From c788e693e678c83e094cc4e80f265014287ec1a3 Mon Sep 17 00:00:00 2001 From: Sreeharsha Ramanavarapu Date: Thu, 26 Mar 2015 07:40:35 +0530 Subject: Bug #20730155: BACKPORT BUG#19699237 TO 5.1 Backport from mysql-5.5 to mysql-5.1 Bug# 19699237: UNINITIALIZED VARIABLE IN ITEM_FIELD::STR_RESULT LEADS TO INCORRECT BEHAVIOR ISSUE: ------ When the following conditions are satisfied in a query, a server crash occurs: a) Two rows are compared using a NULL-safe equal-to operator. b) Each of these rows belong to different charsets. SOLUTION: --------- When one charset is converted to another for comparision, the constructor of "Item_func_conv_charset" is called. This will attempt to use the Item_cache if the string is a constant. This check succeeds because the "used_table_map" of the Item_cache class is never set to the correct value. Since it is mistakenly assumed to be a constant, it tries to fetch the relevant null value related fields which are yet to be initialized. This results in valgrind issues and wrong results. The fix is to update the "used_table_map" of "Item_cache". This will allow "Item_func_conv_charset" to realise that this is not a constant. --- sql/item.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/sql/item.h b/sql/item.h index 1c7cf7e6db5..c82d23b6d5a 100644 --- a/sql/item.h +++ b/sql/item.h @@ -1,4 +1,4 @@ -/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. +/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -3024,7 +3024,11 @@ public: collation.set(item->collation); unsigned_flag= item->unsigned_flag; if (item->type() == FIELD_ITEM) + { cached_field= ((Item_field *)item)->field; + if (cached_field->table) + used_table_map= cached_field->table->map; + } return 0; }; enum Type type() const { return CACHE_ITEM; } -- cgit v1.2.1