Compliance Impact

This vulnerability involves a potential data leak where the GPU can read stale sensitive data directly from DRAM, bypassing CPU caches. Such a leak of sensitive data from previously freed pages of other processes could potentially impact compliance with data protection regulations like GDPR and HIPAA, which require the protection of sensitive and personal data from unauthorized access or disclosure.

However, the provided information does not explicitly discuss compliance with any specific standards or regulations.

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Executive Summary

This vulnerability exists in the Linux kernel's drm/xe/uapi component where the system fails to properly reject a specific PAT (Page Attribute Table) index called coh_none for CPU cached memory in the madvise operation.

The issue arises because using the coh_none coherency mode with CPU cached buffers is a security problem. When the kernel clears pages before reallocating them, the clearing operation remains in the CPU cache as dirty data. However, the GPU using coh_none can bypass the CPU caches and directly read stale sensitive data from DRAM. This can lead to leaking data from previously freed pages belonging to other processes.

The fix involves adding validation in the xe_vm_madvise_ioctl() function to reject PAT indices with the XE_COH_NONE coherency mode when applied to CPU cached memory, preventing this data leakage.

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Impact Analysis

This vulnerability can lead to sensitive data leakage between processes on the same system. Specifically, because the GPU can bypass CPU caches and read stale data directly from DRAM, it may access information that was previously stored in memory pages freed by other processes.

Such data leakage could expose confidential information, potentially compromising user privacy and security.

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Mitigation Strategies

The vulnerability has been resolved by adding validation in the Linux kernel's xe_vm_madvise_ioctl() function to reject PAT indices with XE_COH_NONE coherency mode when applied to CPU cached memory.

To mitigate this vulnerability immediately, you should update your Linux kernel to a version that includes this fix.

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