Linux Kernel Vulnerability in KVM Affecting NX Bit Handling

CVE-2022-50224

What is CVE-2022-50224?

A vulnerability in the Linux kernel's KVM module arises from improper handling of the NX (No-eXecute) bit in the Shadow Page Table Entry (SPTE) during Nested Page Table (NPT) operations. Specifically, KVM was not validating the NX bit as expected when the NX huge page mitigation feature was enabled. This oversight could trigger warnings and potential system instability when reserved SPTE bits are set incorrectly. The issue is particularly notable because KVM requires NX support for Secure Virtual Machine (SVM) to function properly, posing risks in environments reliant on virtualization for performance and security.

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