CVE-2023-52815 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/vkms: fix a possible null pointer dereference
In amdgpu_vkms_conn_get_modes(), the return value of drm_cvt_mode() is assigned to mode, which will lead to a NULL pointer dereference on failure of drm_cvt_mode(). Add a check to avoid null pointer dereference.
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Analysis
by VulDB Data Team • 11/22/2025
The vulnerability identified as CVE-2023-52815 resides within the Linux kernel's amdgpu driver subsystem, specifically affecting the vkms (Virtual Kernel Mode Setting) component. This issue manifests as a potential null pointer dereference that could compromise system stability and security. The vulnerability occurs in the amdgpu_vkms_conn_get_modes() function where the return value from drm_cvt_mode() is directly assigned to a mode variable without proper validation. When drm_cvt_mode() fails to generate a valid mode structure, it returns NULL, but the calling function does not check this condition before proceeding with operations that assume a valid pointer. This flaw represents a classic null pointer dereference vulnerability that can lead to kernel crashes or potentially exploitable conditions. The vulnerability is categorized under CWE-476 as a null pointer dereference, which is a common class of software defects that can result in system instability and denial of service conditions. The attack surface for this vulnerability is primarily within graphics driver operations, specifically when handling display mode configurations in virtualized graphics environments. The impact extends to systems utilizing AMDGPU graphics hardware with virtualized display capabilities, where the vkms driver is actively managing display modes and connections. When this vulnerability is exploited or triggered through normal operation, it can cause the kernel to crash due to attempting to dereference a NULL pointer, leading to a system panic or reboot. This represents a denial of service condition that could be particularly problematic in server environments or embedded systems where continuous operation is critical. The vulnerability demonstrates a failure in proper error handling and input validation within kernel space code, where the assumption that drm_cvt_mode() will always succeed leads to dangerous code execution paths. The vulnerability is particularly concerning because it operates within kernel space, where such defects can have far-reaching consequences beyond simple application crashes, potentially affecting system integrity and availability. This issue highlights the importance of rigorous input validation and error handling in kernel code, particularly in graphics drivers that must manage complex display configurations and mode negotiations. The fix implemented addresses this by adding a null pointer check after calling drm_cvt_mode(), ensuring that the mode variable is validated before any operations are performed on it. This approach aligns with the defensive programming principles recommended by the ATT&CK framework for kernel-level security, where proper error handling and validation are essential to prevent exploitation. The vulnerability also relates to the broader category of kernel memory safety issues that can be leveraged for privilege escalation or system compromise, making it a significant concern for system administrators and security professionals managing Linux-based systems with AMDGPU hardware. The fix demonstrates the critical need for thorough testing of error conditions in kernel drivers, particularly those handling hardware-specific operations like display mode generation and management. This vulnerability serves as an example of how seemingly minor oversight in error handling can lead to serious system stability issues, emphasizing the importance of comprehensive testing and code review processes for kernel components. The resolution of this vulnerability through proper null pointer validation represents a standard security hardening practice that aligns with industry best practices for maintaining kernel stability and preventing potential exploitation. The fix ensures that the kernel's graphics subsystem maintains proper operational integrity when encountering edge cases in display mode generation, thereby preventing both system crashes and potential security implications that could arise from improper error handling in kernel space operations.