CVE-2011-2022 in Linux
Summary
by MITRE
The agp_generic_remove_memory function in drivers/char/agp/generic.c in the Linux kernel before 2.6.38.5 does not validate a certain start parameter, which allows local users to gain privileges or cause a denial of service (system crash) via a crafted AGPIOC_UNBIND agp_ioctl ioctl call, a different vulnerability than CVE-2011-1745.
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Analysis
by VulDB Data Team • 11/07/2021
The vulnerability identified as CVE-2011-2022 resides within the Linux kernel's AGP (Accelerated Graphics Port) subsystem, specifically in the agp_generic_remove_memory function located in drivers/char/agp/generic.c. This flaw represents a critical security issue that affects Linux kernel versions prior to 2.6.38.5, where the kernel fails to properly validate the start parameter during AGP memory management operations. The vulnerability is particularly concerning because it operates at the kernel level, providing potential attackers with direct access to core system functions that manage graphics memory allocation and deallocation.
The technical flaw manifests when a local user executes a crafted AGPIOC_UNBIND agp_ioctl ioctl call without proper parameter validation. This function is responsible for removing AGP memory mappings from the system, but due to the missing validation of the start parameter, an attacker can manipulate this value to cause unpredictable behavior within the kernel's memory management subsystem. The lack of input validation creates a path for privilege escalation where malicious users can potentially elevate their privileges from standard user level to root access, or alternatively trigger a system crash that results in denial of service conditions. This vulnerability falls under CWE-129, Input Validation, as it represents a failure to validate input parameters before processing them within kernel space.
The operational impact of this vulnerability extends beyond simple privilege escalation or denial of service scenarios. When exploited, the vulnerability can lead to complete system compromise, as attackers gain the ability to manipulate kernel memory structures directly. The AGP subsystem is critical for graphics hardware acceleration, and compromising this functionality allows attackers to potentially corrupt system memory, manipulate graphics drivers, or even bypass kernel security mechanisms. The vulnerability demonstrates the dangerous nature of kernel-level flaws where insufficient validation of user-supplied parameters can result in arbitrary code execution or system instability. According to ATT&CK framework, this vulnerability maps to T1068, Valid Accounts, and T1059, Command and Scripting Interpreter, as attackers can leverage the privilege escalation to gain elevated system access and execute malicious code within kernel space.
Mitigation strategies for CVE-2011-2022 primarily focus on kernel updates and system hardening measures. The most effective solution involves upgrading to Linux kernel version 2.6.38.5 or later, where the validation issue has been addressed through proper parameter checking in the agp_generic_remove_memory function. System administrators should also implement strict access controls for AGP-related interfaces and consider disabling unnecessary AGP functionality when not required for system operation. Additional protective measures include monitoring for suspicious AGPIOC_UNBIND ioctl calls, implementing kernel module signing requirements, and maintaining comprehensive system logging to detect potential exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel space operations and serves as a reminder of the critical security implications that can arise from seemingly minor validation oversights in core system components.