From 4693f01f57406f86a26b7ccc605522dac6a9abb2 Mon Sep 17 00:00:00 2001
From: Eugene Kosov <claprix@yandex.ru>
Date: Wed, 5 Jul 2017 18:27:03 +0300
Subject: [PATCH] Fix warning discovered by ASAN
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Patch submitted by Eugene Kosov <claprix@yandex.ru>,
comments added by commiter.

Signed-off-by: Vicențiu Ciorbaru <vicentiu@mariadb.org>
---
 sql/sql_explain.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sql/sql_explain.cc b/sql/sql_explain.cc
index 6d208121e34..ac6bee05001 100644
--- a/sql/sql_explain.cc
+++ b/sql/sql_explain.cc
@@ -349,10 +349,13 @@ int print_explain_row(select_result_sink *result,
   item_list.push_back(new (mem_root) Item_string_sys(thd, jtype_str),
                       mem_root);
   
-  /* 'possible_keys' */
+  /* 'possible_keys'
+     The buffer must not be deallocated before we call send_data, otherwise
+     we may end up reading freed memory.
+  */
+  StringBuffer<64> possible_keys_buf;
   if (possible_keys && !possible_keys->is_empty())
   {
-    StringBuffer<64> possible_keys_buf;
     push_string_list(thd, &item_list, *possible_keys, &possible_keys_buf);
   }
   else