CVE-2011-1023 in Linux
Summary
by MITRE
The Reliable Datagram Sockets (RDS) subsystem in the Linux kernel before 2.6.38 does not properly handle congestion map updates, which allows local users to cause a denial of service (BUG_ON and system crash) via vectors involving (1) a loopback (aka loop) transmit operation or (2) an InfiniBand (aka ib) transmit operation.
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Analysis
by VulDB Data Team • 12/05/2021
The vulnerability identified as CVE-2011-1023 resides within the Reliable Datagram Sockets RDS subsystem of the Linux kernel, specifically affecting versions prior to 2.6.38. This flaw represents a critical design oversight in how the kernel handles congestion map updates, creating a pathway for local privilege escalation through denial of service attacks that can result in system crashes. The RDS protocol is designed to provide reliable datagram communication over networks, particularly leveraging InfiniBand hardware for high-performance computing environments, making this vulnerability particularly concerning for enterprise and high-performance computing deployments.
The technical flaw manifests when the kernel fails to properly validate or process congestion map updates within the RDS subsystem during specific transmission operations. When local users execute crafted loopback transmit operations or InfiniBand transmit operations, the subsystem encounters a condition that triggers the BUG_ON macro, which is a kernel debugging mechanism designed to catch programming errors. This improper handling of congestion information leads to kernel panic conditions where the system becomes unresponsive and requires manual reboot to recover. The vulnerability stems from inadequate input validation and state management within the kernel's network subsystem, particularly in how it processes network congestion information during data transmission.
The operational impact of this vulnerability extends beyond simple system crashes as it provides local attackers with a reliable method to disrupt system availability through carefully constructed network operations. Since the vulnerability is accessible through local user accounts, it can be exploited without network access or specialized privileges, making it particularly dangerous in multi-user environments. The exploitation process involves leveraging the RDS subsystem's specific transmit operations to trigger the malformed congestion map handling, which then causes the kernel to enter an unrecoverable state. This type of vulnerability directly violates the principle of least privilege and can be used to create persistent denial of service conditions that impact system reliability and availability.
Mitigation strategies for CVE-2011-1023 primarily focus on kernel version upgrades to 2.6.38 or later, where the vulnerability has been addressed through proper congestion map handling and validation. System administrators should implement immediate patch management procedures to update affected systems, particularly in environments where InfiniBand or loopback network operations are actively used. Additional defensive measures include monitoring for unusual network activity patterns that might indicate exploitation attempts, implementing proper access controls to limit local user privileges, and considering disabling RDS functionality if it is not required for specific system operations. This vulnerability aligns with CWE-129, which addresses improper validation of array indices, and maps to ATT&CK technique T1499.004 for network denial of service, emphasizing the need for comprehensive system hardening and kernel security updates to maintain operational resilience against such attacks.