Linux Kernel Infinite Fault Loop Vulnerability in mshv GPA Intercept Handling

A vulnerability in the Linux kernel's Hyper-V lightweight virtualization feature (mshv) can lead to an infinite fault loop when a guest virtual machine accesses memory regions without the proper permissions. This issue arises because the function responsible for handling guest physical address intercepts attempts to remap pages for all faults on movable memory regions, regardless of the access type allowed. As a result, when a guest writes to a read-only area, the remap is successful but the region remains read-only, causing an immediate re-fault and trapping the virtual CPU in an endless loop. This vulnerability also presents a potential denial-of-service risk, as malicious guests could exploit the fault loops to drain host resources.

Impact

Exploitation of this vulnerability causes the virtual CPU to spin indefinitely, consuming host resources and potentially leading to a denial-of-service condition on the host.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been addressed. Instructions for downloading the patched version are available on the Linux kernel official website.