDB Data Team • 05/06/2018
The vulnerability identified as CVE-2013-3302 represents a critical race condition within the Linux kernel's Server Message Block implementation, specifically affecting the smb_send_rqst function in the fs/cifs/transport.c file. This flaw exists in kernel versions prior to 3.7.2 and demonstrates a fundamental timing issue that can be exploited by local attackers to compromise system stability and potentially achieve more severe consequences. The vulnerability stems from improper handling of concurrent operations during network reconnection events, creating a window where multiple threads or processes can interfere with each other's execution paths.
The technical implementation of this race condition occurs when the smb_send_rqst function processes requests during SMB network reconnection scenarios. Under normal circumstances, the function should maintain proper synchronization between connection state changes and request processing. However, the race condition allows for a situation where a connection object may be freed or set to NULL while another thread attempts to access it, resulting in a NULL pointer dereference. This specific flaw falls under CWE-362, which categorizes race conditions as a well-known weakness in software design where multiple threads or processes access shared resources concurrently without proper synchronization mechanisms. The vulnerability manifests as a kernel oops, which represents a critical system error that typically results in system instability and requires immediate rebooting.
The operational impact of CVE-2013-3302 extends beyond simple denial of service, as local attackers can leverage this weakness to cause system crashes or potentially achieve privilege escalation. When a NULL pointer dereference occurs in kernel space, the system experiences an oops condition that can lead to complete system lockup or reboot, effectively creating a denial of service scenario that can be exploited repeatedly. The vulnerability is particularly concerning because it exists within the core SMB transport layer, which is commonly used in enterprise environments for file sharing and network access. Attackers can exploit this condition by triggering reconnection events while simultaneously initiating SMB requests, creating the timing window necessary to cause the race condition. This vulnerability aligns with ATT&CK technique T1068, which covers 'Local Privilege Escalation' through race conditions, as the kernel-level exploitation can potentially allow attackers to gain elevated privileges.
Mitigation strategies for CVE-2013-3302 require immediate kernel updates to versions 3.7.2 or later, where the race condition has been properly addressed through improved synchronization mechanisms. System administrators should prioritize patching affected systems, particularly those running older kernel versions that may be processing SMB network connections. Additionally, monitoring for unusual reconnection patterns or system oops messages can help detect exploitation attempts. The fix implemented by the kernel developers typically involves adding proper locking mechanisms around the connection state transitions and ensuring that all references to connection objects are validated before access. Organizations should also consider implementing network segmentation and access controls to limit local user privileges, reducing the attack surface for potential exploitation. The vulnerability demonstrates the importance of thorough testing for race conditions in kernel-level code, particularly in network protocols where timing and state management are critical factors for system stability and security.