Fix cf_option if parse_cf_option fail

Summary: Seems my previous fix missed one case. If the cf_parse_option fails, we may leave a dangling ptr. Changing the code a little bit to avoid this.

Reviewed By: lth

Differential Revision: D15880761

fbshipit-source-id: 84edc55

storage/rocksdb/ha_rocksdb.cc

@@ -13640,12 +13640,8 @@ static int rocksdb_validate_update_cf_options(
   int length;
   length = sizeof(buff);
   str = value->val_str(value, buff, &length);
-  // In some cases, str can point to buff in the stack.
-  // This can cause invalid memory access after validation is finished.
-  // To avoid this kind case, let's alway duplicate the str if str is not
-  // nullptr
-  *(const char **)save = (str == nullptr) ? nullptr : my_strdup(str, MYF(0));
 
+  *(const char **)save = nullptr;
   if (str == nullptr) {
     return HA_EXIT_SUCCESS;
   }
@@ -13658,11 +13654,18 @@ static int rocksdb_validate_update_cf_options(
     my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), "rocksdb_update_cf_options", str);
     return HA_EXIT_FAILURE;
   }
+
   // Loop through option_map and create missing column families
   for (Rdb_cf_options::Name_to_config_t::iterator it = option_map.begin();
        it != option_map.end(); ++it) {
     cf_manager.get_or_create_cf(rdb, it->first);
   }
+
+  // In some cases, str can point to buff in the stack.
+  // This can cause invalid memory access after validation is finished.
+  // To avoid this kind case, let's alway duplicate the str.
+  *(const char **)save = my_strdup(str, MYF(0));
+
   return HA_EXIT_SUCCESS;
 }