CVE-2024-26914 in Linux
Summary
by MITRE • 04/17/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: fix incorrect mpc_combine array size
[why]
MAX_SURFACES is per stream, while MAX_PLANES is per asic. The mpc_combine is an array that records all the planes per asic. Therefore MAX_PLANES should be used as the array size. Using MAX_SURFACES causes array overflow when there are more than 3 planes.
[how]
Use the MAX_PLANES for the mpc_combine array size.
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Analysis
by VulDB Data Team • 09/16/2025
The vulnerability CVE-2024-26914 represents a critical memory management flaw within the AMD display driver component of the Linux kernel's direct rendering manager subsystem. This issue specifically affects the mpc_combine array initialization within the display multi-plane composition functionality, creating a potential for buffer overflow conditions that could compromise system stability and security. The flaw exists in the drm/amd/display driver module where the array size calculation incorrectly uses MAX_SURFACES instead of MAX_PLANES, leading to memory corruption when handling display configurations with more than three planes per asic.
The technical root cause of this vulnerability stems from a fundamental mismatch between the conceptual definitions of system resources and their implementation within the driver's memory allocation strategy. MAX_SURFACES represents the maximum number of surfaces that can be associated with a single display stream, while MAX_PLANES correctly reflects the hardware limitation of planes that can be processed by a given asic. When the driver attempts to manage display composition for configurations exceeding three planes, the mpc_combine array becomes insufficiently sized, causing memory overflows that can result in arbitrary code execution or system crashes. This type of error falls under the CWE-121 CWE category for stack-based buffer overflow, though it manifests as a heap-based issue due to dynamic array allocation patterns.
The operational impact of this vulnerability extends beyond simple system instability to encompass potential security implications for systems utilizing AMD graphics hardware. An attacker could exploit this condition by crafting specific display configurations that trigger the overflow during normal operation, potentially leading to privilege escalation or denial of service scenarios. The vulnerability affects Linux kernel versions that include the drm/amd/display subsystem, particularly impacting systems with AMD Radeon graphics cards that support multi-plane display outputs. This issue is particularly concerning in enterprise environments where display management systems may be subjected to complex rendering scenarios involving multiple overlapping planes. The vulnerability demonstrates the critical importance of proper resource management in graphics driver code, where incorrect assumptions about hardware capabilities can lead to serious security consequences.
Mitigation strategies for CVE-2024-26914 should focus on applying the official kernel patch that corrects the array size calculation by using MAX_PLANES instead of MAX_SURFACES for the mpc_combine array initialization. System administrators should prioritize updating their kernel versions to include the fix, particularly in environments where AMD graphics hardware is extensively used. Additional protective measures include implementing proper input validation for display configuration parameters and monitoring for unusual graphics driver behavior that might indicate exploitation attempts. Organizations should also consider implementing runtime protections such as stack canaries or address space layout randomization to mitigate potential exploitation of similar memory corruption vulnerabilities. The fix aligns with industry best practices for kernel security and represents a standard approach to correcting resource allocation errors in graphics subsystems, following established patterns for memory safety in kernel space drivers. This vulnerability highlights the importance of thorough code review processes for graphics driver components and demonstrates how seemingly minor configuration errors can create significant security risks in operating system subsystems.