arch/powerpc/kvm/book3s_rtas.c in the Linux kernel through 5.13.5 on the powerpc platform allows KVM guest OS users to cause host OS memory corruption via rtas_args.nargs, aka CID-f62f3c20647e.
https://www.debian.org/security/2021/dsa-4978
https://security.netapp.com/advisory/ntap-20210917-0005/
https://lore.kernel.org/linuxppc-dev/87im0x1lqi.fsf%40mpe.ellerman.id.au/T/#u