CVE-2023-52812 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd: check num of link levels when update pcie param
In SR-IOV environment, the value of pcie_table->num_of_link_levels will be 0, and num_of_levels - 1 will cause array index out of bounds
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability identified as CVE-2023-52812 resides within the Linux kernel's display subsystem, specifically affecting the amdgpu driver's implementation of the DisplayPort Configuration (DPCD) link training mechanism. This flaw manifests in Single Root I/O Virtualization (SR-IOV) environments where the PCIe topology information is incorrectly processed, leading to potential system instability and security implications. The vulnerability stems from inadequate validation of PCIe link level parameters during the dynamic update of PCIe configuration parameters, particularly when the num_of_link_levels field is set to zero in virtualized environments.
The technical root cause involves a classic buffer overflow condition occurring when the driver attempts to access array elements using an invalid index calculation. Specifically, when processing PCIe table data in SR-IOV contexts, the code calculates num_of_levels - 1 to determine an array index, but fails to validate that num_of_link_levels is greater than zero before performing this arithmetic operation. This results in an array index out of bounds access when num_of_link_levels equals zero, which is a legitimate value in virtualized environments where the PCIe topology information may be incomplete or unavailable. The flaw operates at the kernel level within the graphics subsystem, making it particularly dangerous as it can lead to privilege escalation or system crashes that compromise the integrity of the entire computing environment.
The operational impact of this vulnerability extends beyond simple system instability, as it represents a critical security weakness in virtualized graphics environments where multiple tenants share the same physical hardware. Attackers could potentially exploit this condition to cause denial of service attacks against virtual machines running graphics-intensive workloads, or in more sophisticated scenarios, leverage the memory corruption to execute arbitrary code with kernel privileges. The vulnerability particularly affects systems using AMD graphics hardware in virtualized environments, making it relevant to cloud computing platforms, containerized applications, and enterprise virtualization deployments where SR-IOV is commonly implemented for performance optimization. This weakness aligns with CWE-129, which describes improper validation of array index bounds, and can be mapped to ATT&CK technique T1068, representing the exploitation of system privileges through kernel vulnerabilities.
Mitigation strategies for CVE-2023-52812 should focus on implementing proper input validation and bounds checking within the amdgpu driver's PCIe configuration handling code. System administrators should ensure that all Linux kernel updates are applied promptly, particularly those containing the patched drm/amd driver code that includes proper validation of num_of_link_levels before array indexing operations. The fix involves adding conditional checks to verify that num_of_link_levels is greater than zero before performing the calculation that leads to the out-of-bounds access, effectively preventing the array corruption. Organizations using SR-IOV configurations should also consider implementing additional monitoring for graphics-related kernel panics or system crashes that may indicate exploitation attempts. Network segmentation and privilege separation practices should be maintained to limit the potential impact of successful exploitation, while regular vulnerability assessments should be conducted to identify similar flaws in other kernel subsystems. The patched implementation should be tested thoroughly in virtualized environments to ensure that legitimate zero values are handled correctly without breaking existing functionality.