domctl/sysctl: don't leak hypervisor stack to toolstacks

This is XSA-132.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1200,7 +1200,7 @@ long arch_do_domctl(
     case XEN_DOMCTL_gettscinfo:
     {
         struct domain *d;
-        xen_guest_tsc_info_t info;
+        xen_guest_tsc_info_t info = { 0 };
 
         ret = -ESRCH;
         d = rcu_lock_domain_by_id(domctl->domain);
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -95,7 +95,7 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xe
     case XEN_SYSCTL_getdomaininfolist:
     { 
         struct domain *d;
-        struct xen_domctl_getdomaininfo info;
+        struct xen_domctl_getdomaininfo info = { 0 };
         u32 num_domains = 0;
 
         rcu_read_lock(&domlist_read_lock);