CVE-2011-1746 in Linux
Summary
by MITRE
Multiple integer overflows in the (1) agp_allocate_memory and (2) agp_create_user_memory functions in drivers/char/agp/generic.c in the Linux kernel before 2.6.38.5 allow local users to trigger buffer overflows, and consequently cause a denial of service (system crash) or possibly have unspecified other impact, via vectors related to calls that specify a large number of memory pages.
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Analysis
by VulDB Data Team • 11/06/2021
The vulnerability described in CVE-2011-1746 represents a critical integer overflow issue within the Linux kernel's graphics processing unit memory management subsystem. This flaw exists in the generic agp (Accelerated Graphics Port) driver implementation located in drivers/char/agp/generic.c, affecting kernel versions prior to 2.6.38.5. The vulnerability specifically impacts two core functions: agp_allocate_memory and agp_create_user_memory, which handle memory allocation requests for graphics hardware acceleration. These functions fail to properly validate input parameters when processing large memory page requests, creating opportunities for integer overflow conditions that can lead to serious system instability.
The technical exploitation of this vulnerability occurs when local users submit malicious requests specifying an excessive number of memory pages to the AGP memory allocation functions. Integer overflows in the kernel's memory management code cause the calculated buffer sizes to wrap around to small values, resulting in insufficient memory allocation for the actual data structures. This creates buffer overflow conditions where subsequent memory operations write beyond allocated boundaries, potentially corrupting kernel memory structures. The vulnerability is particularly dangerous because it operates within kernel space, allowing attackers to manipulate critical system resources and potentially escalate privileges beyond the initial local access vector.
The operational impact of CVE-2011-1746 manifests primarily as system crashes and denial of service conditions, but the potential for more severe consequences cannot be ruled out. When the integer overflow occurs during memory allocation, the kernel's memory management subsystem becomes corrupted, leading to system panics and complete system crashes. The vulnerability affects systems utilizing AGP graphics hardware, which were prevalent in desktop and server environments during the affected kernel versions. Attackers can leverage this vulnerability to repeatedly crash systems, creating persistent denial of service conditions that can severely impact system availability and reliability.
The vulnerability aligns with CWE-190, which classifies integer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1068, which covers exploit for privilege escalation. The flaw represents a classic kernel-level buffer overflow vulnerability that can be exploited to compromise system stability and potentially achieve privilege escalation. System administrators should prioritize patching affected kernel versions to prevent exploitation, as the vulnerability provides local users with direct access to critical kernel memory management functions. The recommended mitigation strategy involves updating to Linux kernel version 2.6.38.5 or later, where the integer overflow conditions have been properly addressed through enhanced input validation and proper boundary checking in the affected AGP memory allocation functions.