KVM: PPC: fix information leak to userland

Structure kvm_ppc_pvinfo is copied to userland with flags and
pad fields unitialized.  It leads to leaking of contents of
kernel stack memory.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/powerpc/kvm/powerpc.c

@@ -617,6 +617,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
 	switch (ioctl) {
 	case KVM_PPC_GET_PVINFO: {
 		struct kvm_ppc_pvinfo pvinfo;
+		memset(&pvinfo, 0, sizeof(pvinfo));
 		r = kvm_vm_ioctl_get_pvinfo(&pvinfo);
 		if (copy_to_user(argp, &pvinfo, sizeof(pvinfo))) {
 			r = -EFAULT;