A flaw was found in KVM AMD Secure Encrypted Virtualization (SEV) in the Linux kernel. A KVM guest using SEV-ES or SEV-SNP with multiple vCPUs can trigger a double fetch race condition vulnerability and invoke the VMGEXIT handler recursively. If an attacker manages to call the handler multiple times, they can trigger a stack overflow and cause a denial of service or potentially guest-to-host escape in kernel configurations without stack guard pages (CONFIG_VMAP_STACK).

References

• https://nvd.nist.gov/vuln/detail/CVE-2023-4155
• https://access.redhat.com/security/cve/CVE-2023-4155
• https://bugzilla.redhat.com/show_bug.cgi?id=2213802