esx: Avoid null dereference on error in esxDomainGetInfo

Add missing early exits and convert error logging to proper API level
error reporting.

Centralize cleanup code for the PerfQuerySpec object.

Reported by Eric Blake, detected by clang.

src/esx/esx_driver.c

@@ -2356,9 +2356,6 @@ esxDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info)
 
             if (esxVI_QueryPerf(priv->host, querySpec,
                                 &perfEntityMetricBaseList) < 0) {
-                querySpec->entity = NULL;
-                querySpec->metricId->instance = NULL;
-                querySpec->format = NULL;
                 goto cleanup;
             }
 
@@ -2371,16 +2368,20 @@ esxDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info)
                   esxVI_PerfEntityMetric_DynamicCast(perfEntityMetricBase);
 
                 if (perfEntityMetric == NULL) {
-                    VIR_ERROR(_("QueryPerf returned object with unexpected type '%s'"),
+                    ESX_ERROR(VIR_ERR_INTERNAL_ERROR,
+                              _("QueryPerf returned object with unexpected type '%s'"),
                               esxVI_Type_ToString(perfEntityMetricBase->_type));
+                    goto cleanup;
                 }
 
                 perfMetricIntSeries =
                   esxVI_PerfMetricIntSeries_DynamicCast(perfEntityMetric->value);
 
                 if (perfMetricIntSeries == NULL) {
-                    VIR_ERROR(_("QueryPerf returned object with unexpected type '%s'"),
+                    ESX_ERROR(VIR_ERR_INTERNAL_ERROR,
+                              _("QueryPerf returned object with unexpected type '%s'"),
                               esxVI_Type_ToString(perfEntityMetric->value->_type));
+                    goto cleanup;
                 }
 
                 for (; perfMetricIntSeries != NULL;
@@ -2395,10 +2396,6 @@ esxDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info)
                 }
             }
 
-            querySpec->entity = NULL;
-            querySpec->metricId->instance = NULL;
-            querySpec->format = NULL;
-
             VIR_DEBUG("usedCpuTimeCounterId %d END", priv->usedCpuTimeCounterId);
 
             /*
@@ -2411,6 +2408,19 @@ esxDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info)
     result = 0;
 
   cleanup:
+    /*
+     * Remove values owned by data structures to prevent them from being freed
+     * by the call to esxVI_PerfQuerySpec_Free().
+     */
+    if (querySpec != NULL) {
+        querySpec->entity = NULL;
+        querySpec->format = NULL;
+
+        if (querySpec->metricId != NULL) {
+            querySpec->metricId->instance = NULL;
+        }
+    }
+
     esxVI_String_Free(&propertyNameList);
     esxVI_ObjectContent_Free(&virtualMachine);
     esxVI_PerfMetricId_Free(&perfMetricIdList);