kernel: KVM: double fetch in nested_svm_vmrun can lead to unrestricted MSR access

A flaw was found in the Linux kernel. A KVM guest on AMD can launch a nested guest without the Intercept VMRUN control bit by exploiting a TOCTOU vulnerability in nestedsvmvmrun. A malicious guest could use this flaw to gain unrestricted access to host MSRs, possibly leading to guest-to-host esca...