CVE-2009-3620 in Linux
Summary
by MITRE
The ATI Rage 128 (aka r128) driver in the Linux kernel before 2.6.31-git11 does not properly verify Concurrent Command Engine (CCE) state initialization, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly gain privileges via unspecified ioctl calls.
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Analysis
by VulDB Data Team • 08/24/2021
The CVE-2009-3620 vulnerability resides within the ATI Rage 128 graphics driver implementation in the Linux kernel, specifically affecting versions prior to 2.6.31-git11. This flaw manifests in the driver's insufficient validation of Concurrent Command Engine state initialization, creating a critical security gap that impacts system stability and potentially enables privilege escalation. The vulnerability is particularly concerning as it affects the core graphics subsystem that many Linux distributions rely upon for proper system operation. The r128 driver, designed for older ATI graphics hardware, continues to be included in kernel distributions for backward compatibility reasons, making this a persistent threat vector that remains relevant in legacy system environments.
The technical exploitation of this vulnerability occurs through unspecified ioctl system calls that interact with the graphics driver's Concurrent Command Engine functionality. When the driver fails to properly verify CCE state initialization, it creates conditions where a local attacker can manipulate the graphics subsystem to trigger a NULL pointer dereference. This type of error represents a classic kernel-level memory corruption vulnerability that can lead to immediate system crashes or more sophisticated exploitation scenarios. The vulnerability's classification as a NULL pointer dereference aligns with CWE-476, which specifically addresses the dereferencing of null pointers in software systems. The improper state validation creates a condition where the driver operates with uninitialized or improperly configured hardware state, leading to unpredictable behavior when processing graphics commands.
From an operational impact perspective, this vulnerability presents a significant risk to system availability and potentially system integrity. The local user can cause a denial of service through system crashes, effectively rendering the affected system unusable until reboot. This type of attack is particularly dangerous in multi-user environments where a malicious user could disrupt system operations or in embedded systems where availability is critical. The potential for privilege escalation, while not definitively confirmed in the original report, represents a serious concern given that graphics drivers often operate with elevated privileges and have direct access to hardware resources. The vulnerability's impact extends beyond simple service disruption to potentially enabling more sophisticated attacks that could compromise system security.
Mitigation strategies for CVE-2009-3620 primarily involve kernel version upgrades to 2.6.31-git11 or later, where the driver properly validates CCE state initialization. System administrators should prioritize patching affected systems, particularly those running legacy kernel versions that continue to support the r128 driver for compatibility reasons. In environments where upgrading is not immediately feasible, implementing additional access controls and monitoring for suspicious ioctl activity can provide some protection. The vulnerability's nature as a kernel-level flaw means that traditional application-level security measures are insufficient, requiring system-level interventions. Organizations should also consider implementing hardware abstraction layers or virtualization strategies that can isolate graphics processing from core system operations. Security monitoring should include detection of unusual graphics driver behavior and potential NULL pointer dereference patterns, aligning with ATT&CK technique T1059 for system command execution and T1499 for endpoint denial of service.
The broader implications of this vulnerability highlight the importance of proper driver validation and state management in kernel space code. Graphics drivers, due to their direct hardware interaction requirements, represent complex attack surfaces that require rigorous security validation. This vulnerability demonstrates how seemingly minor state validation issues can lead to catastrophic system failures and potential privilege escalation. The issue also underscores the challenges of maintaining legacy driver support while ensuring security, as many organizations continue to operate systems with outdated graphics drivers for compatibility reasons. Proper security testing of kernel modules, particularly those with direct hardware access, should include comprehensive state validation and error condition testing to prevent similar vulnerabilities from being introduced in future implementations.