File 6569ad03-libxg-mem-leak-in-cpu-policy-get-set.patch of Package xen.33341

# Commit 1571ff7a987b88b20598a6d49910457f3b2c59f1
# Date 2023-12-01 10:53:07 +0100
# Author Alejandro Vallejo <alejandro.vallejo@cloud.com>
# Committer Jan Beulich <jbeulich@suse.com>
tools/xg: Fix potential memory leak in cpu policy getters/setters

They allocate two different hypercall buffers, but leak the first
allocation if the second one failed due to an early return that bypasses
cleanup.

Remove the early exit and go through _post() instead. Invoking _post() is
benign even if _pre() failed.

Fixes: 6b85e427098c ('x86/sysctl: Implement XEN_SYSCTL_get_cpu_policy')
Fixes: 60529dfeca14 ('x86/domctl: Implement XEN_DOMCTL_get_cpu_policy')
Fixes: 14ba07e6f816 ('x86/domctl: Implement XEN_DOMCTL_set_cpumsr_policy')
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>

--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -137,20 +137,20 @@ static int get_system_cpu_policy(xc_inte
     DECLARE_HYPERCALL_BOUNCE(msrs,
                              *nr_msrs * sizeof(*msrs),
                              XC_HYPERCALL_BUFFER_BOUNCE_OUT);
-    int ret;
+    int ret = -1;
 
-    if ( xc_hypercall_bounce_pre(xch, leaves) ||
-         xc_hypercall_bounce_pre(xch, msrs) )
-        return -1;
-
-    sysctl.cmd = XEN_SYSCTL_get_cpu_policy;
-    sysctl.u.cpu_policy.index = index;
-    sysctl.u.cpu_policy.nr_leaves = *nr_leaves;
-    set_xen_guest_handle(sysctl.u.cpu_policy.leaves, leaves);
-    sysctl.u.cpu_policy.nr_msrs = *nr_msrs;
-    set_xen_guest_handle(sysctl.u.cpu_policy.msrs, msrs);
+    if ( !xc_hypercall_bounce_pre(xch, leaves) &&
+         !xc_hypercall_bounce_pre(xch, msrs) )
+    {
+        sysctl.cmd = XEN_SYSCTL_get_cpu_policy;
+        sysctl.u.cpu_policy.index = index;
+        sysctl.u.cpu_policy.nr_leaves = *nr_leaves;
+        set_xen_guest_handle(sysctl.u.cpu_policy.leaves, leaves);
+        sysctl.u.cpu_policy.nr_msrs = *nr_msrs;
+        set_xen_guest_handle(sysctl.u.cpu_policy.msrs, msrs);
 
-    ret = do_sysctl(xch, &sysctl);
+        ret = do_sysctl(xch, &sysctl);
+    }
 
     xc_hypercall_bounce_post(xch, leaves);
     xc_hypercall_bounce_post(xch, msrs);
@@ -175,20 +175,20 @@ static int get_domain_cpu_policy(xc_inte
     DECLARE_HYPERCALL_BOUNCE(msrs,
                              *nr_msrs * sizeof(*msrs),
                              XC_HYPERCALL_BUFFER_BOUNCE_OUT);
-    int ret;
+    int ret = -1;
 
-    if ( xc_hypercall_bounce_pre(xch, leaves) ||
-         xc_hypercall_bounce_pre(xch, msrs) )
-        return -1;
-
-    domctl.cmd = XEN_DOMCTL_get_cpu_policy;
-    domctl.domain = domid;
-    domctl.u.cpu_policy.nr_leaves = *nr_leaves;
-    set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
-    domctl.u.cpu_policy.nr_msrs = *nr_msrs;
-    set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
+    if ( !xc_hypercall_bounce_pre(xch, leaves) &&
+         !xc_hypercall_bounce_pre(xch, msrs) )
+    {
+        domctl.cmd = XEN_DOMCTL_get_cpu_policy;
+        domctl.domain = domid;
+        domctl.u.cpu_policy.nr_leaves = *nr_leaves;
+        set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
+        domctl.u.cpu_policy.nr_msrs = *nr_msrs;
+        set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
 
-    ret = do_domctl(xch, &domctl);
+        ret = do_domctl(xch, &domctl);
+    }
 
     xc_hypercall_bounce_post(xch, leaves);
     xc_hypercall_bounce_post(xch, msrs);
@@ -215,32 +215,24 @@ int xc_set_domain_cpu_policy(xc_interfac
     DECLARE_HYPERCALL_BOUNCE(msrs,
                              nr_msrs * sizeof(*msrs),
                              XC_HYPERCALL_BUFFER_BOUNCE_IN);
-    int ret;
+    int ret = -1;
 
-    if ( err_leaf_p )
-        *err_leaf_p = -1;
-    if ( err_subleaf_p )
-        *err_subleaf_p = -1;
-    if ( err_msr_p )
-        *err_msr_p = -1;
-
-    if ( xc_hypercall_bounce_pre(xch, leaves) )
-        return -1;
-
-    if ( xc_hypercall_bounce_pre(xch, msrs) )
-        return -1;
-
-    domctl.cmd = XEN_DOMCTL_set_cpu_policy;
-    domctl.domain = domid;
-    domctl.u.cpu_policy.nr_leaves = nr_leaves;
-    set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
-    domctl.u.cpu_policy.nr_msrs = nr_msrs;
-    set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
     domctl.u.cpu_policy.err_leaf = -1;
     domctl.u.cpu_policy.err_subleaf = -1;
     domctl.u.cpu_policy.err_msr = -1;
 
-    ret = do_domctl(xch, &domctl);
+    if ( !xc_hypercall_bounce_pre(xch, leaves) &&
+         !xc_hypercall_bounce_pre(xch, msrs) )
+    {
+        domctl.cmd = XEN_DOMCTL_set_cpu_policy;
+        domctl.domain = domid;
+        domctl.u.cpu_policy.nr_leaves = nr_leaves;
+        set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
+        domctl.u.cpu_policy.nr_msrs = nr_msrs;
+        set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
+
+        ret = do_domctl(xch, &domctl);
+    }
 
     xc_hypercall_bounce_post(xch, leaves);
     xc_hypercall_bounce_post(xch, msrs);