Common: cert util memory free fix

This is a bit of a style thing, as freeing a NULL pointer isn't
dangerous. Still, we hould only try to free the certificate name
if non-NULL, and then set it to NULL so it may not be accidentally
re-used if the code is later modified.

common/cert_util.c

@@ -579,7 +579,10 @@ void cert_fill_X509_store(X509_STORE *store, X509 **certs, size_t cert_count)
                             (name ? name : ""));
                 }
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
-                free(name);
+                if (NULL != name) {
+                    free(name);
+                    name = NULL;
+                }
 #endif
             }
         }
@@ -646,7 +649,10 @@ void cert_store_export_certs(X509_STORE *store, X509 *additional_ca_cert)
                         (name ? name : ""));
             }
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
-            free(name);
+            if (NULL != name) {
+                free(name);
+                name = NULL;
+            }
 #endif
         }
     } while (0);

common/mac/cert_util_mac.m

@@ -351,7 +351,10 @@ cl_error_t cert_store_load(X509 **trusted_certs, size_t trusted_cert_count)
                         mprintf("!Failed conversion of DER format to X.509\n");
                     }
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
-                    free(name);
+                    if (NULL != name) {
+                        free(name);
+                        name = NULL;
+                    }
 #endif
 
                     CFRelease(cert_data);