Linux Kernel x86 Fix: Clear CPU Buffers After Register Restore in NMI Return to Fix RDFS Mitigation

From this webpage screenshot, we can extract the following key information about the vulnerability: 1. Vulnerability Description: - Title: x86/entry_32: Clear CPU buffers after register restore in NMI return - Description: CPU buffers are cleared after NMI return, but prior to that, register state has not yet been restored. This may be effective for MDS (Microarchitectural Data Sampling) mitigations, but ineffective for RDFS (Return Data Flow Sampling) mitigations, as RDFS mitigations require clearing CPU buffers only when registers do not contain sensitive data. 2. Fix Measures: - Move the CLEAR_CPU_BUFFERS operation to after RESTORE_ALL_NMI. 3. Fix Patch: - Git hash of the fix patch: - Download link for the patch: linux-227358e89703c344008119be7e8ffa3fdb5b92de.tar.gz 4. Patch Content: - The content of the fix patch is displayed on the right side of the webpage, including code to clear CPU buffers after NMI return. 5. Patch Status: - The patch has been merged into upstream. 6. Related Patches and Recommendations: - Git hash of related patch: - Download link for the patch: commit 48a2440d0f20c826b884e04377ccc1e4696c84e9 upstream 7. Authors and Contributors: - Author: Pawan Gupta - Contributor: Dave Hansen 8. Patch Status: - The patch has been merged into upstream. With this information, we can understand the fix process and specific contents of the patch, enabling further analysis and verification.

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Linux Kernel x86 Fix: Clear CPU Buffers After Register Restore in NMI Return to Fix RDFS Mitigation